A secreted chitinase-like protein (OsCLP) supports root growth through calcium signaling in Oryza sativa.

Chitinases belong to a conserved protein family and play multiple roles in defense, development and growth regulation in plants. Here, we identified a secreted chitinase-like protein, OsCLP, which functions in rice growth. A T-DNA insertion mutant of OsCLP (osclp) showed significant retardation of root and shoot growth. A comparative proteomic analysis was carried out using root tissue of wild-type and the osclp mutant to understand the OsCLP-mediated rice growth retardation. Results obtained revealed that proteins related to glycolysis (phosphoglycerate kinase), stress adaption (chaperonin) and calcium signaling (calreticulin and CDPK1) were differentially regulated in osclp roots. Fura-2 molecular probe staining, which is an intracellular calcium indicator, and inductively coupled plasma-mass spectrometry (ICP-MS) analysis suggested that the intracellular calcium content was significantly lower in roots of osclp as compared with the wild-type. Exogenous application of Ca2+ resulted in successful recovery of both primary and lateral root growth in osclp. Moreover, overexpression of OsCLP resulted in improved growth with modified seed shape and starch structure; however, the overall yield remained unaffected. Taken together, our results highlight the involvement of OsCLP in rice growth by regulating the intracellular calcium concentrations.