1 research outputs found
Flower abscission in Vitis vinifera L. triggered by gibberellic acid and shade discloses differences in the underlying metabolic pathways
Understanding abscission is both a biological and an agronomic challenge. Flower
abscission induced independently by shade and gibberellic acid (GAc) sprays was
monitored in grapevine (Vitis vinifera L.) growing under a soilless greenhouse system
during two seasonal growing conditions, in an early and late production cycle.
Physiological and metabolic changes triggered by each of the two distinct stimuli were
determined. Environmental conditions exerted a significant effect on fruit set as showed
by the higher natural drop rate recorded in the late production cycle with respect to
the early cycle. Shade and GAc treatments increased the percentage of flower drop
compared to the control, and at a similar degree, during the late production cycle.
The reduction of leaf gas exchanges under shade conditions was not observed in
GAc treated vines. The metabolic profile assessed in samples collected during the
late cycle differently affected primary and secondary metabolisms and showed that
most of the treatment-resulting variations occurred in opposite trends in inflorescences
unbalanced in either hormonal or energy deficit abscission-inducing signals. Particularly
concerning carbohydrates metabolism, sucrose, glucose, tricarboxylic acid metabolites
and intermediates of the raffinose family oligosaccharides pathway were lower in shaded
and higher in GAc samples. Altered oxidative stress remediation mechanisms and
indolacetic acid (IAA) concentration were identified as abscission signatures common
to both stimuli. According to the global analysis performed, we report that grape flower
abscission mechanisms triggered by GAc application and C-starvation are not based
on the same metabolic pathways