Susceptible Cultivars Research Articles

Genetic Mapping, Identification, and Characterization of a Candidate Susceptibility Gene for Powdery Mildew in Cannabis sativa.

Powdery mildew (PM) in Cannabis sativa is most frequently caused by the biotrophic fungus Golovinomyces ambrosiae. Based on previously characterized variation in susceptibility to PM, biparental populations were developed by crossing the most resistant cultivar evaluated, 'FL 58', with a susceptible cultivar, 'TJ's CBD'. F1 progeny were evaluated and displayed a range of susceptibility, and two were self-pollinated to generate two F2 populations. In 2021, the F2 populations (n = 706) were inoculated with PM and surveyed for disease severity. In both F2 populations, 25% of the progeny were resistant, while the remaining 75% showed a range of susceptibility. The F2 populations, as well as selected F1 progeny and the parents, were genotyped with a single-nucleotide polymorphism array, and a consensus genetic map was produced. A major effect quantitative trait locus on C. sativa chromosome 1 (Chr01) and other smaller-effect quantitative trait loci (QTL) on four other chromosomes were identified. The most associated marker on Chr01 was located near CsMLO1, a candidate susceptibility gene. Genomic DNA and cDNA sequencing of CsMLO1 revealed a 6.8-kb insertion in FL 58, relative to TJ's CBD, of which 846 bp are typically spliced into the mRNA transcript encoding a premature stop codon. Molecular marker assays were developed using CsMLO1 sequences to distinguish PM-resistant and PM-susceptible genotypes. These data support the hypothesis that a mutated MLO susceptibility gene confers resistance to PM in C. sativa and provides new genetic resources to develop resistant cultivars. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Damage Intensity of Pod Borer Attack on Seven Soybean Cultivars on Mahogany and Pine Agroforestry

Damage Intensity of Pod Borer Attack on Seven Soybean Cultivars on Mahogany and Pine Agroforestry

Exploring OsHAK Transporters for the Salt Responsiveness in Rice

Environmental stresses are the major constraint in crop growth and productivity, particularly in rice. Improving rice against major abiotic stressors such as salinity is one of the major thrust areas. In this direction, the trait of sodium exclusion was the primary focus among the rice breeders to enhance salt tolerance. Along similar lines, increased uptake of potassium, the counter ion of Na+, through high-affinity potassium transporters (HAK) assumes significance in the context of maintaining a favorable Na/K ratio, a low Na/K is an indicator of salt tolerance. The OsHAK family in rice includes 27 members and an insight into the evolution, structure, and expression through in silico approaches was attempted. Phylogenetic analysis exhibited four distinct groupings of the OsHAK family, and functional motif analysis revealed a characteristic consensus sequence among the OsHAK transporters. Relative gene expression analysis based on published microarray data put forth the differential regulation of OsHAK3 X2, OsHAK8, OsHAK14(X2), OsHAK15 and OsHAK26 between salt-tolerant landrace Pokkali and susceptible cultivar IR29 and their tissue-specific expression profiles predicted. This study narrowed down a set of putative OsHAKs from the larger family for their role in enhancing cellular potassium under salt stress thus paving the way for crop improvement.

Breakdown of Ty-1-Based Resistance to Tomato Yellow Leaf Curl Virus in Tomato Plants at High Temperatures.

