Diseases caused by begomoviruses are becoming the major limiting factors for the production of watermelon in India. Survey for the incidence of plants showing symptoms typical to begomovirus infection was conducted in watermelon fields. The study revealed that 40% of the watermelon plants were showing the yellowing and downward curling symptoms. Twenty infected samples were collected from the different farmer’s fields to know the association of begomoviruses. The PCR amplification using begomovirus-specific primers resulted in an expected 1.2 kb PCR product indicating the begomovirus association with the watermelon samples. The sequence comparison results of 1.2 kb representing partial genome revealed that all sequences obtained from watermelon samples have a nucleotide (nt) identity of more than 98% among them and are maximum homology with Tomato leaf curl New Delhi virus (ToLCNDV). One watermelon sample (WM1) was selected for complete genome amplification using RCA method (rolling-circle amplification). Amplification of DNA B and no amplification of betasatellites and alphasatellite indicated this virus as bipartite. Sequence Demarcation Tool (SDT) analysis of the DNA A component of the WM1 isolate showed the maximum nt identity of 94.6–97.9% and 85.2–95.8% with ToLCNDV infecting cucurbits. The recombinant analysis showed that the genome was likely to be derived from the recombination of already reported begomoviruses (ToLCNDV, ToLCPalV, and MYMIV) infecting diverse crops. The whitefly cryptic species predominant in the begomovirus-infected watermelon fields were identified as Asia-II-5 group. The LAMP assay developed based on coat protein gene sequence was able to detect the ToLCNDV in the infected samples. Visual detection of the LAMP-amplified products was observed with the hydroxy naphthol blue. LAMP assay was also validated with ToLCNDV infected sponge gourd, spine gourd, ivy gourd, ridge gourd, and cucumber. This is the first report of ToLCNDV association with leaf curl and yellowing disease of watermelon from India and World based on complete genome sequencing.

由begomoviruses引起的疾病正成为印度生产西瓜的主要限制因素。在西瓜田中进行了调查，调查显示出典型的被begomovirus感染的症状的植物的发生率。研究表明，有40％的西瓜植株出现发黄和向下卷曲的症状。从不同农场主的田地中收集了二十个感染样本，以了解初疫病毒的关联。使用begomovirus特异性引物进行的PCR扩增产生了预期的1.2 kb PCR产物，表明begomovirus与西瓜样品相关。1.的序列比较结果 代表部分基因组的2 kb表明，从西瓜样品中获得的所有序列在其中的核苷酸（nt）同源性均超过98％，并且与番茄卷曲新德里病毒（ToLCNDV）具有最大同源性。选择一个西瓜样品（WM1）用于使用RCA方法进行完整的基因组扩增（滚环扩增）。DNA B的扩增以及β卫星和α卫星的未扩增表明该病毒为二分病毒。DNA的序列标定工具（SDT）分析显示，用ToLCNDV感染葫芦科病菌，WM1分离株的最大nt同一性为94.6–97.9％和85.2–95.8％。重组分析表明，该基因组很可能源自已感染多种作物的已报道的牛瘟病毒（ToLCNDV，ToLCPalV和MYMIV）的重组。在被bemomovirus感染的西瓜田中主要存在的粉虱隐性物种被确定为Asia-II-5组。基于外壳蛋白基因序列开发的LAMP分析能够检测受感染样品中的ToLCNDV。用羟基萘酚蓝观察到LAMP扩增产物的视觉检测。还使用ToLCNDV感染的海绵丝瓜，脊椎丝瓜，常春藤丝瓜，丝瓜和黄瓜对LAMP分析进行了验证。这是基于完整的基因组测序，ToLCNDV与印度和世界西瓜的叶片卷曲和黄化病相关的第一份报道。用羟基萘酚蓝观察到LAMP扩增产物的视觉检测。还使用ToLCNDV感染的海绵丝瓜，脊椎丝瓜，常春藤丝瓜，丝瓜和黄瓜对LAMP分析进行了验证。这是基于完整的基因组测序，ToLCNDV与印度和世界西瓜的叶片卷曲和黄化病相关的第一份报道。用羟基萘酚蓝观察到LAMP扩增产物的视觉检测。还使用ToLCNDV感染的海绵丝瓜，脊椎丝瓜，常春藤丝瓜，丝瓜和黄瓜对LAMP分析进行了验证。这是基于完整的基因组测序，ToLCNDV与印度和世界西瓜的叶片卷曲和黄化病相关的第一份报道。