Biology subjects

Sharma Poudel, R.

Publications and source records attributed to Sharma Poudel, R..

3 recordsLinked to original sources

bioRxiv2024

Rpt5 encodes a receptor-like protein that provides broad and effective net form net blotch (Pyrenophora teres f. teres) resistance in barley

The foliar disease net form net blotch (NFNB), caused by the necrotrophic fungal pathogen Pyrenophora teres f. teres (Ptt), causes significant yield and quality losses of barley worldwide. Dominant resistance conferred by the Resistance to Pyrenophora teres 5(Rpt5) gene from barley line CI5791 is the broadest and most effective resistance reported in this pathosystem. The Rpt5 locus was identified in multiple independent genetic studies utilizing diverse host populations and Ptt isolates, and harbors both dominant Rpt5 resistance and isolate-specific susceptibility genes/alleles that are dominant in the absence of Rpt5, designated susceptibility to Pyrenophora teres 1 (Spt1). Ptt virulence and avirulence effectors from diverse pathogen isolates genetically interact with the Rpt5/Spt1 locus, suggesting a complex locus with a function targeted by the evolution of a diversity of pathogen effectors. High-resolution mapping utilizing 1,920 recombinant gametes from a CI5791 x Tifang biparental population, identified 12 candidate genes in an [~]4.6 Mb delimited region in the cv Morex V3 genome assembly, but is 1.1 - 2.2 Mb in the pangenome assemblies, containing 5-12 genes. Analysis revealed a strong correlation between the CI5791 allele of a receptor-like protein (RLP), provisionally designated Rpt5 candidate gene 1, (Rcg1), and broad Rpt5-mediated resistance. Two independent transformants of the CI5791 Rcg1 allele in the susceptible cv Golden Promise background showed significantly increased resistance when challenged with Rpt5 avirulent Ptt isolates 6A, 15A, and 0-1 compared to the Golden Promise wildtype. Thus, Rpt5, encodes an RLP and is the first net blotch resistance gene cloned in barley. Significance StatementNet form net blotch (NFNB) causes substantial yield and quality losses of barley worldwide. Despite decades of ongoing research into genetic resistance to Pyrenophora teres f. teres, the causal agent of NFNB, no host resistance or susceptibility genes in this pathosystem had been previously identified. We present the identification and validation of Rpt5, which confers the broadest and most effective resistance against NFNB. To our knowledge Rpt5 is the first genetically defined resistance gene in a monocot to encode an RLP.

plant biology↗

bioRxiv2021

Genome wide association mapping of Pyrenophora teres f. maculata and Pyrenophora teres f. teres resistance loci utilizing natural Turkish wild and landrace barley populations

Unimproved landraces and wild relatives of crops are sources of genetic diversity that were lost post domestication in modern breeding programs. To tap into this rich resource, genome wide association studies in large plant genomes have enabled the rapid genetic characterization of desired traits from natural landrace and wild populations. Wild barley (Hordeum spontaneum), the progenitor of domesticated barley (H. vulgare), is dispersed across Asia and North Africa, and has co-evolved with the ascomycetous fungal pathogens Pyrenophora teres f. teres and P. teres f. maculata, the casual agents of the diseases net form of net blotch and spot form of net blotch, respectively. Thus, these wild and local adapted barley landraces from the region of origin of both the host and pathogen represent a diverse gene pool to identify new sources of resistance, due to millions of years of co-evolution. The barley - P. teres pathosystem is governed by complex genetic interactions with dominant, recessive, and incomplete resistances and susceptibilities, with many isolate-specific interactions. Here we provide the first genome wide association study of wild and landrace barley from the Fertile Crescent for resistance to both forms of P. teres. A total of 14 loci, four against P. teres f. maculata and ten against Pyrenophora teres f. teres, were identified in both wild and landrace populations, showing that both are genetic reservoirs for novel sources of resistance. We also highlight the importance of using multiple algorithms to both identify and validate additional loci.

genetics↗

bioRxiv2020

Localization of hyphal growth associated with mycotoxin production during the malting of Fusarium head blight infected grains

Fusarium head blight (FHB) and the occurrence of mycotoxins is the largest food safety threat to malting and brewing grains. Objectives of the current study were to localize the growth of Fusarium within FHB infected kernels and to associate it with the production of DON that occurred during malting. FHB infected barley, wheat, rye, and triticale grains that exhibited large increases in Fusarium Tri5 DNA and trichothecene mycotoxins following malting, were screened for hyphal localization. The growth of hyphae, both on the surface of kernels and within tissues of grain and malt was, imagined by scanning electron microscopy and confocal laser scanning microscopy assisted with WGA-Alexa Fluor 488 pre-staining, respectively. In barley, hyphae were primarily present on or within husk, vascular bundle, and pericarp cavities. Following malting, large amounts of hyphal growth were observed in not only these regions, but also in the aleurone layer, endosperm, and embryo. Extensive fungal growth was also observed following malting of wheat, rye, and triticale. Interestingly, these grains already had an extensive internal presence of hyphae in unmalted grain, occurring in the pericarp, testa, vascular bundle, nucellar projection, aleurone layer, endosperm, pericarp and endosperm cavities, and embryo. Shotgun sequencing followed by metagenomics analysis verified that Fusarium spp. accounted for above 90% of the fungal hyphae growing in the interior of grains during malting, which coincided with the significant production of mycotoxins.

plant biology↗