Storage Roots Research Articles

Sweetpotato storage root formation as affected by soil organic amendment applications

Organic amendments have been utilised as a source of nutrients to improve the growth and yield of many crops, including sweetpotato. However, none of the studies examined the relationship between organic amendments and the initiation of sweetpotato storage roots (SRs). A study was conducted in sweetpotato Orleans cultivar to investigate anatomical changes to roots during storage root formation aiming to elicit if organic amendment affects SR formation by changing soil available nitrogen (N) concentration. Two locally available organic amendments including poultry manure (PM) and sugarcane trash (SCT), were used in this experiment at different rates. Six treatments were included in the study: unamended soil (control), unamended soil with chemical fertiliser, PM 22 Mg/ha, PM 66 Mg/ha, SCT 10 Mg/ha and SCT 30 Mg/ha. Compared with unamended control, SCT application at both rates, 10 or 30 Mg ha−1, significantly promoted the formation of SRs and reduced root lignification, while PM amendment from 22 to 66 Mg ha−1 significantly inhibited SR initiation and enhanced the formation of lignified roots, which appear to be associated to high soil available N caused by PM addition. During the SR initiation, all amended treatments increased N accumulation in plants compared to the control. These results indicated that excessive soil available N introduced by PM amendment could inhibit the formation of SR of sweetpotato. Thus, when applying a lower rate of PM to sweetpotato, and planting should be delayed from 2 to 3 weeks after amending to avoid the detrimental effect on SR initiation. Excessively high rates of PM soil amendment (66 Mg ha−1) should be avoided. A suitable rate of SCT may be applied (~ 10 Mg ha−1 in this study) to promote SR formation of sweetpotato in soil with adequate available N level, but high rates could lead to immobilisation of N and suppress crop growth.

Sugar Beet Root Storage Properties Are Unaffected by Cercospora Leaf Spot.

Cercospora leaf spot (CLS; causal agent Cercospora beticola Sacc.) is endemic in many sugar beet production regions due to the widespread distribution of C. beticola and the inability of current management practices to provide complete control of the disease. Roots harvested from plants with CLS, therefore, are inevitably incorporated into sugar beet root storage piles, even though the effects of CLS on root storage properties are largely unknown. Research was conducted to determine the effects of CLS on storage properties including root respiration rate, sucrose loss, invert sugar accumulation, loss in recoverable sucrose yield, and changes in sucrose loss to molasses with respect to CLS disease severity and storage duration. Roots were obtained from plants with four levels of CLS severity in each of three production years, stored at 5°C and 95% relative humidity for up to 120 days, and evaluated for storage characteristics after 30, 90, and 120 days storage. No significant or repeatable effects of CLS on root respiration rate, sucrose loss, invert sugar accumulation, loss in recoverable sucrose yield, or change in sucrose loss to molasses were detected after 30, 90, or 120 days storage regardless of the severity of CLS disease symptoms. Therefore, no evidence was found that CLS accelerates sugar beet storage losses, and it is concluded that roots harvested from plants with CLS can be stored without additional or specialized precaution, regardless of CLS symptom severity.

Sweet potato ADP-glucose pyrophosphorylase small subunit affects vegetative growth, starch content and storage root yield

The development of storage roots is a key factor determining the yields of crop plants, including sweet potato. Here, using combined bioinformatic and genomic approaches, we identified a sweet potato yield-related gene, ADP-glucose pyrophosphorylase (AGP) small subunit (IbAPS). We found that IbAPS positively affects AGP activity, transitory starch biosynthesis, leaf development, chlorophyll metabolism, and photosynthesis, ultimately affecting the source strength. IbAPS overexpression in sweet potato led to increased vegetative biomass and storage root yield. RNAi of IbAPS resulted in reduced vegetative biomass, accompanied with a slender stature and stunted root development. In addition to the effects on root starch metabolism, we found that IbAPS affects other storage root development-associated events, including lignification, cell expansion, transcriptional regulation, and production of the storage protein sporamins. A combinatorial analysis based on transcriptomes, as well as morphological and physiological data, revealed that IbAPS affects several pathways that determine development of vegetative tissues and storage roots. Our work establishes an important role of IbAPS in concurrent control of carbohydrate metabolism, plant growth, and storage root yield. We showed that upregulation of IbAPS results in superior sweet potato with increased green biomass, starch content, and storage root yield. The findings expand our understanding of the functions of AGP enzymes and advances our ability to increase the yield of sweet potato and, perhaps, other crop plants.

