Development of an Australian Bread Wheat Nested Association Mapping Population, a New Genetic Diversity Resource for Breeding under Dry and Hot Climates.

Charity Chidzanga,Melissa Garcia,Ute Baumann,Peter Langridge,Delphine Fleury,Priyanka Kalambettu,Sayuri Watanabe,Dan Mullan,Debbie Wong,James Edwards,Ken Chalmers,Robert Pontre,Kerrie Forrest

doi:10.3390/ijms22094348

Charity Chidzanga, Melissa Garcia + Show 11 more

Open Access

https://doi.org/10.3390/ijms22094348

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Abstract

Genetic diversity, knowledge of the genetic architecture of the traits of interest and efficient means of transferring the desired genetic diversity into the relevant genetic background are prerequisites for plant breeding. Exotic germplasm is a rich source of genetic diversity; however, they harbor undesirable traits that limit their suitability for modern agriculture. Nested association mapping (NAM) populations are valuable genetic resources that enable incorporation of genetic diversity, dissection of complex traits and providing germplasm to breeding programs. We developed the OzNAM by crossing and backcrossing 73 diverse exotic parents to two Australian elite varieties Gladius and Scout. The NAM parents were genotyped using the iSelect wheat 90K Infinium SNP array, and the progeny were genotyped using a custom targeted genotyping-by-sequencing assay based on molecular inversion probes designed to target 12,179 SNPs chosen from the iSelect wheat 90K Infinium SNP array of the parents. In total, 3535 BC1F4:6 RILs from 125 families with 21 to 76 lines per family were genotyped and we found 4964 polymorphic and multi-allelic haplotype markers that spanned the whole genome. A subset of 530 lines from 28 families were evaluated in multi-environment trials over three years. To demonstrate the utility of the population in QTL mapping, we chose to map QTL for maturity and plant height using the RTM-GWAS approach and we identified novel and known QTL for maturity and plant height.

Highlights

The expression of most traits of agronomic importance in crop species vary in degree and are determined by the cumulative effect of multiple interacting genetic loci and the environment [1]
We present phenotypic best linear unbiased predictors (BLUPs) and genome‐wide association mapping (GWAS) results from a subset of the OzNAM population field trialled at four sites over a three‐year period across the Australian wheat belt
Exotic germplasm carries a range of undesired traits, which limit their suitability for modern agriculture

Summary

Introduction

The expression of most traits of agronomic importance in crop species vary in degree and are determined by the cumulative effect of multiple interacting genetic loci and the environment [1]. The underlying genetic loci for quantitative traits can be dissected through QTL mapping to provide valuable insights into the genetic architecture of these traits [2]. Understanding the genetic architecture of quantitative traits such as yield is important in the development of improved crop varieties [3]. In the development of bi‐parental mapping populations, the number of recombination events is limited, and the amount of genetic diversity is restricted to that which is present in the two parents [5]. QTL mapping in bi‐parental populations, successful in detecting numerous QTL in various crops [6,7,8,9], is constrained by low resolution, lack of genetic diversity and potentially an inability to detect the same QTL in other germplasm

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Conclusion