Potato Production Regions Research Articles

Genetic Diversity and Pathogenicity of Phytophthora infestans Isolates on Four Solanum tuberosum (Potato) Cultivars in Nariño, Colombia

Phytophthora infestans remains a major threat to global potato production. This study focused on characterizing and assessing the pathogenicity of P. infestans isolates on detached potato leaves and in greenhouse trials across four cultivars. Seven isolates were obtained from high potato-producing regions in the department of Nariño, Colombia. The isolates were analyzed using 12 microsatellite markers to determine genetic distances. Two genetically distinct isolates showed markedly different pathogenicity on detached leaves: isolate P00921 caused complete infection by day five, whereas P00321 showed no symptoms. These two isolates (P00921 and P00321) selected for having the greatest genetic distance and highest pathogenicity among the seven analyzed were further tested in a greenhouse setup on four potato cultivars using a randomized block design. Disease progression was monitored over nine days. The results indicated significant variations in pathogenicity linked to genetic diversity among isolates. Notably, Capiro and Margarita cultivars were more prone to severe disease than Suprema and Única. These findings highlight the complex nature of host–pathogen interactions and suggest the need for tailored approaches in disease management and cultivar selection.

Antagonism and Synergism Characterize the Interactions between Four North American Potato Virus Y Strains

Potato virus Y (PVY) is one of the most important constraints to potato production worldwide. There is an increasing occurrence of recombinant PVY strains PVYNTN and PVYN-Wi and a decline in the incidence of the nonrecombinant PVYO. We hypothesized that this may be due to the ability of these recombinant strains to antagonize and/or outcompete PVYO in mixed infections. To determine this, we investigated interactions between PVYO and three recombinant PVY strains common in North America: PVYNTN, PVYN-Wi, and PVYN:O. Overall, our study showed that these interactions are tissue-dependent. Specifically, PVYNTN, the main causal agent of potato tuber necrotic ringspot disease (PTNRD), was found to be more adaptable than PVYO, especially in potato leaves due, at least in part, to the Ny gene that confers hypersensitive resistance (HR) to PVYO. Furthermore, PVYN-Wi was found to repress PVYO in potato tubers but act synergistically in potato leaves. The PVYO-induced foliage necrosis in cultivar ‘Ranger Russet’ was observed to be more severe in plants co-infected by PVYN-Wi and PVYN:O, respectively, resulting in plant death. Strikingly, this PVYO -induced necrosis was suppressed by PVYNTN in doubly infected plants. These interactions may, at least partially, explain the decreasing incidence of PVYO in United States potato production regions, especially given that many cultivars contain the Ny gene, which likely limits PVYO enabling PVYNTN and PVYN-Wi to outcompete. We also found that replication and cell-to-cell movement of these PVY strains in tubers at 4 °C was similar to levels at ambient temperature.

Understanding the Temporal Dynamics of Invasive Late Blight Populations in India for Improved Management Practices.

The microbial oomycete pathogen Phytophthora infestans causes severe epidemics of potato late blight in crops globally. Disease management benefits from an understanding of the diversity of pathogen populations. In this study, we explore the dynamics of P. infestans populations in the late blight-potato agro-ecosystem across the Indian subcontinent. Investigations of the macroecological observations at the field level and microbial ecological principles provided insights into future pathogen behavior. We use a comprehensive simple sequence repeat allele dataset to demonstrate that an invasive clonal lineage called EU_13_A2 has dominated populations over 14 years across India, Bangladesh, and Pakistan. Increasing levels of subclonal variation were tracked over time and space, and, for the first time, populations in Asia were also compared with the source populations from Europe. Within India, a regional pathogen population structure was observed with evidence for local migration, cross-border movement between surrounding countries, and introductions via imports. There was also evidence of genetic drift and between-season transmission of more strongly pathogenic subclones with a complete displacement of some subclonal types. The limited introduction of novel genotypes and the use of resistant potato cultivars could contribute to the dominance of the 13_A2 lineage. The insights will contribute to the management of the pathogen in these key global potato production regions.

First report of sweepoviruses infecting Ipomeas batatas L. cultivars and landraces in Trinidad.

