QTL Mapping and Transcriptome Analysis to Identify Differentially Expressed Genes Induced by Septoria Tritici Blotch Disease of Wheat

Odilbekov Odilbekov,Armoniené Armoniené,Chawade Chawade,Henriksson Henriksson,Singh Singh,He He,Saripella Saripella

doi:10.3390/agronomy9090510

Abstract

Resistance to Septoria tritici blotch (STB) is an economically important trait in many wheat-breeding programs across the world. Several quantitative trait loci (QTL) for STB resistance were identified in wheat but due to the dynamic pathogen population it is necessary to continuously identify new resistance genes/QTL and determine the underlying resistance mechanism. In this work, we integrated QTL mapping and transcriptome profiling to identify candidate genes underlying QTL associated with STB resistance in bread wheat at the seedling stage. The results revealed four QTL on chromosomes 1BS, 1BL, 3AS and 3DL for STB resistance. Among these, two QTL on 2BL and 3DL were mapped for chlorosis, necrosis and pycnidia while the other two on 1BS and 3AS were associated with necrosis and pycnidia. Among the four identified QTL, genes were identified in three QTL (1BS, 2BL and 3DL). In total, 238 differentially expressed genes (DEGs) were localized in 1BS, 16 DEGs in 2BL and 80 DEGs in 3DL QTL region respectively. F-box protein, NBS-LRR disease resistance genes and receptor-like protein kinase were the most over-represented. The results emphasize the importance of integrating QTL and transcriptome analysis to accelerate the identification of key genes underlying the traits of interest.

Highlights

Septoria tritici blotch(STB), caused by the ascomycete fungus Zymoseptoria tritici, is currently one of the most devastating foliar diseases on wheat crops globally
STB has a prolonged symptomless phase of up to three weeks following infection and sudden switch to symptomatic phase leading to leaf chlorosis which develops into necrotic irregularly-shaped blotches in which fungal asexual sporulation structures develop [5,6]
Integrating analysis of linkage and putative genes responsible for resistance can facilitate the improvement of wheat through the mapping and putative genes responsible for resistance can facilitate the improvement of wheat identification and utilization of molecular markers for effective marker-assisted selection [27]

Summary

Introduction

Septoria tritici blotch(STB), caused by the ascomycete fungus Zymoseptoria tritici ( known as Mycosphaerella graminicola), is currently one of the most devastating foliar diseases on wheat crops globally. STB is a major concern among European wheat producers, especially in humid, temperate areas, such as north-western Europe [1]. In Europe, airborne ascospores of Z. tritici discharged from either distant or local infected wheat debris and deposited in young wheat plants in the fall are the primary source of STB [2]. STB has a prolonged symptomless phase of up to three weeks following infection and sudden switch to symptomatic phase leading to leaf chlorosis which develops into necrotic irregularly-shaped blotches in which fungal asexual sporulation structures (pycnidia) develop [5,6]

Objectives

Methods

Results

Conclusion