Effect of water stress on the endogenous content of brassinosteroids in sunflower plants during late vegetative growth (V8)

RAMÍREZ, FEDERICO; BOERO, ALDANA; JANA OKLESTKOVA; MIROSLAV STRNAD; VIGLIOCCO ANA; ANDRADE, ANDREA; ALEMANO, SERGIO

Congreso; XXXIV Argentinian Meeting of Plant Physiology RAFV Conference 2023. 24-27 de Septiembre de 2023; 2023

Water stress is considered one of the most pressing abiotic stresses that negatively affect the growth, physiology and metabolic functions of plants. A common physiological modification under water stress is the alteration in the endogenous concentration of phytohormones, including brassinosteroids. Our aim was to evaluate the impact of water stress on the endogenous levels of brassinosteroids (BRs) in the aerial part and roots of sunflower plants. For this, six inbred lines -previously characterized as tolerant to water stress (B71), sensitive to water stress (B59), intermediate tolerant to water stress (C803, B481-6 and R461-4) and intermediate sensitive to water stress. (R453)- were subjected to moderate water stress caused by irrigation suppression for 15 days under controlled environmental conditions, during their late vegetative growth (V8). The plants were harvested, sectioned into aerial part and roots and endogenous hormonal determinations were performed. The extraction and purification of the BRs was carried out from 5 mg of dry weight of plant tissue, using acetonitrile and immunoaffinity columns; identification and quantification was performed by UHPLC-MS/MS. Regarding the quantified BRs, the B481-6 line showed the greatest changes: in the aerial part the levels of 24 epibrassinolide (EBL), castasterone (CS), 28-homocastasterone (28 HCTS), 28-norcastasterone (28-NCTS) and brassinolide (BL) increased, while in roots increased 28-HCTS, 28-NCTS and CS. The sensitive line showed increases in EPL, 28-HCTS, BL and CS in aerial part and decreases in EPL, 28-HCTS and 28-NCTS in roots. In the tolerant line, EPL, 28-NCTS and CS increased and BL decreased in aerial part. In roots, only a decrease of 28 HCTS was observed. The detection of BRs from different C28 (CS, BL and EBL) and C29 (28-HCTS and 28-NCTS) synthesis pathways suggests the existence of independent pathways for BRs biosynthesis in sunflower plants under our experimental conditions.