The global dissemination of the Israel (IL) and mild (Mld) strains of tomato yellow leaf curl virus (TYLCV) (family Geminiviridae, genus Begomovirus) is a major threat to tomato production in many regions worldwide. The use of resistant hybrid cultivars bearing the dominant resistance genes Ty-1, Ty-3, and Ty-3a has become a common practice for controlling tomato yellow leaf curl disease (TYLCD) caused by TYLCV. However, TYLCD symptoms have been sporadically observed in resistant cultivars grown in seasons when temperatures are high. In this study, we used TYLCV-resistant cultivars with confirmed presence of Ty-1, which were determined using newly developed allele-specific markers based on polymorphisms within the locus. These Ty-1-bearing resistant tomato plants and susceptible plants were infected with TYLCV and grown at moderate or high temperatures. Under high-temperature conditions, the Ty-1-bearing tomato cultivar Momotaro Hope (MH) infected with TYLCV-IL had severe TYLCD symptoms, which were almost equivalent to those of the susceptible cultivar. However, MH plants infected with TYLCV-Mld were symptomless or had slight symptoms under the same temperature condition. The quantitative analysis of the TYLCV-IL viral DNA content revealed a correlation between symptom development and viral DNA accumulation. Furthermore, under high-temperature conditions, TYLCV-IL caused severe symptoms in multiple commercial tomato cultivars with different genetic backgrounds. Our study provided the scientific evidence for the experientially known phenomenon by tomato growers, and it is anticipated that global warming, associated with climate change, could potentially disrupt the management of TYLCV in tomato plants mediated by the Ty-1 gene.

Unveiling mungbean yellow mosaic virus: molecular insights and infectivity validation in mung bean (Vigna radiata) via infectious clones.

Yellow mosaic disease (YMD) with typical symptoms of alternating bright yellow to green patches associated with stunting, downward cupping, and wrinkling has been observed in mung bean on agricultural farms in Coimbatore, Tamil Nadu, India. PCR using gene-specific primers indicated the presence of the yellow mosaic virus in symptomatic plants. Rolling circle amplification (RCA) followed by restriction digestion detected ~2.7 kb of DNA-A and DNA-B, allowing the identification of a bipartite genome. The full-length genome sequences were deposited in NCBI GenBank with the accession numbers MK317961 (DNA-A) and MK317962 (DNA-B). Sequence analysis of DNA-A showed the highest sequence identity of 98.39% to the DNA-A of mungbean yellow mosaic virus (MYMV)-Vigna radiata (MW736047), while DNA-B exhibited the highest level of identity (98.21%) to the MYMV-Vigna aconitifolia isolate (DQ865203) reported from Tamil Nadu. Recombinant analysis revealed distinct evidence of recombinant breakpoints of DNA-A within the region encoding the open reading frame (ORF) AC2 (transcription activation protein), with the major parent identified as MYMV-PA1 (KC9111717) and the potential minor parent as MYMV-Namakkal (DQ86520.1). Interestingly, a recombination event in the common region (CR) of DNA-B, which encodes the nuclear shuttle protein and the movement protein, was detected. MYMIV-M120 (FM202447) and MYMV-Vigna (AJ132574) were identified as the event's major and minor parents, respectively. This large variation in DNA-B led us to suspect a recombination in DNA-B. Dimeric MYMV infectious clones were constructed, and the infectivity was confirmed through agroinoculation. In future prospects, unless relying on screening using whiteflies, breeders and plant pathologists can readily use this agroinoculation procedure to identify resistant and susceptible cultivars to YMD.

Evaluation of foliar fungicides for frogeye leaf spot control and yield protection in soybean in Arkansas

The efficacy of fifteen foliar fungicides to control frogeye leaf spot (caused by Cercospora sojina K. Hara) and protect soybean grain yield was investigated over three years (2014–2016) in two field experiments. Experiments were divided into two fungicide groups: premix fungicides, which included combinations of quinone outside inhibitors (QoI), demethylation inhibitors (DMI), succinate dehydrogenase inhibitors (SDHI), or methyl benzimidazole carbamates (MBC), and solo fungicides, all DMI fungicides. Fungicides were applied once at the full pod (R4) in 2014 and 2015 and at the beginning seed (R5) growth stage in 2016. A very susceptible frogeye leaf spot cultivar, Armor 48R40, was used. Frogeye leaf spot severity at fungicide application timing average 1.0, 0.5, and 8.0% in 2014, 2015, and 2016, respectively. Final disease severity averaged 21.7, 14.5, and 15.1% in 2014, 2015, and 2016, respectively on the non-treated control. Azoxystrobin provided no disease control, suggesting the presence of QoI-resistant C. sojina. Three fungicides: azoxystrobin + difenoconazole, flutriafol, and thiophanate-methyl + tebuconazole applied at R4 provided effective disease control compared to the non-treated control. Fungicides applied at R5 provided no disease control. No fungicide provided significant grain yield protection in either experiment. Overall, the average yield protection trend by fungicides applied at R4 and R5 was 6.8 and 3.0%, respectively compared to the non-treated control. These data suggest that although foliar fungicides can provide effective frogeye leaf spot control, yield protection may be limited when applied at the R4 growth stage, particularly when disease severity exceeds 0.5% on a very susceptible soybean cultivar.

