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2 resultados encontrados para: AUTOR: Abdala Roberts, Luis
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1.
Artículo
Resumen en: Inglés |
Resumen en inglés

•The induction of defences in response to herbivory is a key mechanism of plant resistance. While a number of studies have investigated the time course and magnitude of plant induction in response to a single event of herbivory, few have looked at the effects of recurrent herbivory. Furthermore, studies measuring the effects of the total amount and recurrence of herbivory on both direct and indirect plant defences are lacking. To address this gap, here we asked whether insect leaf herbivory induced changes in the amount and concentration of extrafloral nectar (an indirect defence) and concentration of leaf phenolic compounds (a direct defence) in wild cotton(Gossypium hirsutum). •We conducted a greenhouse experiment where we tested single event or recurrent herbivory effects on defence induction by applying mechanical leaf damage and caterpillar (Spodoptera frugiperda) regurgitant. •Single events of 25% and 50% leaf damage did not significantly influence extrafloral nectar production or concentration. Extrafloral nectar traits did, however, increase significantly relative to controls when plants were exposed to recurrent herbivory (two episodes of 25% damage). In contrast, phenolic compounds increased significantly inresponse to single events of leaf damage but not to recurrent damage. In addition, we found. that local induction of extrafloral nectar production was stronger than systemic induction, whereas the reverse pattern was observed for phenolics. •Together, these results reveal seemingly inverse patterns of induction of direct andindirect defences in response to herbivory in wild cotton.


2.
Artículo
Floral longevity and scent respond to pollen manipulation and resource status in the tropical orchid Myrmecophila christinae
Parra Tabla, Víctor ; Abdala Roberts, Luis (coaut.) ; Rojas, Julio C. (coaut.) ; Navarro Alberto, Jorge Augusto (coaut.) ; Salinas Peba, Luis Higinio (coaut.) ;
Contenido en: Plant Systematics and Evolution Vol. 282, no. 1/2 (August 2009), p. 1-11 ISSN: 0378-2697
Resumen en: Inglés |
Resumen en inglés

Floral longevity (FL) is a key aspect in plant reproductive ecology. Despite this, the effect of resource status on FL has usually been ignored, and never has resource status been linked to the effects of pollen manipulation on FL. In addition, immediate changes in floral scent characteristics subsequent to pollen addition/removal have not been looked at. Here we use the tropical orchid Myrmecophila christinae to address the following: (1) Does flower bud removal (resource status change) increase FL? (2) Does pollen manipulation (addition/removal) decrease FL, and do such effects interact with plant resource status? (3) Are there rapid changes in floral scent production and composition after pollen manipulation? To answer the first question, we removed 50% of the flower buds on 24 plants (24 more were controls). To test the second question, 1 month after removing buds, one of four flowers on each inflorescence received one of the following treatments: no manipulation, pollinia removal, pollination, or pollination + pollinia removal. Finally, to answer the third question, one of four flowers on each of 15 plants (different site) received one of the above-mentioned pollen treatments. Flowers were collected 2, 4, and 6 h after manipulation to measure scent production/composition. Results showed that flowers on bud-removed plants remained open significantly longer relative to those on control plants, and that pollination significantly decreased FL. Additionally, scent production increased throughout the morning and responded differently depending on the pollen manipulation treatment; scent composition on the other hand, remained relatively unchanged throughout the sampling period. By studying both floral scent and physical changes in M. christinae, this study intends to offer a more integrated view of floral senescence within the context of resource and pollen status conditions.