TheYABBYGeneDROOPING LEAFRegulates Carpel Specification and Midrib Development inOryza sativa [W]

Abstract

In this article, we report that carpel specification in the Oryza sativa (rice) flower is regulated by the floral homeotic gene DROOPING LEAF (DL) that is distinct from the well-known ABC genes. Severe loss-of-function mutations of DL cause complete homeotic transformation of carpels into stamens. Molecular cloning reveals that DL is a member of the YABBY gene family and is closely related to the CRABS CLAW (CRC) gene of Arabidopsis thaliana. DL is expressed in the presumptive region (carpel anlagen), where carpel primordia would initiate, and in carpel primordia. These results suggest that carpel specification is regulated by DL in rice flower development. Whereas CRC plays only a partial role in carpel identity, DL may have been recruited to have the more essential function of specifying carpels during the evolution of rice. We also show that DL interacts antagonistically with class B genes and controls floral meristem determinacy. In addition, severe and weak dl alleles fail to form a midrib in the leaf. The phenotypic analysis of dl mutants, together with analyses of the spatial expression patterns and ectopic expression of DL, demonstrate that DL regulates midrib formation by promoting cell proliferation in the central region of the rice leaf.

Genetic modification of plant architecture and variety improvement in rice

“…In maize, two YABBY genes are expressed on the adaxial side of the leaf, suggesting that YABBY genes may direct lateral outgrowth rather than determine cell fate (Juarez et al, 2004b). Consistent with this view, mutations in the rice YABBY gene DROOPING LEAF resulted in defects in midrib formation, possibly owing to reduced cell division (Yamaguchi et al, 2004). Cosuppression of the YABBY transcription factor YAB1 expression induces a rolled-leaf phenotype, but the midrib seems to be normal (Dai et al, 2007).…”

The AGL6-like gene OsMADS6 regulates floral organ and meristem identities in rice

“…OsMADS13 and OsMADS21 are grouped as D class genes on the basis of their expression pattern and functional analyses [22]. More interestingly, another C-function gene, DROOPING LEAF (DL), orthologous to Arabidopsis gene, CRABS CLAW (CRC), encoding a YABBY domain protein in rice has been identified, playing roles in carpel specification, floral meristem determinacy and the antagonistic function with class B genes [23]. Rice has diverse SEP-like genes, with at least five members in the genome [24].…”

Dynamic Cytology and Transcriptional Regulation of Rice Lamina Joint Development

“…Four C2C2-YABBY genes, DROOPING LEAF (Os03g11600), OsYABBY3 (Os04g45330), OsYABBY4 (Os02g42950), and OsYABBY1 (Os07g06620), which are reported to regulate midrib formation, lateral organ development, vascular development, and leaf angle (Dai et al, 2007;Liu et al, 2007;Tanaka et al, 2012;Yamaguchi et al, 2004), display rapid down-regulation from stage 2 to stage 4 (C1 and C2 patterns) and may regulate early lamina joint development and organogenesis. MYB members show dramatic changes from stage 2 to stage 4 (17 genes with the C1 pattern and eight genes with the C5 pattern), suggesting their potential roles in secondary cell wall synthesis in early lamina joint development and stress tolerance at later stages (Yang et al, 2014;Zhu et al, 2015).…”