Determinantes virais envolvidos na adaptabilidade diferencial de dois begomovírus em tomateiro e Nicotiana benthamiana / Viral determinants involves in the differential adaptation of two begomovirus in tomato and Nicotiana benthamiana

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

16/12/2011

RESUMO

Begomoviruses (family Geminiviridae) have a genome composed of a one or two components of circular, single-stranded DNA and infect dicotyledoneous plants. Symptoms induced by the begomovirus Tomato yellow spot virus (ToYSV) in tomato and Nicotiana benthamiana are more severe and appear earlier compared to those induced by Tomato rugose mosaic virus (ToRMV). Furthermore, ToYSV invades the mesophyll in N. benthamiana, whereas ToRMV is phloem-restricted in this host (both viruses are phloem-restricted in tomato). These observations suggest a differential adaptation of each virus to its host. In order to map the viral genetic determinants responsible for this differential adaptation, three recombinants were constructed based on the exchange of the MP and NSP genes and the BRi region between the two viruses, in different combinations. Experiments with the recombinants were performed to determine the gain or loss of the following characteristics: intensity of symptoms, viral DNA accumulation and tissue tropism. Reciprocal recombinants in which the MP and NSP genes were swapped induced symptoms of intermediate intensity compared to the parental viruses in both hosts, and had the same tissue tropism in N. benthamiana. The recombinant in which the ToYSV BRi region was placed in the ToRMV DNA-B background was capable of invading the mesophyll in N. benthamiana. Together, these results indicate that the MP and NSP proteins as well as the BRi region are involved in the adaptation of ToYSV in tomato and N. benthamiana, and that the BRi region is the viral determinant of tissue tropism in N. benthamiana. Other proteins and regulatory sequences present in the DNA-A could also be involved in the adaptation of these viruses, however further experiments, including the analysis of a recombinant in which the BRi region from ToRMV is placed in the ToYSV background, are necessary for their precise identification.

ASSUNTO(S)

nicotiana benthamiana adaptabilidade diferencial begomovírus tomateiro fitopatologia nicotiana benthamiana differential adaptation begomovírus tomato

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