Overexpression of the calcium-dependent protein kinase OsCDPK2 in transgenic rice is repressed by light in leaves and disrupts seed development

Independent transgenic rice lines overexpressing the rice CDPK isoform OsCD PK2 were generated by particle bombardment. High levels of OsCDPK2 were det ected in leaves removed from etiolated plants, as well as in stems and flow ers. However, there was no overexpression in green leaves that had been exp osed to light, confirming that OsCDPK2 protein stability was subject to lig ht regulation. The morphological phenotype of transgenic plants producing h igh levels of recombinant OsCDPK2 was normal until the onset of seed develo pment. Flowers developed normally, producing well-shaped ovaries and stigma s, and mature anthers filled with pollen grains. However, seed formation in these plants was strongly inhibited, with only 3-7% of the flowers produci ng seeds. Seed development was arrested at an early stage. We discuss these data with respect to the possible requirement for specific CDPK isoforms d uring rice seed development.