Identification of a Pm4 Allele as a Powdery Mildew Resistance Gene in Wheat Line Xiaomaomai.

Danyu Yao,Shihe Xiao,Xiaolan Wen,Dan Qiu,Wentao Peng,Guozhong Sun,Hongjie Li,Juan Wang,Jinghuang Hu,Waqas Ijaz,Yi Liu,Bowen Zhang

doi:10.3390/ijms23031194

Abstract

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most destructive foliar diseases of wheat. In this study, we combined the bulked segregant RNA sequencing (BSR-seq) and comparative genomics analysis to localize the powdery mildew resistance gene in Chinese landrace Xiaomaomai. Genetic analysis of F1 plants from a crossing of Xiaomaomai × Lumai23 and the derived F2 population suggests that a single recessive gene, designated as pmXMM, confers the resistance in this germplasm. A genetic linkage map was constructed using the newly developed SNP markers and pmXMM was mapped to the distal end of chromosome 2AL. The two flanking markers 2AL15 and 2AL34 were closely linked to pmXMM at the genetic distance of 3.9 cM and 1.4 cM, respectively. Using the diagnostic primers of Pm4, we confirmed that Xiaomaomai carries a Pm4 allele and the gene function was further validated by the virus-induced gene silencing (VIGS). In addition, we systematically analyzed pmXMM in comparison with the other Pm4 alleles. The results suggest that pmXMM is identical to Pm4d and Pm4e at sequence level. Pm4b is also not different from Pm4c according to their genome/amino acid sequences. Only a few nucleotide variances were detected between pmXMM and Pm4a/b, which indicate the haplotype variation of the Pm4 gene.

Highlights

This study suggests that Pm4 is a powdery mildew resistance gene valuable for developing future disease-resistant wheat cultivars
Forty Blumeria graminis f. sp. tritici (Bgt) isolates collected from the northern part of China were used to examine the virulence spectrum of Xiaomaomai together with the wheat cultivars carrying Pm4a, Pm4b, and Pm4c (Supplementary Table S1)
BSR-Seq analysis demonstrated that powdery mildew in Chinese landrace

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Wheat (Triticum aestivum L.) is one of the most widely grown food crops worldwide. Its stable yield plays an important role in food security. Powdery mildew, caused by Blumeria graminis f. Tritici (Bgt), is one of the most devastating foliar diseases of wheat. The most efficient and environmentally safe approach to counteract epidemics of powdery mildew is to breed disease-resistant cultivars in production. Most of powdery mildew resistance (R) genes are race-specific which confer strong immunity to some but not all of the pathogen races.

Methods

Results

Conclusion