The rice narrow leaf2 and narrow leaf3 loci encode WUSCHEL-related homeobox 3 A ( Os WOX3 A) and function in leaf, spikelet, tiller and lateral root development.

In order to understand the molecular genetic mechanisms of rice ( Oryza sativa) organ development, we studied the narrow leaf2 narrow leaf3 ( nal2 nal3; hereafter nal2/3) double mutant, which produces narrow-curly leaves, more tillers, fewer lateral roots, opened spikelets and narrow-thin grains., We found that narrow-curly leaves resulted mainly from reduced lateral-axis outgrowth with fewer longitudinal veins and more, larger bulliform cells. Opened spikelets, possibly caused by marginal deformity in the lemma, gave rise to narrow-thin grains., Map-based cloning revealed that NAL2 and NAL3 are paralogs that encode an identical Os WOX3 A ( Os NS) transcriptional activator, homologous to NARROW SHEATH1 ( NS1) and NS2 in maize and PRESSED FLOWER in Arabidopsis. Os WOX3 A is expressed in the vascular tissues of various organs, where nal2/3 mutant phenotypes were displayed. Expression levels of several leaf development-associated genes were altered in nal2/3, and auxin transport-related genes were significantly changed, leading to pin mutant-like phenotypes such as more tillers and fewer lateral roots., Os WOX3 A is involved in organ development in rice, lateral-axis outgrowth and vascular patterning in leaves, lemma and palea morphogenesis in spikelets, and development of tillers and lateral roots. [ABSTRACT FROM AUTHOR]