苹果花脸病田间病情发展及ASSVd在组培条件下的传播

为了明确苹果锈果类病毒(apple scar skin viroid,ASSVd)引起的苹果花脸病在田间的病情发展情况以及ASSVd在组培条件下的传播方式,2012—2015年对河北省顺平南神南村3个果园进行持续调查和检测。结果显示,果园A、B、C的显症率分别从3.00%、19.35%和10.00%上升至10.00%、34.41%和22.00%,带毒率分别从11.00%、20.43%和14.00%上升至23.00%、37.63%和30.00%,带毒率和显症率都逐年增加,而且带毒率大于显症率,即有些带毒果树不显症。发病果树田间分布有明显的发病中心。通过高通量测序发现显症果树ASSVd vsiRNA reads数是带毒未显症reads数的4.08倍,同时实时荧光定量PCR检测发现显症树ASSVd病毒积累量显著高于带毒未显症树。以携带ASSVd的组培苗和无毒组培苗为试材,利用RT-PCR检测明确了ASSVd可通过伤口沾染带毒汁液、组培剪污染、含毒培养基、根系接触进行传播,其中根系接触传染率较高。

The Disease Development of Apple Scar Skin Viroid in the Field and Its Transmission Mode in Tissue Culture

Apple scar skin disease caused by apple scar skin viroid（ASSVd）is common in apple producing areas northern in China and it has led to serious economic losses in recent years. At present，there are no effective treatment measures. In order to clarify the disease development and transmission mode in the field，three orchards in Nanshennan Village，Shunping，Baoding were continuously investigated and tested from 2012 to 2015. In orchard A，B，C，the change of symptom rate from 3.00%，19.35% and 10.00% to 10.00%，34.41% and 22.00%，and the change of virus-taking rate from 11.00%，20.43% and 14.00% to 23.00%，37.63% and 30.00%. The rate of symptom-showing and virus-taking increased year by year，and the virus-taking rate was greater than the symptom-showing rate. The incidence of fruit trees in the field distribution has an obvious incidence center. Some fruit tree taking virus did not show symptom. By high-throughput sequencing method，it was found that the number of ASSVd vsiRNA reads in symptomatic fruit trees was 4.08 times that of asymptomatic fruit trees with virus，and the accumulation of ASSVd in symptomatic fruit trees was significantly higher than that in asymptomatic fruit trees with virus by quantitative real-time PCR detection. ASSVd-carrying tissue culture seedlings and non-ASSVd- carrying tissue culture seedlings were used as test materials to simulate different transmission modes in the field，and RT-PCR was used to confirm that ASSVd could be transmitted through wound contamination，tissue culture shear pollution，virus-taking medium and root contact，among which the root contact transmission rate was the highest.