Biocontrol effect of the complex inoculants of Trichoderma and Bacillus amyloliquefaciens on chrysanthemum white rust

In this study, the Chrysanthemum morifolium susceptible cultivar ‘Jinba’ was used as the experimental material to perform prevention and treatment testing of complex inoculants of Trichoderma on chrysanthemum white rust (CWR) and growth promotion and disease-prevention testing of Bacillus amyloliquefaciens. The treatment test results showed that the number of teliospores in the diseased leaves treated with the complex inoculants of Trichoderma was considerably reduced, and the germination of teliospores was inhibited. The results of the prevention experiment showed that test group two (T2) significantly reduced the infection rate of pathogens and enhanced the SOD, POD, CAT, PPO, PAL and CHI compared to the control group and test group one (T1). The RT-qPCR results revealed that T2 could induce the up-regulation of the NPR1, PAL, COI1, and PDF1.2 genes. The treatment of B. amyloliquefaciens root irrigation promoted the growth of ‘Jinba’. The plant height, fresh aboveground weight, fresh underground weight, root-shoot ratio, and root activity increased by 5.38%, 31.67%, 64.63%, 5.26%, and 283.33%, respectively. Moreover, the activities of soil protease, urease, sucrase, and phosphatase increased significantly. The incidence of CWR in the field decreased by 20.0%. In summary, the complex inoculants of Trichoderma can significantly inhibit the germination of teliospores, reduce the infection rate of pathogens and improve the resistance of CWR by inducing the enhancement of related enzyme activity and the up-regulation of disease-resistant gene expression. B. amyloliquefaciens can promote plant growth by increasing soil enzyme activity, thereby reducing the incidence of CWR.

Pathogenically altered Colletotrichum lindemuthianum transformants help in understanding the biochemical defense and colonization dynamics in Phaseolus vulgaris

Colletotrichum lindemuthianum poses a serious threat to common bean production and impacts food security. It is essential to comprehend the intricate nature of the pathogen infection process and the underlying biochemical systems regulating plant defence to create tactics that effectively increase plant resistance. This study leveraged a stable C. lindemuthianum transformant library to examine these intrinsic mechanisms in a susceptible Phaseolus vulgaris cultivar, Jawala. Among the 57 mitotically stable transformants employed to screen for altered virulence, 51 were pathogenically similar to wild type and the remaining six transformants were either reduced or impaired. Nine transformants (three pathogenically similar and all impaired and reduced mutants) were selected for subsequent studies. These mutants exhibited an array of morpho-cultural variations. The biochemical studies of these mutants revealed free radicals as double-edged swords, exerting a pivotal influence on the infection process. The free radical (H2O2) elevated at an early stage (24 hpi) in the cases of reduced (CT-51) and impaired (CT-225) mutants. However, at the later stage (72 hpi), H2O2 was promoted in the case of R-2047 and equal to wild type (CT-101) transformant. Contrary, superoxide (O2−) increased considerably at 48 hpi in the incompatible interaction of reduced (CT-51) and impaired (CT-225) mutants. The microscopic images revealed how easily the wild type (CT-101) could germinate, penetrate, and infect the leaves. The pathogenically reduced transformant (CT-51), however, had delayed germination as well as a decreased growth rate and spore production. Additionally, the pathogenicity of the impaired transformant (CT-225) was completely lost, and its conidia failed to properly germinate. This is the first account of C. lindemuthianum in planta colonization with a GFP tag. This study increased our understanding of the mechanics of the reactions triggered by C. lindemuthianum and may be used to develop novel strategies for the effective control of bean anthracnose. Additionally, identifying the genes disrupted by the insertion of Agrobacterium T-DNA will help in identifying the genes necessary for bean plant colonization.

