Study On The Promoters Of Banana Bunchy Top Virus DNA Components And Primary Identification Of Banana Streak Virus

Banana bunchy top disease is one of major diseases in banana, the pathogen of the disease is banana bunchy top virus. The virus genome consists of at least 6 components of circular ssDNA about 1.0-1.1kb. Each DNA component contains encoding region and non-coding one. The studies both at home and abroad indicated the non-coding regions of BBTV DNA components possess the function of promoter. On the basis of forefathers' research, we want to understand further promoter function of BBTV DNA components. According as the genomic sequence of BBTV Hainan isolate, a 540bp fragment (BV3.1) generated by PCR amplification, which is the promoter sequence of BBTV DNA3 component. By the analysis of the sequence, some elements such as TATA-box, I-box, G-box, G/CC/GTATG sequence, CCA(N)nTGG sequence and the analogous sequence associated with phloem-specific expression are found in BV3.1. A 646bp splicing sequence (BV23) consisting of non-coding regions of DNA2 and DNA3 components generated by overlapping PCR amplification. By the analysis of the sequence, some elements such as TATA-box, I-box, G-box, G/CC/GTATG sequence and CCA(N)nTGG sequence are found in it. This two sequences substitute 35S promoter sequence in pBI121 carrier and fuse with gus gene respectively, and then plant expression carrier named for pBIBV3.1(540bp), pBIVBV23(646bp) are constructed.By GUS histochemical staining, the very weak GUS activity is limited in the leave veins of pBIBV3.1 transgenic tobacco; the most faint GUS activity are detected in the leaf margin of pBIVBV23 transgenic tobacco, in some leaf veins as well. By the quantitative analysis of GUS extract with colourimetric method, the result indicates the CaMV 35S promoter provided the high level of GUS activity about 3- to 4-fold higher than BV23 promoter, about 8- to 12- fold than BV3.1 promoter.Banana streak disease caused by banana streak virus is one of major virus diseases in banana, which brings just little harm than banana mosaic disease and banana bunchy top disease. But BSV genome sequence may integrate into chromosome of banana, it's injury is potential. In addition, the BSV genome nucleotide sequence vary greatly among different isolates. And there is a very few of research on BSV interiorly. So it is necessary to purify...