Abstract
The shoot apical meristem (SAM) is responsible for the morphogenetic events in plants. In order to understand the mechanisms underlie the SAM formation and organization, we tried to isolate two genes named SHOOT ORGANIZATION1 (SHO1) and SHOOTLESS2 (SHL2) from seedling lethal and embryo lethal mutants, sho1 and shl2, respectively. Defects in sho1 mutant include abnormal leaf shape, short plastochron, and irregular phyllotaxis, and those defects are supposed to be caused by flattened shape of sho1 SAM. shl2 lacks SAM during embryogenesis. Recently, weak alleles of shl2 were isolated and those showed quite similar phenotypes to sho1. This indicates that SHO1 and SHL2 could act in the same pathway in the SAM formation or the organization. Map based cloning of these genes revealed that both genes encode proteins related to RNAi interference (RNAi) pathway. This result suggests that genes related to RNAi mechanisms regulate the shoot formation and organization in rice.
