Abstract
BackgroundRoot system architecture is important for water acquisition and nutrient acquisition for all crops. In soybean breeding programs, wild soybean alleles have been used successfully to enhance yield and seed composition traits, but have never been investigated to improve root system architecture. Therefore, in this study, high-density single-feature polymorphic markers and simple sequence repeats were used to map quantitative trait loci (QTLs) governing root system architecture in an inter-specific soybean mapping population developed from a cross between Glycine max and Glycine soja.ResultsWild and cultivated soybean both contributed alleles towards significant additive large effect QTLs on chromosome 6 and 7 for a longer total root length and root distribution, respectively. Epistatic effect QTLs were also identified for taproot length, average diameter, and root distribution. These root traits will influence the water and nutrient uptake in soybean. Two cell division-related genes (D type cyclin and auxin efflux carrier protein) with insertion/deletion variations might contribute to the shorter root phenotypes observed in G. soja compared with cultivated soybean. Based on the location of the QTLs and sequence information from a second G. soja accession, three genes (slow anion channel associated 1 like, Auxin responsive NEDD8-activating complex and peroxidase), each with a non-synonymous single nucleotide polymorphism mutation were identified, which may also contribute to changes in root architecture in the cultivated soybean. In addition, Apoptosis inhibitor 5-like on chromosome 7 and slow anion channel associated 1-like on chromosome 15 had epistatic interactions for taproot length QTLs in soybean.ConclusionRare alleles from a G. soja accession are expected to enhance our understanding of the genetic components involved in root architecture traits, and could be combined to improve root system and drought adaptation in soybean.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1334-6) contains supplementary material, which is available to authorized users.
Highlights
Root system architecture is important for water acquisition and nutrient acquisition for all crops
The recombinant inbred lines (RILs) developed from these two parents showed a transgressive segregation for root morphology (Figure 2): many genotypes had longer or shorter taproots and varied total root length compared with the G. max and wild parent, respectively (Table 1)
Most of the previous mapping works in root studies focused on coarse/thicker roots; understanding the finer roots and their distribution are important, because they are the ones involved in nutrient and water absorption by increasing the root surface area
Summary
Root system architecture is important for water acquisition and nutrient acquisition for all crops. Wild soybean alleles have been used successfully to enhance yield and seed composition traits, but have never been investigated to improve root system architecture. In China, the cultivated soybean was domesticated from wild soybean more than 5,000 years ago [1] and underwent two rounds of whole genome duplication [2]. The first genome duplication occurred within the last 60 million years and the latter between 5 and 13 million years ago Both G. soja and Glycine max have prominent differences for various morphological and physiological characters, known as domestication syndrome [3]. The genetic diversity among 99% of North American cultivars released between 1947 and 1988 could be traced back to only 0.02% of the landraces [1] This loss in diversity among high-yielding adapted lines inhibits
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