Root crops, referred to as ground provisions in the Caribbean, are traditional staples in Trinidad. One widely consumed example is sweet potato (Ipomeas batatas L.). The crop is mainly produced by subsistence farming which together with imports from neighboring Caribbean countries meet domestic demand (Singh et al. 2008). The Central Experiment Station, situated in the eastern part of Trinidad, maintains a sweet potato germplasm collection comprising both imported and locally-sourced landraces for cultivar development and distribution of propagules. In May 2017 chlorosis and leaf curling symptoms, typically associated with sweepoviruses, were observed on imported cultivars, Centennial, Jewel, 86 BM 31, TIB 313, TIB 8 21 1, and S128, and the landraces, Kick Up Jenny, John, and Carrot. Leaf samples from these nine symptomatic plants were collected for analysis, along with samples from the asymptomatic landrace, Chickenfoot. Total nucleic acids were extracted (Sharma et al. 2008) and the samples were assayed by PCR using degenerate primers SPG1 and SPG2 (Li et al. 2004) that target the replication associated protein gene (ORF C1), a highly conserved region of sweepoviruses. Amplicons of 912-bp were obtained from two of the nine symptomatic plants (TIB 8 21 1, Kick Up Jenny), but not from the asymptomatic Chickenfoot. The same samples were assayed by PCR amplification using primers SpvF and SpvR (Avelar 2015) which are specific to a highly conserved 632-bp region of the coat protein gene (ORF V1) of sweet potato leaf curl virus (SPLCV). All 10 samples tested positive for SPLCV, including the asymptomatic landrace, Chickenfoot. The ORF V1 PCR products from three of the 10 samples, namely Chickenfoot, TIB 8 21 1, and Kick Up Jenny, were cloned and sequenced (two clones per sample). Comparison of the sequences (GenBank accession nos. OR882007 [Chickenfoot], OR913125 [TIB 8 21 1] and OR913126 [Kick Up Jenny]) identified up to 4% nt sequence variability between samples. In BLASTn analysis, they were most closely related to the SPLCV isolate China:Sichuan (GenBank accession no. KJ013557), sharing 94 to 98% nt identity. Total nucleic extracts from one representative sample (TIB 8 21 1) was used as template for rolling circle amplification (RCA, TempliPhi Amplification Kit, GE Healthcare Life Sciences, Piscataway, NJ, USA). Digestion of the RCA product with StuI (Thermo Scientific, MA, USA) yielded ~2.8 kb DNA fragments indicative of monomeric full length genomes. Digested fragments were cloned, completely sequenced and deposited in GenBank under the accession nos. OR866202 (2,821 nts) and OR866203 (2,828 nts). Two species of sweepoviruses were detected. In BLASTn analysis, OR866202 showed 95% nt identity with sweet potato golden vein associated virus (SPGVaV) US:MS:1B-3 (GenBank accession no. HQ333143.1) which is a recombinant virus comprised of SPLCV and sweet potato leaf curl Georgia virus (SPLCGV) (Zhang and Ling 2011) and in BLASTx analysis OR866202 was most similar (92-99%) to SPLCV isolates from Brazil (GenBank accession nos. ACI23475.1, AGW16179.1, ACY79479.1), Peru (GenBank accession no. ACY79466.1) and China (GenBank accession nos. ACY79439.1). OR866203 shared 96% nt identity with SPLCV China:Henan25(8):2012 (GenBank accession no. KF040465.1) in BLASTn analysis and BLASTx analysis revealed ≥ 94% aa sequence identity with SPLCV from Brazil (GenBank accession nos. ACI23475.1, AGW16179.1, ADZ96559.1), Peru (GenBank accession no. ACY79479.1), China (GenBank accession no. ACY79466.1). and Spain (GenBank accession no. QWQ56365.1). Both Trinidad isolates also showed 90-96% nt identity with SPLCV from Korea (GenBank accession no.s KT992061.1, KT992064.1, unpublished). This is the first detection of sweepoviruses in Trinidad. SPGVaV has been reported in Brazil, the United States and Korea (Kil et al. 2014), while SPLCV has been described in other Caribbean islands, including Cuba, Jamaica, Puerto Rico, St. Vincent (Cuellar et al. 2015), and Barbados (Alleyne et al. 2019), as well as several countries in South America. Although Koch's postulates were not completed, our findings suggest that sweet potato crops in Trinidad harbor sweepoviruses, notwithstanding efforts to distribute pathogen-free materials and, in some instances, the apparent absence of visible symptoms on infected plants. Further studies on the management and impact of these viruses are necessary, including their prevalence in the sweet potato production regions of Trinidad.

Host-status of sixteen crops used in potato-based crop rotation systems against Meloidogyne javanica in South Africa

Root-knot nematodes (Meloidogyne species) are the most important group of plant nematodes in potato-producing regions of South Africa. Prior to the withdrawal of synthetic chemical fumigant nematicides from the agrochemical markets, Meloidogyne species were viewed as a minor pest in potato-producing regions. Currently, it has been established that all potato cultivars are host to Meloidogyne species, with the preferred management option of the genus being the use of resistant crops. However, the host status of most crops used in potato-based crop rotations intended to manage nematode population densities of the genus had not been established. Globally, M. incognita is viewed as being more aggressive than M. javanica, whereas in South Africa the opposite is true. Therefore, the objective of the study was to determine whether the reproduction potential (RP) values of M. javanica on 16 crops used in potato crop rotation systems would be below unity. The experiment was conducted under greenhouse conditions at the University of Limpopo during autumn (February-April) 2022 and validated in spring (September-November) of the same year in South Africa. Treatments (16 crops) were laid out in a randomized complete block design, with six replications. The crops were inoculated with 250 eggs + second-stage juveniles (J2). At 56 days after inoculation, nematodes variables were collected and expressed as RP, which demonstrated that there were similarities and differences in RP of the 16 crops to infection by M. javanica, but with the values being below one in white maluti oats, tillage radish, forage sorghum, and jap radish. In conclusion, the four crops with RP values below one could be used in a potato-crop rotation system intended to manage the population densities of M. javanica.