Deciphering the hormone regulatory mechanisms of storage root initiation in sweet potato: challenges and future prospects.

Sweet potato (Ipomoea batatas) is an economically important food crop that is grown primarily for its edible storage roots. Several researchers have consequently been conducting studies to increase sweet potato yield, and an important aspect of this research involves understanding how storage root initiation occurs. Although significant progress has been made, several challenges associated with studying this crop have resulted in lagging progress compared to other crops and thus sweet potato storage root initiation is not clearly understood. This article highlights the most important aspects of the hormone signalling processes during storage root initiation that needs to be investigated further and suggests candidate genes that should be prioritized for further study, based on their importance in storage organ formation in other crops. Lastly, ways of overcoming the challenges associated with studying this crop are suggested.

Influence of Planting Density on Sweet Potato Storage Root Formation by Regulating Carbohydrate and Lignin Metabolism.

An appropriate planting density could realize the maximum yield potential of crops, but the mechanism of sweet potato storage root formation in response to planting density is still rarely investigated. Four planting densities, namely D15, D20, D25, and D30, were set for 2-year and two-site field experiments to investigate the carbohydrate and lignin metabolism in potential storage roots and its relationship with the storage root number, yield, and commercial characteristics at the harvest period. The results showed that an appropriate planting density (D20 treatment) stimulated cambium cell differentiation, which increased carbohydrate accumulation and inhibited lignin biosynthesis in potential storage roots. At canopy closure, the D20 treatment produced more storage roots, particularly developing ones. It increased the yield by 10.18-19.73% compared with the control D25 treatment and improved the commercial features by decreasing the storage root length/diameter ratio and increasing the storage root weight uniformity. This study provides a theoretical basis for the high-value production of sweet potato.

Principal Component Analysis and Clustering of Cassava Germplasm based on N and K Efficiency

The present study was undertaken at ICAR-CTCRI, Sreekaryam to identify and group N and K efficient genotypes from a pool of released varieties, pre-breeding lines and elite landraces of cassava during 2021-2022. Thirty genotypes of cassava were evaluated for their diversity based on N and K efficiency along with some of its contributing plant characters using statistical tools like principal component analysis, and dendrogram clustering. The variation existing among the selected genotypes was observed through PCA, where the first six principal components accounted for nearly 81% of the total variability. Characters like tuber yield, plant height, stem girth, tuber length and tuber girth contributed to the greater variability among the genotypes. The dendrogram analysis classified the genotypes into six clusters based on the 18 parameters contributing to nutrient use efficiency. The proportion of the variance accounted by these clusters came up to the extent of 50% displaying the association of the genotypes with similar characters in these clusters. These analyses helped to realize the wide range of variability existing among the selected genotypes for the 18 characters studied. A simple correlation was also worked out between N and K use efficiency with root traits, which revealed that characters such as weight of storage roots, number of storage roots, and number of basal roots showed a positive correlation with both N and K use efficiency in cassava.

Magnesium chelatase subunit D is not only required for chlorophyll biosynthesis and photosynthesis, but also affecting starch accumulation in Manihot esculenta Crantz

BackgroundMagnesium chelatase plays an important role in photosynthesis, but only a few subunits have been functionally characterized in cassava.ResultsHerein, MeChlD was successfully cloned and characterized. MeChlD encodes a magnesium chelatase subunit D, which has ATPase and vWA conservative domains. MeChlD was highly expressed in the leaves. Subcellular localization suggested that MeChlD:GFP was a chloroplast-localized protein. Furthermore, the yeast two-hybrid system and BiFC analysis indicated that MeChlD interacts with MeChlM and MePrxQ, respectively. VIGS-induce silencing of MeChlD resulted in significantly decreased chlorophyll content and reduction the expression of photosynthesis-related nuclear genes. Furthermore, the storage root numbers, fresh weight and the total starch content in cassava storage roots of VIGS-MeChlD plants was significantly reduced.ConclusionTaken together, MeChlD located at the chloroplast is not only required for chlorophyll biosynthesis and photosynthesis, but also affecting the starch accumulation in cassava. This study expands our understanding of the biological functions of ChlD proteins.

