Resumo

TEJEDA-SARTORIUS, Miriam; MARTINEZ-GALLARDO, Norma Angélica; OLALDE-PORTUGAL, Víctor  e  DELANO-FRIER, John Paul. Jasmonic Acid Accelerates the Expression of a Pathogen-Specific Lipoxygenase (POTLX-3) and Delays Foliar Late Blight Development in Potato (Solanum tuberosum L.). Rev. mex. fitopatol [online]. 2007, vol.25, n.1, pp.18-25. ISSN 2007-8080.

The induced resistance to Phytophthora infestans (Phi) in potato plants (Solanum tuberosum) treated with combinations of jasmonic acid (JA), systemin (SYS), and β- amino butyric acid (BABA) was analyzed. Changes in the levels of β-1,3-glucanase (BG) and chitinase (CHI) activity and POTLX-3 expression, a pathogen-induced leaf lipooxygenase, were also measured. BABA + SYS induced a weak accumulation of POTLX-3 transcripts in uninfected plants, whereas all BABA-containing mixtures enhanced POTLX-3 expression 48 h after Phi infection which was not correlated to an increased resistance response. Conversely, plants treated with JA and JA + SYS showed a delayed progression of the disease, which coincided with a rapid and transient increase of POTLX-3 expression observed 24 h postinfection. These effects were suppressed when JA was applied simultaneously with BABA, an elicitor which generally made plants more susceptible to Phi, even though it induced significant increases in CHI and BG activity levels. Accordingly, a possible antagonism between JA and BABA signalling pathways is discussed. Furthermore, the positive correlation found between an earlier expression of POTLX-3 and resistance to late blight, suggested that it could be part of the mechanism through which JA- and JA+SYS treatments induced the observed protection.

Palavras-chave : Phytophthora infestans; systemin; β-aminobutyric acid; induced resistance.

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