Exploring and Mobilizing the Gene Bank Biodiversity for Wheat Improvement

Abstract

Identifying and mobilizing useful genetic variation from germplasm banks to breeding programs is an important strategy for sustaining crop genetic improvement. The molecular diversity of 1,423 spring bread wheat accessions representing major global production environments was investigated using high quality genotyping-by-sequencing (GBS) loci, and gene-based markers for various adaptive and quality traits. Mean diversity index (DI) estimates revealed synthetic hexaploids to be genetically more diverse (DI= 0.284) than elites (DI = 0.267) and landraces (DI = 0.245). GBS markers discovered thousands of new SNP variations in the landraces which were well known to be adapted to drought (1273 novel GBS SNPs) and heat (4473 novel GBS SNPs) stress environments. This may open new avenues for pre-breeding by enriching the elite germplasm with novel alleles for drought and heat tolerance. Furthermore, new allelic variation for vernalization and glutenin genes was also identified from 47 landraces originating from Iraq, Iran, India, Afghanistan, Pakistan, Uzbekistan and Turkmenistan. The information generated in the study has been utilized to select 200 diverse gene bank accessions to harness their potential in pre-breeding and for allele mining of candidate genes for drought and heat stress tolerance, thus channeling novel variation into breeding pipelines. This research is part of CIMMYT’s ongoing ‘Seeds of Discovery’ project visioning towards the development of high yielding wheat varieties that address future challenges from climate change.

Mining Centuries Old In situ Conserved Turkish Wheat Landraces for Grain Yield and Stripe Rust Resistance Genes

“…Superior selections from the landraces have been identified with high yield at individual sites and across three locations, with high expression of spike productivity traits. The average diversity index (DI) of the landrace panel investigated in the study was 0.260; close to the value reported for landraces from Afghanistan and India (DI = 0.266 for both) but less than that of Iraq and Pakistan (DI = 0.340 and 0.300, respectively) using GBS markers (Sehgal et al, 2015). The panel was found to be structured broadly into two subpopulations; bread ( T. aestivum ssp.…”

“…Ltd., Yarralumla, Australia. The detailed protocol is described in Sehgal et al (2015). A consensus map version 3.0 developed by DArT Pty Ltd. (http://www.diversityarrays.com/sequence-maps) was provided as part of the service which contained ~64 K GBS markers and 4000 DArTs as anchored markers.…”

Strategic crossing of biomass and harvest index—source and sink—achieves genetic gains in wheat

“…Several hundred landraces were selected for superior yield and biomass. Some of these were identified by the Focused Identification of Germplasm Strategy (FIGS) (Sehgal et al 2015).…”

“…Yield gains are achieved through unspecified recombination of genes of minor effect when elite lines are intercrossed, as well as the introgression of new genetic diversity from landraces or wild relatives (Braun et al 2010), typically as sources of disease resistance and grain quality traits (Ortiz et al 2008;Sehgal et al 2015). Additional information about candidate parents can help design more complementary crosses.…”

Genetic Diversity, Population Structure, and Linkage Disequilibrium of a Core Collection of Ziziphus jujuba Assessed with Genome-wide SNPs Developed by Genotyping-by-sequencing and SSR Markers

“…It is also relevant for genetic diversity and population structure analyses (Burrell et al, 2015; Kujur et al, 2015; Sehgal et al, 2015). GBS technology was recently used to develop SNP markers, which were then used to construct a jujube genetic map (Zhang et al, 2016).…”