Abstract: In order to investigate the incidence of known viral diseases of pear in Tianjin Region,the total RNA of snow pear leaves was extracted by improved CTAB method. And the latent virus species of the 70 pear trees from three regions of Tianjin were detected through RT-PCR identification,including Apple cholortotic leaf spot virus (ACLSV), Apple scar skin viroid (ASSVd), Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV) and Apple dimple fruit viroid (ADFVd). The results showed that the improved CTAB-mercaptoethanol method was a kind of comparatively ideal method for total RNA extraction from snow pear,the RNA had less impurity, the rate of total RNA extrate was higher, and the mean concentration was 73.880 μg/g. The obtained RNA meted the requirements for the next analysis. By RT-PCR technique the infection rates of the 70 pear trees with the above five viruses were 47.1%,11.4%,10.0%,8.6%,and 1.4%,respectively,and the mixed infection rate was 28.6% on average. The higher the age of pear trees, the higher the virus carrying rate. And the sensitivity of different varieties to viruses was different. The results showed that the pear virus disease in Tianjin was common, in which apple chlorotic leaf spot virus was the main type of virus, and had a certain proportion of multiple virus complex infection. The low level of pear planting management and the lack of standardized detection and monitoring of pear introduction among regions could lead to the occurrence and spread of pear virus disease. It was very unfavorable for the healthy development of Tianjin pear industry.

Key words: Total RNA extraction, Pear viral disease, Viroid, Molecular detection

CLC Number: 

• S661.2