Abstract
KNOX genes play an important role in formation and maintenance of the shoot apical meristem (SAM), and their ectopic expression in leaf results in its abnormal morphology. Thus, the SAM-specific expression of KNOX genes is essential for normal development of plants. To understand the mechanism we identified and analysed a rice mutant resembling KNOX-overexpressors. The mutant knox leaf expression1 (kle1) showed ectopic expression of KNOX genes and produced very small shoot. kle1 was seedling-lethal and showed defects in SAM maintenance and leaf morphology. KLE1 was shown to encode a fatty acid elongase similar to Arabidopsis FIDDLEHEAD. KLE1 was specifically expressed in an L1 layer of shoot during embryo, vegetative and reproductive development. These results suggest that KLE1 regulates shoot development by controlling fatty acid composition of an L1 layer and that a signal, which controls shoot development, might be transmitted from an L1 layer to inner cells.
