Identificação molecular de um fitoplasma associado à malformação das folhas das ornamentais Celosia argentea L. e Celosia spicata L. / Molecular identification of a phytoplasma associated with malformation of the leaves of Celosia argentea L. and Celosia spicata L.

AUTOR(ES)

Bárbara Eckstein

DATA DE PUBLICAÇÃO

2009

RESUMO

Plants belonging to the species Celosia argentea and Celosia spicata are appreciated as ornamentals due to their colorful flowers. Recently, plants of both species exhibiting typical symptoms induced by phytoplasmas, characterized by deformed leaves, proliferation of axillary shoots, stunt and phyllody were found in public places in Piracicaba, SP, Brazil. The present study was done to demonstrate that phytoplasmas were associated with these diseased plants. Twenty four samples composed by leaves and young shoots were obtained from symptomatic plants. Total DNA was extracted and used as template in nested PCR primed by P1/P7 or P1/Tint and 16F2n/16R2. Total DNA extracted from asymptomatic plants of celosia was used as negative control and plants of periwinkle experimentally infected with phytoplasmas were used as positive control. Phytoplasmas were detected in 50% of the symptomatic plants through the amplification of a genomic fragment of 1.2kb visualized as band in agarose gel. Amplification were also obtained for the positive control, but no band was visualized when DNA from asymptomatic plants was used in the PCR reactions. Nested PCR performed with specific primers pair revealed that the phytoplasmas found in all samples belonged to group 16SrIII. RFLP analyses conducted with the restriction enzymes HinfI, HpaII, TaqI, RsaI, KpnI, HaeIII, MseI, HhaI and Bsh 1236I, plus phylogenetic analysis based on the 16S rRNA gene sequences confirmed that the phytoplasma detected in diseased plants was affiliated to group 16SrIII, subgroup J. Positive experimental transmission of the phytoplasma from celosia to periwinkle, using Cuscuta subinclusa, indicated that the disease is infectious and that phytoplasma is, probably, the causal agent.

ASSUNTO(S)

celosia. genética molecular plantas ornamentais. fitoplasmas filogenia diagnosis phytoplasma

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