Identification and Expression under Salt Stress of NHXs in Brassica napus L.

  Objective  Members of the Na+/H+ antiporter (NHX) family in Brassica napus L. were identified, and genes related to salt stress screened.

  Methods  The genome of B. napus cv. Zhongshuang 11 was used to obtain the candidate genes, and NHXs sequences by homologous alignment. Physicochemical properties, evolutionary relationship, and expressions under salt stress of the genes were analyzed.

  Results  Twenty-one BnNHXs were identified with 71 to 1265 amino acids, an isoelectric (pI) ranging from 5.54 to 7.68, and 0 to 24 introns. Among the BnNHXs, BnNHX1 was in the plasma membrane, BnNHX5 and BnNHX12 in the cell and vacuole membranes, and the remainders in the vacuole only. Phylogenetically, NHXs could be divided into 3 subfamilies scattered on 11 chromosomes containing a variety of abiotic stress response elements. The qRT-PCR expressions on most BnNHXs were upregulated under salt stress, with overall higher expression in the leaves than in the roots. Notably, BnNHX2, BnNHX6, BnNHX8, BnNHX11, and BnNHX19 had relatively more pronounced changes in the expression.

  Conclusion  Five NHXs, namely, BnNHX2, BnNHX6, BnNHX8, BnNHX11, and BnNHX19, could be the candidate genes for breeding salt-tolerant new varieties as well as for studying molecular mechanisms of rapeseed.