Genetics and Resistance / Génétique et Résistance High-confidence genomic regions associated with leaf stripe and spot blotch resistance in barley

Detection and Heritability of Genes Conferring Resistance to Potato Pests and Viruses in Hybrid Potato Progeny (Solanum tuberosum L.)

Potato viral infections are among the main factors contributing to reduced quality of planting material and decreased tuber productivity. Currently, no reliable chemical control methods are available for plant viral diseases. Therefore, the development of potato cultivars carrying virus resistance genes remains one of the most effective and comprehensive approaches to this problem. In this study, 29 Russian and foreign potato cultivars, as well as 31 Far Eastern potato hybrids were evaluated. Resistance genes were identified using PCR analysis. The following cultivars carrying target resistance genes were used as positive controls for method calibration: Meteor (Rysto, Rx1, Sen1, Gpa2, H1), Vektor (Rx1, Gpa2), Yubilyar (Gpa2), and Zhukovsky ranniy (Gpa2, Rx1). Method calibration enabled determination of optimal magnesium chloride concentrations: 2.0 mM for Gpa2 and 2.5 mM for Rx1. Genotyping of 29 potato cultivars identified several highly resistant accessions, including Yubilyar, Zhukovsky ranniy, Bellarosa, Sante, Smak, Red Scarlett, and Laperla. These cultivars combined resistance to Potato virus X (Rx1) with complex resistance to two nematode species (Gpa2, H1). In the studied population, high frequencies of the Gpa2 (82.8%) gene and the H1 (65.5–69.0%) gene group were observed. Statistical analysis provided strong evidence for tight genetic linkage between the Rx1 and the Gpa2 loci on chromosome 12. The association was highly significant (p < 0.001). Analysis of 31 potato hybrids revealed 14 multi-marker genotypes with high breeding potential. A stable combination of five target resistance markers was consistently detected in their genomes. A dominant hybrid family derived from the Yantar × Smak cross was identified, represented by five related lines. For the first time, a precise heritability coefficient was calculated for the STS marker of the Rx1 gene in a Far Eastern hybrid population. The estimate reached h2 = 0.835 at p = 0.01. This value significantly exceeded the critical threshold for breeding reliability (h2 > 0.7), indicating largely additive genetic control of the trait. These results support targeted selection of parental combinations for breeding programs aimed at improving virus and nematode resistance in potato.

Unlocking the potential of spring wheat genetic resources: uncovering resistance sources against leaf rust and yellow rust

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.

Identification of stripe rust resistance loci in Gansu wheat landraces using genome-wide association analysis

Genetics and Resistance / Génétique et Résistance Genetic mapping and marker development for the leaf rust resistance gene Lr30 in wheat ( Triticum aestivum L.)

This study generated the first linkage map of Lr30, a gene that confers resistance against leaf rust caused by Puccinia triticina Eriks, and developed Kompetitive allele-specific PCR (KASP) markers linked to Lr30 for marker-assisted breeding.

A successful stacking of multiple biotic stress resistance in rice facilitated by genes and precision breeding tools

Genetic improvement of rice for biotic stress is a major and continuous breeding objective owing to changing pest and disease scenarios. In response to climate change, an outbreak of new pathotypes and biotypes results in huge yield loss which directly impacts the economic stability and food security. The development of varieties with multiple resistance genes for a particular disease is the most effective approach to the combating mechanism against evolving pathogens and insects. Multiple resistance genes against blast (Pi54), bacterial leaf blight (xa5, xa13, Xa21), and brown plant hopper (Bph17, Bph3, bph2) were pyramided through marker-assisted forward breeding by attempting multiple crosses involving six parental lines. The F4 lines were screened and the resistant lines were further reconfirmed at the F5 stage through precise phenotyping and also by genotyping with trait-specific markers. Finally, the selected lines were evaluated for the agronomic performance. Four lines were selected from the population which carrying seven resistance genes against BL, BB, BPH with superior agronomic performance. Another line, x21302-239, harboring all the resistant genes and showing a resistant response in screening experiments for all three stresses, with marginal agronomic performance (single-plant yield: 33 g), can be utilized as a desirable donor to develop elite rice cultivars with multiple biotic stress resistance. Homozygous genetic background is more favorable for epidemic outbreak in a short period of time in comparison with the population of multiple genetic background. Since this complex genetic background disturbs the infectious cycle of the pathogen. So that a variety or a hybrid which developed from multiple parental lines are notable for their durable resistance than the monogenic resistance variety.

Marker-assisted backcross breeding to develop wheat lines with stable yellow rust resistance without yield penalties

Wheat production faces severe yield threats globally and regionally in India from rust diseases caused by Puccinia species. Genetic resistance breeding is the most sustainable approach to mitigate these losses, but traditional phenotypic selection is often constrained by environmental fluctuations and rapid pathogen evolution. Here we utilized marker-assisted backcross breeding (MABB) to introgress broad-spectrum yellow rust resistance genes, Yr10 and Yr15 , from the donor genetic stock PBW703 into the elite, high-yielding wheat cultivar DBW88 to develop two high-yielding rust-resistant genotypes DBW476 and DBW477. Foreground selection was executed using gene-linked molecular markers PSP3000 ( Yr10 ) and Xbarc8 ( Yr15 ). Background selection with 107 polymorphic simple sequence repeat (SSR) markers accelerated recurrent parent genome recovery up to 95% within just two backcross generations, significantly outperforming conventional breeding timelines. Seedling resistance tests and adult plant resistance evaluations confirmed that the introgressed lines exhibited a high degree of immune response and comprehensive resistance against virulent Puccinia striiformis pathotypes, including 238S119 and 110S119. Multi-year agronomic testing across multiple environments demonstrated that the improved near-isogenic lines achieved equal or superior grain yield performance compared to their recurrent parents and commercial checks. These findings indicate successful gene introgression without any associated linkage drag or yield penalties. These advanced, stable lines were nominated for multi-location varietal trials, presenting a strategically superior asset for sustainable rust management and food security in the rust-prone environments of India.