Harnessing genetic potential of wheat germplasm banks through impact-oriented-prebreeding for future food and nutritional security

Abstract

The value of exotic wheat genetic resources for accelerating grain yield gains is largely unproven and unrealized. We used next-generation sequencing, together with multi-environment phenotyping, to study the contribution of exotic genomes to 984 three-way-cross-derived (exotic/elite1//elite2) pre-breeding lines (PBLs). Genomic characterization of these lines with haplotype map-based and SNP marker approaches revealed exotic specific imprints of 16.1 to 25.1%, which compares to theoretical expectation of 25%. A rare and favorable haplotype (GT) with 0.4% frequency in gene bank identified on chromosome 6D minimized grain yield (GY) loss under heat stress without GY penalty under irrigated conditions. More specifically, the ‘T’ allele of the haplotype GT originated in Aegilops tauschii and was absent in all elite lines used in study. In silico analysis of the SNP showed hits with a candidate gene coding for isoflavone reductase IRL-like protein in Ae. tauschii. Rare haplotypes were also identified on chromosomes 1A, 6A and 2B effective against abiotic/biotic stresses. Results demonstrate positive contributions of exotic germplasm to PBLs derived from crosses of exotics with CIMMYT’s best elite lines. This is a major impact-oriented pre-breeding effort at CIMMYT, resulting in large-scale development of PBLs for deployment in breeding programs addressing food security under climate change scenarios.

Elucidating the genetic basis of biomass accumulation and radiation use efficiency in spring wheat and its role in yield potential

“…In the last decades, exotic parents have been used in breeding programmes with the aim of introducing greater diversity into elite gene pools (Singh et al, 2018). The exotic parents that are most frequently used are those from the primary gene pool represented by germplasm that share a common genome but that have become isolated from mainstream gene pools such as landraces (Reynolds et al, 2009a,b), which have been shown to be not only genetically, but epigenetically diverse (Gardiner et al, 2018).…”

Assessing the Potential of Extra-Early Maturing Landraces for Improving Tolerance to Drought, Heat, and Both Combined Stresses in Maize

“…These landrace accessions should be further explored to identify the genes underlying their high tolerance and they could be exploited in maize breeding as a resource for broadening the genetic base and increasing the abiotic stress resilience of elite maize varieties.Agronomy 2020, 10, 318 2 of 23 and preserved in germplasm banks for avoiding the threat of extinction due to adoption of modern varieties or hybrids [3]. Historically, maize breeders identified and composited the most productive of these landraces to generate genetically diverse populations, constituting the foundation of hybrid maize breeding and developing open-pollinated varieties (OPVs) that displayed high yielding with tolerance to biotic and abiotic stresses [4,5].Nonetheless, nowadays breeders are generally reluctant to use landraces because of the long-term commitment required to identify useful, novel diversity and introgress it into well-adapted elite cultivars while reducing the effects of undesired linked genes [6]. Breeders often resort to their own working collection consisting of elite breeding lines and some germplasm lines as parents in crossing, resulting in recirculating of the same germplasm.…”

“…Nonetheless, nowadays breeders are generally reluctant to use landraces because of the long-term commitment required to identify useful, novel diversity and introgress it into well-adapted elite cultivars while reducing the effects of undesired linked genes [6]. Breeders often resort to their own working collection consisting of elite breeding lines and some germplasm lines as parents in crossing, resulting in recirculating of the same germplasm.…”

Origin Specific Genomic Selection: a simple process to optimize the favourable contribution of parents to progeny

“…The application of OSGS could be extended to multi-parental crosses using predictions based on identity-by-descent relationships due to originating parents. Multi-parent populations based on two or more elite lines and a single exotic parent are already in use in pre-breeding (Hao et al 2019; Singh et al 2018). There is a strong risk that phenotypic or genomic selection in these populations will discriminate against favourable alleles carried by the exotic parent to an even greater extent than we have shown in bi-parental populations (see also simulations by Gorjanc et al 2016).…”