Os02g0491300

Please input one-sentence summary here.

Annotated Information

Function

Please input function information here. MICROSPORE AND TAPETUM REGULATOR1 (MTR1) is a rice fascilin glycoprotein protein. It may act as an extracellular adhesion molecule in male reproductive development by regulating the cell-to-cell communication between reproductive cells and their adjacent somatic cells.

• an essential gene for programmed tapetal cell fate and pollen formation in rice.

• is required for both the development of the diploid anther wall cells and maturation of the postmeiotic haploid microspores.

• effect the deposition of sporopollenin precursors on the surface.

Gene Structure

Please input Gene Structure information here.

MTR1 locus was located on chromosome 2 between two InDel markers, TH239 and TH234. The MTR1 transcript is approximately 2 kb in length and contains a 1,752 bp coding sequence without any intron, a 55 bp 5' untranslated region (UTR) and a 193 bp 3' UTR. The predicted MTR1 protein is 583 amino acids long and contains a putative N-terminal signal peptide; two fasciclin domains (amino acids 257–356 and 435–535); and two potential N-glycosylation sites (amino acids 433 and 554).

Mutation and Phenotype

Please input Mutation and Phenotype information here.

mtr1 shows normal vegetative and nonreproductive floral organ development, but has smaller and pale-yellow anthers that fail to produce viable pollen grains.(A: wiletype; B: mtr1)

The result of (DAPI) stain show that start from stage 9 mtr1 microspores show slow development, did not seem to go through mitosis, and were eventually aborted. Transverse section analysis showe mtr1 anther wall layers were less degenerated than wild-type and microspores were collapsed.transmission electron microscopy (TEM) and scanning electron microscopy (SEM) of the anther show mtr1 tapetal cells were highly vacuolated and microspores were irregularly shaped with less deposition of sporopollenin precursors on the surface. And, at stage 7 and 8b, when wild-type tapetal cells showed TUNEL-positive nuclei. However, the mtr1 tapetal cells had no detectable TUNEL signals. Several rice tapetum-expressed genes, which are known to be involved in tapetal function and degeneration, displayed abnormal expression patterns in mtr1 .

Expression and Location

Please input expression and location information here. RT-PCR, RNA in situ hybridization and translational fusion between the full-length MTR1 coding region and GFP (Green Fluorescent Protein) under the control of MTR1’s native promoter (pMTR1:MTR1-GFP) all show the expression of MTR1 only in the anthers(specifically in the microsporocytes and the tetrads). The MTR1 transcripts started to be detectable at stage 7 and reached the maximum level at stage 8a, when meiosis occurs to form dyads. At stage 9, when the young microspores are released from the tetrad, the transcript level of MTR1 began to decrease and was hardly detectable at stage 10.

MTR1 was found to localize in the microsporocyte cytoplasm, in the extracellular matrix between the microsporocytes, and at the interface between the microsporocyte and the tapetal cell. And the N-terminal peptide, which is required for MTR1’s localization on the plasma membrane, is critical for MTR1’s role in rice anther development.

Evolution

Please input evolution information here. using the full-length MTR1 sequence and the sequence containing the two fasciclin domains (amino acids 248–539), respectively, as queries. Fourteen sequences were retrieved from Arabidopsis thaliana, Brachypodium distachyon, Hordeum vulgare, Mimulus guttatus, Populus trichocarpa, Panicum virgatum, Sorghum bicolor, Triticum aestivum, Vitis vinifera (grape vine), and Zea mays, each containing high sequence similarity with MTR1 in the fasciclin domain. Further phylogenetic tree using sequences from the region covering the two fasciclin domains show two sequences from sorghum, one single member from Brachypodium, barley, maize, wheat, and switch grass, respectively, were grouped in a small clade.

Labs working on this gene

Please input related labs here.

1 State Key Laboratory of Hybrid Rice, School of Life Sciences and Biotechnology

2 Bio-X Center, Key Laboratory of Genetics & Development and Neuropsychiatric Diseases, Ministry of Education Shanghai Jiao Tong University

3 Department of Energy Plant Research Laboratory, Michigan State University

References

Please input cited references here.

Hexin Tan, et al. MTR1 Encodes a Secretory Fasciclin Glycoprotein Required for Male Reproductive Development in Rice. Developmental Cell, 22, 1127–1137 (2012)