Advancements in Spongospora subterranea: Current Knowledge, Management Strategies, and Research Gaps

AbstractPowdery scab was first documented on locally sampled potatoes in Braunschweig, Germany. A hundred and eighty-one years later, the disease has spread globally to most potato-producing regions and is considered one of the most destructive potato diseases. Here, we review the knowledge of powdery scab and causative agent, Spongospora subterranea f. sp. subterranea, highlighting research progress made in the last 7 years. Much work has been done to increase our understanding of how zoospores respond to their environment (e.g. root exudates, Ca2C signalling, and root metabolites) and the management of the disease by chemical and biological control agents. Recent research has utilised omics approaches — metabolomics, proteomics, and genomics — to gain a deeper understanding of the host–pathogen interaction in the powdery scab pathosystem. The management of powdery scab can be achieved using a combination of strategies that include (1) the planting of resistant potato varieties, (2) strategies that avoid disease (field selection and planting date), those that (3) reduce initial soil inoculum (crop rotation, organic soil amendments, and soil fumigation), and (4) in-crop approaches (soil chemical applications, biological control, proper field, fertility, crop, irrigation management, and crop sanitation). Lastly, we discuss research gaps for future research, including the disease’s interaction with other potato diseases that may be impacting disease expression and opportunities to enable a greater understanding of the powdery scab pathosystem.

Common vetch intercropping with reduced irrigation ensures potato production by optimizing microbial interactions

ContextInner Mongolia is a major potato-producing region in China. Soil quality degradation and water deficiency limit the local potato industry. Legumes can improve soil fertility and moisture, an intercropping system of common vetch with reduced irrigation was established to achieve potato production and soil restoration considering the annual cultivation system in Inner Mongolia. MethodsA two-factor field experiment design was then used. The first factor was the plant pattern with two levels, namely, potato monoculture (M) and potato-common vetch intercropping (I). The second factor was the irrigation amount with two levels, namely, reduced irrigation (R) and conventional irrigation (C). qPCR and high-throughput sequencing were used to determine soil microbial abundances and communities. ResultsAfter two years of field experiments, reduced irrigation significantly (p < 0.05) reduced the aboveground biomass of common vetch by 36.06%. Reduced irrigation reduced potato quality by 11.87–31.37%, but intercropping compensated for this shortcoming. Compared with potato monoculture, common vetch incorporation into the soil significantly (p < 0.05) increased the soil water content and available nutrients, by 10.98% and 13.75–55.08%, respectively. Although intercropping significantly (p < 0.05) increased the abundance of bacteria and fungi, it did not change (p > 0.05) the abundance of protists. The Beta-diversity of fungi and protists were also affected (p < 0.05) by intercropping and irrigation, whereas the bacterial Beta-diversity did not change (p > 0.05). The network complexity and connection between protists and fungi under the IR treatment were higher than those under the MC treatment. Soil available nutrients and network topological indices such as edges linking protists to fungi were significantly positively correlated with potato production. Conclusions or significanceCommon vetch intercropping with reduced irrigation could ensure potato tuber yield and quality, and improve soil quality, our research provides a sustainable cropping system suitable for potato cultivation in Inner Mongolia.

First report of Phytophthora infestans lineage EU23 causing potato and tomato late blight in South Africa.

