甘薯病毒病发生关键因素研究

[目的]明确甘薯种薯携带的病毒种类与苗期病毒病发生率和严重度之间的关系,以及甘薯田烟粉虱发生量和带毒率与种薯带毒率之间的关系,建立甘薯苗期病毒病预测预报方法和种薯质量早期预警技术,为甘薯无病毒种薯生产和病毒病防控提供理论依据.[方法]利用PCR和RT-PCR方法对随机采集的不同来源的甘薯种薯进行病毒检测,检测的病毒种类...

An Investigation into Key Factors Influencing the Occurrence of Virus Disease in Sweet Potato

【Objective】 This study aimed to clarify the relationship between sweet potato virus types in storage roots and virus incidence and severity on root sprouts, and the relationship between numbers and SPCSV-carrying rate of Bemisia tabaci and SPCSV-carrying rate of storage roots, establish the prediction method and early warning technology for viral disease in sweet potato seedlings, so as to provide the theoretical basis for virus-free storage root production, and prevention and control of virus disease in sweet potato.【Method】 PCR and RT-PCR were performed to detect eight major sweet potato viruses including sweet potato feathery mottle virus (SPFMV), sweet potato virus C (SPVC), sweet potato virus G (SPVG), sweet potato latent virus (SPLV) and sweet potato virus 2 (SPV2) in the genus of Potyvirus, sweet potato chlorotic stunt virus (SPCSV) in the genus of Crinivirus, cucumber mosaic virus (CMV) in the genus of Cucumovirus, and sweepoviruses in the genus of Begomovirus in China in storage roots collected from different sources. The PCR-detected roots were planted in plastic pots and allowed to sprout under greenhouse conditions. The types and severity scores of viral symptoms on root sprouts were surveyed and recorded to analyze the relationship between virus species in roots and virus symptom severity on root sprouts. Virus-eliminated sweet potato cultivar Shangshu 19 (S19) plants with the same source were cultivated in the different locations in Henan, Ningxia and Shaanxi in 2018 and 2019. The number of B. tabaci in each test site was calculated by using yellow sticky traps, and was sampled for SPCSV detection during the growth period of sweet potato. The roots selected randomly from each test site were used for SPCSV detection after harvesting to analyze the relationship between numbers and SPCSV-carrying rate of B. tabaci and SPCSV-carrying rate of storage roots.【Result】 Of the 665 storage roots, 463 were infected with one or more of the eight viruses. After root sprouting, visual symptoms, such as leaf chlorosis, vein-clearing, rugosity and stunting were observed on the 333 root sprouts. Virus severity scores on root sprouts ranged from 0 to 1 (60.6% for score of 0 and 31.8% for score of 1) when roots were infected with potyvirus (es). Virus severity scores on root sprouts ranged from 0 to 1 (55.3% for score of 0 and 32.9% for score of 1) when roots were infected with sweepoviruses or co-infected with sweepoviruses and potyvirus (es). Root sprouts were observed with more severe symptoms when roots carried SPCSV, especially the combination of SPCSV and potyvirus (es), which caused visible symptoms on all sprouts with severity scores from 3 to 9 (49.0% for scores of 3 and 5, 51.0% for scores of 7 and 9). Results from two successive years field trial revealed that there was a positive correlation between SPCSV-carrying rate (X₁) and numbers (X₂) of B. tabaci and SPCSV-carrying rate (Y) of storage roots, and the equation of linear regression was Y=9.628X₁+0.008X₂+6.537, R²=0.914.【Conclusion】 Storage root carrying SPCSV is the key factor for serious occurrence of sweet potato viruses at seedling stage. Viral symptom appearance rate and severity scores increase significantly when roots are co-infected with SPCSV and potyvirus (es). There is a positive correlation between SPCSV-carrying rate and numbers of B. tabaci and SPCSV-carrying rate of storage roots, indicating that B. tabaci is the key factor influencing the SPCSV-carrying rate of storage root.