Tendril Coiling in Grapevine: Jasmonates and a New Role for GABA?

Abstract

Grapevine (Vitis vinifera L., Vitaceae) belongs to the genus Vitis, and is characterized as a vine due to the presence of tendrils, which are located opposite to leaves. Tendrils are thigmo-responsive organs, able to carry out delicate mechanosensory responses upon touch and related stimuli. These organs are an adaptation of the plant to climb with the help of support to higher places and finally remain at a position with favorable light quality. In previous studies on Bryonia dioica (Cucurbitaceae), phytohormones of the jasmonate class were identified as the endogenous hormone signals to initiate coiling of the tendrils. Strikingly, this is still the only example for jasmonate-induced tendril coiling. In grapevine, three compounds (12-oxo-phytodienoic acid, jasmonic acid (JA), and JA isoleucine conjugate) of the jasmonate class were found at higher concentrations in non-coiled tendrils when compared with coiled ones. Upon treatment with phytohormones, we could confirm the activity of jasmonates on tendril coiling in grapevine. However, not jasmonates but a non-proteinogenic amino acid, γ-aminobutyric acid (GABA), was detected to accumulate in grapevine tendrils at significantly higher levels than in all other tissues, independent of their coiling status. For GABA we detected a significant, transient positive effect on tendril coiling. Use of a GABA synthesis blocker, 3-mercaptopropionic acid, caused reduced GABA-but not JA-induced coiling scores. No additive effect of JA plus GABA was detectable on the tendrils' coiling score. Thus, for grapevine, our data demonstrate a strong activity of jasmonates in tendril coiling induction even without mechanical stimuli and, furthermore, the data also suggest that GABA can independently promote tendril coiling.

γ Aminobutyric Acid (GABA): A Key Player in Alleviating Abiotic Stress Resistance in Horticultural Crops: Current Insights and Future Directions

“…Increasing GABA production in guard cells reduces stomatal opening and transpiration, and regulating the release of tonoplast-localized anion transporters improves water use efficiency and drought tolerance [10,81]. The drought stress tolerance of various plant species, such as apples [82], tomatoes [83], and grapevines [84], can be improved by applying exogenous GABA, as demonstrated in previous studies. The optimal dosage and application method of GABA for achieving maximum drought stress tolerance may differ depending on the plant species and environmental conditions.…”

Morphological plasticity in the kelpNereocystis luetkeana(Phaeophyceae) is sensitive to the magnitude, direction, and location of mechanical loading

“…2008, 2012, Malabarba et al. 2019). These substances are probably the reason that thigmomorphogenetic effects can be induced in tissue regions far from where a mechanical stimulus was actually applied (Erner et al.…”

“…When the signals generated in response to mechanical stimulation ultimately influence growth and development, the entire physiological process, from stimulus detection to ultimate response, is referred to as thigmomorphogenesis (Jaffe 1973). Phytohormones are thought to be among the various signaling molecules involved in mediating this process (e.g., Erner and Jaffe 1982, Biro and Jaffe 1984, Chehab et al 2008, Malabarba et al 2019. These substances are probably the reason that thigmomorphogenetic effects can be induced in tissue regions far from where a mechanical stimulus was actually applied (Erner et al 1980, Coutand et al 2000.…”

The study of hormonal metabolism of Trincadeira and Syrah cultivars indicates new roles of salicylic acid, jasmonates, ABA and IAA during grape ripening and upon infection with Botrytis cinerea

“…4 Therefore, ABA biosynthesis, catabolism and signaling are dependent on the cultivar and 5 also on the ripening stage. Recently, the short-term effects of ABA on different organs of 6 grapevine were studied and showed that the responses of each organ were unique 7 indicating that ABA signaling varies with the organ [58,59]. It may be that it also varies 8 with the tissue; therefore differences in ABA metabolism between skin and pulp may 9 partially account for the differences noticed here between the whole berries of the two 1 0 cultivars.…”