Effect of Growth Stages on Anthocyanins and Polyphenols in the Root System of Sweet Potato.

The storage roots of purple-fleshed sweet potato contain a variety of anthocyanins and polyphenols. Little is known about changes in the total content and composition of anthocyanins and polyphenols in the early growth stages of the root system. In this study, we investigated the changes in anthocyanins and polyphenols in the root system of purple-fleshed sweet potato cultivars at 15, 30, 45, and 60 days after transplant (DAT). Unexpectedly, the highest percentage of acylated anthocyanins in three purple-fleshed cultivars among all growth stages was at 15 DAT. On the other hand, the total polyphenol content in the early growth stages of the root system increased rapidly toward 45 DAT, just before the beginning of storage root enlargement, and then decreased rapidly as the storage roots began to enlarge. These data indicate that the early growth stage of the root system is a critical time. This timing may present a strategy to maximize the accumulation of polyphenols with high antioxidant activity, as well as acylated anthocyanins, to protect against abiotic and biotic stresses.

Yeast One-Hybrid Screening for Transcription Factors of IbbHLH2 in Purple-Fleshed Sweet Potato.

The transcription factor IbbHLH2 has been identified as involved in the biosynthesis of anthocyanins in purple-flesh sweet potatoes. However, little is known about the upstream transcription regulators of the promoter of IbbHLH2 in terms of their involvement in anthocyanin biosynthesis. For this study, the transcription regulators of the promoter of IbbHLH2 were screened via yeast one-hybrid assays in purple-fleshed sweet potato storage roots. Seven proteins, namely IbERF1, IbERF10, IbEBF2, IbPDC, IbPGP19, IbUR5GT, and IbDRM, were screened as upstream binding proteins of the promoter of IbbHLH2. The interactions between the promoter and these upstream binding proteins were verified using dual-luciferase reporter and yeast two-hybrid assays. Furthermore, the gene expression levels of transcription regulators, transcription factors, and structural genes involved in the anthocyanin biosynthesis of different root stages of purple and white-fleshed sweet potatoes were analyzed via real-time PCR. The obtained results indicate that IbERF1 and IbERF10 are key transcription regulators of the promoter of IbbHLH2 and are involved in anthocyanin biosynthesis in purple-fleshed sweet potatoes.

Photosynthesis Product Allocation and Yield in Sweet Potato in Response to Different Late-Season Irrigation Levels.

Soil water deficit is an important factor affecting the source-sink balance of sweet potato during its late-season growth, but water regulation during this period has not been well studied. Therefore, the aim of this study was to determine the appropriate irrigation level in late-season sweet potato, and the effect of irrigation level on accumulation and allocation of photosynthetic products. In this study, two yield-based field trials (2021-2022) were conducted in which five late-season irrigation levels set according to the crop evapotranspiration rate were tested (T0: non-irrigation, T1: 33% ETc, T2: 75% ETc, T3: 100% ETc, T4: 125% ETc). The effects of the different irrigation levels on photosynthetic physiological indexes, 13C transfer allocation, water use efficiency (WUE), water productivity (WP), and the yield and economic benefit of sweet potato were studied. The results showed that late-season irrigation significantly increased the total chlorophyll content and net photosynthetic rate of functional leaves, in addition to promoting the accumulation of above-ground-source organic biomass (p < 0.05). The rate of 13C allocation, maximum accumulation rate (Vmax), and average accumulation rate (Vmean) of dry matter in storage root were significantly higher under T2 irrigation than under the other treatments (p < 0.05). This suggests that both non-irrigation (T0) and over-irrigation (T4) were not conducive to the transfer and allocation of photosynthetic products to storage roots in late-season sweet potato. However, moderate irrigation (T2) effectively promoted the source-sink balance, enhanced the source photosynthetic rate and stimulated the sink activity, such that more photosynthate was allocated to the storage sink. The results also showed that T2 irrigation treatments significantly increased yield, WUE and WP compared to T0 and T4 (p < 0.05), suggesting that moderate irrigation (T2) can significantly promote the potential of storage root production and field productivity. There was a close relationship between economic benefit and marketable sweet potato yield, and both were highest under T2 (p < 0.05), increasing by 36.1% and 59.9% compared with T0 over the two-year study period. In conclusion, irrigation of late-season sweet potato with 75% evapotranspiration (T2) can improve both the yield and production potential. Together, these results support the use of late-season water management in the production of sweet potato.

