Tomato leaf curl virus from Bangalore (ToLCV-Ban4): sequence comparison with Indian ToLCV isolates, detection in plants and insects, and vector relationships}

Abstract

Tomato leaf curl virus (ToLCV) is a whitefly (Bemisia tabaci) transmitted geminivirus (family Geminiviridae, genus Begomovirus) causing a destructive disease of tomato in many regions of India, East Asia and Australia. While ToLCV isolates from Australia and Taiwan have a single genomic component (designated DNA-A), those from Northern India have two components (DNA-A and DNA-B). The ToLCV isolates from Southern India (Bangalore) previously cloned seem to have a DNA-A-like monopartite genome. We have used degenerate DNA-A-specific PCR primers to clone the genome of a ToLCV isolate (named ToLCV-Ban4) from field-infected tomato plants growing in Bangalore, India, in 1997. Degenerate DNA-B-specific PCR primers have not allowed to amplify a putative DNA-B from infected tomato, at the time when DNA-B fragments were amplified from plants infected by known bipartite begomoviruses. The full-length 2759 nucleotide-long DNA-A-like viral genome was sequenced. Similarly to other monopartite ToLCV and TYLCV isolates, ToLCV-Ban4 contains six open reading frames, two on the virion strand and four on the complementary strand. Sequence comparisons indicated that ToLCV-Ban4 is similar to the other three isolates from Bangalore previously sequenced, and is closely related to ToLCV-Ban2 (approximately 91% nucleotide sequence identity). Phylogenetic analysis showed that the ToLCV isolates from Bangalore constitute a group of viruses separated from those of Northern India. ToLCV-Ban4 was detected in tomato and in its whitefly vector Bemisia tabaci by one or by a combination of ELISA, Southern blot hybridization and PCR. Parameters of virus acquisition, retention and transmission by the whitefly vector were investigated in the laboratory. Single whiteflies were able to acquire ToLCV-Ban4 from infected tomato and to transmit the virus to tomato test plants, but five insects were necessary to achieve 100% transmission. Minimum acquisition access and inoculation access periods were 10 min and 20 min, respectively. A latent period of 6 h was required for B. tabaci to efficiently infect tomato test plants. Following a 24 h acquisition access period the insect retained its ability to infect tomato test plants for 12 days, but not for its entire life. In one insect/one plant inoculation tests, female whiteflies were more efficient (approximately 95%) than males (approximately 25%) in transmitting the virus.

Tomato yellow vein streak virus: relationship with Bemisia tabaci biotype B and host range

“…Results similar to the ones observed in the present study were obtained in the transmission of Cotton leaf curl virus form India (CLCuKV), Squash leaf curl virus (SLCV), Tomato leaf curl Bangalore virus -C (ToLCBV-C) (sin. Tomato leaf curl virus from Bangalore, India -ToLCVBan4), and Tomato yellow leaf curl virus (TYLCV-EG) isolate from Egypt by B. tabaci biotype B (Cohen et al, 1983;Nateshan et al, 1996;Muniyappa et al, 2000;Mehta et al, 1994a). A TYLCV isolate from Jordan had minimum acquisition and inoculation access periods of 60 and 30 minutes, respectively (Mansour & Al-Musa, 1992).…”

“…Sinaloa tomato leaf curl virus -STLCV) (Idris & Brown, 1998), 11 to 12 days for ToLCBV-C (Muniyappa et al 2000), 11 to 20 days for TYLCV isolate from Jordan (Cohen & Nitzany, 1966;Mansour & Al-Musa, 1992), and 26 days for SLCV (Cohen et al, 1983). These differences in virus AAP, IAP, LP, and period of retention within the insect are expected because, besides the variations in the conditions of the various experiments, especially with respect to insect numbers and the manner by which those insects were handled, other variables, such as begomovirus species, geographic origin of the virus isolate and of the B. tabaci biotype B population might affect these parameters, as reported in studies involving other begomoviruses (Picó et al, 1996;Muniyappa et al, 2000).…”

“…The acquisition and transmission of begomoviruses by B. tabaci has been extensively studied, and these parameters can vary depending on the virus and the aleyrodid biotype (Cohen & Nitzany, 1966;Polston et al, 1990;Zeidan & Czosnek, 1991;Mehta et al, 1994a;Rubinstein & Czosnek, 1997;Muniyappa et al, 2000). Determining these parameters, together with knowledge on the range of virus hosts, allows to elucidate the epidemiology of different begomovirus diseases, as well as to develop disease management strategies.…”

Supervirulent pseudorecombination and asymmetric synergism between genomic components of two distinct species of begomovirus associated with severe tomato leaf curl disease in India

“…Begomoviruses are transmitted by whiteflies [Bemisia tabaci (Gennadius)] and usually possess a bipartite genome of two approximately 2.7 kb DNA components, designated DNA-A and DNA-B. Monopartite begomoviruses are also known to occur in the Old World (Navot et al, 1991;Dry et al, 1993;Muniyappa et al, 2000;Chatchawankanphanich & Maxwell, 2002;Chakraborty et al, 2003a, b).…”

First report of a whitefly-transmitted geminivirus infectingMimosa invisain Malaysia

“…DNA from the M. invisa leaves from the same samples as above was extracted using a DNeasy Plant Mini Kit (Qiagen, UK) according to the manufacturer's instructions. PCR was performed using a begomovirus-specific degenerate primer pair PAV1v722 and PAC1c1960, which is predicted to anneal within the coat protein (CP) open reading frame and the AC1 open reading frame encoding the replicon associated proteins, respectively (Muniyappa et al 2000). All samples produced viral DNA amplicons of~1.3 kb, which incorporated part of the CP and AC1 open reading frames and the entire open reading frames of proteins AC2 and AC3.…”