Identification of Resistant Germplasm and Detection of Genes for Resistance to Powdery Mildew and Leaf Rust from 2,978 Wheat Accessions

Abstract

Powdery mildew and leaf rust, caused by Blumeria graminis f. sp. tritici (Bgt) and Puccinia triticina (Pt), respectively, are widespread diseases of wheat worldwide. Utilizing resistant cultivars is considered as the most economical, environmental-friendly, and effective method to control these diseases. In the present study, a collection of 2,978 wheat accessions consisting of 1,394 advanced breeding lines, 1,078 Chinese cultivars, 291 introduced cultivars, 132 lines containing alien chromosomes, and 83 landraces was tested for reactions to powdery mildew and leaf rust. The results indicated that 659 (22.1%) wheat accessions were highly resistant to a widely prevalent Bgt isolate, E09, at the seedling stage, and 390 were consistently resistant to the mixture of Bgt isolates at the adult-plant stage. Meanwhile, 63 (2.1%) accessions were highly resistant to leaf rust at the adult-plant stage, of which 54 were resistant to a predominant and highly virulent Pt race, THTT, at the seedling stage. Notably, 17 accessions were resistant to both powdery mildew and leaf rust. To detect known genes for resistance to powdery mildew and leaf rust, these accessions were tested with gene-specific or tightly linked markers for seven Pm genes (Pm2, Pm4, Pm5, Pm6, Pm8, Pm21, and Pm24) and ten Lr genes (Lr1, Lr9, Lr10, Lr19, Lr20, Lr24, Lr26, Lr34, Lr37, and Lr46). Of the 659 powdery mildew-resistant accessions, 328 might carry single Pm genes and 191 carry combined Pm genes. Pm2 was detected at the highest frequency of 59.6%, followed by Pm8, Pm6, Pm21, Pm4, and Pm5, while Pm24 was not detected. Besides, 139 accessions might contain unknown Pm genes different from those tested in this study. In the 63 accessions resistant leaf rust, four Lr genes (Lr1, Lr10, Lr26, and Lr34) were detected in 41 accessions either singly or in combination, while six genes (Lr9, Lr19, Lr20, Lr24, Lr37, and Lr46) were not detected. Twenty-two accessions might contain unknown Lr genes different from those tested in this study. This study not only provided important information for rationally distributing resistance genes in wheat breeding programs, but also identified resistant germplasm that might have novel genes to enrich the diversity of resistance sources.

Genetic basis analysis of key Loci in 23 Yannong series wheat cultivars/lines

“…Further sequencing analysis showed that their sequences were same with cloned Pm2. It is likely that there is only one resistant haplotype at Pm2 locus in hexaploid wheat (Jin et al, 2021;Yu et al, 2022)…”

Mining of Wheat Pm2 Alleles for Goal-Oriented Marker-Assisted Breeding

“…For each population, equal amounts of gDNAs from 10 random homozygous resistant and 10 random homozygous susceptible F 2:3 families were pooled to construct resistant and susceptible DNA bulks, respectively. The Pm2 -linked marker Cfd81 ( Ma et al, 2016 ) and the Pm2 -diagnostic marker Pm2b-map-3 ( Jin et al, 2021 ) were tested for polymorphisms between the resistant and susceptible parents and bulks. The polymorphic markers were genotyped on the corresponding F 2:3 families.…”

Identification of the Powdery Mildew Resistance in Chinese Wheat Cultivar Heng 4568 and its Evaluation in Marker-Assisted Selection

“…Forty-eight molecular markers closely linked to 37 known Pm genes were firstly screened for their polymorphisms between Heng 4568, Daimai 2173, and their derived resistant and susceptible bulks ( Supplementary Table S1 ). When the Pm gene in Heng 4568 was preliminarily to Pm2 locus, other Pm2 linked markers Cfd81 , Bwm20 , Bwm21 , Bwm25 , and Swgi067 ( Lu et al, 2015 ; Ma et al, 2018 ) and the diagnostic marker Pm2b-map-3 ( Jin et al, 2021 ) were also used to add the marker density for conducting the linkage map ( Supplementary Table S2 ). PCR was performed in a 10-μl reaction volume containing 1 µl of 40–50 ng/μl template genomic DNA, 4.5 µl of 2×Taq Master Mix (Vazyme, China), and 0.5 µl of 10 μM/μl primer mix.…”