Genetic characterization for lesion mimic and other traits in relation to spot blotch resistance in spring wheat

Shweta Singh,Sundeep Kumar,Vinod Kumar Mishra,Arun Kumar Joshi,Dwijesh Chandra Mishra,Uttam Kumar,Ramesh Chand,Neeraj Budhlakoti,Ravindra Nath Kharwar,Suneel Kumar,Ram Narayan Ahirwar,Manoj Prasad

doi:10.1371/journal.pone.0240029

Abstract

Lesion mimic (Lm) mutants display hypersensitive responses (HR) without any pathogen attack; their symptoms are similar to those produced by a pathogen and result in cell death. In wheat, such mutants have been reported to be resistant against leaf rust due to their biotrophic nature. However, Lm mutants tend to encourage spot blotch (SB) disease caused by Bipolarissorokiniana since dead cells facilitate pathogen multiplication. In this study, 289 diverse wheat germplasm lines were phenotyped in three consecutive growing seasons (2012-2015). Genotype data was generated using the Illumina iSelect beadchip assay platform for wheat germplasm lines. A total of 13,589 single-nucleotide polymorphisms (SNPs) were selected andused for further association mapping. Lm was positively associated with Area Under Disease Progress Curve (AUDPC) for SB but negatively with glaucous index (GI), leaf tip necrosis (Ltn) and latent period (LP). Ltn had a negative association with AUDPC and Lm but a positive one with LP. In a genome-wide association study (GWAS), 29 markers were significantly associated with these traits and 27 were an notated. Seven SNP markers associated with Lm were on chromosome 6A; another on 1B was found to be linked with Ltn. Like wise, seven SNP markers were associated with GI; one on chromosome 6A with the others on 6B. Five SNP markers on chromosomes 3B and 3Dwere significantly correlated with LP, while nine SNP markers on chromosomes 5A and 5B were significantly associated with AUDPC for SB. This study is the first to explore the interaction in wheat between Lm mutants and the hemibiotrophic SB pathogen B.sorokiniana.

Highlights

Plant lesion mimic(Lm) mutants exhibitnecrotic symptoms on the leaves that appear in the absence of any pathogen
We found seven markers closely associated with Lesion mimic (Lm), all on chromosome 6A, one for leaf tip necrosis (Ltn) on 1B, and seven for glaucous index (GI) across 6A and 6B
The genotype analysis showed significant positive correlations between Lm and Area Under Disease Progress Curve (AUDPC), Ltn and latent period (LP), and between LP and GI, whereas Lm was significantly negatively associated with Ltn, LP, and GI

Summary

Introduction

Plant lesion mimic(Lm) mutants exhibitnecrotic symptoms on the leaves that appear in the absence of any pathogen. It confers no resistance to hemibiotrophs or necrotrophic pathogens [14] such as Botrytis cinerea [15], where cell death follows infection [16] Another trait, leaf tip necrosis (Ltn), provides resistance against various plant pathogens at the adult plant stage and is linked to genes such as Lr34 [17]. Leaf tip necrosis (Ltn), provides resistance against various plant pathogens at the adult plant stage and is linked to genes such as Lr34 [17] This gene was first reported in wheat PI58548 [18] and was later described in many wheat varieties [19,20,21]. Disease potential of the crop may be reduced by utilizing genotypes with a long LP [17] and a high GI

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Discussion

Conclusion