Phylogeny and Evolution of Calcineurin B-Like (CBL) Gene Family in Grass and Functional Analyses of Rice CBLs

Calcium signals play critical functions in regulating diverse arrays of plant growth and development and mediating a variety of biotic and abiotic stress responses as a second messenger. Calcineurin B-like (CBL) proteins were involved with plant-specific Ca2+signaling as calcium sensors. In this work, we retrieved 152 CBL gene members from 15 different grass species, surveyed their phylogenetic relationships and sequence features and also performed expression patterns and functional analyses of rice CBLs. Phylogenetic analysis indicated that grass CBLs fall into four different groups (Group A–D). Sequence analysis showed that CBL proteins harboring four conserved calcium-binding EF-hand have key amino acid residues Asp and Glu which had relatively high proportion in the average abundance. Molecular evolutionary analyses revealed that group A, B and C CBLs in their evolution process suffered the purifying selection, while group D CBLs were subjected to positive selection. Moreover, expression analyses showed significant divergent expression patterns of OsCBLs in various organs and under different hormones and abiotic stresses. Furthermore, tolerance analysis revealed that OsCBL3 and OsCBL8 overexpression transgenic rice seedlings improved salt tolerance and OsCBL5, OsCBL6 and OsCBL7 positively regulated drought stress. In general, the domain and base sequence of the CBL gene family is highly conserved in grasses. OsCBL genes had specific gene expression profiles and function in different stresses.