In South Africa, potato (Solanum tuberosum) late blight epidemics from 1996 to 2007 were caused by Phytophthora infestans clonal lineage US-1 (McLeod et al. 2001; Pule et al. 2013). Similarly, surveys on tomatoes in the mid-1990s only identified the US-1 clonal lineage in South Africa (McLeod et al., 2001). On potatoes, populations from the Southern Cape and Western Cape regions consisted of persistent mefenoxam-resistant populations (McLeod et al. 2001; Pule et al. 2013). Limited mefenoxam (R-enantiomer of metalaxyl) screening in 2021 in the Western Cape showed that potato isolates were sensitive, which prompted our study. Potato late blight samples were collected in 13 potato fields in the 2021 to 2023 seasons in the Western Cape (n = 4), Free State (n = 7), Limpopo (n = 1) and Kwazulu-Natal (n = 1) Provinces, and one tomato sample in 2022 in the Limpopo Province. Fourteen samples, one per field, were simple sequence repeat (SSR) genotyped for 12 loci (Li et al. 2013) using as DNA template, FTA cards, or genomic DNA extracted from cultures. P. infestans isolations from lesions and DNA culture extractions were conducted as previously described (Pule et al. 2013). SSR genotyping revealed that all 14 P. infestans samples belonged to clonal lineage EU_23_A1 (EU23), which has a phenotype (A1 and metalaxyl sensitive) and SSR genotype matching the US-23 lineage (Saville et al., 2021). As expected, minor polymorphisms were detected among the samples at loci Pi02, G11, D13 and SSR4. Mefenoxam sensitivity testing of seven potato isolates from the Free State (n = 3) and Western Cape (n = 4), and one tomato isolate was conducted as previously described (Mcleod et al. 2001). All isolates were sensitive to mefenoxam since no infection and sporulation occurred at 3 µg/ml. This was expected since EU23 has been reported as mefenoxam sensitive in other countries (Kawchuk et al., 2011; McGrath et al., 2015). Replacement of the US-1 clonal lineage by EU23 suggests that the latter lineage is more aggressive or fit than US-1, but this must be verified especially on potatoes. On tomatoes, on the other hand, EU23 is known as a highly aggressive lineage (Kawchuk et al., 2011; McGrath et al., 2015; Saville et al., 2021). Therefore, population displacements may have first occurred on tomatoes from where the lineage spread to potatoes. In the Cape coastal potato production regions, population displacement may have been supported by the withdrawal of mefenoxam/metalaxyl from the region since 1996 because the EU23 lineage is mefenoxam sensitive, as opposed to the previously prevailing US-1 mefenoxam-resistant lineage. More severe potato late blight epidemics has not been observed in recent years in South Africa. However, tomato late blight has increased and is more prevalent in the Limpopo province. The source of the introduction of EU23 into South Africa is unknown. Only test-tube plants and/or greenhouse tubers may be imported into South Africa since 1997. Therefore, the illegal importation of planting material may have introduced the new genotype. Whether this could have occurred from neighbouring African countries is unknown since P. infestans genotyping has not been conducted in these countries. In Africa, EU23 has been reported in northern African countries (Tunisia, Algeria and Egypt) (Saville et al., 2021; El-Ganainy et al., 2023). Mefenoxam and metalaxyl applications will likely be effective again in the Western Cape, but more samples will have to be tested to confirm this. This will provide growers with a more cost-effective fungicide (metalaxyl) since alternative actives with comparable systemic and curative activity are more expensive.

Regional-Scale Virtual Nitrogen, Phosphorus, and Potassium Factors of Potato Production in China

Improving yield in potato production with minimal environmental impact is of great significance for China’s potato staple food policy. Previous research has been limited by the absence of regional-scale parameters to evaluate the environmental costs of regional potato production. To address this gap, we utilized the input–output analysis method to offer a thorough estimation of nitrogen (N), phosphorus (P), and potassium (K) inputs and outputs in the potato production stage at a regional scale, leveraging a meta-analysis dataset from plenty of the literature. On this basis, we calculated the virtual N, P, and K factors (VNFs, VPFs, and VKFs) for different potato production regions, under both conventional and optimal management practices. China’s potato production suffered from excessive N and P inputs, while K inputs remained insufficient. Significant spatial heterogeneities were observed for the VNFs, VPFs, and VKFs across different potato production regions. Northeast China and northwest China emerged as the most suitable potato cultivation regions because they demonstrated high potato yields with relatively low inputs and, consequently, lower VNFs and VPFs. Southwest China was the most vital region where targeted efforts could lead to reducing VNF and VPF, thus significantly mitigating environmental N and P losses. In addition to reducing fertilizer inputs, site-specific and whole optimization measures are proposed to lower the environmental costs and promote the sustainable development of potato production.

Brassica Cover Crops and Natural Spongospora subterranea Infestation of Peat-Based Potting Mix May Increase Powdery Scab Risk on Potato.

Spongospora subterranea is a soilborne plasmodiophorid that causes powdery scab and root gall formation in potato. In this study, 18 cover crops suitable for use in dry, high-altitude potato production regions were assessed in potting mix trials to determine whether these cover crops altered S. subterranea population levels. Although S. subterranea appeared to invade roots of all plant species tested, the pathogen was unable to complete its life cycle on 11 of 18 cover crops based on postharvest qPCR and microscopy results. Buckwheat, legumes, and scarlet barley do not appear to support pathogen replication, but the pathogen may be able to complete its life cycle in some mustards. High variability occurred in the experiments and part of this may be due to the natural infestations of peat-based potting mix with S. subterranea. A tomato bioassay was used to confirm that commercial sources of peat-based potting mix were infested with S. subterranea. Dry heat and autoclaving were tested as sanitation methods and multiple rounds of autoclaving were required to reduce viable S. subterranea in potting mix. A second cover crop experiment with autoclaved potting mix was conducted and it confirmed that buckwheat, legumes, and barley do not support S. subterranea replication but that some brassica crops may be hosts of this pathogen. The results suggest that buckwheat, legumes, and barley pose the least risk as cover crops in S. subterranea infested fields and show that peat-based potting mix should not be used in seed potato production.

