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A complex of Begomoviruses affecting tomato crops in Nicaragua

Rojas, Aldo (2004). A complex of Begomoviruses affecting tomato crops in Nicaragua. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae. Agraria, 1401-6249 ; 492
ISBN 91-576-6772-1
[Doctoral thesis]

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Abstract

Diseases caused by begomoviruses (family Geminiviridae, genus Begomovirus) constitute a serious constraint to vegetable production in Nicaragua as they are associated with large economical losses. This thesis was done in an effort to identify and characterize the begomoviruses responsible for the tomato diseases and to understand their relationships. The cropping system used by small-holding farmers comprises essentially five crops: maize and bean as consumption crops, and tomato, pepper and cucurbits as cash crops. These crops are grown in the three different growing seasons all the year around. Except maize, all the other crops are hosts for begomoviruses and whiteflies. In this study, begomovirus sequences detected with universal and virus specific primers were cloned, sequenced and used for phylogenetic analysis. The plants from which the viruses were detected were tomato, pepper, cucurbits and Euphorbia heterophylla. The sequence comparisons revealed high identity with other already described begomovirus species, including Euphorbia mosaic virus (EuMV), Squash yellow mild mottle virus (SYMMoV) Tomato severe leaf curl virus (ToSLCV), Tomato leaf curl Sinaloa virus (ToLCSinV) and Pepper golden mosaic virus (PepGMV). One viral sequence from tomato showed only low identity to previously sequenced begomoviruses (84%) and represents a new tentative species designated as Tomato leaf curl Las Playitas virus (ToLCLPV). The complete nucleotide (nt) sequences of the DNA-A and DNA-B components were determined for ToLCSinV, and the complete nt sequence was determined for the DNA-A component of two isolates of ToSLCV. The genome organization of ToLCSinV and ToSLCV was identical to the bipartite genomes of other begomoviruses described from the Americas. A phylogenetic analysis of DNA-A showed that the indigenous begomoviruses of the New World can be divided into three major clades and an intermediate group, and that ToLCSinV and ToSLCV belong to different clades. Computer-based predictions indicated that recombination with another begomovirus had taken place within AV1 of ToSLCV dividing this species into two strains. Mixed infection with different strains of the same virus, and mixed infections with up to three begomovirus species were detected in tomato plants. Three begomoviruses were detected in both tomato and pepper in the field. Detection of predicted recombinant viral isolates is consistent with other findings of this study which indicate that begomoviruses commonly occur as mixed infections in the field, and that intraspecific sequence variability within an infected plant may be as high as between different plants. These conditions provide a high risk for evolution of new virus strains and species via recombination. Acquisition and transmission of ToLCSinV and ToSLCV by their whitefly vector, Bemisia tabaci, required only 10 min on tomato plants. Longer acquisition and inoculation access periods tended to increase the virus transmission rates. Whiteflies transmitted the viruses for seven days without new virus acquisition.

Authors/Creators:Rojas, Aldo
Title:A complex of Begomoviruses affecting tomato crops in Nicaragua
Year of publishing :January 2004
Volume:492
Number of Pages:44
Papers/manuscripts:
NumberReferences
ALLI. Rojas, A., Kvarnheden, A., and Valkonen, J. P. T. 2000. Geminiviruses infecting tomato crops in Nicaragua. Plant Dis. 84:843-846. II. Ala-Poikela, M., Svensson, E., Rojas, A., Horko, T., Paulin, L., Valkonen, J. P. T. and Kvarnheden, A. 2004. Genetic diversity and mixed infections of begomoviruses infecting tomato, pepper and cucurbit crops in Nicaragua. (Submitted) III. Rojas, A., Kvarnheden, A., Marcenaro, D., and Valkonen, J. P. T. 2004. Sequence characterization of Tomato leaf curl Sinaloa virus and Tomato severe leaf curl virus: Phylogeny for New World begomoviruses and detection of recombination. Arch. Virol. (accepted pending revision). IV. Rojas, A., Marcenaro, D., Rayo, M., Salinas, C., Zeledón, K., Kvarnheden, A., and Valkonen, J. P. T. 2004. Transmissión of Nicaraguan begomovirus isolates by whiteflies on tomato. (Manuscript)
Place of Publication:Uppsala
ISBN for printed version:91-576-6772-1
ISSN:1401-6249
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F30 Plant genetics and breeding
Subjects:Not in use, please see Agris categories
Agrovoc terms:geminiviruses, lycopersicon esculentum, capsicum annuum, cucurbita, plant diseases, genomes, genetic inheritance, phylogeny, nicaragua
Keywords:plant disease, Lycopersicon esculentum, Capsicum annuum, Cucurbita argyrosperma, begomovirus evolution
URN:NBN:urn:nbn:se:slu:epsilon-468
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-468
ID Code:727
Department:(NL, NJ) > Dept. of Plant Biology and Forest Genetics (until 131231)
Deposited By: Aldo Rojas
Deposited On:10 Jan 2005 00:00
Metadata Last Modified:02 Dec 2014 10:06

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