Transcriptome and metabolome profiling identify factors potentially involved in pro-vitamin A accumulation in cassava landraces

Cassava (Manihot esculenta Crantz) is a predominant food security crop in several developing countries. Its storage roots, rich in carbohydrate, are deficient in essential micronutrients, including provitamin A carotenoids.Increasing carotenoid content in cassava storage roots is important to reduce the incidence of vitamin A deficiency, a public health problem in sub-Saharan Africa. However, cassava improvement advances slowly, mainly due to limited information on the molecular factors influencing β-carotene accumulation in cassava.To address this problem, we performed comparative transcriptomic and untargeted metabolic analyses of roots and leaves of eleven African cassava landraces ranging from white to deep yellow colour, to uncover regulators of carotenoid biosynthesis and accumulation with conserved function in yellow cassava roots.Sequence analysis confirmed the presence of a mutation, known to influence β-carotene content, in PSY transcripts of deep yellow but not of pale yellow genotypes. We identified genes and metabolites with expression and accumulation levels significantly associated with β-carotene content. Particularly an increased activity of the abscisic acid catabolism pathway together with a reduced amount of L-carnitine, may be related to the carotenoid pathway flux, higher in yellow than in white storage roots. In fact, NCED_3.1 was specifically expressed at a lower level in all yellow genotypes suggesting that it could be a potential target for increasing carotenoid accumulation in cassava.These results expand the knowledge on metabolite compositions and molecular mechanisms influencing carotenoid biosynthesis and accumulation in cassava and provide novel information for biotechnological applications and genetic improvement of cassava with high nutritional values.

Genome-Wide Comparative Analysis of the R2R3-MYB Gene Family in Six Ipomoea Species and the Identification of Anthocyanin-Related Members in Sweet Potatoes.

Sweet potatoes (Ipomoea batatas) are one of the important tuberous root crops cultivated worldwide, and thier storage roots are rich in antioxidants, such as anthocyanins. R2R3-MYB is a large gene family involved in various biological processes, including anthocyanin biosynthesis. However, few reports about the R2R3-MYB gene family of sweet potatoes have been released to date. In the present study, a total of 695 typical R2R3-MYB genes were identified in six Ipomoea species, including 131 R2R3-MYB genes in sweet potatoes. A maximum likelihood phylogenetic analysis divided these genes into 36 clades, referring to the classification of 126 R2R3-MYB proteins of Arabidopsis. Clade C25(S12) has no members in six Ipomoea species, whereas four clades (i.e., clade C21, C26, C30, and C36), including 102 members, had no members in Arabidopsis, and they were identified as Ipomoea-specific clades. The identified R2R3-MYB genes were unevenly distributed on all chromosomes in six Ipomoea species genomes, and the collinearity analysis among hexaploid I. batatas and another five diploid Ipomoea species suggested that the sweet potato genome might have undergone a larger chromosome rearrangement during the evolution process. Further analyses of gene duplication events showed that whole-genome duplication, transposed duplication, and dispersed duplication events were the primary forces driving the R2R3-MYB gene family expansion of Ipomoea plants, and these duplicated genes experienced strong purifying selection because of their Ka/Ks ratio, which is less than 1. Additionally, the genomic sequence length of 131 IbR2R3-MYBs varied from 923 bp to ~12.9 kb with a mean of ~2.6 kb, and most of them had more than three exons. The Motif 1, 2, 3, and 4 formed typical R2 and R3 domains and were identified in all IbR2R3-MYB proteins. Finally, based on multiple RNA-seq datasets, two IbR2R3-MYB genes (IbMYB1/g17138.t1 and IbMYB113/g17108.t1) were relatively highly expressed in pigmented leaves and tuberous root flesh and skin, respectively; thus, they were identified to regulate tissue-specific anthocyanin accumulation in sweet potato. This study provides a basis for the evolution and function of the R2R3-MYB gene family in sweet potatoes and five other Ipomoea species.

