IMPACT OF WATER STRESS ON THE ENDOGENOUS PHYTOHORMONES CONTENT IN SUNFLOWER PLANTS DURING LATE VEGETATIVE GROWTH (V8)

F. RAMIREZ; ALEMANO S.; A. VIGLIOCCO; BOERO A.; A. ANDRADE

Otro; IV Reunión Conjunta de Sociedades de Biología de la República Argentina; 2020

It has been well documented that water stress produces morpho-physiological, biochemical, and molecular alterations. A physiological change typically observed under water stress is the modification in endogenous levels of phytohormones. The aim of this study was to evaluate the impact of water stress on the endogenous hormonal levels of Abscisic acid (ABA), Jasmonic acid (JA), Salicylic acid (SA), Brassinosteroids (BRs) and Strigolactones (SLs) in shoot and roots of sunflower plants. The experiment was conducted on plants of four inbred lines of sunflower, previously characterized as tolerant to water stress (B71), sensitive to water stress (B59), moderate tolerant to water stress (C803) and moderate sensitive to water stress (R461-4), subjected to moderate water stress by watering suppression for 15 days, under controlled environmental conditions, during the late vegetative growth (V8). The extraction and purification of endogenous phytohormones was carried out from 200 mg of dry weight of shoot and roots; the identification and quantification were performed by LC-ESI/MS-MS. Our results showed that in the four inbred lines the ABA level increased in shoot and roots of water-stressed plants, whereas SA significantly increased its level only in the shoot. Regarding BRs, an increase of Epibrassinolide was detected in shoot of stressed plants of all inbred lines, and in shoot of B71 line there was an increment of Catasterona. In shoot, the endogenous level of both SLs (Dimetilsorgolactone and Deoxistrigol) did not show modifications in response to water stress, whereas in roots a reduction in their levels was quantified. Finally, no evident changes in JA endogenous level were observed. These findings suggest that in the sensitive B59 line the accumulation of various phytohormones detected as response to water stress treatment could be probably related to the demand of high adjustment capactity in signaling and regulation of its hormonal response. The tolerant line (B71) did not present significant changes in hormonal levels, which would confirm its tolerance to water deficit in late stages of vegetative growth. The R461-4 line triggered its endogenous hormonal levels as a consequence of imposed water stress in a similar fashion to the sensitive B59 line, therefore was characterized as moderately sensitive to water stress. The C803 line had a similar hormonal profile to B59 line although its morphological response was comparable to B71, accordingly it was identified as moderately tolerant to water stress.