The tomato leaf curl New Delhi virus (ToLCNDV) is a bipartite begomovirus (genus Begomovirus, family Geminiviridae) that was originally isolated in India, but has become a serious threat to various horticultural crops in the Indian subcontinent, Southeast Asia, East Asia, Middle East, and western Mediterranean Basin. In Southeast Asia, East Asia, and the western Mediterranean Basin, ToLCNDV has caused huge economic damage to cucurbit crops (cucumber, melon, squash, and zucchini) for which commercial ToLCNDV-resistant cultivars are currently unavailable. In this study, full-length ToLCNDV viral sequences were isolated from cucumber, melon, and zucchini plants exhibiting yellow leaf curl disease in Almeria, Spain. Phylogenetic analysis showed that the isolated viruses consisted of the ToLCNDV-ES strain and strains that were genetically distant from ToLCNDV-[BACu-20] in Southeast Asia, which were previously isolated in the Aceh province of Indonesia. Infectious clones of ToLCNDV-[ES-Alm-Cuc-16] from Spain and of ToLCNDV-[BACu-20] from Indonesia were prepared, and ToLCNDV isolates were agroinoculated to Nicotiana benthamiana, tomato, and cucurbit crops (cucumber, melon, and zucchini). Infection rates were nearly 100% for all inoculated plant species, and disease symptoms were consistently more severe in plants inoculated with ToLCNDV-[BACu-20] compared to plants inoculated with ToLCNDV-[ES-Alm-Cuc-16]. For tomatoes inoculated with ToLCNDV-[ES-Alm-Cuc-16], infection occurred without symptoms in most plants, and only a few plants showed slight vein-yellowing symptoms. In contrast, ToLCNDV-[BACu-20] infection induced typical begomoviral disease symptoms of yellowing and curling of leaves in the same tomato cultivar. The present study highlights the importance of screening genetic resources for ToLCNDV resistance by using ToLCNDV isolates from the intended production area; furthermore, the agroinoculation method used in this study will facilitate breeding resistance against both the Southeast Asian and Mediterranean ToLCNDV isolates.

番茄曲叶新德里病毒（ToLCNDV）是一个二分双生病毒（属菜豆金色花叶病毒，家庭联体病毒科) 最初在印度孤立，但已成为对印度次大陆、东南亚、东亚、中东和地中海西部盆地的各种园艺作物的严重威胁。在东南亚、东亚和地中海西部盆地，ToLCNDV 对葫芦科作物（黄瓜、甜瓜、南瓜和西葫芦）造成了巨大的经济损失，目前还没有商业抗 ToLCNDV 品种。在这项研究中，从西班牙阿尔梅里亚表现出黄叶卷曲病的黄瓜、甜瓜和西葫芦植物中分离出全长 ToLCNDV 病毒序列。系统发育分析表明，分离的病毒由 ToLCNDV-ES 毒株和与东南亚的 ToLCNDV-[BACu-20] 遗传距离较远的毒株组成，这些毒株以前在印度尼西亚的亚齐省分离。本氏烟草、番茄和葫芦科作物（黄瓜、甜瓜和西葫芦）。所有接种的植物物种的感染率接近 100%，与接种 ToLCNDV-[ES-Alm-Cuc-16] 的植物相比，接种 ToLCNDV-[BACu-20] 的植物的疾病症状始终更严重。对于接种ToLCNDV-[ES-Alm-Cuc-16]的番茄，大多数植株无症状感染，仅有少数植株出现轻微的叶脉黄化症状。相比之下，ToLCNDV-[BACu-20] 感染在同一番茄品种中诱导了典型的变种病毒病症状，即叶片变黄和卷曲。本研究强调了通过使用来自预期生产区的 ToLCNDV 分离株来筛选 ToLCNDV 抗性遗传资源的重要性；此外，