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| FANTA,NORA; ORTEGA,XIMENA; PÉREZ,LUZ M. |
| In addition to phytoalexin synthesis, the defense response of intact Citrus limon seedlings against Alternaria alternata involves both constitutive and induced enzyme activities such as chitinases (Ch) and ß-1,3-glucanases (Glu). A. alternata conidial germination was prevented by protein extracts from inoculated lemon seedlings, but also by extracts from mock-inoculated specimens. On the other hand, degradation of mycelia was accomplished only by protein extracts from inoculated seedlings. The presence of six Ch isoenzymes and of four Glu isoenzymes was detected in protein extracts from mock-inoculated seedlings. As a result of fungal inoculation, the isoenzyme pattern of Ch and Glu changed, making possible the detection of a new Ch isoenzyme and of three... |
| Tipo: Journal article |
Palavras-chave: Alternaria alternata; Lemon; Hypersensitive response; Chitinases; Glucanases. |
| Ano: 2003 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602003000300012 |
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| ORTEGA,XIMENA; POLANCO,RUBÉN; CASTAÑEDA,PATRICIA; PEREZ,LUZ M. |
| The development of an effective hypersensitive response (HR) in any plant system relies, not only in their gene composition and expression, but also on an effective and rapid signal transduction system. Lemon seedlings induce the phenylpropanoid pathway, which results in the de novo biosynthesis of the phytoalexin scoparone, as part of the hypersensitive response against Alternaria alternata. In order to elucidate some of the signaling elements that participate in the development of HR in lemon seedlings, we used several compounds that are known as activators or inhibitors of signal transduction elements in plants or in animal cells. Lemon seedlings treated either with cholera toxin or with phorbol 12-myristate 13-acetate (PMA), in the absence of A.... |
| Tipo: Journal article |
Palavras-chave: Citrus limon; Hypersensitive response; Signal transduction. |
| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602002000300012 |
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| ORTEGA,XIMENA; VELÁSQUEZ,JUAN CARLOS; PÉREZ,LUZ M. |
| IP3 increase and de novo synthesis of scoparone are produced in the hypersensitive response (HR) of lemon seedlings against the fungus Alternaria alternata. To elucidate whether a G-protein and/or a protein tyrosine kinase (PTK) are involved in signal transduction leading to the production of such a defensive response, we studied the HR in this plant system after treatment with G-protein activators alone and PTK inhibitors in the presence of fungal conidia. No changes in the level of IP3 were detected in response to the treatment with the G-protein activators cholera toxin or mastoparan, although the HR was observed in response to these compounds as determined by the scoparone synthesis. On the contrary, the PTK inhibitors lavendustin A and 2,5-dihidroxy... |
| Tipo: Journal article |
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| Ano: 2005 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602005000100011 |
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| ORTEGA,XIMENA; PÉREZ,LUZ M.. |
| Lemon seedlings inoculated with Alternaria alternata develop a hypersensitive response (HR) that includes the induction of Phenylalanine ammonia-lyase (PAL, E. C. 4.3.1.5) and the synthesis of scoparone. The signal transduction pathway involved in the development of this response is unknown. We used several inhibitors of the Phosphoinositide (PI) animal system to study a possible role of Inositol-1,4,5-triphosphate (IP3 ) in the transduction of the fungal conidia signal in Citrus limon. The HR was only partially inhibited by EGTA, suggesting that not only external but internal calcium as well are necessary for a complete development of the HR. In this plant system, Alternaria alternata induced an early accumulation of the second messenger IP3. When lemon... |
| Tipo: Journal article |
Palavras-chave: Citrus limon; IP3; Phosphoinositides; Rutaceae; Signal transduction. |
| Ano: 2001 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602001000100014 |
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