The rice narrow leaf2 and narrow leaf3 loci encode WUSCHEL‐related homeobox 3A (OsWOX3A) and function in leaf, spikelet, tiller and lateral root development

Abstract

SummaryIn 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 OsWOX3A (OsNS) transcriptional activator, homologous to NARROW SHEATH1 (NS1) and NS2 in maize and PRESSED FLOWER in Arabidopsis. OsWOX3A 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 transportrelated genes were significantly changed, leading to pin mutant-like phenotypes such as more tillers and fewer lateral roots.OsWOX3A 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.

Rice WUSCHEL-related homeobox 3A (OsWOX3A) modulates auxin-transport gene expression in lateral root and root hair development

“…nal2/3 mutants produce narrow-curly leaves, more tillers, fewer lateral roots, opened spikelets and narrow-thin grains, indicating that OsWOX3A regulates development of several organs. Although we demonstrated the role of OsWOX3A in lateral root development, 3 its possible involvement in root hair development remained unclear. Thus, we examined the nal2/3 root hair phenotype to elucidate the specific role of OsWOX3A in root organ development.…”

“…WOX genes are well-known developmental regulators; there are 14 Arabidopsis and 12 rice WOX family members, 3 and some of these WOX genes play important roles in regulating cell division and differentiation during root system development in both monocot and dicot plants. For example, in Arabidopsis, WOX2 and WOX8 regulate cell fates during basal embryonic root formation.…”

“…7 Our recent study demonstrated that OsWOX3A regulates the development of lateral roots, but not adventitious roots. 3 The OsWOX3A transcriptional activator contains a WUS homeodomain and a WUS-box domain, homologous to NARROW SHEATH 1 (NS1) and NS2 in maize and PRESSED FLOWER (PRS) in Arabidopsis. 3 OsWOX3A is encoded by duplicated genes, NAL2 and NAL3 (hereafter NAL2/3).…”

“…3 The OsWOX3A transcriptional activator contains a WUS homeodomain and a WUS-box domain, homologous to NARROW SHEATH 1 (NS1) and NS2 in maize and PRESSED FLOWER (PRS) in Arabidopsis. 3 OsWOX3A is encoded by duplicated genes, NAL2 and NAL3 (hereafter NAL2/3). nal2/3 mutants produce narrow-curly leaves, more tillers, fewer lateral roots, opened spikelets and narrow-thin grains, indicating that OsWOX3A regulates development of several organs.…”

Characterization and gene cloning of the rice (Oryza sativa L.) dwarf and narrow-leaf mutant dnl3

“…This contrasts with the basis of the narrow-leaf phenotype of the Arabidopsis thaliana ANGUSTIFOLIA mutant, which is caused by a reduced cell size without any decrease in cell number (Tsuge et al, 1996). In the rice nal2 and nal3 mutants, the number of large leaf veins is marginally lower than in the WT, while the number of small ones is reduced by almost 50% (Cho et al, 2013). The dnl3 mutant exhibited a significant decrease in the number of small vascular bundles.…”