Resumo

DIAZ-VALASIS, Margarita et al. Etiology and effect in genotypes of browning and abnormal sprout associated to phytoplasmas in potato tubers. Rev. Mex. Cienc. Agríc [online]. 2010, vol.1, n.4, pp.525-540. ISSN 2007-0934.

Potato purple top affects yield and tubers quality by browning and the abnormal sprout associated with it. This disease is considered of phytoplasmic origin, although Koch postulates have not been properly proven. This investigation tries to determine etiology for browning and abnormal sprouting in potato; taking this into account isolations coming from 19 genotypes of field potato with four varieties were transmitted by means of graft: Sangema that had 52.63% transmission, Michoacán that had 42.1%, Norteña with 31.57% and NAU-6 that reached 65.2%. The greenhouse potatoes cuttings with symptoms of purple tip transmitted by seed-tuber, induced symptoms of "popotillo" in red tomato; however, when grafting again in potato symptoms were not observed in the foliage, neither browning in the tubers and phytoplasma was not detected by means of reaction technique in polymerase chain. The transmission percentage for potato purple tip in greenhouse was of 37%. The browning and the abnormal sprouting in tubers were induced by an infectious pathogen, transmitted until for six successive grafts in greenhouse. The percentage of phytoplasma detection with polymerase in foliage and tuber of used varieties NAU-6, Norteña, Michoacán and Alpha were of 37.5, 10, 35.7 and 28.6 respectively. In chili manzano and mixquic, this was of 70.83% and 66.6%, in tomato there were not recorded phytoplasmas. In chili plants, it can act as intermediary host in transmission of pathogen involved with this disease.

Palavras-chave : apical roll; phytoplasmas; potato purple tip.

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