A novel begomovirus with distinct genomic and phenotypic features infects tomato in Bangladesh

M. N. Maruthi¹*, A. R. Rekha¹, S. N. Alam², K. A. Kader², A. Cork¹ and J. Colvin¹

¹ Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
² Bangladesh Agricultural Research Institute, Joydebpur, Gazipur, Bangladesh

*m.n.maruthi@gre.ac.uk

Accepted for publication 10/05/05

In Bangladesh tomato is cultivated over ca. 40,000 acres annually. Tomato leaf curl virus disease (ToLCVD) normally reduces tomato production significantly; often causing up to 100% yield loss. Diseased tomato plants were collected from Joydebpur, Bangladesh, in September 2003, because they exhibited unusually mild ToLCVD symptoms of yellowing and leaf curling. In addition, ‘mosaic-like’ symptoms developed on the older leaves of a susceptible tomato variety ‘Moneymaker’, which is atypical for leaf curl-inducing viruses.

Figure 1: ‘Mosaic-like’ symptoms expressed on the older leaves of tomato variety Moneymaker upon infection by ToLCJV.	Figure 2: Most parsimonious trees showing the relationship of ToLCJV-Mld and associated DNA-β molecule to other begomoviruses. Sequences of this study are highlighted. Numbers at nodes indicate percentage bootstrap values out of 100 replicates.

Total DNA was extracted from leaves with symptoms and putative viral genomes were amplified by polymerase chain reaction using degenerate primers specific to DNA-A and -B (Muniyappa et al., 2003), and DNA-β molecules (Briddon et al., 2002). Sequences generated from the amplicons were either used to design virus-specific primers or to obtain directly complete viral sequences. A previously undescribed monopartite begomovirus, designated Tomato leaf curl Joydebpur virus-Mild (ToLCJV-Mld), was found associated with these mild symptoms. Based on DNA-A sequences (2761 nucleotides, EMBL Accession No. AJ875159), ToLCJV-Mld was most similar to Pepper leaf curl Bangladesh virus (AF314531) at 87.1% nt identity. ToLCJV-Mld satellite DNA-β molecule (1366 nt, AJ966244) shared highest (59.0%) nt identity with a molecule isolated from ToLCVD in India (AY438558). No DNA-B component was detected. The number and arrangement of ToLCJV-Mld DNA-A open reading frames (ORFs) was identical to monopartite begomoviruses, except that an additional ORF of 849 nt (282 amino acids) was predicted to occur on the complementary strand between nt positions 1139 and 291 encompassing the entire length of the coat protein gene. The association of a DNA-β molecule with begomoviruses is known to cause severe symptoms, but to our knowledge this is the first report where it was associated with mild symptoms. ToLCJV-Mld DNA-A shared 86.0% and 74.4% nt identities with the previously reported Tomato leaf curl Bangladesh virus (AF188481) (Green et al., 2001) and Tomato leaf curl New Delhi virus-Severe[Jessore] (AJ875157) (Maruthi et al., 2005), respectively. These results confirm the occurrence of at least three begomovirus species in tomato in Bangladesh.

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Green SK, Tsai WS, Shih SL, Black LL, RezajanA, Rashid MH, Roff MMN, Myint YY, Hong LTA, 2001. Molecular characterisation of begomoviruses associated with leafcurl diseases of tomato in Bangladesh, Laos, Malaysia, Myanmar and Vietnam. Plant Disease 85, 1286.

Maruthi MN, Rekha AR, Cork A, Colvin J, Alam SN, Kader KA, (submitted). First report of Tomato leaf curl New Delhi virus infecting tomato in Bangladesh. Plant Disease

Muniyappa V, Maruthi MN, Babitha CR, Colvin J, Briddon RW, Rangaswamy KT, 2003. Characterisation of pumpkin yellow vein mosaic virus from India. Annals of Applied Biology 142, 323-331.

The British Society for Plant Pathology