Lara-Núñez, Aurora , Anaya, Ana Luisa , Cruz-Ortega, Rocio .
Allelochemical stress and abscisic acid in Lycopersicon esculentum Mill.
Allelochemical stress can be defined as an important mechanism of plant interference mediated by the addition of plant-produced secondary products (allelochemicals) to the soil rhizosphere. Our studies have focused in knowing the physiological targets of the phytotoxic compounds released by a noxious and endemic weed Sicyos deppei G. Don (Cucurbitaceae), using as the model of the receptor plant Lycopersicon esculentum Mill (Solanaceae), since in Mexican crop-fields is common to find both plants. In this study we wanted to know whether ABA is involved in tomato response to the allelochemicals of S. deppei. We exposed tomato seeds to S. deppei aqueous leachate (0.5%) for 3, 9, 12, 24 and 48 h. In all times we found that levels of ABA were high in treated- compared with control-seeds. Five to 10 Î¼M ABA applied exogenously had similar effects on germination rate and radicle growth as S. deppei treatment. To test if the high levels of ABA were related with radicle protusion, we analyzed the activity and gene expression of some mycropilar endosperm-cell wall degrading enzymes. Activity of Î±-galactosidase, endo- Î² mananase, and Î²-glucanase was decreased, corresponding to a down-regulation in their expression; exo-poligalacturonase activity decreased but did not show changes in expression. Experiments with diniconazole, an inhibitor of ABA catabolism, showed that a delay in the degradation of ABA might be involved in allelochemical stress. To test if ABA is regulating cell cycle we analyzed gene expression of cycD3;1 and cycB2;1, and CDKB2;1; finding both cyclins down regulated only at 48 h. On the contrary, CDKB2;1 was down regulated since 3h-treatment. Currently, we are analyzing if levels of gibberelic acid can overcome the phytotoxic effect caused by S. deppei.
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1 - Universidad Nacional Autonoma de Mexico. Instituto de Ecologia., Ecologia Funcional, Circuito Exterior s/n., Ciudad Universitaria, UNAM., Mexico, DF, 04510, Mexico
2 - Universidad Nacional Autonoma de Mexico. Instituto de Ecologia, Ecologia Funcional
ABA, allelochemical stress, Sicyos deppei, Lycopersicon esculentum, mycropilar endosperm, cell cycle.
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM