Systematic Analysis of the Maize OSCA Genes Revealing ZmOSCA Family Members Involved in Osmotic Stress and ZmOSCA2.4 Confers Enhanced Drought Tolerance in Transgenic Arabidopsis

Abstract

OSCAs are hyperosmolality-gated calcium-permeable channel proteins. In this study, two co-expression modules, which are strongly associated with maize proline content, were screened by weighted correlation network analysis, including three ZmOSCA family members. Phylogenetic and protein domain analyses revealed that 12 ZmOSCA members were classified into four classes, which all contained DUF221 domain. The promoter region contained multiple core elements responsive to abiotic stresses and hormones. Colinear analysis revealed that <i>ZmOSCAs</i> had diversified prior to maize divergence. Most <i>ZmOSCAs</i> responded positively to ABA, PEG, and NaCl treatments. <i>ZmOSCA2.3</i> and <i>ZmOSCA2.4</i> were up-regulated by more than 200-fold under the three stresses, and showed significant positive correlations with proline content. Yeast two-hybrid and bimolecular fluorescence complementation indicated that ZmOSCA2.3 and ZmOSCA2.4 proteins interacted with ZmEREB198. Over-expression of <i>ZmOSCA2.4</i> in <i>Arabidopsis</i> remarkably improved drought resistance. Moreover, over-expression of <i>ZmOSCA2.4</i> enhanced the expression of drought tolerance-associated genes and reduced the expression of senescence-associated genes. We also found that perhaps <i>ZmOSCA2.4</i> was regulated by miR5054.The results provide a high-quality molecular resource for selecting resistant breeding, and lay a foundation for elucidating regulatory mechanism of <i>ZmOSCA</i> under abiotic stresses.