National Institute for Biotechnology and Genetic Engineering, Agricultural Biotechnology Division, Faisalabad, Pakistan.
King Faisal University, Central Laboratories, Al Ahsa, Saudi Arabia.
Braz J Biol. 2022 Jul 25;84:e260922. doi: 10.1590/1519-6984.260922. eCollection 2022.
Alphasatellites (family Alphasatellitidae) are circular, single-stranded (ss) DNA molecules of ~1350 nucleotide in size that have been characterized in both the Old and New Worlds. Alphasatellites have inherent ability to self-replicate, which is accomplished by a single protein, replication-associated protein (Rep). Although the precise function of alphasatellite is yet unknown, and these consider dispensable for infectivity, however, their Rep protein functions as a suppressor of host defence. While alphasatellites are most frequently associated with begomoviruses, particularly with monopartite than bipartite begomoviruses, they have recently been found associated with mastreviruses. The in planta maintenance of alphasatellites by helper geminivirus is still an enigma, with no available study on the topic. This study aimed to investigate whether a widely distributed bipartite begomovirus, tomato leaf curl New Delhi virus (ToLCNDV), can maintain cotton leaf curl Multan alphasatellite (CLCuMuA) in the presence or absence of cotton leaf curl Multan betasatellite (CLCuMuB). The findings of this study demonstrated that ToLCNDV or its DNA A could maintain CLCuMuA in Nicotiana benthamiana plants. However, the presence of CLCuMuB interferes with the maintenance of CLCuMuA, and mutations in the CP of ToLCNDV further reduces it. Our study highlighted that the maintenance of alphasatellites is impaired in the presence of a betasatellite by ToLCNDV. Further investigation is needed to unravel all the interactions between a helper virus and an alphasatellites.
阿尔法卫星（Alphasatellitidae 科）是大小约为 1350 个核苷酸的圆形、单链（ss）DNA 分子，在新旧世界均有特征。阿尔法卫星具有内在的自我复制能力，这是通过一种单一的蛋白质，即复制相关蛋白（Rep）来实现的。尽管阿尔法卫星的确切功能尚不清楚，而且这些功能对于感染性来说是可有可无的，但它们的 Rep 蛋白可以作为宿主防御的抑制剂。虽然阿尔法卫星最常与番茄黄曲叶病毒（begomoviruses）相关，特别是与单分体比二分体番茄黄曲叶病毒相关，但最近它们也被发现与烟粉虱黄曲叶病毒（mastreviruses）相关。辅助双生病毒在植物体内维持阿尔法卫星仍然是一个谜，目前还没有关于这个主题的可用研究。本研究旨在探讨广泛分布的二分体番茄黄曲叶病毒（tomato leaf curl New Delhi virus，ToLCNDV）是否能够在存在或不存在棉花曲叶多面体病毒（cotton leaf curl Multan betasatellite，CLCuMuB）的情况下维持棉花曲叶多面体病毒（cotton leaf curl Multan alphasatellite，CLCuMuA）。本研究的结果表明，ToLCNDV 或其 DNA A 可以在 Nicotiana benthamiana 植物中维持 CLCuMuA。然而，CLCuMuB 的存在会干扰 CLCuMuA 的维持，并且 ToLCNDV CP 中的突变进一步降低了它的维持。我们的研究强调了在 ToLCNDV 的存在下，贝塔卫星会损害阿尔法卫星的维持。需要进一步的研究来揭示辅助病毒和阿尔法卫星之间的所有相互作用。
