Abstract
Water and nutrient acquisition is a critical function of plant root systems. Root system architecture (RSA) traits are often complex and controlled by many genes. This is the first genome-wide association study reporting genetic loci for RSA traits for field-grown soybean (Glycine max). A collection of 289 soybean genotypes was grown in three environments, root crowns were excavated, and 12 RSA traits assessed. The first two components of a principal component analysis of these 12 traits were used as additional aggregate traits for a total of 14 traits. Marker–trait association for RSA traits were identified using 31,807 single-nucleotide polymorphisms (SNPs) by a genome-wide association analysis. In total, 283 (non-unique) SNPs were significantly associated with one or more of the 14 root traits. Of these, 246 were unique SNPs and 215 SNPs were associated with a single root trait, while 26, four, and one SNPs were associated with two, three, and four root traits, respectively. The 246 SNPs marked 67 loci associated with at least one of the 14 root traits. Seventeen loci on 13 chromosomes were identified by SNPs associated with more than one root trait. Several genes with annotation related to processes that could affect root architecture were identified near these 67 loci. Additional follow-up studies will be needed to confirm the markers and candidate genes identified for RSA traits and to examine the importance of the different root characteristics for soybean productivity under a range of soil and environmental conditions.
Highlights
Survival and performance of plants depend on efficient exploration of the soil in search for available water and nutrients (Gruber et al, 2013)
Other traits associated with the Upper Primary Lateral Root Number (UPLN), including Upper Secondary Lateral Root Density (USLD), Upper Primary Lateral Root Angle Average (ULAA), and Upper Primary Lateral Angle Range (UPAR) exhibited large genotypic differences in each environment
Substantial heritability for some Root system architecture (RSA) traits of field-grown soybean reveals promise for breeding, and numerous genetic loci were uncovered for all traits
Summary
Survival and performance of plants depend on efficient exploration of the soil in search for available water and nutrients (Gruber et al, 2013). Roots are often referred to as the “hidden half ” of the plant yet are critically important (Waisel et al, 2002). RSA varies within and among species due to genetics yet displays phenotypic plasticity in Soybean Root Architecture Loci response to the environment (Lynch, 1995). Root system characteristics largely have been ignored by plant breeders and were not targeted as selection criteria as part of the 1960’s green revolution. Understanding RSA holds promise for the discovery, manipulation, and exploitation of root characteristics to both increase plant yield and optimize agricultural land use (Waines and Ehdaie, 2007; Den Herder et al, 2010)
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