Impacts of long-term application of best management practices on yields and root carbohydrate content in asparagus (Asparagus officinalis) (UK)

Yield physiology of asparagus (Asparagus officinalis L.) is strongly influenced by biotic factors such as crown and root rot caused by Fusarium spp. and by abiotic conditions such as precipitation or temperatures, duration of each harvest, and field management practices. Asparagus yields are linked to the availability of soluble carbohydrates (CHO) in the storage root system which is considered a key factor in asparagus productivity. The aim of this study was to quantify the impacts of the long-term application of a range of potential Best Management Practices (BMPs) on yield and storage root carbohydrate content in green asparagus in a long-term field trial. The trial was established in 2016 with the asparagus ‘Gijnlim’ variety. Commercial yields were collected in 2018, 2019 and 2020. Root carbohydrate content was determined in 2019 and 2020. BMPs included (1) companion crops - Rye (Secale cereale L.), Mustard (Sinapis alba L.), (2) interrow surface mulch applications of either straw mulch or PAS 100 compost (Publicly available specification) in combination with shallow soil disturbance (SSD), (3) the conventional practice and modifications of the conventional tillage practice by applying SSD or not applying SSD and (4) a zero-tillage option. Annual re-ridging (R) and not ridging (NR) were applied to BMP options 1–3. SSD had no significant impact on asparagus yields while annual re-ridging negatively affected total yields of treatments with bare soil interrows, which were managed without SSD. Conventional practice was associated with a 22% yield reduction and ∼€4250 ha−1 annual loss in potential revenue as compared to the Zero-tillage treatment. Companion cropping with mustard did not have a significant impact on asparagus yields. Rye without annual re-ridging was however associated with yield reductions of > 20% as compared to the Conventional practice. PAS 100 Compost applied in asparagus interrows (at 25 t ha−1 per year) in combination with SSD without annual re-ridging resulted in improvements to yields of 20%, 10% and 34% in 2018, 2019 and 2020, respectively, as compared to the Conventional practice. No correlation was observed between storage root soluble carbohydrate content and asparagus yields. The results of this study confirmed that asparagus yield, and thus total farm income can be significantly improved through implementation of several of the BMPs investigated.

Selection of new sweetpotato hybrids for West Africa using accelerated breeding scheme and genotype × environment interaction under drought stress

West Africa is a dry region and drought tolerant sweetpotato cultivar was not reported. The objective of this study was to develop higher yielding drought tolerant sweetpotato hybrids following accelerated breeding scheme (ABS), and study G × E interaction. During advanced yield trial, the assessment of clones was conducted in six locations: four in Niger and two in Nigeria. Data were collected on storage root yield (SRY), harvest index (HI) and root dry matter content (DMC). Twenty-three hybrids were evaluated under drought and irrigation. Terminal drought was imposed. SAS and GenStat softwares were used for analyses. Based on drought susceptibility index (DSI), drought tolerant expression (DTE) and HI, clones 4 × 5 – 3, 9 × 7 – 1, 5 × 9 – 2, 3 × 6 – 2, and 3 × 12 – 3 were the best in SRY under drought stress and well-watered in combined data. Using AMMI stability value (ASV) and stability cultivar superiority (SCS), results revealed that the most superior cultivars were unstable. Clones 12 × 5 – 1 and 9 × 10 – 1 were recommended under drought for SRY stability combined with high DMC and high total carotene (TC). Under irrigation, the 13 × 8 – 2 is good candidate for stability across all locations combined with high DMC and medium TC, while clone 4 × 3 – 2, 13 × 8 – 2, 4 × 6 – 2 and 6 × 8 – 5 were stable SRY with high DMC. Therefore, these hybrids could be evaluated at on-farm trials to release the best to farmers.

Genetic Variation of New Purple-Fleshed Sweet Potato (Ipomoea batatas L.) Genotypes in Indonesia by Multivariate Analysis

