Sugarcane calcineurin B-like ( CBL ) genes play important but versatile roles in regulation of responses to biotic and abiotic stresses

Free calcium ions are common second messengers in plant cells. The calcineurin B-like protein (CBL) is a special calcium sensor that plays an important role in plant growth and stress response. In this study, we obtained three CBL genes (GenBank accession nos. KX013374, KX013375, and KX013376) from sugarcane variety ROC22. The open reading frames of ScCBL genes ranged from 642 to 678 base pairs in length and encoded polypeptides from 213 to 225 amino acids in length. ScCBL2-1, ScCBL3-1, and ScCBL4 were all located in the plasma membrane and cytoplasm. ScCBL2-1 and ScCBL3-1 expression was up-regulated by treatment with salicylic acid (SA), methyl jasmonate (MeJA), hydrogen peroxide (H2O2), polyethylene glycol (PEG), sodium chloride (NaCl), or copper chloride (CuCl2). ScCBL4 expression was down-regulated in response to all of these stresses (abscisic acid (ABA), SA, MeJA, and NaCl) except for H2O2, calcium chloride (CaCl2), PEG, and CuCl2. Expression in Escherichia coli BL21 cells showed that ScCBLs can enhance tolerance to NaCl or copper stress. Overexpression of ScCBLs in Nicotiana benthamiana leaves promoted their resistance to infection with the tobacco pathogen Ralstonia solanacearum. The results from the present study facilitate further research regarding ScCBL genes, and in particular, their roles in the response to various stresses in sugarcane.