NHX1 Gene in Sugarcane cv. KPS94-13 and Wild Sugarcane and Gene Expression Pattern in Mimicking Saline Soil

Abstract

Saline soil affects both plant growth and productivity especially sugarcane which is an economic crop but sensitive to saline soil. One of sugarcane breeding program’s goals is to improve salt tolerance in sugarcane cultivars. The objectives of this research were to clone and identify the NHX1 gene from a commercial sugarcane cv. KPS94-13 and wild sugarcane, and to study the expression pattern of the genes in salt stress condition. It was found that the full length of the gene was 1,623 bp. The comparison of the sequence to nucleotide data base of GenBank found that the sequence was similar to that of NHX1 gene of many monocotlydon plants. We named the sequence cloned from KPS 94-13 and wild sugarcane as SoNHX1KPS and SsNHX1WT, respectively. The sequence encoded a polypeptide of 540 amino acid residues. There were 5 amino acid residues difference between the amino acid sequences deduced from the genes of the two sugarcane species. The phylogenetic tree analysis indicated that the SoNHX1KPS and SsNHX1WT were closely related to AtNHX1. The analysis of hydrophobicity found 11 transmembrane domains in both polypeptide sequences. Gene expression study of NHX1 in the two kinds of sugarcane used in this experiment revealed that when subjected to 100 mM and 200 mM of NaCl for 5 days the expression patterns of the NHX1 gene depended on the concentrations of NaCl. The expression levels of the gene in roots and leaves of wild sugarcane were higher than those of KPS94-13 and the expression levels of the gene in leaves were higher than those in roots.