Gene ontology analysis further indicated coordinated regulation of defence responses, oxidative stress processes, transcriptional regulation, and membrane-associated cellular components in bacterial wilt-resistant eggplant cultivars through integrated breeding approaches.
These findings establish qPB10 as the primary locus governing Phytophthora blight resistance in sesame, and kompetitive allele-specific PCR (KASP) markers were developed based on sequence polymorphisms within the qPB10 interval that reliably discriminates resistant genotypes.
Jeongeun Lee, Eunyoung Oh, Sungup Kim et al.· BMC Plant Biology· 0 citations
Kiwifruit bacterial canker, caused by Pseudomonas syringae pv. actinidiae (Psa), severely restricts the sustainable development of the kiwifruit industry. Screening stable resistant germplasm and establishing efficient disease resistance evaluation methods are core prerequisites for breeding resistant cultivars. In this study, 86 Actinidia accessions were systematically assessed for Psa susceptibility over three consecutive years using the reported detached shoot inoculation assay. Seven representative accessions with contrasting resistance phenotypes, namely ‘Cuiyu’, ‘Chuhong’, ‘Jinmei’, ‘Hongyang’, ‘Cuixiang’, ‘Avfs08’, and ‘G3’, were selected to measure the activities of four defense-related enzymes post Psa inoculation to dissect the physiological mechanisms driving divergent Psa resistance in kiwifruit. Lesion lengths across years exhibited a significant positive correlation, demonstrating that this inoculation method delivers repeatable, genetically stable phenotypic data with limited environmental interference. Two accessions belonging to A. valvata and A. eriantha exhibited stable high resistance via synergistic biochemical defenses. By contrast, the widely grown cultivar ‘Hongyang’ was highly susceptible, while moderately resistant materials such as ‘Cuiyu’ and ‘Yannong 3’ were discovered within the inherently susceptible species A. chinensis. Highly resistant accessions rapidly induced coordinated increases in SOD and PAL activity at 24 h post inoculation to maintain ROS homeostasis and lignin biosynthesis, whereas susceptible accessions displayed chaotic, ineffective enzymatic stress responses. Temporal synergy of PAL and POD may act as the key defensive regulatory mode. This study uncovered substantial interspecific variation in Psa resistance across Actinidia germplasm, identified elite donors with stable resistance, and elucidated the physiological mechanisms of kiwifruit resistance to Psa. These findings provided a theoretical foundation and valuable germplasm for subsequent resistance gene mining and disease resistance breeding.
Mengjie Chen, Jia-Le Tang, Sha Mo et al.· Plants· 0 citations
Abstract Bacterial wilt, caused by Ralstonia spp., poses a major threat to blueberry (Vaccinium corymbosum) production due to its persistence and rapid spread through soil and infected stock, highlighting the need for genetic insights to guide breeding strategies. This study investigated the genetic basis of bacterial wilt resistance in blueberry using a genome‐wide association study (GWAS) across two populations comprising 401 advanced selections from the University of Florida Blueberry Breeding and Genomics Program. A high‐throughput screening assay was developed to evaluate southern highbush blueberry responses to bacterial wilt based on leaf wilting severity and stem necrosis. Capture sequencing identified 38,379 single‐nucleotide polymorphisms. Moderate narrow‐sense heritability estimates were observed for leaf severity (0.26) and stem necrosis (0.20), and GWAS identified five small‐effect quantitative trait loci on chromosomes 1, 2, 5, and 11, each explaining 4.0%–7.4% of the phenotypic variance. Candidate gene analysis revealed putative pentatricopeptide repeat (PPR), serine/threonine protein kinase, and MYB‐related proteins for leaf severity, and Mlo genes and polysaccharide biosynthesis genes for stem necrosis. Genomic selection (GS) analyses demonstrated potential for improving bacterial wilt resistance, with the GS de novo GWAS approach achieving the highest predictive ability by leveraging two key markers on chromosomes 1 and 11. These results elucidate the genetic architecture of bacterial wilt resistance in blueberries and provide resources for molecular breeding strategies to enhance resistance and ensure sustainable production.
Lushan Ghimire, N. Flor, P. Adunola et al.· The Plant Genome· 0 citations
Integrating high-throughput phenotyping with multiple complementary GWAS models reduces method-dependent bias and enables reliable identification of novel loci and elite germplasm for durable yellow and leaf rust resistance in wheat. The causal agents of yellow and leaf rust in wheat, Puccinia striiformis f. sp. tritici and Puccinia triticina, pose a serious threat to grain yield and quality worldwide. Growing durable resistant wheat cultivars is an effective protection measure contributing to sustainable agriculture. Many of the known resistance genes, however, have been overcome due to the high genetic diversity and adaptability of pathogen populations. Therefore, the present study aimed to identify novel loci associated with yellow rust and leaf rust in a genome-wide association study using 1984 spring wheat accessions from the German Federal ex situ Genebank. Phenotypic data obtained from a detached-leaf assay were combined with 90,283 genotyping-by-sequencing genome-wide markers. Six significant peak marker-trait associations were identified for yellow rust and leaf rust, respectively. These are located on chromosomes 1D, 2B, 3B, 4A, 4B, 4D, 5A, 6B, and 7D. Six candidate genes were identified close to the identified loci. These findings may be valuable for identifying and deploying genetic resources to broaden the genetic basis of resistance and safeguard durability of resistance against yellow and leaf rust.
