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Developmental gene families have diversified during land plant evolution. The primary role of YABBY gene family is promoting abaxial fate in model eudicot, Arabidopsis thaliana. However recent results suggest that roles of YABBY genes are not conserved in the angiosperms. In this paper, a rice YABBY gene was isolated, and its expression patterns were analyzed in detail. Sequence characterization and phylogenetic analyses showed the gene is OsYABBY4, which is group-classified into FIL/YAB3 subfamily. Beta-glucuronidase reporter assay and in situ analysis consistently revealed that OsYABBY4 was expressed in the meristems and developing vascular tissue of rice, predominantly in the phloem tissue, suggesting that the function of the rice gene is different from those of its counterparts in eudicots. OsYABBY4 may have been recruited to regulate the development of vasculature in rice. However, transgenic Arabidopsis plants ectopically expressing OsYABBY4 behaved very like those over-expressing FIL or YAB3 with abaxialized lateral organs, suggesting the OsYABBY4 protein domain is conserved with its Arabidopsis counterparts in sequences. Our results also indicate that the functional diversification of OsYABBY4 may be associated with the divergent spatial–temporal expression patterns, and YABBY family members may have preserved different expression regulatory systems and functions during the evolution of different kinds of species. [ABSTRACT FROM AUTHOR]

Lectin plays an important role in defense signaling in plants, but its function in plant growth and development is not well known. Previously, we cloned a rice ( Oryza sativa L.) gene OsJAC1 encoding a mannose-binding jacalin-related lectin, and found that OsJAC1 was jasmonic acid (JA) inducible. Here we cloned the promoter of OsJAC1, and GUS activity was detected in young roots, coleoptiles, sheaths, leaves, nodes of stems, stems, rachises, pistils, stamens and lemmas of OsJAC1::GUS transgenic rice, suggesting that OsJAC1 is a constitutive expression gene in rice. Moreover, OsJAC1-overexpressed ( Ubi::OsJAC1) rice showed dwarfism with shorter coleptiles resulting from the failure of cell elongation of coleoptiles. In addition, compared with coleoptiles of wild-type plants, those of OsJAC1 overexpression rice were more sensitive to JA treatment. These data revealed that, besides its roles in defense response, lectin plays an important role in rice growth and development. [ABSTRACT FROM AUTHOR]

Heterotrimeric G proteins are known to function as messengers in numerous signal transduction pathways. The null mutation of RGA (rice heterotrimeric G protein α subunit), which encodes the α subunit of heterotrimeric G protein in rice, causes severe dwarfism and reduced responsiveness to gibberellic acid in rice. However, less is known about heterotrimeric G protein in brassinosteroid (BR) signaling, one of the well-understood phytohormone pathways. In the present study, we used root elongation inhibition assay, lamina inclination assay and coleoptile elongation analysis to demonstrated reduced sensitivity of d1 mutant plants (caused by the null mutation of RGA) to 24-epibrassinolide (24-epiBL), which belongs to brassinosteroids and plays a wide variety of roles in plant growth and development. Moreover, RGA transcript level was decreased in 24-epiBL-treated seedlings in a dose-dependent manner. Our results show that RGA is involved in rice brassinosteroid response, which may be beneficial to elucidate the molecular mechanisms of G protein signaling and provide a novel perspective to understand BR signaling in higher plants.Cell Research (2006) 16: 916–922. doi: 10.1038/sj.cr.7310111; published online November 21 2006 [ABSTRACT FROM AUTHOR]

Little systematic analysis has been undertaken in rice (Oryza sativaL.) on the stages of male meiosis from leptotene to telophase II or of pollen development from microspores to mature pollen grains. The present study describes multiple stages in detail from analysis of rice chromosome spreading with staining of 4′,6-diamidino-2-phenylindole. The description of normal wild-type male meiosis provides an important morphological reference for analyses of meiotic mutants. Meiosis in rice is largely similar to those of the well characterizing model plantsArabidopsis thalianaL. andZea maysL. However, rice meiosis differs from that inArabidopsisin that rice meiosis I is followed by the formation of a cell plate, instead of an organelle band that forms between the two nuclei and persist through meiosis II. This suggests a difference in the control of organelle biogenesis and distribution and cytokinesis. Our results should facilitate studies of rice meiosis and pollen development using molecular genetic and cell biological approaches. [ABSTRACT FROM AUTHOR]

Abstract AtFPF1 (FLOWERING PROMOTING FACTOR 1) is a gene that promotes flowering in Arabidopsis. An expression vector containing AtFPF1 driven by a Ubi-1 promoter was constructed. The gene was introduced into rice callus by Agrobacterium-mediated transformation and fertile plants were obtained. The presence of AtFPF1 in rice plants was confirmed by PCR, Southern and Northern blot analyses, as well as by -glucuronidase assay. The results showed that, as in Arabidopsis, AtFPF1 reduced flowering time in rice. Furthermore, introduction of AtFPF1 enhanced adventitious root formation but inhibited root growth in rice during the seedling stage. The results suggest that AtFPF1 promotes flowering time in both dicots and monocots, and plays a role in the initiation of adventitious roots in rice. [ABSTRACT FROM AUTHOR]

Abstract A gain-of-function Arabidopsis mutant was identified via activation tagging genetic screening. The mutant exhibited clustered ectopic floral buds on the surface of inflorescence stems. The mutant was designated as sef for stem ectopic flowers. Our detailed studies indicate that the ectopic flower meristems are initiated from the differentiated cortex cells. Inverse PCR and sequence analysis indicated that the enhancer-containing T-DNA from the activation tagging construct, SKI015, was inserted upstream of the previously cloned WUS gene encoding a homeodomain protein. Studies from RT-PCR, RNA in situ hybridization and transgenic plant analysis further confirmed that the phenotypes of sef are caused by the overexpression of WUS. Our results suggest that overexpression of WUS could trigger the cell pluripotence and reestablish a new meristem in cortex. The type of new meristems caused by WUS overexpression was dependent upon the developmental and physiological stages of a plant. With the help of some undefined factors in the reproductive organs the new meristems differentiated into floral buds. In a vegetative growth plant, however, only the new vegetative buds can be initiated upon the overexpression of WUS. These studies provide new insights of WUS on flower development. [ABSTRACT FROM AUTHOR]

A vernalization-related gene VER2 was isolated from winter wheat (Triticum aestivum L.) using a differential screening approach. The deduced VER2 is a lectin-like protein of 300 amino acids, which contains the presence of a jacalin-like GWG domain. RNA in situ hybridization results demonstrated that VER2 gene expression is restricted to the marginal meristems of immature leaves in vernalized wheat seedlings. No hybridization signal was detected in the epidermal tissue and vascular bundles. However, "devernalization" resulted in the silencing of VER2 gene activity. The gene expression pattern of VER2 induced by jasmonate was similar to that induced by vernalization. Antisense inhibition of VER2 in transgenic wheat showed that heading and maturation time were delayed up to 6 weeks compared with non-transformed wheat and the pBI121empty-vector-transformed wheat. Tissue degeneration at the top of the spike was also noticed in the antisense inhibited transgenic wheat. These results suggest that VER2 plays an important role in vernalization signaling and spike development in winter wheat. [ABSTRACT FROM AUTHOR]