Abstract
The shoot apical meristem (SAM) is responsible for the morphogenetic events in plants. In order to understand the mechanisms underlie SAM formation, we have isolated SHOOTLESS4 (SHL4) gene from an embryo lethal mutant, shl4. shl4 lacks SAM and coleoptile, but radicle and scutellum form normally during embryogenesis. Map based cloning of SHL4 revealed that it encodes proteins related to RNAi interference (RNAi). Next, we investigated the expression of SHL4 by in situ hybridization. SHL4 is expressed at the several cells of the outermost layer of the globular embryo, which are flanked by a future region of SAM as indicated by the expression of a marker of SAM region, OSH1. In the vegetative stage, SHL4 is expressed at the outermost layer of SAM and at the adaxial tip of leaf primordia. Based on these observations, we will discuss the function of SHL4 in SAM formation and maintenance.