Comparative Physiological and Transcriptome Analyses of Tolerant and Susceptible Cultivars Reveal the Molecular Mechanism of Cold Tolerance in Anthurium andraeanum.

Anthurium andraeanum is a tropical ornamental flower. The cost of Anthurium production is higher under low temperature (non-freezing) conditions; therefore, it is important to increase its cold tolerance. However, the molecular mechanisms underlying the response of Anthurium to cold stress remain elusive. In this study, comparative physiological and transcriptome sequencing analyses of two cultivars with contrasting cold tolerances were conducted to evaluate the cold stress response at the flowering stage. The activities of superoxide dismutase and peroxidase and the contents of proline, soluble sugar, and malondialdehyde increased under cold stress in the leaves of the cold tolerant cultivar Elegang (E) and cold susceptible cultivar Menghuang (MH), while the soluble protein content decreased in MH and increased in E. Using RNA sequencing, 24,695 differentially expressed genes (DEGs) were identified from comparisons between cultivars under the same conditions or between the treatment and control groups of a single cultivar, 9132 of which were common cold-responsive DEGs. Heat-shock proteins and pectinesterases were upregulated in E and downregulated in MH, indicating that these proteins are essential for Anthurium cold tolerance. Furthermore, four modules related to cold treatment were obtained by weighted gene co-expression network analysis. The expression of the top 20 hub genes in these modules was induced by cold stress in E or MH, suggesting they might be crucial contributors to cold tolerance. DEGs were significantly enriched in plant hormone signal transduction pathways, trehalose metabolism, and ribosomal proteins, suggesting these processes play important roles in Anthurium's cold stress response. This study provides a basis for elucidating the mechanism of cold tolerance in A. andraeanum and potential targets for molecular breeding.

Host suitability of pepper cultivars to (a)virulent root-knot nematodes isolates

Root-knot nematodes (RKNs) are polyphagous and cause yield losses to crops worldwide. Using the resistant plant is the most effective and environmental method to manage RKNs. Mi-1.2 gene in tomatoes is commonly used to control Meloidogyne. However, the Mi-1.2-virulent isolates can overcome this gene. In fields infested with Mi-1.2-virulent populations, plant species with different resistance genes are recommended instead of tomatoes. Therefore, investigating the host suitability of pepper cultivars to Mi-1.2-virulent RKNs is needed for management practices. This study was conducted in Akdeniz University Faculty of Agriculture Department of Plant Protection Nematology Laboratory in 2019. In this study, the response of resistant and susceptible pepper cultivars was investigated to Meloidogyne incognita (Kofoid & White,1919), Chitwood, 1949, Meloidogyne javanica (Treub, 1885) Chitwood, 1949, Meloidogyne arenaria (Neal, 1889) Chitwood, 1949, Meloidogyne luci Carneiro et al., 2014 (Tylenchida: Meloidogynidae), Mi-1.2-virulent M. incognita and Mi-1.2-virulent M. javanica. Meloidogyne arenaria, M. incognita and Mi-1.2-virulent M. incognita isolates multiplied very well on susceptible peppers but did not reproduce on resistant peppers. Mi-1.2-(a)virulent M. javanica isolates did not multiply on any pepper cultivars. Meloidogyne luci reproduced on all peppers tested. A pepper carrying N resistance gene was first tested with M. luci and did not confer resistance to M. luci. These results could be used to control RKNs in vegetable-growing areas.

Genetic Diversity and Classification of Colletotrichum sublineola Pathotypes Using a Standard Set of Sorghum Differentials.

