Spatiotemporal variations in salicylic acid and hydrogen peroxide in sunflower seeds during transition from dormancy to germination

DEL BEL, ZOÉ; ZIRULNIK, FANNY; VIGLIOCCO, ANA; MOLINA, ALICIA; ALEMANO, SERGIO; PÉREZ CHACA, MARÍA VERÓNICA; ANDRADE, ANDREA MARÍA

PHYSIOLOGIA PLANTARUM

WILEY-BLACKWELL PUBLISHING, INC

Año: 2019

0031-9317

Phytohormones and reactive oxygen species mediate processes such as germination and dormancy. The elucidation of the physiological and biochemicalevents implicated in the transition from dormancy to germination in differentplant species such as sunflower becomes a topic of interest. In this study, weinvestigated the spatiotemporal variation of salicylic acid (SA), hydrogen peroxide (H2O2) and the activity of two antioxidant enzymes (catalase, CAT ? EC1.11.1.6 and ascorbate peroxidase ? EC 1.11.1.11) in embryonic axis andcotyledons of dry and imbibed seeds of dormant (B123) and non-dormant(B91) sunflower lines. The results showed that embryonic axis had higher levelof SA and H2O2 than cotyledons in both lines. In dry seeds, B123 embryo(embryonic axis+cotyledons) showed a higher SA content than B91. Afterdry storage at room temperature, SA decreased in B123 embryos to a valueclose to that registered in B91 embryos. B123 embryonic axis of dry seedspresented higher H2O2 levels than B91. Dry storage led to an increase ofH2O2 levels and a decrease of CAT activity in B123 embryonic axis. Duringimbibition, B123 seeds stored for 33 days displayed an increase in SA level inthe embryonic axis (3 h of imbibition) and this lower level correlated with adecrease in H2O2 (6 h of imbibition). Thus, the embryo-imposed dormancy inB123 dry seeds was associated with high levels of SA and low H2O2, whereasthe dormancy release was linked with SA decrease and increase of H2O2 as aconsequence of lower CAT activity