Regulation Of Banana MaASR1Transcription Fator On Arabidopsis Flowering Cycle

The normal regulation of flowering-time was guaranteed for normal offspring and successful evolution preservation of species. On crops, normal flowering stage had a tight relation with output and fruit quality. So, study on plant floral and fruit had important meaning on agricultural production. There were four clear flowering regulatory pathways in model plant Arabidopsis:photoperiod pathway in response to the external optical signal, vernalization pathway answering low temperature, autonomous pathway which feel own development status, and gibberellin pathway which can response to endogenous hormone signals.ASR gene was a peculiar function gene in higher plants. It played an important role on regulating the fruit mature, and resisting of abiotic stress. From now on, ASR has been cloned in lots of plants, while not found in Arabidopsis. We have obtained an ASR fragment from banana fruit SSH library, and the full length of this gene was obtained by RACE technology, named MaASRl (accession number:AY628102). The MaASR1was overexpressed in Arabidopsis thaliana, found that the transgenic plants had significant delayed floral. In order to find out the regulate mechanism of delay-flowering in transgenic Arabidopsis, a series of experiments such as gene chips, q-RT PCR, and so on were used to screen and identify the related genes. The results were shown below:1. When the first flower can be seen, the number of rosette leaves in MaASR1transgenic lines L14and L38was more than in wild type. In other word, the flowering of transgenic plants had a certain delay, the delay phenomenon was obvious in L14than in L38. The bud period, midflower period and flower period of L14and L38lines appeared later than the wild-type. At the same time, the floral organs of the three lines were observed through the dissecting microscope, it was found that there were many trichomes in sepal and pedicel of L14and L38, and L14had more trichomes than L38.2. Used gene chips technique, the expression profile was comparative analysised in transgenic lines L14and wide-type Arabidopsis, and11flowering-related genes which were differential expressed were gained.7of them were at the photoperiod pathway, one was the vernalization pathway gene, and3of them were connected with flower organ growth. CO, Coll, Col2,Col9, ELF3, ELF4and TCH2, these7genes of photoperiod pathway were expression analysed by q-RT PCR. The expression levels of key genes CO which can promote flowering in photoperiod in transgenic lines were lower than that in the wild type, while the expression levels of its suppressor gene Co19in transgenic plants was higher than in the wild type; the expression levels of circadian rhythms clock-related genes Coll, Col2, ELF3and ELF4were decreased; When flowering, the vernalization gene MAF5which can promote flowering had a lower expression in transgenic lines than in wide-type. The floral organ development gene NGA1can delay flowering by control the expression of SOC1, our result showed that in transgenic lines, NGA1had a higher suppression to SOC1. The profile chip showed that MaASRl's regulate of flowering was mainly achieved by regulating photoperiod pathway genes.3. In order to more fully understand the regulation mechanism of MaASRl delay flowering, the expressions of important genes in other3flowering pathways of Arabidopsis and the flowering integrons were analysis.(1) The important flowering repressors of the vernalization pathway, FLC and FRI had a higher experssion levels in the L14and L38than the wild-type in the flowering transition period.(2) The autonomous genes FLK, FCA and FVE were highly expressed in the first period of vegetative growth in Arabidopsis. While the differences of expression level of the three genes in transgenic and wild-type plant were not significant.(3) The expression levels of GAI and RGL1in GA pathway were inhibited when the MaASR1was expressed in plants. Both of them were belonged to the DELLA family, which could promote plants bloom.(4) Flowering integron meant that genes which could integrate many tegulation ways to one central integration. There were two important flowering integrons, SOC1and LFY. The expression of SOC1was inhibited in transgenic plants. The inhibitory effect of L38was not significant that L14, but the ability to recover of L38was higher than L14. LFY was an important flowering promoting factor, its expression time was delayed in the L14and L38transgenic plants.Synthesize the results above, we found that MaASR1could delate the flowering time in transgenic Arabidopsis mainly depended on the related of photoperiod pathway, and GA pathway and floral integrons were also had the roles. Our results first expanded ASR gene's function on the plant's floral stage, which could offer the effective genetic resources on using genes to regulate flowering phase. And also provide the foundation for using gene regulation technology to change plant's flowering phase in future, which had important theoretical and realistic significance.