Anthracnose, incited by Colletotrichum sublineola, is the most destructive foliar disease of sorghum and, under severe conditions, yield losses can exceed 80% on susceptible cultivars. The hyper-variable nature of the pathogen makes its management challenging despite the occurrence of several resistant sources. In this study, the genetic variability and pathogenicity of 140 isolates of C. sublineola, which were sequenced using restriction site-associated sequencing (RAD-Seq), resulted in 1244 quality SNPs. The genetic relationship based on the SNP data showed low to high genetic diversity based on isolates' origin. Isolates from Georgia and North Carolina were grouped into multiple clusters with some level of genetic relationships to each other. Even though some isolates from Texas formed a cluster, others clustered with isolates from Puerto Rico. The isolates from Puerto Rico showed scattered distribution, indicating the diverse nature of these isolates. A population structure and cluster analysis revealed that the genetic variation was stratified into eight populations and one admixture group. The virulence pattern of 30 sequenced isolates on 18 sorghum differential lines revealed 27 new pathotypes. SC748-5, SC112-14, and Brandes were resistant to all the tested isolates, while BTx623 was susceptible to all. Line TAM428 was susceptible to all the pathotypes, except for pathotype 26. Future use of the 18 differentials employed in this study, which contains cultivars/lines which have been used in the Americas, Asia, and Africa, could allow for better characterization of C. sublineola pathotypes at a global level, thus accelerating the development of sorghum lines with stable resistance to the anthracnose pathogen.

The effect of sublethal doses of Bacillus thuringiensis Berliner on Tuta absoluta (Meyrick) on resistant and susceptible tomato cultivars

The effect of sublethal doses of Bacillus thuringiensis Berliner on Tuta absoluta (Meyrick) on resistant and susceptible tomato cultivars

Genome-wide identification and expression profiles of the Phytophthora infestans responsive CYPome (cytochrome P450 complement) in Solanum tuberosum.

Cytochrome P450s represent one of the largest protein families across all domains of life. In plants, biotic stress can regulate the expression of some P450 genes. However, the CYPome (cytochrome P450 complement) in Solanum tuberosum and its response to Phytophthora infestans infection remains unrevealed. In this study, 488 P450 genes were identified from potato genome, which can be divided into 41 families and 57 subfamilies. Responding to the infection of P. infestans, 375 potato P450 genes were expressed in late blight resistant or susceptible cultivars. A total of 14 P450 genes were identified as resistant related candidates, and 81 P450 genes were identified as late blight responsive candidates. Several phytohormone biosynthesis, brassinosteroid biosynthesis, and phenylpropanoid biosynthesis involved P450 genes were differentially expressed during the potato-pathogen interactions. This study firstly reported the CYPome in S. tuberosum, and characterized the expression patterns of these P450 genes during the infection of P. infestans.

A QTL of eggplant shapes the rhizosphere bacterial community, co-responsible for resistance to bacterial wilt

Abstract Resistant crop cultivars can recruit beneficial rhizobacteria to resist disease. However, whether this recruitment is regulated by quantitative trait loci (QTL) is unclear. The role of QTL in recruiting specific bacteria against bacterial wilt (BW) is an important question of practical significance to disease management. Here, to identify QTL controlling BW resistance, Super-BSA was performed in F2 plants derived from resistant eggplant cultivar R06112 × susceptible cultivar S55193. The QTL was narrowed down through BC1F1-BC3F1 individuals by wilting symptoms and KASP markers. Rhizosphere bacterial composition of R06112, S55193, and resistant individuals EB158 (with the QTL) and susceptible individuals EB327 (without QTL) from BC2F1 generation were assessed by Illumina sequencing-based analysis, and the activation of plant immunity by the bacterial isolates was analyzed. Evidence showed that BW-resistant is controlled by one QTL located at the 270 kb region on chromosome 10, namely EBWR10, and nsLTPs as candidate genes confirmed by RNA-Seq. EBWR10 has a significant effect on rhizobacteria composition and significantly recruits Bacillus. pp. A SynCom of three isolated Bacillus. pp trains significantly reduced the disease incidence, changed activities of CAT, PPO, and PAL and concentration of NO, H2O2, and O2−, activated SA and JA signaling-dependent ISR, and displayed immune activation against Ralstonia solanacearum in eggplant. Our findings demonstrate for the first time that the QTL can recruit beneficial rhizobacteria, which jointly promote the suppression of BW. This method charts a path to develop the QTL in resistant cultivar-driven probiotics to ameliorate plant diseases.