How to Break the Bottleneck of Potato Production Sustainable Growth—A Survey from Potato Main Producing Areas in China

China is the world’s largest potato producer, and the potato’s role in ensuring food security and rural development is irreplaceable. Therefore, how to achieve sustainable growth in potato production has attracted widespread attention from academia. However, few existing studies have analyzed how to achieve sustainable growth in main potato-producing areas based on farmers’ micro perspectives in terms of both technical efficiency and output elasticity of input factor. This paper investigates the output elasticities of input factors, technical efficiency, and its influencing factors among 398 potato farmers from China’s main potato-producing regions in 2021 to fill this knowledge gap. The stochastic frontier production is applied to calculate the technical efficiency and elasticities of input factors in main potato-producing areas. The Tobit model is utilized to analyze influencing factors of technical efficiency. Our findings indicate that the technical efficiency of the main potato production regions is 0.67, with an efficiency loss of 0.33. And, the output elasticity of land input and labor input is negative, and the output elasticity of capital input is positive. Moreover, the factors that affect the technical efficiency in main potato-producing areas include age, whether to be a village leader, income from other crops, labor input, potato price, and disaster impact. Our findings suggest that the agricultural authorities should strengthen the cultivation of potato producers, control the scale of potato production, and optimize the allocation of input factors.

Temporal and inter-farm variability of economic and environmental farm performance: A resilience perspective on potato producing regions in the Netherlands

In the context of resilience and sustainability of farming systems it is important to study the trade-offs and synergies between economic and environmental variables. In this study, we selected food production, economic and environmental performance indicators of farms in three potato producing regions in the Netherlands: Flevoland, Zeeland and Veenkoloniën. We studied the period 2006 to 2019 using farm accountancy data. We used threshold regressions to determine gradual development and year-to-year variation of those indicators. Subsequently we applied a sparse Partial Least Square (sPLS) regression to study the response of performance, gradual development and year-to-year variation under different conditions regarding weather, market and farm structure. sPLS-model performance was at best moderate. Best model performance was attained for Veenkoloniën, a region with relatively little inter-farm variability and relatively stable economic prices. Model results were very sensitive to the selection of response variables. We found that food production, economic and environmental performance levels and gradual developments were primarily determined by input intensity levels. How these performance levels were determined by input intensity, i.e. positively or negatively, differed per case study. Year-to-year variability was determined by average yearly weather conditions and weather extremes. Overall, we conclude that the method applied to the data we had available mostly provided insights that confirm existing knowledge at case study level. sPLS can be seen as a filter and projector of high-dimensional data that accentuates patterns in the data. In the context of resilience of farms, while using a relatively small dataset, the applicability of our methodology seems limited to a rather homogeneous farm population in a stable economic environment. Researchers intending to apply this method to (arable) farming systems should be well aware of the influence they can have on the results through their selection of response variables.

Impacts of two years of autumn cover crops in northwestern Washington on winter annual weed populations

AbstractCover cropping is a suggested soil conservation practice widely investigated in cropping systems. Cover crops suppress weeds and often are part of an integrated weed management plan that could lead to reduced herbicide use and possibly reduce the weed seedbank. Winter brassica cover crops are popular in the eastern Washington potato (Solanum tuberosum L.) production region, but in western Washington, the production of brassica seed crops presents disease issues along with the risk of cross-pollination, which limits the use of brassica cover crops. Research for this article was conducted in two trials from 2018 to 2020 and 2019 to 2021in Mount Vernon, Washington, to identify winter cover crops compatible with regional restrictions and climatic challenges in western Washington cropping systems. Treatments including a no-cover control, eight single species (including brassicas, grasses, and legumes), and a grass–legume mixture were investigated. Cover crop and weed biomass production were measured, and percent ground cover for cover crops and weeds by species was estimated. Cover crop biomass and weed suppression varied by year due to variable environments, but annual ryegrass (Lolium multiflorum Lam.) and the mixture were most consistent in producing large amounts of biomass and reducing weed biomass and cover in all years. The variability of percent weed cover response to environment was ameliorated when weed cover was normalized within each year’s control.

First report of Alternaria alternariacida causing potato leaf blight in the Far East, Russia.

