Mechanisms of powdery mildew resistance of wheat – a review of molecular breeding

Abstract

Powdery mildew (Blumeria graminis f. sp. tritici) results in serious economic loss in wheat production. Exploration of plant resistance to wheat powdery mildew over several decades has led to the discovery of a wealth of resistance genes and quantitative trait loci (QTLs). We have provided a comprehensive summary of over 200 powdery mildew genes (permanently and temporarily designated genes) and QTLs reported in common bread wheat. This highlights the diverse and rich resistance sources that exist across all 21 chromosomes. To manage different data for breeders, here we also present a bridged mapping result from previously reported powdery mildew resistance genes and QTLs with the application of a published integrated wheat map. This will provide important insights to empower further breeding of powdery mildew resistant wheat via marker‐assisted selection (MAS).

Mapping Powdery Mildew (Blumeria graminis f. sp. tritici) Resistance in Wild and Cultivated Tetraploid Wheats

“…The explained genetic variance (R 2 ) of APR QTL was relatively small (range from 5.0% to 9.2%); similar values were reported in GWAS for stem rust [104,105,109] and powdery mildew [72,110,111]. The relatively high number of detected QTL for APR suggested that different mechanisms of PM resistance [17] could be involved in the diverse genetic background of the examined tetraploid wheat accessions.…”

“…In fact, 17 PM resistance genes have been already reported on chromosomes 2A, 2B, 3B, 4A, 5B, 6B and 7A of ssp. dicoccoides [17].…”

“…speltoides, Ae. ovata, or from more distant species, such Secale cereale and Dasypyrum villosum) to cultivated durum and bread wheat [17]. Ten PM resistance genes, all encoding the nucleotide binding sites and leucine-rich repeat (NBS-LRR) proteins, have been cloned to date: Pm3 [18], Pm38 [19], Pm8 [20], Pm46 [21], Pm2 [22], Pm21 [23][24][25], Pm17 [26], Pm60 [27], Pm5 [28], Pm24 [29] and Pm41 [30].…”

“…Quantitative resistance is usually analyzed by quantitative genetics methods, including estimating genetic components, heritability, and effective gene numbers. So far, several studies have mapped more than 100 QTL on all chromosomes [17], none of which have yet been cloned. The classical genetic analysis of quantitative traits is carried out on segregating biparental populations evaluated for the traits of interest and genotyped with DNA-based molecular markers.…”

From Genetic Maps to QTL Cloning: An Overview for Durum Wheat

“…Therefore, one of the most important purposes of breeding programs is to make resistant durum wheat. To achieve this goal, several studies, including a careful analysis of the environmental conditions that can influence the host–pathogen interactions, a study of the genetic and molecular interactions between the host and pathogen, and the search for new sources of resistance to be transferred in varieties, are required [ 93 ].…”