Rice anther tapetum; a vital reproductive cell layer for sporopollenin biosynthesis and pollen exine patterning.

Tapetum is the innermost layer among the four layers of rice anther that provides protection and essential nutrients to pollen grains development and delivers precursor for pollen exine formation. Tapetum has a key role in the normal development of pollen grains and tapetal programmed cell death (PCD) that is linked with sporopollenin biosynthesis and its transportation. Recently, dozens of genes have been identified that are involved in the tapetum formation in rice and Arabidopsis. Genetic mutation in PCD associated genes could affect normal tapetal PCD which finally leads to aborted pollen grains and male sterility in rice. In this review, we discussed the most updated research progress on rice tapetum development which includes genomic, transcriptomic and proteomic level studies. Furthermore, tapetal PCD, sporopollenin biosynthesis, ROS activity for tapetum function and its role in male reproductive development are discussed in detail. It will improve our understanding of the role of tapetum in male fertility of using rice as a model system and its associated information applied in rice hybridization for other major crops.