Early blight of potato (Solanum tuberosum) is caused by Alternaria species and occurs annually in major potato producing regions of Russia. Diseased potato leaves displaying early blight symptoms were collected in July 2016 from a commercial field in Primorsky Krai, Russia (43.8242° N, 131.6219° E). The disease incidence was 30 to 40%. The initial symptoms appeared as typical early blight symptoms with a dark brown margin and diffused chlorosis on the leaf blade. Symptomatic leaves from different plants were randomly collected to isolate axenic cultures of the causal agents. Infected leaves were placed in wet chambers (moist filter papers in Petri dishes), and incubated at 25°C, 16 h/8 h dark/light photoperiod for 2-4 d. Single conidia were transferred to potato dextrose agar (PDA, Crous et al. 2009) in Petri dishes and incubated at 25°C for 7 d in the dark. Colonies were white-olivaceous, reverse side - olivaceous. Isolates were transferred onto potato carrot agar (PCA, Crous et al. 2009) and incubated at 22°C under a 16 h/8 h dark/light photoperiod for 7 d to stimulate sporulation. Most isolates (85%) were identified as A. protenta according to the morphological characteristics and molecular data, although one isolate showed sporulation that was somewhat atypical, having a smaller (especially narrower or more slender) conidia. Conidiophores were long, erect, and 65 to 100 µm × 5 to 6 µm in size. Conidia were solitary, long-ovoid in body with six to eight transverse septa, and 85 to 100 µm× 6 to 10 µm in size. Conidial beaks were filamentous, 110 to 200 µm × 2 to 5 µm in size. Genomic DNA was extracted from cultured isolates using the CTAB-chloroform extraction method (Griffith & Shaw 1998), and five gene regions including the internal transcribed spacer (ITS) region, translation elongation factor 1-alpha (tef1), RNA polymerase second largest subunit (rpb2), Alternaria major allergen (Alt a 1) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes were amplified with the primer pairs ITS1/ITS4, EF1-728F/EF1-986R, RPB2-5F2/FRPB2-7cR, Alt-for/Alt-rev, and gpd1/gpd2 respectively (Woudenberg et al. 2014). PCR products were Sanger sequenced. All sequences for isolate A16PrPL21 were identical to isolate CBS 105.51; (accession nos.: ITS, KJ718105; tef1, KJ718454; rpb2, KJ718279; Alt a 1, KJ718625; gpd KJ717959) of A. alternariacida Woudenb. & Crous. ITS, tef1, rpb2, Alt a 1 and gpd sequences were deposited in GenBank under the accessions OM348531, MN580518, MN580529, MN562258 and MN544404 respectively. Based on morphological and molecular data, the isolate was identified as Alternaria alternariacida Woudenb. & Crous. A. alternariacida is closely related to A. silybi, which is also found in the Far East (Woudenberg et al. 2014). Phylogenetic distances between these strains are based on differences at the ITS, TEF1 and Alt a 1 gene regions. A pathogenicity test was carried out with isolate A16PrPL21 on nine 5-week-old healthy potato plants (cv. Nevsky) grown in a greenhouse at 23 ± 2 °C. Seed tubers were grown in the greenhouse to obtain the seedlings. Inoculation was performed by spraying a conidial suspension (105 spores/ml) prepared from 10-day-old A. alternariacida culture grown on PCA at 23° C with a 12-h photoperiod. Nine negative control plants were treated with sterile distilled water. The inoculated plants were then maintained in a greenhouse at 25 °C with high humidity and 12-h light period. All test plants were covered with plastic bags for 24 h to maintain high relative humidity and incubated at 24 to 28°C. Leaf spot symptoms, brown lesions with chlorotic halos, similar to those previously observed in naturally infected plants, appeared 5 d post inoculation for all inoculated plants. After 7 d, the spots reached 18 to 25 mm in size. The symptoms were similar to the original symptoms that occurred in the field. Negative control leaves were symptomless. Koch's postulates were fulfilled by reisolating the pathogen from inoculated leaves and identified as A. alternaricida by rpb2 gene sequence and morphological characteristics. To our knowledge, this is the first report of disease caused by A. alternaricida on potato plants. Early blight, caused by large-spored Alternaria, is a widespread disease on potato. A. alternaricida is among a group of species that cause early blight, according to current research. Studies of the Alternaria species' biology and analyses of their distribution are important for improving potato protection from early blight.

Synergizing potato productivity and environmental performance with Nutrient Expert recommendation approach in northern China

Lack of evidence-based fertilizer recommendation has resulted in low productivity and nutrient use efficiency as well as nitrogen (N) pollution for potato in northern China. An innovative nutrient recommendation approach, Nutrient Expert (NE), has been developed for potato through adoption of 4R (applying the right nutrient source at the right rate, time, and place) nutrient stewardship technologies. However, large-scale evaluation of NE on improving potato productivity while minimizing environmental risks are not yet available. Here, we compared the performance of NE with farmers' practice (FP) and soil test (ST) based fertilizer recommendations in 38 potato farm fields in five provinces of China from 2017 to 2020. Compared to FP, NE significantly increased potato yield by 7% with 21% less N input, reduced N balance and N loss by 48% and 31%, and improved nutrient use efficiencies. Compared to ST, NE significantly reduced N input by 19 kg ha−1 without yield and profit losses, and decreased N balance and N losses by 27% and 13%, respectively. Based on a linear relationship between N balance and N application rate, the N application thresholds of 179–191 kg ha−1 were obtained to increase tuber yield and minimize N losses. The NE based N recommendation rate (182 kg ha−1) was within the range of N application thresholds, indicating the synergistic effect of NE on productivity and environmental performance. The NE tool could potentially be expanded to help achieve synergistic yield and environmental improvements in other potato production regions.

Identification of symptoms related to potato Verticillium wilt from UAV-based multispectral imagery using an ensemble of gradient boosting machines

Potato Verticillium wilt is a harmful and widespread disease which causes losses between 20% and 50% of crop production in Colombia. Diagnostics of Verticillium wilt in potato crops is challenging due that the known symptoms are often associated with other diseases. While recent studies have explored the potential of high spatial resolution imagery for detection of diseases and physiological disorders in potato crops, results are not-conclusive yet. Thus, to contribute to improving identification of Verticillium wilt symptoms, we evaluate a machine learning method to classify disease severity from multidate UAV-based multispectral images. It uses an ensemble of gradient boosting machines (GBMs) to differentiate, at grid level, six levels of Verticillim wilt disease severity. The proposed method was tested in a commercial potato crop in Cundinamarca, one of the top potato production regions in Colombia, using multispectral images acquired in four different field campaigns conducted between 99 and 141 days after planting. Accuracy assessment of results indicates that classification of severity levels of Verticillium wilt infection was satisfactory with F1 scores of 82% for the training dataset and 84% for the testing dataset. This study results shows both potential and challenges of using machine learning ensemble methods for identification of Verticillium wilt symptoms in potato crops from high spatial resolution multispectral images.

