香蕉條紋病調查與細胞病理學觀察及感染系統之建立
Date Issued
2006
Date
2006
Author(s)
DOI
en-US
Abstract
Banana streak virus (BSV) is becoming a serious threat to banana industry. One character of BSV is that its sequence can integrate into the host genome and the episomal infection may occur after the activation of the BSV integrant. In this study, 27 out of 50 economically important banana collected in Taiwan Banana Research Institution were screened to be free of BSV by PCR detection and could be used for breeding programs. Three B genome containing bananas were BSV free which is inconsistent with previous studies that all B genome bananas contain BSV genome. Field survey in Taiwan showed that the incidence of BSV in cv. Cavendish was relatively low. Only five out of 130 cv. Cavendish contained BSV sequence and no visible symptoms were observed. In B genome containing cultivars, a high incidence of BSV was detected but only one sample showed typical streak symptoms. The result is in accordance with the prediction that the BSV integration infection occurred in B genome bananas. However, lacking of a rapid detection method that can be used in high throughput screening to differentiate integrated form and episomal form of BSV, we are not sure that how many BSV positive bananas contain episomal BSV infection. To overcome the problem, based on the report that the integrated DNA is highly methylated thus the transcription of mRNA may be inhibited, a RT-PCR method to examine the existence of RNA of integrated BSV was developed. In addition, cytopathological observation was conducted to understand ultrastrucural changes in banana leaves caused by BSV. Interestingly, in both BSV episomal infection and integrated in genome leaves, the nuclei of the companion cells enlarged. Enlargement of starch grains also appeared in the chloroplast of these plants. To reveal the phylogenetic relationships of BSV isolated in Taiwan, the complete genome of Taiwanese isolate was sequenced. Sequence analysis revealed that it shares highly sequence identity (99%) to Banana streak mysore virus. For further study of the gene function of BSV, an infectious clone containing 1.26 copies of BSV complete genome were constructed. However, the clone could not infect cv. Cavendish successfully.
Subjects
香蕉條紋病毒
細胞病理學
banana streak virus
cytopathology
Type
other