The minimal sequence essential for replication and movement of Cotton leaf curl Multan betasatellite DNA by a helper virus in plant cells

Abstract Background Alphasatellites are small coding DNA satellites frequently associated with a begomovirus/betasatellite complex, where they are known to modulate virulence and symptom development. Two distinct alphasatellites, namely, Cotton leaf curl Multan alphasatellite (CLCuMuA), and Gossypium darwinii symptomless alphasatellite (GDarSLA) associated with Cotton leaf curl Multan virus-India (CLCuMuV-IN) and Ludwigia leaf distortion betasatellite (LuLDB) were found to be associated with yellow mosaic disease of hollyhock (Alcea rosea) plants. In this study, we show that alphasatellites CLCuMuA and GDarSLA attenuate and delay symptom development in Nicotiana benthamiana. The presence of either alphasatellites reduce the accumulation of the helper virus CLCuMuV-IN. However, the levels of the associated betasatellite, LuLDB, remains unchanged. These results suggest that the alphasatellites could contribute to the host defence and understanding their role in disease development is important for developing resistance strategies. Methods Tandem repeat constructs of two distinct alphasatellites, namely, CLCuMuA and GDarSLA associated with CLCuMuV-IN and LuLDB were generated. N. benthamiana plants were co-agroinoculated with CLCuMuV and its associated alphasatellites and betasatellite molecules and samples were collected at 7, 14 and 21 days post inoculation (dpi). The viral DNA molecules were quantified in N. benthamiana plants by qPCR. The sequences were analysed using the MEGA-X tool, and a phylogenetic tree was generated. Genetic diversity among the CLCuMuA and GDarSLA was analysed using the DnaSP tool. Results We observed a reduction in symptom severity and accumulation of helper virus in the presence of two alphasatellites isolated from naturally infected hollyhock plants. However, no reduction in the accumulation of betasatellite was observed. The phylogenetic and genetic variability study revealed the evolutionary dynamics of these distinct alphasatellites , which could explain the role of hollyhock-associated alphasatellites in plants. Conclusions This study provides evidence that alphasatellites have a role in symptom modulation and suppress helper virus replication without any discernible effect on the replication of the associated betasatellite.

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Implication of the Whitefly Protein Vps Twenty Associated 1 (Vta1) in the Transmission of Cotton Leaf Curl Multan Virus

Microorganisms ◽

10.3390/microorganisms9020304 ◽

2021 ◽

Vol 9 (2) ◽

pp. 304

Author(s):

Yao Chi ◽

Li-Long Pan ◽

Shu-Sheng Liu ◽

Shahid Mansoor ◽

Xiao-Wei Wang

Keyword(s):

Coat Protein ◽

Molecular Mechanisms ◽

Cotton Leaf ◽

Yeast Two Hybrid ◽

Yeast Two Hybrid System ◽

Vacuolar Protein ◽

Leaf Curl Disease ◽

Two Hybrid ◽

Asia Ii 1 ◽

Leaf Curl

Cotton leaf curl Multan virus (CLCuMuV) is one of the major casual agents of cotton leaf curl disease. Previous studies show that two indigenous whitefly species of the Bemisia tabaci complex, Asia II 1 and Asia II 7, are able to transmit CLCuMuV, but the molecular mechanisms underlying the transmission are poorly known. In this study, we attempted to identify the whitefly proteins involved in CLCuMuV transmission. First, using a yeast two-hybrid system, we identified 54 candidate proteins of Asia II 1 that putatively can interact with the coat protein of CLCuMuV. Second, we examined interactions between the CLCuMuV coat protein and several whitefly proteins, including vacuolar protein sorting-associated protein (Vps) twenty associated 1 (Vta1). Third, using RNA interference, we found that Vta1 positively regulated CLCuMuV acquisition and transmission by the Asia II 1 whitefly. In addition, we showed that the interaction between the CLCuMuV coat protein and Vta1 from the whitefly Middle East-Asia Minor (MEAM1), a poor vector of CLCuMuV, was much weaker than that between Asia II 1 Vta1 and the CLCuMuV coat protein. Silencing of Vta1 in MEAM1 did not affect the quantity of CLCuMuV acquired by the whitefly. Taken together, our results suggest that Vta1 may play an important role in the transmission of CLCuMuV by the whitefly.

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