Adaptive Traits to Improve Durum Wheat Yield in Drought and Crown Rot Environments

Abstract

Durum wheat (Triticum turgidum L. ssp. durum) production can experience significant yield losses due to crown rot (CR) disease. Losses are usually exacerbated when disease infection coincides with terminal drought. Durum wheat is very susceptible to CR, and resistant germplasm is not currently available in elite breeding pools. We hypothesize that deploying physiological traits for drought adaptation, such as optimal root system architecture to reduce water stress, might minimize losses due to CR infection. This study evaluated a subset of lines from a nested association mapping population for stay-green traits, CR incidence and yield in field experiments as well as root traits under controlled conditions. Weekly measurements of normalized difference vegetative index (NDVI) in the field were used to model canopy senescence and to determine stay-green traits for each genotype. Genome-wide association studies using DArTseq molecular markers identified quantitative trait loci (QTLs) on chromosome 6B (qCR-6B) associated with CR tolerance and stay-green. We explored the value of qCR-6B and a major QTL for root angle QTL qSRA-6A using yield datasets from six rainfed environments, including two environments with high CR disease pressure. In the absence of CR, the favorable allele for qSRA-6A provided an average yield advantage of 0.57 t·ha−1, whereas in the presence of CR, the combination of favorable alleles for both qSRA-6A and qCR-6B resulted in a yield advantage of 0.90 t·ha−1. Results of this study highlight the value of combining above- and belowground physiological traits to enhance yield potential. We anticipate that these insights will assist breeders to design improved durum varieties that mitigate production losses due to water deficit and CR.

Wheat root systems as a breeding target for climate resilience

“…First identified by GWAS of seminal root phenotype in elite germplasm (Sanguineti et al 2007 ; Canè et al 2014 ), and subsequently validated on the whole root system under field conditions (Maccaferri et al 2016 ; Fig. 2 ), the effect of this QTL on root angle and agronomic performance was further validated in a durum NAM population (Alahmad et al 2019 , 2020 ) and via GWAS conducted with Ethiopian durum accessions (Alemu et al 2021 ). A recent use of GWAS for analysis of root traits in bread wheat is reported by Voss-Fels et al ( 2017 ), who identified two epistatic loci on chromosome 5B controlling root biomass.…”

Wheat Breeding through Genetic and Physical Mapping

“…A QTL for CR tolerance and stay-green was detected on chromosome 6B (qCR-6B) with a major QTL for root angle on 6A (qSRA-6A) detected using yield datasets from six rainfed environments, including two environments with high CR disease pressure. Results of this study highlight the value of combining above-and belowground physiological traits to enhance wheat yield potential [9].…”

“…A study of the incidence of crown rot (CR) on yield in field experiments as well as root traits under controlled conditions was reported by Alahmad et al [9]. Researchers identified quantitative trait loci (QTLs) through a GWAS (Genome Wide Association Study) using DArTseq markers.…”

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

“…The NAM design for QTL mapping was developed in maize [ 176 , 177 ] and later applied to other crops including soybean [ 178 ], sorghum [ 179 ], barley [ 180 ], bread wheat [ 181 ], and durum wheat [ 182 , 183 , 184 ].…”