Abstract:

Lespedeza potaninii is one of the most drought tolerant Lespedeza species and widely distributed in arid, semi-arid and desert grassland. It is an ideal model plant used for the investigating the individual variation of drought tolerant at single nucleotide polymorphisms (SNP) level. In the present study, the drought tolerant candidate gene LpDREB was cloned from five provenances of L. potaninii by chromosome walking method. The organ-and inducible-expression patterns of the LpDREB gene were also investigated. Furthermore, the gene structure and phylogeny, and SNP type and distribution were characterized. The results indicated that the full length cDNA sequence of LpDREB gene was 1 611 bp containing a 957 bp open reading frame (ORF) which encodes a 318 amino acid residues with a highly conserved DREBP/AP2 domain. Phylogeny analysis revealed that the LpDREB gene had a closest evolutionary relationship with soybean GmDREB 3 gene in terms of high similarity in the common conserved region. Expression of the LpDREB gene was induced by drought stress and varied in different organs with the highest expression level in roots followed by leaves and stems. In the L. potaninii populations, 23 SNPs were detected. Among them four located in promoter and 5' non-coding regions, and 17 were distributed in the coding region, and two in 3' non-coding region. A total of 12 SNPs were in transitions, while 11 SNPs were in transversions. For 17 SNPs in the coding region, 9 were synonymous mutation and 8 were non-synonymous mutations, with a ratio of 1.1. This study paved a foundation for association analysis with drought tolerant candidate genes in L. potaninii at SNP level.

Key words: Lespedeza potaninii, LpDREB gene, inducible expression, sequence analysis, single nucleotide polymorphism