Geminiviruses cause devastating diseases in solanaceous crops, with the bipartite begomoviruses tomato yellow leaf curl Kanchanaburi virus (TYLCKaV) and pepper yellow leaf curl Thailand virus (PYLCThV) major threats in Southeast Asia. To determine the molecular mechanism of geminivirus infection, we constructed infectious clones of TYLCKaV and PYLCThV. Both constructs infected Nicotiana benthamiana, but only TYLCKaV could infect Solanum lycopersicum ‘A39’. A genome-swapping of TYLCKaV with PYLCThV revealed the TYLCKaV-B genome segment as the determinant of TYLCKaV infectivity in tomato. We constructed five geminivirus clones with chimeric TYLCKaV-B and PYLCThV-B genome segments to narrow down the region determining TYLCKaV infectivity in tomato. Only chimeric clones carrying the TYLCKaV intergenic region (IR) showed infectivity in S. lycopersicum ‘A39’, indicating that the IR of TYLCKaV-B is essential for TYLCKaV infectivity in tomato. Our results provide a foundation for elucidating the molecular mechanism of geminivirus infection in plants.

双生病毒在茄科作物中引起毁灭性的疾病，其中二分体病毒、北碧府番茄黄曲叶病毒 (TYLCKaV) 和泰国辣椒黄曲叶病毒 (PYLCThV) 是东南亚的主要威胁。为了确定双生病毒感染的分子机制，我们构建了 TYLCKaV 和 PYLCThV 的感染性克隆。两种构建体都感染本塞姆氏烟草，但只有 TYLCKaV 可以感染番茄'A39'。 TYLCKaV 与 PYLCThV 的基因组交换揭示了 TYLCKaV-B 基因组片段是 TYLCKaV 在番茄中感染性的决定因素。我们构建了五个具有嵌合 TYLCKaV-B 和 PYLCThV-B 基因组片段的双生病毒克隆，以缩小决定番茄中 TYLCKaV 感染性的区域。只有携带 TYLCKaV 基因间区域 (IR) 的嵌合克隆在番茄“A39”中显示出感染性，表明 TYLCKaV-B 的 IR 对于番茄中 TYLCKaV 的感染性至关重要。我们的结果为阐明双生病毒感染植物的分子机制奠定了基础。