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Nowadays, hulless barley (Hordeum vulgare L.) is gaining importance as a raw material for food industry due to its highly nutritive value. Non-availability of high yield and disease resistant varieties has restricted its production in marginal areas over the last two decades. Therefore, an experiment was conducted during 2017–18 and 2018–19 at the Seed and Research Farm of ICAR-Indian Institute of Wheat and Barley Research, Karnal, Haryana to characterized 11 exotic hulless barley genotypes and 4 Indian barley cultivars for morpho-physiological characters and stripe rust resistance. Seedling resistant test for stripe rust was done at Regional Station (ICAR-Indian Institute of Wheat and Barley Research), Flowerdale, Shimla, Himachal Pradesh. Highly significant genotypic differences were found for morpho-physiological traits during analysis of variance. Genotype DWRNB28 showed a good combination of desirable traits, viz. early maturity (118 days), dwarf plant height (64.4 cm) and high 1000-grain weight (55.2 g). Maximum number of tillers per meter (149) was observed in DWRNB17. Genotype DWRNB25 was found resistant to maximum pathotypes (6S0, 7S0, and Q) at the seedling stage. DWRNB23 and DWRNB25 with pooled ACI=0 and ACI=0.04 respectively, were found immune to stripe rust in field conditions. These promising genotypes can be utilized as donor parents for the development of high-yielding and stripe-rust-resistant hulless barley varieties.

[This corrects the article DOI: 10.1371/journal.pone.0167702.].

Brown (leaf) rust of wheat, caused by Puccinia triticina was widely distributed in all the wheat growing areas. To identify new pathotypes and determine the virulence pattern of Puccinia triticina, rust samples were analyzed from the wheat growing areas in India, Bangladesh, Bhutan and Nepal. A new pathotype 93R57 (104-4=NHKSP) was identified from Arki area of Solan district in Himachal Pradesh. Among the 37 pathotypes identified in 2124 samples analyzed during 2008-2013, four predominant pathotypes 121R63-1(77-5=THTTS), 21R55 (104-2=PHTTL), 121R60-1(77-9=MHTTS) and 21R63 (104-3=PHTKL) accounted for 68% of the population. These four pathotypes have virulence to Lr1, Lr3, Lr10, Lr11, Lr12, Lr13, Lr14a, Lr16, Lr17, Lr23, Lr26. Virulence on Lr19 was found in 7 samples only whereas the proportion of pathotype 121R60-1 (77-9=MHTTS) has increased recently in Tamil Nadu and was identified in about 40% of the samples from that area. Virulent pathotypes on Lr9, Lr24, Lr25, Lr32, Lr39 and Lr45 were not observed in the field population of brown rust in the Indian subcontinent during the last five cropping seasons.

A comprehensive germplasm evaluation study of wheat accessions conserved in the Indian National Genebank was conducted to identify sources of rust and spot blotch resistance. Genebank accessions comprising three species of wheat-Triticum aestivum, T. durum and T. dicoccum were screened sequentially at multiple disease hotspots, during the 2011-14 crop seasons, carrying only resistant accessions to the next step of evaluation. Wheat accessions which were found to be resistant in the field were then assayed for seedling resistance and profiled using molecular markers. In the primary evaluation, 19,460 accessions were screened at Wellington (Tamil Nadu), a hotspot for wheat rusts. We identified 4925 accessions to be resistant and these were further evaluated at Gurdaspur (Punjab), a hotspot for stripe rust and at Cooch Behar (West Bengal), a hotspot for spot blotch. The second round evaluation identified 498 accessions potentially resistant to multiple rusts and 868 accessions potentially resistant to spot blotch. Evaluation of rust resistant accessions for seedling resistance against seven virulent pathotypes of three rusts under artificial epiphytotic conditions identified 137 accessions potentially resistant to multiple rusts. Molecular analysis to identify different combinations of genetic loci imparting resistance to leaf rust, stem rust, stripe rust and spot blotch using linked molecular markers, identified 45 wheat accessions containing known resistance genes against all three rusts as well as a QTL for spot blotch resistance. The resistant germplasm accessions, particularly against stripe rust, identified in this study can be excellent potential candidates to be employed for breeding resistance into the background of high yielding wheat cultivars through conventional or molecular breeding approaches, and are expected to contribute toward food security at national and global levels.

Wheat stripe rust caused by Puccinia striiformis Westend. f.sp. tritici (Pst) is a global threat to wheat production. Genetic modification of defense-responsive factors in wheat rust interactions could help devise strategies to control stripe rust on wheat. This experiment studied the interaction between Pst pathotype 78S84 in PBW343 and FLW-3 by evaluating the quantitative temporal transcription profiles of defense-related genes at different time points. This is the first attempt to exhibit inter-connections among different proteins and depict a hypothetical model for the mechanism of R gene-mediated resistance. Transcript levels of LTP, AQP1, PR1, PR2, PR4, and PR10 were relatively higher under compatible interaction, while under incompatible interaction, transcript levels of COMT1, PRA2, WCAB, and PR9 were significantly high. This study projected the role of defense-responsive genes, inter-networking of proteins, and R gene-mediated resistance between wheat and stripe rust.

Wheat stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), has re-emerged as one of the major concerns for global wheat production since the evolution of Ug99 and other virulent pathotypes of Pgt from East Africa, Europe, Central Asia, and other regions. Host resistance is the most effective, economic, and eco-friendly approach for managing stem rust. Understanding the virulence nature, genetic diversity, origin, distribution, and evolutionary pattern of Pgt pathotypes over time and space is a prerequisite for effectively managing newly emerging Pgt isolates through host resistance. In the present study, we monitored the occurrence of stem rust of wheat in India and neighboring countries from 2016 to 2022, collected 620 single-pustule isolates of Pgt from six states of India and Nepal, analyzed them on Indian stem rust differentials, and determined their virulence phenotypes and molecular genotypes. The Ug99 type of pathotypes did not occur in India. Pathotypes 11 and 40A were most predominant during these years. Virulence phenotyping of these isolates identified 14 Pgt pathotypes, which were genotyped using 37 Puccinia spp.-specific polymorphic microsatellites, followed by additional phylogenetic analyses using DARwin. These analyses identified three major molecular groups, demonstrating fewer lineages, clonality, and long-distance migration of Pgt isolates in India. Fourteen of the 40 recently released Indian wheat varieties exhibited complete resistance to all 23 Pgt pathotypes at the seedling stage. Twelve Sr genes were postulated in 39 varieties based on their seedling response to Pgt pathotypes. The values of slow rusting parameters i.e. coefficient of infection, area under disease progress curve, and infection rates, assessed at adult plant stage at five geographically different locations during two crop seasons, indicated the slow rusting behavior of several varieties. Six Sr genes (Sr2, Sr57, Sr58, Sr24, Sr31, and Sr38) were identified in 24 wheat varieties using molecular markers closely linked to these genes. These findings will guide future breeding programs toward more effective management of wheat stem rust.