Transfer and mapping of the heat tolerance component traits of Aegilops speltoides in tetraploid wheat Triticum durum

Abstract

Aegilops speltoides is an important genetic resource for wheat improvement and has high levels of heat tolerance. A heat-tolerant accession of Ae. speltoides pau3809 was crossed with Triticum durum cv. PDW274, and BC 2 F 4-6 backcross introgression lines (BILs) were developed, phenotyped for important physiological traits, genotyped using SSR markers and used for mapping the QTL governing heat tolerance component traits. A set of 90 BILs was selected from preliminary evaluation of a broader set of 262 BILs under heat stress. Phenotyping was conducted for physiological traits such as cell membrane thermostability, chlorophyll content, acquired thermotolerance, canopy temperature and stay green. Much variation for these traits was observed in random as well as selected sets of BILs, and comparison of the BILs with the recurrent parent showed improvement for these traits under normal as well as heat stress conditions, indicating that introgressions from Ae. speltoides might have led to the improvement in the heat tolerance potential of the BILs. Introgression profiling of the 90 BILs using SSR markers identified Ae. speltoides introgression on all the 14 chromosomes with introgressions observed on A as well as B genome chromosomes. QTL mapping identified loci for various heat tolerance component traits on chromosomes 2B, 3A, 3B, 5A, 5B and 7A at significant LOD scores and with phenotypic contributions varying from 11.1 to 28.7 % for different traits. The heattolerant BILs and QTL reported in the present study form a potential resource that can be used for wheat germplasm enhancement for heat stress tolerance.

Characterization and Mapping of Spot Blotch in Triticum durum–Aegilops speltoides Introgression Lines Using SNP Markers

“…pau3809 were backcrossed for two generations with T. durum and selfed to generate BC 2 F 10 introgression lines (DSBILs). Details of development of material can be retrieved from Awlachew et al (2016).…”

QTL mapping for stripe rust and powdery mildew resistance in Triticum durum–Aegilops speltoides backcross introgression lines

“…speltoides accession #pau3809 were used in the study. Details of the development of the DS-BILs can be found in Awlachew et al (2016). Ae.…”

“…Kishii (2019) has compiled a list of genes identified or transferred from various Aegilops species, including Aegilops speltoides , which have been the sources of leaf rust resistance genes ( Lr28 , Lr35 , Lr36 , Lr37 , Lr47 , Lr51 and Lr66 ), stem rust resistance genes ( Sr32 , Sr39 and Sr47 ), powdery mildew resistance genes ( Pm1d , Pm12 , Pm32 and Pm53 ) and green bug resistance gene ( Gb5 ). Apart from disease resistance, Aegilops species have been reported to possess resistance to abiotic stresses like heat, salinity and drought tolerance (Monneveux et al ., 2000; Colmer et al ., 2006; Rawat et al ., 2008; Liu et al ., 2015; Awlachew et al ., 2016).…”

A strategy of ideotype development for heat‐tolerant wheat

“…A key component of adaptation to high temperatures is matching phenology to the environment, thus avoiding high temperatures during reproductive development (Ludwig & Asseng, ; Mondal et al, ). Genotypes with cooler canopies also tend to yield more under high temperatures through heat avoidance (Pinto et al, , ; Rebetzke, Rattey, Farquhar, Richards, & Condon, ; Reynolds, Mujeeb‐Kazi, & Sawkins, ), and stay‐green enhances late‐season photosynthetic capacity and ultimately yield (Awlachew, Singh, Kaur, Bains, & Chhuneja, ; Christopher, Manschadi, Hammer, & Borrell, ; Pinto, Lopes, Collins, & Reynolds, ). Chlorophyll content and normalized difference in vegetation index (NDVI) have been used to indirectly select heat‐tolerant wheat material with stay‐green characteristics (Lopes & Reynolds, ; Reynolds et al, ).…”