Abstract
Biological nitrogen fixation (BNF) is a key process, but despite the economic and environmental importance, few studies about quantitative trait loci (QTL) controlling BNF traits are available, even in the economically important crop soybean Glycine max (L.) Merr. In this study, a population of 157 F2:7 RILs derived from crossing soybean cultivars Bossier (high BNF capacity) and Embrapa 20 (medium BNF capacity) was genotyped with 105 simple sequence repeat markers (SSRs). The genetic map obtained has 1231.2 cM and covers about 50% of the genome, with an average interval of 18.1 cM. Three traits, nodule number (NN), the ratio nodule dry weight (NDW)/NN and shoot dry weight (SDW) were used to evaluate BNF performance. A composite interval mapping for multiple traits method (mCIM) analysis mapped two QTLs for SDW (LGs E and L), three for NN (LGs B1, E and I), and one for NDW/NN (LG I); all QTLs were of small effect (R-values ranging from 1.7% to 10.0%) and explained 15.4%, 13.8% and 6.5% of total variation for these three traits, respectively.
Highlights
Biological nitrogen fixation (BNF) is a key process, but despite the economic and environmental importance, few studies about quantitative trait loci (QTL) controlling BNF traits are available, even in the economically important crop soybean Glycine max (L.) Merr
A composite interval mapping for multiple traits method analysis mapped two QTLs for shoot dry weight (SDW) (LGs E and L), three for nodule number (NN) (LGs B1, E and I), and one for nodule dry weight (NDW)/NN (LG I); all QTLs were of small effect (R2-values ranging from 1.7% to 10.0%) and explained 15.4%, 13.8% and 6.5% of total variation for these three traits, respectively
Negative correlations were verified between NN and NDW/NN
Summary
Biological nitrogen fixation (BNF) is a key process, but despite the economic and environmental importance, few studies about quantitative trait loci (QTL) controlling BNF traits are available, even in the economically important crop soybean Glycine max (L.) Merr. The BNF results from the symbiosis between legumes with a diverse group of nitrogen fixing soil bacteria collectively known as rhizobia. This association is mutually beneficial: while bacteria provide a source of nitrogen to plant development, plants provide carbon sources for maintaining bacteria metabolism. The elicitation and the development of an effective nodule are accompanied by the expression of specific genes in both rhizobia and their host-plants.
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