Response of Tomato Quality and Yield to Elevated Temperatures under Controlled Environment

The experiment was carried out during 2020-2021 at the Department of Plant Physiology, College of Agriculture, Vellayani, Kerala Agricultural University. The experiment was carried out with the aim of characterization of contrasting tomato genotypes for high temperature tolerance under high temperature condition and control condition to identify key quality and yield traits controlling high temperature tolerance in tomato. The experiment was designed in completely randomized design (CRD) with 2 treatment levels- control and high temperature conditions (36+/-2oC) wherein 3 tolerant and 3 susceptible genotypes were selected for the study. These genotypes were selected from the summer varietal screening experiment performed during the summer months of 2021 from March to May. The best performing genotypes were selected in terms of pollen viability, leaf membrane thermo-stability, chlorophyll fluorescence, number of fruits, fruit set %. One set of treatment was maintained under ambient condition and the other set with high temperature stress was maintained under polyhouse facility from transplanting stage to the harvesting stage. The quality parameters and yield traits were analysed at the harvesting stage of the crop. From this study it can be understood that many of the quality parameters like lycopene content, total sugars, flavanol content was found decreasing in both tolerant and susceptible genotypes but the extend of this reduction was considerate in tolerant ones. In case of ascorbic acid content and firmness of fruit at the time of ripening these were found to be improved in heat stress (HS) conditions. Yield related qualities like number of fruits, yield per plant, and root-shoot ratio was found decreasing whereas root dry weight, total dry weight and intensity of fruit drop and flower drop was increased under HS. Therefore, this study focused on tomato genotypes reported to be resilient to high-temperature stress, and comparing them to the susceptible cultivars under stress and control settings for analyzing the variations in terms of quality and yield traits in tropical hot climate regions of India. The study performed here highlights the possibility for future breeding programs utilizing the key quality and yield traits enhancing thermo-tolerance in tomato and to develop new genotypes that can combine good yield performances and fruit nutritional quality at high temperatures.

Influence of Grapevine Cultivar on Population Levels of Lobesia botrana (Lepidoptera: Tortricidae) and Effectiveness of Insecticides in Controlling This Pest

The European grapevine moth, Lobesia botrana (Denis and Schiffermüller) (Lepidoptera: Tortricidae), is the most critical pest of vineyards. In the present study, pheromone-baited traps were applied in 2021 and 2022 to monitor the moth population dynamics and to determine the number of L. botrana generations. The number of eggs and larvae was also counted in four vineyards with Askari, Yaghooti, Keshmeshi, and Fakhri cultivars. Moreover, the morphological properties of clusters were evaluated in different grape cultivars to find out the susceptible cultivar to L. botrana. In 2022, different insecticides were used in the Askari cultivar vineyard, and larval damage level was assessed. Three generations were recorded in all vineyards each year. The population of males was not affected by the cultivar. In contrast, the population density of eggs and larvae was significantly higher in Yaghooti than in other tested cultivars. It could be attributed to the cluster compactness and thin skin of berries in Yaghooti, which makes it more susceptible to L. botrana infestations. In contrast, the lowest eggs and larval population density was reported in the Fakhri cultivar indicating the tolerance of this cultivar compared to the other tested cultivars. The field trial showed that the application of insecticides in the second and third generations reduced the damage level of L. botrana. The rotation of insecticides with different modes of action in consecutive generations of L. botrana can be used to reduce damage levels.

Characterization of the Metabolic Profile of Olive Tissues (Roots, Stems and Leaves): Relationship with Cultivars' Resistance/Susceptibility to the Soil Fungus Verticillium dahliae.

