Secondary metabolites in plant defence mechanisms
- Autores: Celia Payá Montes
- Directores de la Tesis: María del Pilar López Gresa (dir. tes.), María Purificación Lisón Párraga (dir. tes.)
- Lectura: En la Universitat Politècnica de València ( España ) en 2023
- Idioma: español
- Tribunal Calificador de la Tesis: Lucia Jorda Miro (presid.), María del Carmen González Mas (secret.), Miguel González Guzmán (voc.)
- Programa de doctorado: Programa de Doctorado en Biotecnología por la Universitat Politècnica de València
- Materias:
- Enlaces
- Tesis en acceso abierto en: RiuNet
- Resumen
In response to biotic and abiotic stress, plants synthesize defence proteins and chemical compounds from diverse nature. These compounds can act directly, trough antioxidant, antifungal or antibacterial properties, or indirectly as defensive metabolites. Among these group of defensive metabolites, phenolic compounds and volatile organic compounds (VOCs) present a major role.
Our research group have a strong background in studying the role of plant secondary metabolites in plant defence mechanisms. On one hand, gentisic acid (GA) was first described as a signal molecule that acts complementary to salicylic acid (SA) in systemic infections. Furthermore, SA conversion to GA trough the salicylate 5-hydroxylase enzyme (S5H) has received much attention. For this purpose, S5H-silenced transgenic tomato plants (RNAi_S5H) have been phenotypically, molecularly, and chemically characterized against both, bacterial and viroidal inoculations. RNAi_S5H tomato plants resulted in enhanced resistance to both Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) and Citrus Exocortis Viroid (CEVd). Moreover, metabolomics analysis of these transgenic plants upon bacterial and viroid infections revealed differences related to SA metabolism, suggesting that SA homeostasis is specific for each tomato-pathogen interaction.
On the other hand, some esters of (Z)-3-hexenol were identified to be differentially emitted by tomato cv. Rio Grande plants upon infection with the avirulent strain of the bacterium Pst DC3000. Particularly, treatments with the volatile (Z)-3-hexenyl butyrate (HB) resulted in significant stomatal closure, defence genes induction and enhanced resistance to the bacteria. Moreover, the efficacy of this compound as a stomata closer was tested in different agronomic crop as Arabidopsis, Medicago, Zea, Citrus y Nicotiana plants, postulating HB as a new universal stomata closer. Due to its potent properties, the signalling pathway of the HB-mediated stomata closure has been deciphered by using different genetic, biochemical, and pharmacological approaches. The perception of this volatile by plant receptors appeared to initiate different defence signalling events, including the activation of Ca2+ permeable channels or reactive oxygen species (ROS) burst. Moreover, HB triggered the activation of the mitogen-activated protein kinases MPK3 and MPK6, inducing stomatal closure independently of abscisic acid (ABA) biosynthesis and signalling. Additionally, HB efficacy has been also tested in field conditions and against both biotic and abiotic stresses, and also during ripening, proposing HB as a new natural phytoprotector for the sustainable control of stresses in agriculture.