Behnaz Soleimani, Anne-Kathrin Pfrieme, Ulrike Beukert et al.· Theoretical and Applied Gene...· 0 citations
PURPOSE
Bacterial wilt caused by Ralstonia solanacearum is a major constraint to bell pepper (Capsicum annuum L. var. grossum Sendt.) production worldwide, with no stable resistance available in commercially cultivated varieties. This study explored induced mutagenesis as a strategy to develop durable bacterial wilt resistance in the widely grown but highly susceptible cultivar 'California Wonder.'
MATERIALS AND METHODS
Genetic variability was induced using gamma irradiation and ethyl methane sulfonate (EMS). Mutant populations were advanced from M1 to M8 generations over 12 years (2012-2023). A total of 1,804 M2 progenies were screened under wilt-sick field conditions to identify putative resistant lines. Resistance was validated through an integrated approach including in vivo field screening, ex vivo seedling assays in Hoagland's nutrient solution, and serological confirmation using DAS-ELISA. Stable mutants were further evaluated across multiple generations and five cropping years for resistance stability, horticultural performance, and fruit quality traits. Molecular validation was performed using the SSR marker CAMS451 to confirm the association between resistance-linked alleles and phenotypic expression.
RESULTS
Screening of M2 progenies identified 22 putative resistant lines, of which 16 consistently expressed stable resistance across generations and environments. Six mutants DPCBWR-12 (1.5% EMS), DPCBWR-4 (1.75% EMS), DPCBWR-15 (1.75% EMS), DPCBWR-5 (1.75% EMS), DPCBWR-8 (16.0 kR gamma rays), and DPCBWR-3 (2.0% EMS) significantly outperformed the parent cultivar for yield-related traits and nutritional quality parameters. SSR marker analysis using CAMS451 confirmed the genetic association of resistance-linked alleles with observed phenotypic resistance.
CONCLUSIONS
This study provides the first evidence of successful induction of bacterial wilt resistance in bell pepper through gamma irradiation and EMS mutagenesis. The identified elite mutant lines possess durable resistance, improved yield, and enhanced fruit quality, making them promising candidates for multi-location testing, varietal release, and use as valuable genetic resources in sustainable bell pepper breeding programs.
Sonia Sood, T. Sood, Ruchi Sood et al.· International Journal of Rad...· 0 citations
Net form net blotch (NFNB), caused by
Pyrenophora teres
f.
teres
(
Ptt
), is a major constraint to barley production. However, the genetic basis of adult plant resistance (APR) and seedling resistance remains incompletely understood. This study aimed to dissect the genetic architecture of NFNB resistance in a diverse panel of 273 spring barley accessions.
APR was evaluated in two contrasting field environments in Kazakhstan, whereas seedling resistance was assessed under greenhouse conditions using two
Ptt
races. Genotyping with the 50K SNP array yielded 31,834 high-quality SNPs. Genome-wide association analyses were performed using four models – MLM, MLMM, FarmCPU, and BLINK – that accounted for population structure and kinship. Candidate genes within QTL intervals were prioritized using transcriptomic data from 16 barley tissues and co-expression network analysis.
Substantial phenotypic variation was observed, with moderate heritability for APR (
h
2
= 50.6%) and seedling resistance (
h
2
= 41.3%), together with strong genotype × environment and genotype × race interactions. In total, 275 marker–trait associations were detected for APR and 48 for seedling resistance. These associations were consolidated into 57 genome-wide significant (P < 1.57E–6) or multi-model-supported QTLs across all seven barley chromosomes, including 39 APR and 18 seedling-resistance QTLs. Forty QTLs co-localized with known resistance genes (
Rpt1
,
Rpt2
,
Rpt3
,
Rpt4
,
Rpt6
,
Rpt8
,
Rpt9
, and
SPN1
) or previously reported net blotch QTLs, whereas 17 were potentially novel. Transcriptomic integration identified 87 highly expressed genes within APR QTL regions and 42 within seedling-resistance QTLs. The potentially novel QTLs
Q_NB_1H.6
,
Q_NB_2H.3
, and
Q_NB_3H.1
harbored genes encoding proteins previously associated with pathogen resistance and stress responses. Co-expression analysis revealed stage-specific transcriptional patterns, with APR-associated genes enriched in regulatory functions and seedling-resistance genes enriched in metabolic and structural functions.
The results demonstrate that NFNB resistance is polygenic and developmentally stage-dependent, with partly distinct mechanisms underlying adult plant and seedling resistance. The identified QTLs and prioritized candidate genes provide targets for independent validation, functional characterization, and the development of molecular markers to support breeding for durable NFNB resistance in barley.
Y. Genievskaya, A. Maulenbay, A. Zatybekov et al.· Frontiers in Agronomy· 0 citations
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