Genetic dissection of the powdery mildew resistance in wheat breeding line LS5082 using BSR-Seq

Powdery mildew of wheat is a destructive disease seriously threatening yield and quality worldwide.Comprehensive dissection of new resistance-related loci/genes is necessary to control this disease.LS5082 is a Chinese wheat breeding line with resistance to powdery mildew.Genetic analysis,using the populations of LS5082 and three susceptible parents(Shannong 29,Shimai 22 and Huixianhong),indicated that a single dominant gene,tentatively designated PmLS5082,conferred seedling resistance to different Blumeria graminis f.sp.tritici(Bgt)isolates.Bulked segregant RNA-Seq was carried out to map PmLS5082 and to profile differentially expressed genes associated with PmLS5082.PmLS5082 was mapped to a 0.7 cM genetic interval on chromosome arm 2BL,which was aligned to a 0.7 Mb physical interval of 710.3–711.0 Mb.PmLS5082 differs from the known powdery mildew(Pm)resistance genes on chromosome arm 2BL based on their origin,chromosome positions and/or resistance spectrum,suggesting PmLS5082 is most likely a new Pm gene/allele.Through clusters of orthologous groups and kyoto encyclopedia of genes and genomes analyses,differentially expressed genes(DEGs)associated with PmLS5082 were profiled.Six DEGs in the PmLS5082 interval were confirmed to be associated with PmLS5082 via qPCR analysis,using an additional set of wheat samples and time-course analysis postinoculation with Bgt isolate E09.Ten closely linked markers,including two kompetitive allele-specific PCR markers,were confirmed to be suitable for marker-assisted selection of PmLS5082 in different genetic backgrounds,thus can be used to detect PmLS5082 and pyramid it with other genes in breeding programs.

Lodging resistance and yield potential of winter wheat:effect of planting density and genotype

Improved lodging resistance is important for achieving high yield in irrigated environments.This study was conducted to determine genotypic variation in lodging resistance and related morphological traits among winter wheat cultivars planted at two densities,and to identify key traits associated with lodging resistance.Lodging performance of 28 genotypes,including 24 released cultivars and four advanced lines,was evaluated at 250 plants per square meter and 500 plants per square meter in Shandong province during the 2008–2009 and 2009–2010 crop seasons.At the higher density,the average grain yield was 2.6%higher,even though lodging score rose by as much as 136%.The higher planting density increased lodging through increased leaf area index(LAI),plant height,center of gravity and length of basal internodes,and reduced grain weight per spike and diameter of the lower two stem internodes.LAI,center of gravity and diameter of first internodes,as the important indicators for lodging resistance,were significantly correlated with lodging score,with R=0.62,0.59 and–0.52(P<0.01),respectively.Plant pushing resistance was significantly associated with diameter and length of the first internodes(R=0.71–0.77,P<0.01),indicating it could be used to assess the strength of the lower stem.Higher planting density could be used to select genotypes with lodging resistance in irrigated environments.Cultivars carrying high plant density tolerance and high yield potential,such as Jimai 22 and Liangxing 66,were recommended as leading cultivars for production as well as elite crossing parents for further increasing yield potential in the Yellow and Huai Valleys Winter Wheat Zone in China.