The Expression Analysis Of Flowering Genes And The Functional Characterictics Of PtFLC In Poncirus Trifoliata (L.) Raf

Woody plants have a long juvenile phase before they can flower, and this trait restricts the breeding efficiency and economic benefits of woody plants, especially fruit trees. Citrus is the most important evergreen fruit crops in the world, and also the most important trees in south of China. How to shorten the juvenile is one of research hotspots at the field of molecular biology today. In 1976, a spontaneous mutant with short juvenile phase (precocious trifoliate orange) derived from Poncirus trifoliata (L.) Raf, was found in Yichang, Hubei province, China. Based on its unique character about flowering process, it is very suitable for molecular biology research.FLC is a critical gene of vernalization pathway, and it also plays very important roles in other flowering pathways. We had already cloned PtFLC of FLC homologous gene from precocious trifoliate orange, and based on it, in this study, we cloned the promotor of PtFLC, and investigated its function characteristics. The main results are as follows:1. We investigated the expression of PtFLC, PtSVP, PtFT, PtLFY and PtAP1 in precocious trifoliate orange which had been treated by photoperiod, GA3 and temperature. Real time PCR results showed that the expression of PtFLC and PtSVP was different, although they both are flowering repressors. The expression of PtFLC showed a downward trend under long-day, GA3 and low temperature treatment, and opposite under short-day treatment, which is corresponded to previous report. The expression of PtSVP increased under GA3 and low temperature, and declined under short-day. Perhaps PtSVP involved in the vegetative growth and self-pruning process. The expression of PtFT, PtLFY and PtAP1 was similar by and large. PtFT, PtLFY and PtAP1 had a upward trend under low and cold temperature, and a downward trend under short-day treatment, which is corresponded to previous report. However, PtLFY and PtAP1 declined, which oppose to the previous report.We speculated it's perhaps because the concentration of GA3 is not suitble.2. Using the method of chromosome walking we cloned PtFLC promoter, and the total length is 1100bp. By bioinformatics analysis, we found it has the specific components associated with the induction of light period, vernalization and gibberellin, and we also found some components about drought stress.3. We constructed a promoter expression vector by inserting it into pCAMBIA1391 vector, and then transformed into Arabidopsis C24. We obtained 24 positive plants by PCR, but no one was stained after GUS staining.4. Previous study had alreay cloned the FLC homolog (PtFLC) from precocious trifoliate oranges, and found it was regulated by alternative splicing. To study the function of PtFLC,4 PtFLC transcripts vectors of pCAMBIA1301 were transformed into Arabidopsis C24. According to the statistics results of the flowering time of T2, most of them flowered later than the wildtype Arabidopsis. The results indicated that the PtFLC mainly involved in flowering control.