Genotypic variation for cellular thermotolerance in Aegilops tauschii Coss., the D genome progenitor of wheat

Abstract

Heat stress is a major productivity lowering factor in wheat. Wild progenitor species offer a wide spectrum of adaptation traits and can serve as valuable donors of stress tolerance. In the present study, genetic variation in 129 accessions of Aegilops tauschii Coss., the D genome donor of wheat, was evaluated for two heat tolerance related traits viz., cell membrane stability (CMS) and TTC (2,3,5-Triphenyl tetrazolium chloride) based cell viability. Cell membrane stability in the Ae. tauschii accessions at vegetative stage ranged from 15.24 to 80.39%. Nineteen Ae. tauschii accessions were superior to the tolerant bread wheat control (C 273). At anthesis stage a similar spectrum of variation was observed with twenty three accessions showing higher cell membrane stability than C 273. The average CMS level of entire germplasm set at anthesis (47.61%) was lower than at vegetative stage (58.89%). Clear genotypic differences were also observed for TTC based cell viability test. Ae. tauschii accessions displayed a range from 18.73 to 84.39% with eight genotypes excelling over tolerant bread wheat. Correlation of CMS values recorded at two stages was significant but of low predictive value (r 2 = 0.137). Similarly significant but moderate correlation was obtained between CMS and TTC test (r 2 = 0.325). Consequently all the three parameters were used to derive a cell thermotolerance index which was in turn used to identify ten tolerant Ae. tauschii genotypes. The identified accessions were re-evaluated for 1 more year and the three parameters viz., CMS at vegetative (r 2 = 0.954) and anthesis stage (r 2 = 0.932) and TTC cell viability at vegetative stage (r 2 = 0.888) showed high correlation Strategy for use of identified accessions as donors is discussed.

Bread wheat progenitors: Aegilops tauschii (DD genome) and Triticum dicoccoides (AABB genome) reveal differential antioxidative response under water stress

“…Aegilops tauschii accession 3769 had displayed highest SOD and CAT activity under rain-fed conditions, with lower membrane injury at tillering stage. It was also identified as a heat tolerant genotype in the study of Gupta et al (2010). Higher activity of antioxidant enzymes like SOD, APX, DHAR, MDHAR, GR and CAT has been reported in tolerant genotypes of wheat (Sairam et al 1997, 1998, Almeselmani et al 2006.…”

Marker‐assisted backcross breeding for improvement of drought tolerance in bread wheat (Triticum aestivum L. em Thell)

“…There are numerous reports on molecular markers linked with expression of QTLs at a phenotypic level for drought tolerance (Gupta et al., , ; Pinto et al., ), but their deployment in wheat‐breeding programmes is still rare. Examples of successful use of MABB in cereals including barley, rice and maize for biotic and abiotic stress tolerance are available, but most of wheat‐breeding projects in countries like Canada, USA, Australia, India and CIMMYT, Mexico are focussed on simple traits like pest resistance, disease resistance and quality traits (Gupta, Kaur, Sehgal, Sharma, & Chhuneja, ). It is hard to see that any research efforts or documentation is available on marker‐assisted backcross breeding for the transfer of identified and mapped quantitative trait loci for drought stress tolerance in wheat.…”

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

“…tauschii and Ae. geniculata have been identified to be highly thermotolerant (Ehdaie and Waines 1992;Waines 1994;Khanna-Chopra and Viswanathan 1999;Zaharieva et al 2001;Gupta et al 2010;Pradhan et al 2012). The evaluation of wild Triticum and Aegilops species at our institute also led to the identification of Ae.…”

“…Genetic variation for heat tolerance and associated traits and identification of donor germplasm are an essential prerequisite for breeding for heat-tolerant crops. Cultivated germplasm however would be the preferred donor option, keeping in view the ease of subsequent utilization (Gupta et al 2010), but limited variability presents a major bottleneck. The wild germplasm, on the other hand, owing to its diverse ecogeographical distribution and adaptation to various stress prone environments, may have novel and yet untapped genetic variability.…”