Os07g0108900
The rice Os07g0108900 gene is reported as MADS-box transcription factor 15(OsMADS15).
Contents
Annotated Information
Function
The rice Os07g0108900 gene is reported as MADS-box transcription factor 15(OsMADS15). Rice OsMADS15 is a member of APETALA1/SQUAMOSA(AP1/SQUA) subfamily, which plays important roles in biological processes such as flowering time regulation, adventitious roots development, stem growth, reproductive development, crown root development and palea development[1]. The OsMADS15 is the ortholog of Arabidopsis AP1 gene. OsMADS15 function in tetramer complexes with OsMADS1, OsMADS8 and OsMADS14, as described in floral quartet model[2]. Rice seedlings overexpressing OsMADS15 showed precocious phenotypes of early internode elongation, shoot-borne crown root development, reduced plant height and early flowering. OsMADS15 interacts with OsMADS1 in yeast two-hybrid experiments[2].
OsMADS15 is required to ensure sexual reproduction in rice and mutations of it lead to the switch of reproductive habit from sexual to asexual in rice. Phylogenetic analyses have characterized OsMADS15 as an APETALA1 (AP1)/FRUITFUL (FUL)-like gene [3]. In addition, previous study has shown that OsMADS15 (RAP1A) RNA was expressed in the incipient floral primordium and later mainly accumulated in empty glumes, lemma, palea and lodicules [4]. The effects of OsMADS15 on cell specifications of all spikelet whorls were histologically examined. In a severely affected dep spikelet, the transformed palea was actually only composed of two PMTs while the PMS was completely lost . This implied that the identity of palea was lost in the dep spikelet with the severe phenotype. The lemma in the dep spikelet was also slightly affected, but its identity was still maintained . The glumes of dep spikelets contained many more bundles than the WT glumes, suggesting a possible partial reversion of glumes to leaf-like organs. No obvious difference was found in the inner three whorls, hinting that they are not affected by the mutation of OsMADS15. Thus, OsMADS15 is required for the specification of PMS and empty glumes.(Fig.1)
Expression
OsMADS15 was previously isolated through a large-scale cDNA analysis conducted by the Rice GenomeResearch Program (RGP). It is expressed in the apical region of the floral meristem at an early stage of spikelet development, and also expressed in developing lemma, palea and lodicules[2]. OsMADS15are expressed in the incipient floral primordium[5]. Transcripts of OsMADS1 and OsMADS15 are eventually accumulated in lemma and palea, suggesting that OsMADS1 and OsMADS15 might also be involved in the development of lemma and palea[6]. Rice seedlings overexpressing OsMADS15 showed precocious phenotypes of early internode elongation, shoot-borne crown root development, reduced plant height and early flowering, and Affected Panicle Development and Produced Ectopic Crown Root Growth.
1.Overexpression of OsMADS15 Decreased Tiller Number(Fig. 2).
2.Overexpression of OsMADS15 Accelerated Flowering(Fig. 3).
RT-PCR with the following primers: OsMADS15-F, 5- TCCGTCGACATGGGGCGGGGGAAGGTG-3; OsMADS15-R, 5- AATGGTACCTTAAGCATTGAGGTGGCTC-3[7].
Evolution
There are over 250,000 angiosperms extant today, and these plants have evolved a wide variety of flowers and inflorescences. Functional analyses by molecular genetic studies in model eudicots, such as Arabidopsis thaliana,have shown that transcription factors encoded by MADS-box genes are essential for the regulation of various aspects of flower development. It is of great interest to study MADS-box gene function in species distantly related to Arabidopsis, such as monocots, because the functional diversification of MADS-box genes has been proposed to be a major driving force behind floral diversity.
The monocots comprise about 50,000 species. A large number of MADS-box genes have been isolated in monocots and functional studies have been carried out. Most of these studies have focused mainly on the expression of genes homologous to the Arabidopsisgenes that specify organ identity. Genetic approaches, however, are now more powerful for elucidating the actual function of the genes thatregulate developmental processes. Indeed, much progress has been recently made in Oryza sativa (rice) and Zea mays(maize), two species of the grass family Poaceae, owing to the availability of genetic approaches. Rice has an additional advantage in evelopmental studies because the genetic transformation of rice is relatively easy and also facilitates the use ofreverse genetic studies. In addition, rice is the only grass plant whose genome has been fully sequenced, and a number of rice MADS-box genes have been isolated experimentally or identified from the DNA database[8] (Fig. 4). Thus, functional studies using loss-of-function mutants or transgenic plants have revealed many novel aspects of MADS-box gene function. 
Grass species have flowers and inflorescences that are highly distinct from those of eudicots. Furthermore, the flowers and inflorescences of rice and maize have also morphologically diversified to some degree. Thus, it is plausible that comparative studies between grasses and eudicots, and between rice and maize, may reveal clues to the diversification of both MADS-box gene function and developmental pathways during evolution.
The rice genome contains at least three AP1-like MADS-box genes, OsMADS14, OsMADS15,and OsMADS18 (also known as RAP1B, RAP1A,and OsMADS28, respectively), which are classified as a monocot-specific lineage of AP1-like genes[9][10] (Fig. 1). Of these, OsMADS14and OsMADS15 are classified as a pair of sister ubclasses, and OsMADS18 is classified as a relatively distant subclass of the monocot AP1-like gene family. It will be interesting to determine whether these genes have functions similar to those of the AP1-like genes in eudicots because the rice floret does not have obvious sepals and petals, but instead has a lemma, a palea, and lodicules.
