Hormonal and metabolic profile of two sunflower inbred lines (Helianthus annuus L.) in response to water stress

A. ANDRADE; V. ARBONA; A. GÓMEZ-CÁDENAS; S. ALEMANO

Congreso; XXI Reunión de la Sociedad Española de Fisiología Vegetal. XIV Congreso-Hispano Luso de Fisiología Vegetal; 2015

Physiological responses of plants to abiotic stress are mediated by phytohormones, such as jasmonic acid (JA), abscisic acid (ABA) and salicylic acid (SA). Among these responses, stress conditions also affect metabolic pathways and therefore alter metabolite composition. This aspect can be characterized through metabolite profile analysis using targeted or non-targeted approaches. This study investigates the effect of water stress conditions on the hormonal and metabolic profiles of two sunflower inbred lines with different ability to tolerate water stress: B59 (sensitive) and B71 (tolerant), during early-growth stages. Extraction and purification of plant hormones was performed according to Durgbanshi et al. (2005) and non-targeted secondary metabolite analysis was carried out essentially as in Zandalinas et al. (2014), using liquid chromatography coupled to mass spectrometry. In both genotypes, the aerial organs showed a hormone accumulation higher than roots, irrespective of the relative tolerance. In stressed B59 seedlings, leaves showed SA levels 4-fold higher than controls whereas in B71 line both ABA and SA showed high accumulation in stressed seedlings (1.4-fold and 3-fold above controls, respectively). In both sunflower lines, SA accumulation was a common response to water stress whereas ABA only significantly accumulated in the tolerant line B71. In addition, JA and IAA levels were also positively altered in leaves of the tolerant line. Non-targeted metabolite profiling analysis showed that 62% of total altered metabolites accumulated under water stress conditions in leaves of the sensitive B59 line whereas the rest reduced their concentration. Interestingly, levels of most of the altered secondary metabolites (87%) increased under stress in the tolerant line. In roots, an opposite response was observed and most of the altered metabolites were repressed. Some of these metabolites have been annotated. Preliminary results indicate that metabolic pathways in leaves were more altered by water stress conditions and this was more evident in B71seedlings.This suggests that the tolerant line could have a differential hormonal and metabolic setup, responsible for its superior performance under water stress conditions.