Involvement Of Cold-induced TaHD2C Gene In Regulating The Floral Transition Of Transgenic Arabidopsis

A Histone Deacetylase gene TaHD2C,cloned from Shanrong No.3(SR3),a new common wheat(Triticum aestivum L.)introgression line preservationin our lab.In our previous investigation,over-expression of TaHD2C of Arabidopsis thaliana has the phenotype of late flowering and insensitive to drought,saline and alkaline stress.The analysis the promoter sequence of TaHD2C gene,it deduced that the TaHD2C gene may response to the temperature stress.Thus,four lines of A.thaliana,including the wild-type(WT),two over-expression lines of TaHD2C(OE17 and OE46)and AtHD2C mutant(athd2c,mu),were used for the following investigation:1.Under normal conditions,the growth of WT,OE and mu lines showed no differences compared with WT.Under cold stress,WT,OE and mu lines were treated with-20? for 1 hour,1.5 h and 2 h after growth on 1/2 MS culture medium for 18d.Then,they were treated with 4? for 12 h and retained at 22? for 7 days,the mortality of each line was observed and recorded.The result showed that the mortality of OE lines was lower than WT and mu after cold treatment,meanwhile the chlorophyll content of OE lines was higher.DAB and NBT staining also showed that the content of H2O2 and O2·-of OE lines were lower compared with WT and mu.The activities of MDA and electrolyte leakage rate of OE lines were significantly lower than those of WT and mu.All these results indicated that OE lines were more cold resistance.2.It was also detected that the late-flowering phenotype of OE lines was recovered after low temperature treatment,after planting all lines in nutrient soil.And the genetic character of late-flowering phenotype of OE lines still maintained in there offspring.3.The results of physicochemical indexes and expression of cold stress related marker genes showed that the phenotype corresponding to cold stress is related to CBF pathway.4.In other hand,the late-flowering phenotype of OE could recover by cold stress,which belonging to the expression of FT and FLC genes,involving to integration factor of FT and FLC in flowering pathway,is enhancing in its offspring.As VRN1/2 and VIN3 can participate in histone deacetylation of FLC through the formation of protein complexes.The expression of FLC was inhibited by raising the expression of VRN2.In the end,over-expression of A.thaliana blooms early.These results indicated that TaHD2C gene could enhance and maintain the cold tolerance of A.thaliana.Low temperature stress regulates the expression of FT and FLC in floral transition of transgenic Arabidopsis,and resumes its late flowering phenotype.