Purple-fleshed sweet potato (PFSP) is a major staple food and feed material in tropical countries. The pandemic of COVID-19 that encouraged healthy lifestyles worldwide further increases the importance of PFSP. Despite its importance, the investment in research to improve PFSP in Indonesia was left behind. The objective of the research was to estimate the genetic variation and genetic distance of new PFSP genotypes prior to variety release. The research trials were arranged in a randomized block design, with nine new PFSP genotypes from polycrosses breeding as treatments and three check varieties in four growing environments in West Java, i.e., Cilembu, Jatinangor, Maja, and Karangpawitan during one season. Agronomic traits data were analyzed by the multivariate analysis. The principal component analysis (PCA) showed high genetic variation of PFSP in four environments. The eigenvalue ranges from 1.92 to 5.29 in Cilembu which contributed to 80.958% variability, 0.543–6.177 which contributed variability to 92.135% in Jatinangor, 0.824–5.695 in Karangpawitan which contributed to 92.117%, and 0.822–4.797 in Maja which contributed to 86.133%. Storage root length, storage root diameter, number of roots per plant, total root weight per plant, number of marketable/commercial roots, marketable/commercial root weight, number of roots per plot, and total storage root weight have a discriminant value of more than 0.7 in PC 1. Agglomerative hierarchical clustering (AHC) showed a wide distribution obtaining two clusters in Cilembu with euclidean distance 1.92–5.29, Jatinangor 1.72–6.09, Karangpawitan 1.28–6.38, and Maja 2.05–5.09. High genetic variation in the four environments greatly supports to the development of PFSP new varieties.

Integrated Metabolomic and Transcriptomic Analyses Reveals Sugar Transport and Starch Accumulation in Two Specific Germplasms of Manihot esculenta Crantz.

As a starchy and edible tropical plant, cassava (Manihot esculenta Crantz) has been widely used as an industrial raw material and a dietary source. However, the metabolomic and genetic differences in specific germplasms of cassava storage root were unclear. In this study, two specific germplasms, M. esculenta Crantz cv. sugar cassava GPMS0991L and M. esculenta Crantz cv. pink cassava BRA117315, were used as research materials. Results showed that sugar cassava GPMS0991L was rich in glucose and fructose, whereas pink cassava BRA117315 was rich in starch and sucrose. Metabolomic and transcriptomic analysis indicated that sucrose and starch metabolism had significantly changing metabolites enrichment and the highest degree of differential expression genes, respectively. Sugar transport in storage roots may contribute to the activities of sugar, which will eventually be exported to transporters (SWEETs), such as (MeSWEET1a, MeSWEET2b, MeSWEET4, MeSWEET5, MeSWEET10b, and MeSWEET17c), which transport hexose to plant cells. The expression level of genes involved in starch biosynthesis and metabolism were altered, which may result in starch accumulation. These results provide a theoretical basis for sugar transport and starch accumulation and may be useful in improving the quality of tuberous crops and increasing yield.

AMMI and GGE Biplot Analyses for Mega Environment Identification and Selection of Some High-Yielding Cassava Genotypes for Multiple Environments

Cassava (Manihot esculenta Crantz) is a staple food and generates income for smallholder farmers in southern Ethiopia. The performance of cassava genotypes varies in different growing environments; thus, the evaluation of genotypes tested in various environments plays an essential role in developing strategies to delineate environments, explore unstable genotypes in target environments, and identify stable genotypes for multiple environments. In this regard, there needs to be more information on the identification of mega-environments and stable genotypes with high yields for wide adaptation. Thus, this study aimed to identify mega-environment and high-yielding cassava genotypes for multiple environments using AMMI and GGE biplots. A total of 25 genotypes were evaluated in six environments using a RCBD during the 2020–2021 cropping season. The AMMI analysis of variances revealed that environments, genotypes, and genotype-environment interaction had a significant ( P ≤ 0.001 ) influence on cassava fresh storage root yield (t·ha−1), showing genetic variability among genotypes by changing environments. The genotype-by-environment interaction showed a 61.36% contribution to the total treatment SS variation, while the environment and genotype effects explained 28.16% and 10.48% of the total treatment SS, respectively. IPCA1 and IPCA2 accounted for 33.42% and 23.5% of the GE interactions SS, respectively. The GGE biplot showed that the six environments used in this study were delineated into three mega-environments, namely, the first (Tarcha and Disa), the second (Wara and Areka), and the third (Jimma and Bonbe). Those mega-environments could be helpful for genotype evaluation and effective breeding. The GGE biplot indicated that the vertex genotypes were G16, G17, and G25. They are regarded as specifically adapted genotypes since they are more responsive to environmental change. The GGE biplot also revealed that Tarcha was ideal, having the most discriminating and representative environment, while G10 was the ideal and the overall winning genotype for the current study. Moreover, the genotypes G10 and G14 were identified as being the most stable, with a higher fresh storage root yield than the grand mean. Thus, G10 and G14 were selected as superior genotypes that could be promoted to advanced yield trials to develop stable cultivars with better storage root yield of cassava.

