β-1,3-glucans, such as paramylon from the unicellular alga Euglena gracilis, are important elicitors in plant defence responses, and their perception triggers the activation of plant basal resistance or PAMP-triggered immunity. One of the pivotal factors of basal resistance in plants is hormonal signaling. Plant hormones such as abscisic acid (ABA), jasmonic acid (JA) and salicylic acid (SA) may act as mobile signals that interact through a complex cross-talk, affecting plant responses to both biotic and abiotic stresses. The aim of the present study was to investigate for the first time the effects of a root treatment with Euglena paramylon on xylem hormonal levels, photosynthetic performance and drought tolerance in tomato (Solanum lycopersicum L.). Paramylon granules (100% glucose) were processed to obtain linear fibrous structures to easily interact with tomato root cell membranes; tomato plants were grown in a non-circulating hydroponic system and treated with different paramylon concentrations (90, 180 and 500 mg l −1 ). Hormonal quali-quantitative profiling (ABA, JA, SA) of xylem sap was performed by GC-MS, and photosynthetic parameters (CO 2 assimilation rate, stomatal and mesophyll conductance, intercellular CO 2 concentration, transpiration rate, water use efficiency, photon yield of photosystem II) were determined in fully expanded and exposed leaves with a portable photosynthesis system. The effects of dehydration on the leaf water potential and the photon yield of PSII were also monitored. The results obtained at different times (before the treatment and 24, 48 and 96 hours after the treatment) show a clear dose-dependent effect of paramylon on hormonal signalling, photosynthetic performance and drought tolerance in tomato plants. Paramylon can enhance plant defence responses against abiotic stress, such as drought, by modulating the conductance to CO 2 diffusion from air to the carboxylation sites and improving the water use efficiency (WUE). Our results provide new informations on the physiological responses of the plant under drought, suggesting the use of Euglena paramylon as a novel treatment for the enhancement of plant water use efficiency.
XYLEM HORMONAL SIGNALING, PHOTOSYNTHETIC RESPONSES AND WATER-USE EFFICIENCY IN TOMATO PLANTS TREATED WITH PARAMYLON FROM EUGLENA GRACILIS L.
SCARTAZZA A.;PICCIARELLI P.;MARIOTTI L.;CURADI M.;
2017-01-01
Abstract
β-1,3-glucans, such as paramylon from the unicellular alga Euglena gracilis, are important elicitors in plant defence responses, and their perception triggers the activation of plant basal resistance or PAMP-triggered immunity. One of the pivotal factors of basal resistance in plants is hormonal signaling. Plant hormones such as abscisic acid (ABA), jasmonic acid (JA) and salicylic acid (SA) may act as mobile signals that interact through a complex cross-talk, affecting plant responses to both biotic and abiotic stresses. The aim of the present study was to investigate for the first time the effects of a root treatment with Euglena paramylon on xylem hormonal levels, photosynthetic performance and drought tolerance in tomato (Solanum lycopersicum L.). Paramylon granules (100% glucose) were processed to obtain linear fibrous structures to easily interact with tomato root cell membranes; tomato plants were grown in a non-circulating hydroponic system and treated with different paramylon concentrations (90, 180 and 500 mg l −1 ). Hormonal quali-quantitative profiling (ABA, JA, SA) of xylem sap was performed by GC-MS, and photosynthetic parameters (CO 2 assimilation rate, stomatal and mesophyll conductance, intercellular CO 2 concentration, transpiration rate, water use efficiency, photon yield of photosystem II) were determined in fully expanded and exposed leaves with a portable photosynthesis system. The effects of dehydration on the leaf water potential and the photon yield of PSII were also monitored. The results obtained at different times (before the treatment and 24, 48 and 96 hours after the treatment) show a clear dose-dependent effect of paramylon on hormonal signalling, photosynthetic performance and drought tolerance in tomato plants. Paramylon can enhance plant defence responses against abiotic stress, such as drought, by modulating the conductance to CO 2 diffusion from air to the carboxylation sites and improving the water use efficiency (WUE). Our results provide new informations on the physiological responses of the plant under drought, suggesting the use of Euglena paramylon as a novel treatment for the enhancement of plant water use efficiency.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
