A Calmodulin-Binding Protein from Rice is Essential to Pollen Development

A pollen-expressed gene from rice, OsPCBP, that was previously cloned and identified encodes a novel calmodulin-binding protein. Here, we investigated its functioning in pollen development. Overexpression of OsPCBP in transgenic rice plants did not lead to phenotypic changes but did delay anther formation by about 1 week. Cytological observations at different stages revealed that microspores from the OsPCBP double-stranded RNA interference plants developed normally until the binucleate stage, but about half were later aborted. Meanwhile, the anther microstructure of those plants was unaffected. Further examination of OsPCBP expression in transgenic lines via RT-PCR showed that a significant reduction in transcripts was correlated with this abortion phenotype. Our experimental results provide convincing evidence that OsPCBP protein plays an important role during the late stage of pollen development.