Workflow for phenotyping sugar beet roots by automated evaluation of cell characteristics and tissue arrangement using digital image processing

BackgroundCell characteristics, including cell type, size, shape, packing, cell-to-cell-adhesion, intercellular space, and cell wall thickness, influence the physical characteristics of plant tissues. Genotypic differences were found concerning damage susceptibility related to beet texture for sugar beet (Beta vulgaris). Sugar beet storage roots are characterized by heterogeneous tissue with several cambium rings surrounded by small-celled vascular tissue and big-celled sugar-storing parenchyma between the rings. This study presents a procedure for phenotyping heterogeneous tissues like beetroots by imaging.ResultsTen Beta genotypes (nine sugar beet and one fodder beet) were included to establish a pipeline for the automated histologic evaluation of cell characteristics and tissue arrangement using digital image processing written in the programming language R. The identification of cells has been validated by comparison with manual cell identification. Cells are reliably discriminated from intercellular spaces, and cells with similar morphological features are assigned to biological tissue types.ConclusionsGenotypic differences in cell diameter and cell arrangement can straightforwardly be phenotyped by the presented workflow. The presented routine can further identify genotypic differences in cell diameter and cell arrangement during early growth stages and between sugar storage capabilities.

Genetic diversity assessment and genome-wide association study reveal candidate genes associated with component traits in sweet potato (Ipomoea batatas (L.) Lam)

The Korean sweet potatoes were bred by various cultivars introduced from Japanese, American, Porto Rico, China, and Burundi. This issue enriched their genetic diversity but also resulted in a mixture of cultivars. For genotyping, we collected and sequenced 66 sweet potato germplasms from different localities around Korea, including 36 modern cultivars, 5 local cultivars, and 25 foreign cultivars. This identified 447.6 million trimmed reads and 324.8 million mapping reads and provided 39,424 single nucleotide polymorphisms (SNPs) markers. Phylogenetic clustering and population structure analysis distinctly classified these germplasms into 5 genetic groups, group 1, group 2, group 3, group 4, and group 5, containing 20, 15, 10, 7, and 14 accessions, respectively. Sixty-three significant SNPs were selected by genome-wide association for sugar composition-related traits (fructose, glucose, and total sugars), total starch, amylose content, and total carotenoid of the storage root. A total of 37 candidate genes encompassing these significant SNPs were identified, among which, 7 genes were annotated to involve in sugar and starch metabolism, including galactose metabolism (itf04g30630), starch and sucrose metabolism (itf03g13270, itf15g09320), carbohydrate metabolism (itf14g10250), carbohydrate and amino acid metabolism (itf12g19270), and amino sugar and nucleotide sugar metabolism (itf03g21950, itf15g04880). This results indicated that sugar and starch are important characteristics to determine the genetic diversity of sweet potatoes. These findings not only illustrate the importance of component traits to genotyping sweet potatoes but also explain an important reason resulting in genetic diversity of sweet potato.

Crop growth and macronutrient extraction and export curves for two arrowroot cultivars

Curves of crop growth and nutrient extraction and export are essential to develop fertilization strategies and management plans to maximize yield and reduce environmental impacts. Our study aimed to evaluate dry matter production and both extraction and export of macronutrients by arrowroots (Maranta arundinacea L.) to be used in further crop fertilization plans. To this purpose, two experiments were carried out in field conditions using the varieties Viçosa and Seta. The experimental design was randomized with four replications and nine periods of analysis, which were defined as days after planting (105, 135, 165, 195, 225, 255, 285, 315, and 345 DAP). Dry matter, extraction, and export of macronutrients by arrowroot seed-rhizomes, aerial parts, roots, and storage roots (rhizomes) were determined. The exports of N, P, K, Ca, Mg, and S of storage rhizomes of the variety Viçosa were 104.6, 51.83, 412.24, 15.85, 36.14, and 64.36 kg ha-1, while those of the seta variety were 160.6, 71.62, 521.31, 17.57, 60.09, and 160.41 kg ha-1, respectively. Both varieties proved to be efficient soil macronutrient extractors, mainly for K. The variety Seta had higher shoot, root, seed-rhizome dry matter contents, as well as greater macronutrient extractions and exports.