Functional Analyses Of Soybean GmGI Gene For Flowering And Abiotic Stress Regulation

Soybean is source of protein, oil and feed, and the demand of soybean in our country has been very high. Over the past 20 years, the import of soybean has increased greatly, while the planting area of domestic soybean has gradually reduced and the total output has continuously declined. The consumption rate of domestic soybean declined sharply, threatening the safety of China’s soybean production. Soybean is one of the typical short day plant, which delays flowering in long day and promotes flowering in short day. The growth sensitivity of photoperiod limites the planting area of many fine soybean varieties. Therefore, decreasing the sensitivity of soybean will be beneficial to increase the adaptation of soybean that increase soybean growth area and improve soybean yield, so as to promote the development of soybean production an d reduce the dependence on imported soybean.Photoperiod as an important factor of affecting flowering, the genes of regulating photoperiod pathway play critical roles. In the photoperiod pathway in Arabidopsis, GI gene is a key factor in the regulation of flowering and biological rhythm, and regulates the expression of CO and FT genes. Exploring the function of GI gene will provide effective methods of transforming flowering time of soybean timely to get more excellent varieties with light insensitivity a nd wide environmental adaptations.In this study, GIGANTEA gene was cloned, with 1094 aa. The expression pattern in the day cycle and blue light of GIGANTEA gene in Soybean was analysed by q RT-PCR; it also analyzed the agronomic traits and the function of plant flowering progress in strain Gm GI transgenic tobacco and soybean. GR expression vector pCAMBIA 3301-Gm GI-GR were constructed and used to produce, Gm GI-GR Arabidopsis, overexpressing transgenic Gm GI and WT Arabidopsis of florescence and other physiological traits was observed. Gm GI-GR Arabidopsis provides transgenic materials for the further analysis of the downstream genes which Gm GI gene regulates. The main results are as follows:(1) Full-length sequence of Gm GI was isolated from soybean based on the primers developed from Gm GI sequence with a single complete open reading frame(ORF, 3285bp). The predicted protein contains 1094 amino acids with molecular weight of 128.835 k Da, Gm GI in an unstable protein, and the protein was hydrophilic, and transmembrane protein.(2) The mRNA abundance changes of soybean GmGI gene in light dark and blue light were analyzed by q RT-PCR. As a preliminary identification, GmGI gene of soybean was the periodic expression pattern which accumulated in light, decreased in dark, and induced by blue light.(3) GR expression vector pCAMBIA 3301-GmGI-GR were constructed and used to produce by Agrobacterium-mediated method. GmGI-GR Arabidopsis, overexpressing transgenic Gm GI Arabidopsis and WT Arabidopsis of florescence was observe d, the results showed that Gm GI gene promoted flowering in long day, but the flowering time is not obvious in advance, delayed flowering and promoted the accumulation of Arabidopsis biomass in short day. Gm GI-GR Arabidopsis of flowering time did not change significantly compared WT Arabidopsis that indicated that the GmGI gene plays a role of regulation of downstream genes the expression as transcription factor, will not affect the Arabidopsis flowering phenotype expression in the cytoplasm.(4) In this research, Gm GI in soybean was transferred into tobacco Havana 425. The non-transgenic tobacco Havana 425 was used as a control, flowering time, yield and other agronomic traits of T3 generation GmGI transgenic tobacco were statistically analyzed. The results showed that compared with non-transgenic tobacco Havana 425, plant height and grain weight per plant were improved obviously in the other three lines except GI6, flowering time averagely advanced 31.5 days.(5) Moreover, root length of Gm GI transgenic tobacco lines were longer than non- transgenic tobacco by mannitol, which indicated Gm GI gene transferred into tobacco to improve the drought resistance of tobacco. Root length of Gm GI transgenic tobacco lines were shorter than non-transgenic tobacco by salt, which indicated Gm GI gene transferred into tobacco will decrease the salt resistant of tobacco.(6) In this study, we transformed soybean by Hydroponics and obtained the transgenic Gm GI soybean. The non-transgenic soybean DN50 was used as a control, flowering time of T6 generation Gm GI transgenic soybean were statistically analyzed. The results showed that compared with non-transgenic soybean, flowering time averagely advanced 5.64 days, Gm GI involved in photoperiod flowering pathway and promoted plants’ flowering.