Comparative expression analysis of heavy metal ATPase subfamily genes between Cd-tolerant and Cd-sensitive turnip landraces

Yuansheng Wu; Xiong Li; Di Chen; Xi Han; Boqun Li; Yonghong Yang; Yongping Yang

doi:10.1016/j.pld.2019.02.001

Comparative expression analysis of heavy metal ATPase subfamily genes between Cd-tolerant and Cd-sensitive turnip landraces

Plant Divers. 2019 Mar 4;41(4):275-283. doi: 10.1016/j.pld.2019.02.001. eCollection 2019 Aug.

Authors

Yuansheng Wu^{1

2}, Xiong Li^{1

3}, Di Chen^{1

4}, Xi Han², Boqun Li^{1

3}, Yonghong Yang², Yongping Yang^{1

3}

Affiliations

¹ China Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.
² College of Plant Protection, Yunnan Agricultural University, Kunming 650201, China.
³ Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.
⁴ School of Life Sciences, Yunnan University, Kunming 650091, China.

Abstract

The heavy metal ATPase (HMA) subfamily is mainly involved in heavy metal (HM) tolerance and transport in plants, but an understanding of the definite roles and mechanisms of most HMA members are still limited. In the present study, we identified 14 candidate HMA genes named BrrHMA1-BrrHMA8 from the turnip genome and analyzed the phylogeny, gene structure, chromosome distribution, and conserved domains and motifs of HMAs in turnip (Brassica rapa var. rapa). According to our phylogenetic tree, the BrrHMAs are divided into a Zn/Cd/Co/Pb subclass and Cu/Ag subclass. The BrrHMA members show similar structural characteristics within subclasses. To explore the roles of BrrHMAs in turnip, we compared the gene sequences and expression patterns of the BrrHMA genes between a Cd-tolerant landrace and a Cd-sensitive landrace. Most BrrHMA genes showed similar spatial expression patterns in both Cd-tolerant and Cd-sensitive turnip landraces; some BrrHMA genes, however, were differentially expressed in specific tissue in Cd-tolerant and Cd-sensitive turnip. Specifically, BrrHMA genes in the Zn/Cd/Co/Pb subclass shared the same coding sequence but were differentially expressed in Cd-tolerant and Cd-sensitive turnip landraces under Cd stress. Our findings suggest that the stable expression and up-regulated expression of BrrHMA Zn/Cd/Co/Pb subclass genes under Cd stress may contribute to the higher Cd tolerance of turnip landraces.

Keywords: CK, control blank; Cadmium; Differential gene expression; GPI, germination percentage index; GRAVY, grand average of hydropathicity; HM, heavy metal; HMA, heavy metal ATPase; Heavy metal ATPase; MW, molecular weight; SSI, seedling survival index; Transmembrane helix; Turnip; pI, isoelectric point.