Khaoula El Hassouni
Filippo M. Bassi
Angéla Juhász, Edith Cowan UniversityFollow
Jason A. Able
Kai P. Voss-Fels
Lee T. Hickey
Frontiers Media SA
School of Science
SA was supported by Monsanto’s Beachell-Borlaug International Scholars Program (MBBISP) Iowa, the United States and a Ph.D. scholarship from The University of Queensland, Australia (UQRS). LH was supported through an Early Career Discovery Research Award (DE170101296) from the Australian Research Council. Genotyping was supported by the Food and Agriculture Organization (FAO; Grant LoA/TF/W3B-PR-02/JORDAN/2016/AGDT).
The optimal root system architecture (RSA) of a crop is context dependent and critical for efficient resource capture in the soil. Narrow root growth angle promoting deeper root growth is often associated with improved access to water and nutrients in deep soils during terminal drought. RSA, therefore is a drought-adaptive trait that could minimize yield losses in regions with limited rainfall. Here, GWAS for seminal root angle (SRA) identified seven marker-trait associations clustered on chromosome 6A, representing a major quantitative trait locus (qSRA-6A) which also displayed high levels of pairwise LD (r2 = 0.67). Subsequent haplotype analysis revealed significant differences between major groups. Candidate gene analysis revealed loci related to gravitropism, polar growth and hormonal signaling. No differences were observed for root biomass between lines carrying hap1 and hap2 for qSRA-6A, highlighting the opportunity to perform marker-assisted selection for the qSRA-6A locus and directly select for wide or narrow RSA, without influencing root biomass. Our study revealed that the genetic predisposition for deep rooting was best expressed under water-limitation, yet the root system displayed plasticity producing root growth in response to water availability in upper soil layers. We discuss the potential to deploy root architectural traits in cultivars to enhance yield stability in environments that experience limited rainfall.
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