Verticillium wilt of olive (VWO) is one of the most widespread and devastating olive diseases in the world. Harnessing host resistance to the causative agent is considered one of the most important measures within an integrated control strategy of the disease. Aiming to understand the mechanisms underlying olive resistance to VWO, the metabolic profiles of olive leaves, stems and roots from 10 different cultivars with varying levels of susceptibility to this disease were investigated by liquid chromatography coupled to mass spectrometry (LC-MS). The distribution of 56 metabolites among the three olive tissues was quantitatively assessed and the possible relationship between the tissues' metabolic profiles and resistance to VWO was evaluated by applying unsupervised and supervised multivariate analysis. Principal component analysis (PCA) was used to explore the data, and separate clustering of highly resistant and extremely susceptible cultivars was observed. Moreover, partial least squares discriminant analysis (PLS-DA) models were built to differentiate samples of highly resistant, intermediate susceptible/resistant, and extremely susceptible cultivars. Root models showed the lowest classification capability, but metabolites from leaf and stem were able to satisfactorily discriminate samples according to the level of susceptibility. Some typical compositional patterns of highly resistant and extremely susceptible cultivars were described, and some potential resistance/susceptibility metabolic markers were pointed out.

White rust: Plant-microbe interaction and plant breedingperspective on Indian mustard

White rust is an important disease of Indian mustard which results in appreciable yield losses. A monogenic dominant gene has been responsible for resistance against this pathogen in B. juncea. In the pathogen, avirulence has been observed to be dominant, governed by a single gene. R gene (resistance gene) present in resistant lines of B. juncea, encodes CC-NB-LRR (coiled coil nucleotide binding leucine rich repeat) protein whereas, susceptible lines have truncated LRR domain of the same protein. Resistant and moderately resistant lines have higher amount of chlorophyll, sugars and total phenols than susceptible cultivars, throughout crop growth. Increased accumulation of phytoalexins such as spirobrassinin, cyclobrassinin and rutalexin have been observed in resistant lines compared to, susceptible ones upon infection by fungi. Molecular markers tagged to R gene are being used in resistance breeding programmes. Scientists have developed intron polymorphism (IP) markers namely;At5g41560, At5g41940 and At2g36360 for positive selection of white rust resistance and, simple sequence repeat (SSR) marker, At2g34700, for negative selection of resistance in different rust resistant sources. The major issue in use of these markers is their transferability as they do not show association with R gene in different set of crosses.

Potato cultivar susceptibility to wireworms: feeding behaviour, fitness and semiochemical-based host selection

Potato cultivar susceptibility to wireworms: feeding behaviour, fitness and semiochemical-based host selection

Exploring soybean cultivar susceptibility to sudden death syndrome: Insights into isoflavone responses and biocontrol potential

Sudden Death Syndrome (SDS) caused by Fusarium tucumaniae is a significant threat to soybean production in Argentina. This study assessed the susceptibility of SY 3 × 7 and SPS 4 × 4 soybeans cultivars to F. tucumaniae and studied changes in root isoflavone levels after infection. Additionally, the biocontrol potential of plant-growth promoting rhizobacteria (PGPR) against SDS was also examined. Our results demonstrated that the SY 3 × 7 cultivar exhibited higher disease severity and total fresh weight loss than SPS 4 × 4. Both cultivars showed induction of daidzein, glycitein, and genistein in response to infection, with the partially resistant cultivar displaying significantly higher daidzein levels than the susceptible cultivar at 14 days post infection (dpi) (2.74 vs 2.17-fold), declining to a lesser extent at 23 dpi (0.94 vs 0.35-fold, respectively). However, daidzein was not able to inhibit F. tucumaniae growth in in vitro assays probably due to its conversion to an isoflavonoid phytoalexin which would ultimately be an effective fungal inhibitor. Furthermore, the PGPR bacterium Bacillus amyloliquefaciens BNM340 displayed antagonistic activity against F. tucumaniae and reduced SDS symptoms in infected plants. This study sheds light on the varying susceptibility of soybean cultivars to SDS, offers insights into isoflavone responses during infection, and demonstrates the potential of PGPR as a biocontrol strategy for SDS management, providing ways for disease control in soybean production.