Regulation Of Development By OsMADS58 In Transgenic Arabidopsis

The ABC model, proposed first according to the flower development researches in model plant Arabidopsis and Antirrhinum, was used to explain the molecular regulation mechanism of four whorls floral organs in dicot. It was modified to ABCDE model along with the production of more and more new research results. However, the evolutionary relationship between monocot and dicot was not clear and the applicability of ABC model to monocot was controversial.Most of the homeotic genes in flower development in Arabidopsis were MADS-box genes. AGAMOUS,encoding a transcription factor, was a MADS-box gene. The agamous mutant and AGAMOUS overexpression plant presented disordered floral organs phenotypes. OsMADS58 was the homologue in rice which was not cloned and researched systematicly. To test whether OsMADS58 had the same function as AGAMOUS, UBIQUITIN::OsMADS58 was constructed and transformed into Arabidopsis. The floral organs of transformed plants were abnormal with different changes such as incomplete petals, stamens instead of petals and Carpel-like sepals. We classified the transgenic plants as weak, moderate and strong phenotype plants .To investigate the effect of OsMADS58 expression level on the floral phenotype, we carried out the Real-time PCR assays.Different whorls of floral organs were altered in transgenic plants with different expression levels of OsMADS58. These suggest that OsMADS58 has dosage effect on floral organs developments. Besides the floral alterations, the leaves of the OsMADS58 overexpression plants except the cotyledons were curled upwards in varying degrees. The rosette leaves were smaller and the total number was less than wild type in the whole life and the plants flowered earlier. The mRNA levels of FLOWERING LOCUS C decrease and SUPPRESSOR OF OVEREXPRESSION OF CO 1 increased by RT-PCR assays,which suggested that the OsMADS58 may regulate FLOWERING LOCUS C directly or indirectly.The phenotypes of flowers in transgenic plants were very similar with the AGAMOUS overexpression plants, which indicated that OsMADS58 may function like AGAMOUS in Arabidopsis, which will help us to investigate its role in rice flower development. It also provided the proof of the functional conservation in evolution between monocot and dicot.