Identification of a Putative Causal Gene of Salinity Tolerance in Soybean.

摘要

Whole genome sequencing data was used to assist genetic studies of wild soybean in our laboratory. Previously 31 soybean germplasms were re-sequenced. Recently, the de novo sequencing of a wild soybean genome (W05) and also re-sequencing of a core panel of 96 recombinant inbred lines originated from a salt tolerant wild soybean (W05) and a salt sensitive cultivated soybean (C08) were completed. Using this information, a major salt tolerance locus spanning 978 Kb in the soybean genome was identified through QTL study of the RI population.;In my research, this salt tolerance locus was further narrowed down to 388 Kb through extreme groups analysis. The observation that W05 accumulated less Na+ in leaves than C08 prompted me to focus on genes within this locus that are related to ion transportation . Making use of the de novo assembled scaffolds of W05 that cover the salt tolerance locus, a gene encoding an ion transporter (GmCHX1) was detected in W05 and the corresponding gene in C08 was found to be disrupted by a retrotransposon. 3'RACE and real-time PCR suggested that C08 produced a putatively loss-of-function truncated variant of GmCHX1. The coding sequence of GmCHX1 was conserved in salt tolerant soybean germplasms, but not in the salt sensitive germplasms. Moreover, the expression of GmCHX1 was found to be higher in the salt tolerant germplasms than in the sensitive germplasms. Ectopic expression of GmCHX1 from W05 can alleviate salt stress as well as reduce Na+ accumulation in transgenic models. Together, the results strongly support that GmCHX1 as a major determinant of salt tolerance in the wild soybean W05.