Defensive response of commercial varieties of Prunus persica L. to the attack of Myzus persicae (Sulzer) APHID

Abstract

Durazneros y nectarines son uno de los frutales más importantes en el mundo, los cuales son atacados por el áfido M. persicae causando daños directos e indirectos. En Chile, durazneros y nectarines son importantes productos frutícolas los cuales son fuertemente atacados por este áfido. Sin embargo, existe muy poca información enfocada en la variación de la susceptibilidad/resistencia entre los cultivares plantados. En este estudio fue enfocado en la interacción entre este áfido y los genotipos comerciales de P. persica. Primero, cultivares comerciales de durazneros y nectarines se seleccionaron buscando la resistencia diferencial en el campo (ocurrencia y desempeño de áfidos), así como en experimentos de laboratorio (pruebas de no elección y comportamiento alimentario). Se pudo encontrar un amplio rango de diferentes respuestas en resistencia a M. persicae en experimentos de campo y laboratorio, con algunos cultivares exhibiendo antibiosis, antixenosis o bien una mezcla de ambas. En un estudio adicional, los cultivares con patrones contrastantes en resistencia, fueron seleccionados con el objetivo de evaluar el efecto del riego sobre la resistencia. Se usaron dos niveles diferentes de riego, plantas bien-regadas (100% capacidad de campo) y plantas con déficit de agua (50% capacidad de campo), y se evaluó la respuesta defensiva de la planta. Este experimento mostró que la resistencia fue modulada por el riego, produciendo que plantas resistentes y susceptibles bajo déficit de agua mostraran similar nivel de enrollamiento provocado por áfidos. También se observó resistencia y susceptibilidad inducida, independiente de los cultivares (resistente y susceptible). Una respuesta tolerante, medida como el crecimiento de la planta después del daño efectuado por el áfido, se observó en ambos cultivares, capacidad que fue dependiente del nivel de riego, particularmente en plantas bien regadas. Finalmente, se evaluó cómo los áfidos responden a plantas con diferencias en resistencia y riego, para lo cual se consideró el perfil proteómico de los áfidos alimentados sobre cultivares de duraznero y tratamiento con diferentes riegos. Los análisis proteómicos mostraron que los áfidos sufrieron más cambios en la regulación de proteínas después de alimentarse en el cultivar más susceptible. Las proteínas sobre-reguladas en áfidos alimentados en el cultivar susceptible actuaban mayoritariamente en el metabolismo de energía, mientras que sobre el cultivar resistente la mayoría fue sobre-regulado en proteínas asociadas al citosqueleto. Todo lo anterior ayudó a entender mejor las respuestas defensivas de Prunus persica y la respuesta proteómica del áfido a las plantas con diferente resistencia y nivel de riego./ABSTRACT:Peaches and nectarines are among the most important fruit worldwide. Unfortunately, they are heavily attacked by the aphid M. persicae causing direct and indirect damages. In Chile, peaches and nectarines are also important fruit products. However, there is little information regarding the variation in susceptibility/resistance among cultivars frequently planted. In this study the interaction between this aphid and commercial genotypes of P. persica was addressed. First, commercial cultivars of peaches and nectarines were screened regarding differential resistance in the field (aphid occurrence and performance), as well as in laboratory experiments (no-choice test and feeding behavior). It was found a wide range of different responses in resistance to M. persicae, either in the field and laboratory experiments, with some cultivar exhibiting antibiosis, antixenosis or mixed resistances. In a further study, the cultivars with most contrasting resistant patterns were selected with the aim to assess the effect of irrigation on resistance. Two different levels of irrigation were used, well-watered (100% field capacity) and water-deficient (50% field capacity) plants, and the plant defensive response was evaluated. This experiment showed that resistance was modulated by irrigation as under water-deficiency curling produced by aphids was similar between the resistant and susceptible cultivars. It was also found induced resistance and induced susceptibility regardless the cultivar genotypes (resistant or susceptible). In addition, a tolerant response, measured as plant growth after aphid damage, was observed in both cultivars, capacity that was also dependent of irrigation levels with higher tolerance displayed by well-watered plants. Finally, in order to assess how aphids respond to plants with differences in resistant and irrigation, the proteomic profile of aphids that fed on peach cultivars with different resistance and different irrigation treatment was also performed. The proteomic analysis showed that aphids suffered of higher changes in the regulation of proteins after feeding on the susceptible cultivar than on the resistant one. The proteins up-regulated on aphid fed in the susceptible cultivar were mostly involved in the energy metabolism, whereas on the resistant cultivar the most up-regulated proteins were those associated to the cytoskeleton. All the above helped to a better understanding of both, the defensive response of Prunus persica and to the proteomic response of the aphid to plants with different resistance and level of irrigation./ABSTRACT: Resistance and tolerance are two mechanisms that plant use to display when confronting herbivore attack. Both are known to be affected by environmental fluctuations, and particularly by resource availability. In the present study, two nectarine genotypes with different resistance to the aphid Myzus persicae were subjected to the attack of this aphid under variable water supply. The results showed that, independently of the water supply, the resistant genotype exhibited a lower growth in number of leaves in the absence of aphids, which is an indication of the cost of resistance in this cultivar.Interestingly, aphid attack was compensated and overcompensated in susceptible and resistant cultivars respectively. Population growth rate (PGR) and index of infestation (IF), indicated with water-deficient diminished 2.3 fold in the susceptible cultivar indicating a decrease in the susceptibility and increased 2.4 fold on the resistant cultivar. Independent of the cultivar, under normal irrigation conditions, induced resistant was exhibited and induced susceptibility was caused in the presence of water deficit. Therefore, the resistance and tolerance in this model is affected by the intrinsic traits of the cultivar and also is influenced by the irrigation conditions, an important to consider in future breeding programs. Key words: resistance, tolerance, overcompensation, water deficit, Myzus persicae./ABSTRACT: The effect of water supply on plant defense to herbivores has been intensively studied. However, the herbivore response to herbivore-resistant plants under water deficit is poorly understood. In this study, the proteomic profile of one clone of the green peach aphid Myzus persicae which was exposed to two genotype of Prunus persica, one susceptible to this aphid (GF305) and another resistant (Rubira®), which were both also subjected to normal and water deficient irrigation was studied. The results showed that after 48 h, as compared to aphids fed on control plants (well-watered), the aphids fed on the susceptible peach genotype under water-deficit exhibited 19 proteins up-regulated, whereas on the resistant genotype only 8 proteins were up-regulated. Most of the proteins exhibiting changes on the susceptible genotypes were involved in energy metabolism (as Regulator of G-protein signaling 7-like and RNA 3' terminal phosphate cyclase), whereas those mainly associated to cytoskeleton functionality (as actin related protein 1 and F-actin capping protein subunit beta) changed in the resistant genotype. Five proteins exhibited similar regulation changes as a consequence of water-deficit in both peach genotypes, proteins mostly related with cytoskeleton. Only one of these proteins was down-regulated, the mitochondrial-processing peptidase, which is associated with aphid response to toxicity. In a parallel experiment using similar treatments as in the proteomic study, the population rate of growth (PGR) of this clone was only affected by peach genotype, finding, as expected, that PGR was higher in the susceptible peach. Thus, these findings suggest that susceptible plant, under water deficit, more than resistance ones, suffers of physiological changes which in turn elicit (or “transferred to”) a significant proteomic changes on aphids.Key words: resistance, water stress, Myzus persicae, Prunus persica, proteomic.