Biological Functional Analysis Of BoSOC1 Gene In Bambusa Oldhamii

Bambusa oldhamii belongs to Poaceae Bambusoideae,which is one of the excellent bamboo shoots in the subtropical zone.However,bamboo will die after it flowers,which resulting in the loss of ecological benefits with bamboo forest declined and causing serious economic losses to the farmers because of the production of bamboo shoots decreased significantly.Moreover,the study of bamboo flowering is limit by the unique flowering biological characteristics of bamboo,such as long growth cycle,uncertain flowering time and death after flowering.Thus,there a certain socio-economic value in the study of molecular mechanism of bamboo flowering.SUPPRESSOR OF OVEREXPRESSION OF CO1(SOC1),a member of the MADS-box gene family,is an important flowering integrator,which regulates the flowering process of plants with the interaction of other flowering-related genes.Our group previously obtained five sequences from Bambusa oldhamii named BoSOC1 A,BoSOC1 B,Bo SOC1 C,BoSOC1 D and BoSOC1 E respectively,which were the results of nucleotide variation in Bo SOC1.The biological function analysis was carried out to understand the function of the SOC1 genes in the Bambusa oldhamii.The main results were as follows:(1)Sequence analysed results showed that the amino acid of five BoSOC1 proteins all belonged to MADS-box gene family and included M,I,K and C domain.The results of phylogenetic analysis showed that five Bo SOC1 sequences were related to SOC1 homologous protein of Gramineae and was more closely related to Phyllostachys violascens and rice.(2)RT-qPCR analysis showed that BoSOC1 was widely expressed in vegetative organs and reproductive organs,and the expression level of BoSOC1 in leaves was the highest,followed by stems and flowers,and the lowest expression level was roots.The expression level of BoSOC1 gene decreased gradually with the development of the floral buds.In flower organ,BoSOC1 was detected in pistil and lemma at relatively low level,and the expression of BoSOC1 in palea,stamen and lodicules at relatively lower level.(3)Transgenic Arabidopsis thaliana experiment showed that the overexpression of each Bo SOC1 all promoted flowering in wild-type Arabidopsis.And BoSOC1 A,BoSOC1 B,BoSOC1 C,Bo SOC1 D and BoSOC1 E can partially complement the delayed flowering phenotype of soc1 Arabidopsis.Further studies have shown that each BoSOC1 upregulated the expression levels of AGL24,CO,LFY,FT and downregulated the expression levels of FLC and SVP.(4)Each BoSOC1 were transformed into rice.Under long days,35S::BoSOC1 transgenic rice caused heading early,and the heading time was not negatively correlated with the expression of Bo SOC1.The overexpression of BoSOC1 in wild-type rice results in not early heading by upregulating Ehd1,RFT1,Ehd2 and OsMADS50 and downregulating Ghd7 and OsMADS56 experssion,but also affected the phenotype of plant height and lower fertility.(5)The upstream promoter 2030 bp of BoSOC1 gene was cloned by homologous comparison,the sequence analysis indicated that it included typical TATA-box,GC-box,as well as components related to light response,such as ACE,G-box,SP1,GT1-motif,Box I and AE-box;Components related to hormonal responses,such as ABRE,CGTCA-motif,TGACG-motif,TCA-element,GARE-motif and components related to adverse response,such as GC-motif,LTR,ARE and HSE.The promoter GUS vector pBI101-2030,pBI101-1409,pBI101-1158,pBI101-681 and pBI101-307 were constructed,respectively,and were infected into Arabidopsis thaliana.It was found that with the increase of the length of the 5’-progressive deletion mutations,the activity of GUS enzyme was decreasing,but the activity of the least fragment 307bp-drive of the BOSOC1 gene promoter was increased.The above results show that BoSOC1 is flowering promoting factor of Bambusa oldhamii and the structure of five BoSOC1 sequences were similar and all have the function of promoting flowering.