Rice Encoding A Pectate Lyase is Critical for Apical Panicle Development.

Panicle morphology is one of the main determinants of the rice yield. Panicle abortion, a typical panicle morphological defect results in yield reduction due to defective spikelet development. To further elucidate the molecular mechanism of panicle abortion in rice, a () mutant with transfer DNA (T-DNA) insertion showing severely aborted apical spikelets during panicle development was identified and characterized. The mutant showed obviously altered cell morphology and structure in the degenerated spikelet. Molecular genetic studies revealed that encodes a pectate lyase protein. Pectate lyase-specific activity of Rice panicle Bald Head 1 (RBH1) protein assay using polygalacturonic acid (PGA) as substrates illustrated that the enzyme retained a significant capacity to degrade PGA. In addition, immunohistochemical analysis showed that the degradation of pectin is inhibited in the mutant. Further analysis revealed that a significant increase in reactive oxygen species (ROS) level was found in degenerated spikelets. Taken together, our findings suggest that is required for the formation of panicle and for preventing panicle abortion.