First detection of the potato cyst nematode (Globodera rostochiensis) in a major potato production region of China.

The potato cyst nematodes (PCN) Globodera rostochiensis and Globodera pallida are the very important quarantine nematode pests of potato [Stone 1973]. Both species cause serious potato tuber yield losses. These species are subjected to strict quarantine regulations in many countries (EPPO 2017). G. rostochiensis was detected in Sichuan and Yunnan province, China in 2022 (Jiang et al. 2022). A survey for cyst nematodes in potato fields was conducted in Guizhou Province from 2018 to 2020. A total of 200 samples, including roots and soil, were collected from 40 potato fields in Hezhang (N27 06.145, E104 39.153) and Weining (N26 50.541, E104 09.885) counties in Guizhou Province, China. The Cobb decanting and sieving method was used to isolate cysts and J2s from the soil samples (Southey 1986). The potato roots were stained with acid fusion to observe cyst development. Morphological and molecular analyses indicated that 27 (13.5%) of the samples contained G. rostochiensis. The cyst density ranged between 1-85 cysts per 100 cm3 of soil and a mean density was 15 cysts per 100 cm3 soil. The smoothly rounded cysts were in brown and golden color, and the terminal cone was absent and circumfenestrate. The key morphometrics of cysts (n=20) were 695 ± 26 (685-757) μm in length excluding neck and 690 ± 30 (668 to769) μm in width; the number of cuticular ridges between anus and vulval fenestra was 16.3 ±2.1 (14 to 18); fenestral length was 15.1 ± 2.1 μm (13.18 to 19.27); distance from anus to the edge of fenestra was 61.12 ± 8.9 (49.22 to76.27) μm; and Granek's ratio was 4.54 ± 0.8 (3.97-5.26). The key morphometrics of J2 (n = 20): 468.0 ± 20.1 (427 to - 521) μm in body length, 20.58 ± 0.7 (20.2 to 21.8) μm in stylet length, 43.9 ± 5.6 (40.3 to 53.9) μm in tail length, and 23.1 ± 1.8 (21.77 to 25.32) μm in hyaline region length. The cyst and J2 morphologies were consistent with those of G. rostochiensis (Subbotin et al. 2010, EPPO 2017). Genomic DNA was isolated from cysts (n=20). DNA extraction was performed in a volume of 20 μl containing 3 μl 10× PCR buffer, 3 μl Proteinase K (600 μg μl-1), 14 μl distilled water and a single cyst was added and ground in an ice bath as described by Ou et al. (2008). The internal transcribed spacer (ITS) regions were amplified using the universal primers: rDNA1 (5'-TTGATTACGTCCCTGCCCTTT-3') and rDNA2 (5'-TTTCACTCGCCGTTACTAAGG-3') (Fleming 1998 ), and the 28S rDNA-D2/D3 regions were amplified using the primers: D2A (5´-ACAAGTACCGTGAGGGAAAGTTG-3´) and D3B (5´-TCGGAAGGAACCAGCTACTA-3´) (Subbotin et al. 2006). After the brackets at the beginning and end of the sequences were closed-up, the ITS rDNA sequences (GenBank Accession No. MZ042367 and MZ042368) showed 99.66% - 99.92% identity to G. rostochiensis sequences available in GenBank (FJ212166.1, GQ294513, FJ212164.1 and KJ409617.1). Sequences from the 28S region (GenBank Accession No. MZ057597 and MZ057598) were 99.23% - 99.74% similar to those of G. rostochiensis isolate from Slovakia (KJ409625.1), Italy (KJ409631.1) and United Kingdom (KJ409633.1). We used species specific primers ITS5（5'-GGAAGTAAAAGTCGTAACAAGG-3'）and PITSr3 (5'AGCGCAGACATGCCGCAA-3') to amplify the product (Bulman & Marshall 1997; EPPO 2017). A single 434bp fragment was obtained from Hezhang and Weining populations. A host test for the Hezhang and Weining populations were performed by inoculating 1,000 eggs per plant of varieties Qingshu 9, Huize 2 and Hezuo 88 grown in the pots containing 800 cm3 of sterilized soil (soil: sand ratio was 3:1), and four replications were tested in greenhouse under 16 h light, 22°C in the day and 8 h dark in the night. At 90 days post inoculation, 32.6 ± 7, 31.2 ± 8, and 29.5 ± 8 females and cysts were extracted from the infected roots and soils of the varieties Qingshu 9, Huize 2 and Hezuo 88, respectively. No females and cysts were observed on the control plants. The trial indicated that potato cultivars Qingshu 9, Huize 2 and Hezuo 88 are hosts for the Hezhang and Weining populations of Globodera rostochiensis. To the best of our knowledge, this is the first detection of potato cyst nematode Globodera rostochiensis in Guizhou Province, China.

