OsPNH1 regulates leaf development and maintenance of the shoot apical meristem in rice

Abstract

SummaryThe Arabidopsis PINHEAD/ZWILLE (PNH/ZLL) gene is thought to play an important role in the formation of the shoot apical meristem (SAM) and in leaf adaxial cell speci®cation. To investigate the molecular mechanisms of rice development, we have isolated a rice homologue of PNH/ZLL, called OsPNH1. Around the SAM, OsPNH1 was strongly expressed in developing leaf primordia, speci®cally in the presumptive vascular domains, developing vascular tissues, a few cell-layers of the adaxial region, and future bundle sheath extension cells. In the SAM, only weak expression was observed in the central region, whereas strong expression was detected in the mid-vein region of leaf founder cells in the peripheral SAM domain. We produced transgenic rice plants containing the antisense OsPNH1 strand. The antisense OsPNH1 plants developed malformed leaves with an altered vascular arrangement and abnormal internal structure. These plants also formed an aberrant SAM with reduced KNOX gene expression. We examined the subcellular localization of the OsPNH1-GFP fusion protein and found that it was localized in the cytoplasm. On the basis of these observations, we propose that OsPNH1 functions not only in SAM maintenance as previously thought, but also in leaf formation through vascular development.

Overexpression analysis suggests that <i>FON2-LIKE CLE PROTEIN1</i> is involved in rice leaf development

“…2, A and D), which may result from enhanced cell proliferation caused by ectopic DL expression in the FCP1-OX shoots. In the wild-type shoot, FCP1 is expressed throughout the leaf primordia from the P1 to P3 stage, whereas both DL and OsPNH1 are expressed in specific and distinct regions from P1 to P4 (Nishimura et al, 2002;Ohmori et al, 2011;Yamaguchi et al, 2004). This spatiotemporally overlapping expression pattern between FCP1 and DL/OsPNH1 is consistent with the idea that FCP1 is likely to be involved in the regulation of both DL and OsPNH1 in wild type.…”

“…In the empty-vector control shoots, OsPNH1 was expressed in the presumptive region of vascular differentiation and the adaxial region of the leaf primordia (Fig. 2C), as previously described (Nishimura et al, 2002). By contrast, OsPNH1 expression in the FCP1-OX shoots was not detected in the leaf primordia except for weak expression in a narrow domain of the leaf center (Fig.…”

“…OsPNH1 is responsible for leaf development and meristem maintenance (Nishimura et al, 2002). In the empty-vector control shoots, OsPNH1 was expressed in the presumptive region of vascular differentiation and the adaxial region of the leaf primordia (Fig.…”

“…Next, we examined the expression patterns of two genes, DROOPING LEAF (DL) and OsPINHEAD1 (OsPNH1), that are expressed in leaf primordia (Nishimura et al, 2002;Ohmori et al, 2011;Yamaguchi et al, 2004). DL is required for midrib formation in the leaf and is expressed in the central region of the leaf primordium (Ohmori et al, 2011;Yamaguchi et al, 2004).…”

RNAi in Plants: An Argonaute-Centered View

“…Rice has one homolog of AGO10 that is strongly expressed in the provascular region of the leaf primordia around SAM and plays an important role in rice SAM maintenance and leaf development (Nishimura et al, 2002), suggesting a conserved function between Arabidopsis and rice AGO10s. It remains to be examined whether rice AGO10 also functions as a miRNA decoy.…”