OsMADS29 plays an important role during seed development of rice and silencing of OsMADS29 Results in the seeds shrunken as well as a reduced grain-filling rate in rice. It is a key regulator of the degradation of the nucellus and nucellar projection, which undergoing PCD during early rice seed development.
Down regulation of OsMADS29 does not affect ovule development but causes seeds to abort or shrivel as they are most likely deficient in endosperm development and starch accumulation.
After rice fertilization, the increased IAA content induces the expression of MADS29, which then stimulates the degradation of the nucellus and the nucellar projection by directly stimulating a Cys protease and NBS-LRR proteins. Acting through MADS29 or other pathways, auxin regulates the PCDprocesses required for normal endosperm development and grain filling.
Figure 1 shows that during the first 6 days after flowering(DAF), there is no obvious difference between wide type line seed (ZH11) and A-MADS29 transgenic lines seeds (A-2, A-14, and A-33) in which the OsMADS29 was suppressed. After 8 DAF, the A-MADS29 seeds become shrunken, and this phenotype persists until 30 DAF because of a defect in dry matter accumulation, whereas the seeds are fully filled with dry matter by 30 DAF in ZH11.
OsMADS29 is Specifically Expressed in Ovules and Developing Seeds.
(1) RT-PCR analyses show that the expression of OsMADS29 initiates at panicles 0.1~5 cm, then increases gradually with the development of panicles at 6-22 cm. After pollination, the expression level reaches the maximum value at 5 DAP-7 DAP, then decreases from 9 DAP. No expression of OsMADS29 is detected in the vegetative organs (Figure 2A).
(2) Results of qRT-PCR show similar expression profiles of OsMADS29 to those of the RT-PCR (Figure 2B).
(3) RT-PCR was also performed to examine the expression of OsMADS29 in different floral organs. Like other known B(sister) genes, OsMADS29 is specifically expressed in the pistils (Figure 2C).
The phylogenetic analyses made by A. Becker et al. reavels that B(sister) genes are the sister clade of the DEF/GLO-like (or AP3/PI-like) genes comprising class B floral organ identity genes . The phylogeny analyses made by Xuelian Yang et al. shows that B(sister) genes of core eudicots and monocots constitute two different clades, suggesting that the most recent common ancestor of both taxa contained one B(sister) gene only. The clade of rice B(sister) genes is divided into three subclades, termed the OsMADS29, OsMADS30 and OsMADS31 subclade.
During flower development in higher plants, the identity of the different floral organs isspecified by different classes of homeotic selector genes, termed class A, B, C, D and E genes, with A specifying sepals, A+B+E petals, B+C+E stamens (male microsporophylls), C+E carpels (female megasporophylls), and D ovules. The genes providing the different floral homeotic functions have been cloned from several plant species. Nearly all of them belong to the family of MADS-box genes, which encode transcription factors. Almost all known MADS-domain proteins from vascular plants share a conserved structural organization, the so-called MIKC-type domain structure, including MADS (M), intervening (I), keratin-like (K) and C-terminal (C) domains. Genes closely related to class B MADS-box genes have been identified by phylogenetic studies, and are referred to as B(sister genes).
Labs working on this gene
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, Peoples Republic of China,
- Department of Genetics, Friedrich Schiller University Jena, Jena, Germany
- Plant Evo-Devo Group, The Institute of Botany, Justus-Liebig-University Gießen, Gießen, Germany
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- Yin L L, Xue H W. The MADS29 transcription factor regulates the degradation of the nucellus and the nucellar projection during rice seed development[J]. The Plant Cell Online, 2012, 24(3): 1049-1065.
- Arora R, Agarwal P, Ray S, Singh A, Singh V, et al. (2007) MADS-box gene family in rice: genome-wide identification, organization and expression profiling during reproductive development and stress. BMC Genomics 8: 242.
- Yang X, Wu F, Lin X, et al. Live and Let Die-The B(sister) MADS-Box Gene OsMADS29 Controls the Degeneration of Cells in Maternal Tissues during Seed Development of Rice (Oryza sativa)[J]. PloS one, 2012, 7(12): e51435.
- Becker A, Kaufmann K, Freialdenhoven A, et al. A novel MADS-box gene subfamily with a sister-group relationship to class B floral homeotic genes[J]. Molecular Genetics and Genomics, 2002, 266(6): 942-950.
- Yamada K, Saraike T, Shitsukawa N, et al. Class D and B sister MADS-box genes are associated with ectopic ovule formation in the pistil-like stamens of alloplasmic wheat (Triticum aestivum L.)[J]. Plant molecular biology, 2009, 71(1): 1-14.