Optimizing planting dates and cultivars can enhance China's potato yield under 1.5 °C and 2.0 °C global warming

Rising temperatures and varying precipitation patterns pose huge challenges to the global potato supply. Understanding the adaptation potential of potato to climate change is urgently needed to help develop effective measures for future agriculture and food security. In this study, we evaluated future potato yield changes under 1.5 °C and 2.0 °C warming scenarios, and explored potential adaptation strategies by optimizing planting dates (PD) and cultivars across China's potato production regions. Compared with the baseline period (1986–2015), potato yields would increase in North single (NS) and Central double (CD) cropping system zones, but would decrease in South winter (SW) and Southwest mixed (SWM) cropping system zones under the 1.5 °C warming scenario without considering adaptation measures. Under the 2.0 °C warming scenario, potato yield would increase across China's potato planting zones except for SWM. Adjusting PD would be more effective for increasing rainfed potato yield across China than changing cultivars under the two warming scenarios. Overall, late PD coupled with a late-maturing cultivar would be the optimal selection for rainfed potato production. For irrigated potato, adjusting PD would be more effective than changing cultivars in NS and SW, but the opposite would be true in CD. The optimization of a single measure would have little impact on yield in SWM. The optimum PD would be early PD in NS and late PD in SW and SWM. The optimum cultivar would be late-maturing in NS, CD, and SWM, and middle-maturing in SW. Under the optimal combination, rainfed and irrigated potato yield would increase by 3.4–44.2% and 2.6–49.3%, respectively, under the 1.5 °C warming scenario, and would increase by 7.1–51.6% and 8.5–65.2%, respectively, under the 2.0 °C warming scenario. Our study results provide valuable information for policymakers and stakeholders involved in potato production to aid in planning agricultural strategies to safeguard potato production.

Modeling Potential production and yield gap of potato using modelling and GIS approaches

Understanding yield potential (Yp) and yield gap (Yg) in current intensive potato (solanum tuberosum L.) production is essential to meet future food demand with the limited resources. Evaluating yield gap is a strong approach to estimate maximum production potential when all factors are in the best condition. A complete estimation of yield gap and potential yield across all major potato producing regions in Iran is lacking. The global yield gap atlas (GYGA) protocol was used to estimate potential yield of potato in Iran. This protocol is based on the climatic zones (CZs) and the reference weather stations (RWS) buffer zones, soil types in each buffer zone. Thirty-five RWS buffer zones in potato producing regions were selected, and total potato area in the RWS buffer zones covered 83% of the whole potato harvest area. According to the results, the average Yp was 67.3 t ha–1 and actual yield (Ya) was 30 t ha–1. Therefore, the average tuber yield gap was 37.3 t ha–1. These results indicate that the Potato producers achieved 45% of the potential yield in Iran. Iranian farmers produced 5 million tons of potato from about 164,000 ha. If they can obtain only 80% of Yp (53.8 t ha–1), amount of potato production will be 8.8 million tones. As result, they can produce 5.2 million tons tuber yield of potato in 97,000 ha cultivation area. Thus, with closing yield gap and increasing potato production, it is possible to decrease potato lands.

Molecular characterization of internal transcribed spacer (ITS) of ribosomal RNA gene, haplotypes and pathogenicity of potato rot nematode Ditylenchus destructor in China

Potato rot nematode Ditylenchus destructor is one of the most damaging pests in potato-producing regions and causes severe yield losses worldwide. However, D. destructor has been rarely reported in potato crops in China. We collected 542 samples from 17 Chinese provinces during 2016–2020 for the detection of D. destructor using species-specific primers and universal primers targeting ribosomal internal transcribed spacer (ITS) or 28S ribosomal RNA (rRNA) sequences. D. destructor was detected in 14.94% of total samples, primarily in Inner Mongolia Autonomous Region (43 sites), Jilin Province (12 sites), and Shaanxi Province (9 sites). The nematode was for the first time detected in Guizhou Province and Ningxia Hui Autonomous Region. Phylogenetic analysis of 33 ITS sequences along with the prediction of the secondary structure of the helix H9 of ITS1 sequences revealed that haplotypes A, B, and C accounted for 6.06%, 9.09%, and 69.70% of our detections, respectively, while 15.15% were comprised of haplotypes H–L, and extensive genetic diversity of ITS sequences was detected in samples from Gansu Province. Using RNAfold software, we analyzed the haplotypes of 124 Chinese D. destructor populations based on their ITS sequences, and the results showed that haplotypes A, B, C, E, F, and new haplotypes M–P accounted for 49.19%, 12.10%, 15.32%, 3.23%, 1.61%, and 18.55% of the total sequences, respectively. Infection tests on the potato cultivar ‘Helan 15’ showed significant difference in infection capacity among different D. destructor populations. The information obtained in this study on spatial patterns of D. destructor haplotypes in China provides valuable insights into the development of an integrated approach for the management of this plant-parasitic nematode.