The rice MADS57 gene plays a important role in controlling tillering.
The MADS-box genes constitute a large gene family named after a few of its earliest members: MCM1 (from yeast),AGAMOUS(from Arabidopsis), DEFICIENS(from A. majus)and SRF (from Homo sapiens). The gene family can be divided into two main lineages,referred to as type I and type II, both of which are present in plants, animals and fungi. All members of the family possess the 180-nucleotide long (on average) MADS box, which encodes the domain of the transcription factors that is responsible for nuclear localization, DNA binding, dimerization and accessory factor binding.
Transcription factors of the MADS-domain family are highly conserved among fungi, animals and plants. In plants, MADS-box family are key regulators of flowering, floral organ identity and development, embryogenesis and meristem differentiation. In rice, most genes of MADS-box family are involved in reproductive growth, whereas AGL17-like clade genes may have a unique function in vegetative development.
OsMADS57 is one of AGL17-like clade genes. This gene play a important role in the differentiation of axillary buds. The osmads57-1 mutant has increased number of tillers. D14 that functions in strigolactone(SL) sigalling to control tillering is a direct target gene of OsMADS57. MADS57 targeted D14 CArG boxes． MADS57 functionally depended on D14．Conversely, OsMADS57 inhibits the espression of D14. OsMADS57 is negatively regulated by OsmiR444a, and OsMADS57 subsequently repress expression of its target genes, thereby affecting tillering. OsMADS57 could interacted directly with OsTB1, and this interaction could partially the relieve the inhibitory effect of OsMADS57 on D14 transcription .
In a word, in rice, miR444a, MADS57, D14 and TB1 form a regulatory network to control tillering.
OsMADS57 expression is higher during tillering and stem-elongation stages than other stages in rice. It is highly expressed in leaf tissues especially sheaths and leaves, and weakly expressed in other organs. The expression levels of OsMADS57 is slightly induced by nitrate.RNA in situ hybridization assays reveals that OsMADS57 is expressed in shoot apical meristems and axillary buds. This suggests that OsMADS57 is involved in the outgrowth of axillary buds. In subcellular localization assays, green fluorescent protein (GFP)-OsMADS57 fluorescence completely overlapped with H33342 nuclear staining in rice protoplasts. By contrast, GFP fluorescence of the transgenic control cells was localized in the plasma membrane and cytoplasm. Strong GUS activity was observed in the leaf parenchyma as well as the veins, including the veins of the spikelet lemma and palea of plants harboring OsMADS57 promoter::Gus fusions. The promoter region of OsMADS57 was also active in the central cylinder of all type of roots.
Rice seedlings were cultivated in liquid medium without nitrate for 7 days, and then 3 mM KNO3 was added to the culture medium. OsMADS57 exhibited a light increase in expression following supplementation of the culture medium with nitrate. Seedlings were cultivated for 7 days on MS/2 medium without hormones, and then, the medium was supplemented with 50 uM GA3. OsMADS57 is repressed by GA3 .
OsMADS57 encode a protein containing a MADS-box domain, a variable I region, a conserved K-box domain and a C-terminal region. Phylogenetic analysis grouped OsMADS57 into the AGL-like lineage. The T-DNA insertion mutant line PFG_3A-05432.L, named henceforth as osmads57-1, was obtained from RiceGE, the Rice Functional Genomics Express Database of Korea. The T-DNA was inserted into P0617A09 at the 86,816-bp position in the rice genome, where the predicted gene OsMADS57 is annotated. The gene contains eight exons and seven introns and is 6,094 bp in total length.
THerefore, osmads57-1 is a T-DNA insertion mutant that overexpresses the truncated OsMADS57.Unlike the other known MADS genes rice mutants, osmads57-1 does not have any significant alterations in floral organogenesis or development, except for crooked anthers and altered primary root growth compared with WT plants.At day 15, osmads57-1 plants showed two axillary bud outgrowths, whereas WT Dongjin(DJ) showed only one. This demonstrates that enhanced expression of truncated OsMADS57 may cause accelerated emergence of axillary bud outgrowth in osmads57-1 plants.
In Oryza sativa,the AGL17-like clade comprises five members, OsMADS23, OsMADS25, OsMADS27, OsMADS57 and OsMADS61. In a first attempt to characterize their functions, we used promoter::Gus reporter gene fusions and RT-qPCR to study the expression patterns of these genes and their regulation by different external stimuli. The OsMADS23, OsMADS25, OsMADS27 and OsMADS57 promoters were active in the root’s central cylinder. In addition, the OsMADS57 promoter was active in leaves, whereas the OsMADS61 promoter was only active in the leaf tips and the stem base. OsMADS25 and OsMADS27 transcripts accumulated in response to osmotic stress, whereas the expression levels of OsMADS25, OsMADS27 and OsMADS57 were slightly induced by nitrate. Each of these five genes was responsive to various hormonal treatments. These distinct expression patterns indicate that these five genes have specific and non-redundant functions that likely differs from those of their A. thaliana homologs.
Labs working on this gene
- The Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
- Université Montpellier 2, Bat 15, CC 002, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
- CIRAD, UMR AGAP, Avenue Agropolis TA A-108/03, 34398 Montpellier Cedex 5, France
- University of Science and Technology of Hanoi, LMI RICE, Agricultural Genetics Institute, Ha Noi, Viet Nam
- IRD, UMR DIADE, Avenue Agropolis, 34398 Montpellier Cedex 5, France
- Guo S, Xu Y, Liu,H, et al. The interaction between OsMADS57 and OsTB1 modulates rice tillering via DWARF14. Nat. Commun. 4:1566 doi: 10.1038/ncomms2542 (2013).
- Stefanie De Bodt, Jeroen Raes, Yves Van de Peer, et al. And then there were many:MADS goes genomic. TRENDS in Plant Science. 8(10):475-483. (2003)
- Puig J, Meynard D, Khong GN, et al. Analysis of the expression of the AGL17-like clade of MADS-box transcription factors in rice. Gene Expression Patterns. 13: 160-170. (2013).
- Arora, R. et al. MADS-box gene family in rice: genome-wide identification, organization and expression profiling during reproductive development and stress. BMC Genomics 8, 242 (2007).