OsMADS14 and OsMADS15 are initially expressed across the whole region of the floral meristem in flower development. Subsequently, the expression domains of these genes are restricted to the primordia of glumes, lemma, palea, and lodicules[10]. Thus, the expression patterns of OsMADS14 and OsMADS15 in rice are similar to that of AP1in Arabidopsis. Ectopic expression of OsMADS14 induces flower development from regenerated shoots at the early stages of development and, in an extreme case,directly from cells in the callus without vegetative growth[9]. This observation suggests that OsMADS14 is involved in promoting flowering and determining the identity of the floral meristem in rice. Studies on loss-of-function or gain-of-function mutants of OsMADS15 have not been reported so far. The functions of OsMADS15may differ from those of OsMADS14 and OsMADS18 because the expression pattern of OsMADS18 is different from those of OsMADS14and OsMADS15. OsMADS18 is expressed in roots, leaves, inflorescences, and flowers, and its expression levels reach a maximum when the plant reaches the reproductive stage. OsMADS18is expressed in all regions of the flower and its overexpression induces early flowering with accelerated development of the axillary shoot meristem. As a whole, the function of AP1-like MADS-box genes in rice is still unclear, as compared to other classes of MADS-box genes, probably owing to the lackof loss-of-function analysis and to the genetic redundancy of these genes.
Mutation
Single amino acid mutation disrupted the transcriptional activation of OsMADS15 in DEP mutant and caused shrunken paleas.DEP mutant was caused by a genetic alteration in OsMADS15. A single nucleotide G to C substitution at position 94 in coding region was found in the first exon of the OsMADS15. This substitution results in a change from a MADS-box conserved alanine residue to proline. Mutations of them lead to the switch of reproductive habit from sexual to asexual in rice. Paleas in severe DEP florets degenerated to glume-like organs that were prone to splitting.
The premier used in this mutation experiment[11]: 
Labs working on this gene
College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China. Patrick S. Schnable, Iowa State University, United States of America.
References
- ↑ Lu Sunjie; Wang Huimei, Yang Ruifang, Zhang Xiaobo, Tu Jumin, 2013.Screening of Rice OsMADS15 Interacting Proteins by Yeast Two Hybrid System,Journol of Agricultural Biotechnology.21,127-136.
- ↑ 2.0 2.1 2.2 Lu, S.J., Wei, H., Wang, Y., Wang, H.M., Yang, R.F., Zhang, X.B. and Tu, J.M., 2012. Overexpression of a Transcription Factor OsMADS15 Modifies Plant Architecture and Flowering Time in Rice (Oryza sativa L.), Plant Molecular Biology Reporter. 30, 1461-1469.
- ↑ . Yamaguchi T, Hirano HY. Function and diversification of MADS-box genes in rice. ScientificWorldJournal. 2006;6:1923–1932.
- ↑ . Kyozuka J, Kobayashi T, Morita M, Shimamoto K. Spatially and temporally regulated expression of rice MADS box genes with similarity to Arabidopsis class A, B and C genes. Plant Cell Physiol. 2000;41:710–718.
- ↑ Lim, J., Moon, Y.H., An, G. and Jang, S.K., 2000. Two rice MADS domain proteins interact with OsMADS1, Plant Mol Biol. 44, 513-27.
- ↑ Kyozuka, J., Kobayashi, T., Morita, M. and Shimamoto, K., 2000. Spatially and temporally regulated expression of rice MADS box genes with similarity to Arabidopsis class A, B and C genes, Plant Cell Physiol. 41, 710-8.
- ↑ Prasad, K., Sriram, P., Kumar, C.S., Kushalappa, K. and Vijayraghavan, U., 2001. Ectopic expression of rice OsMADS1 reveals a role in specifying the lemma and palea, grass floral organs analogous to sepals, Dev Genes Evol. 211, 281-90.
- ↑ . Lee, S., Kim, J., Son, J.S., Nam, J., Jeong, D.H., Lee, K., Jang, S., Yoo, J., Lee, J., Lee, D.Y., Kang, H.G., and An, G. (2003) Systematic reverse genetic screening of T-DNA tagged genes in rice for functional genomic analyses: MADSbox genes as a test case. Plant Cell Physiol. 44,1403–1411.
- ↑ 9.0 9.1 . Jeon, J., Lee, S., Jung, K.H., Yang, W.S., Yi, G.H., Oh, B.G., and An, G. (2000) Production of transgenic rice plants showing reduced heading date and plant heightby ectopic expression of rice MADS-box genes. Mol. Breed. 6,581–592.
- ↑ 10.0 10.1 . Kyozuka, J., Kobayashi, T., Morita, M., and Shimamoto, K. (2000) Spatially and temporally regulated expression of rice MADS box genes with similarity to Arabidopsisclass A, B and C genes. Plant Cell Physiol. 41, 710–718.
- ↑ . Wang, K., Tang, D., Hong, L., Xu, W., Huang, J., Li, M., Gu, M., Xue, Y. and Cheng, Z., 2010. DEP and AFO regulate reproductive habit in rice, PLoS Genet. 6, e1000818.
