Gibberellin metabolism in Vitis vinifera L. during bloom and fruit-set: functional characterization and evolution of grapevine gibberellin oxidases

Abstract

Gibberellins (GAs) are involved in the regulation of flowering and fruit-set in grapes (Vitis vinifera L.), but the molecular mechanisms behind this process are mostly unknown. In this work, the family of grapevine GA oxidases involved in the biosynthesis and deactivation of GAs was characterized. Six putative GA 20-oxidase (GA20ox), three GA 3-oxidase (GA3ox), and eight GA 2-oxidase (GA2ox) proteins, the latter further divided into five C19-GA 2ox and three C20-GA2ox proteins, were identified. Phylogenetic analyses suggest a common origin of the GA3ox and C19-GA2ox groups and challenge previous evolutionary models. In vitro analysis revealed that all GA3ox and GA20ox enzymes prefer substrates of the non-13-hydroxylation pathway. In addition, ectopic expression of GA2ox genes in Arabidopsis thaliana confirmed the activity of their encoded proteins in vivo. The results show that bioactive GA1 accumulates in opening grapevine flowers, whereas at later developmental stages only GA4 is detected in the setting fruit. By studying the expression pattern of the grapevine GA oxidase genes in different organs, and at different stages of flowering and fruit-set, it is proposed that the pool of bioactive GAs is controlled by a fine regulation of the abundance and localization of GA oxidase transcripts.

Breadfruit (Artocarpus altilis) gibberellin 20-oxidase genes: sequence variants, stem elongation and abiotic stress response

“…5). These results are consistent with GA20oxs found in many other species, including A. thaliana (Plackett et al 2012), rice (Sakamoto et al 2004), potato (Carrera et al 1999) and grapevine (Giacomelli et al 2013), and reflect functional divergence between GA20ox family members in their relative contribution to GA biosynthesis in these organs (Phillips et al 1995;Plackett et al 2012).…”

“…The three predicted functional GA20oxs, AaGA20ox1-AaGA20ox3, compared with the large size of GA20-oxidase families found in other species such as grapevines with six genes (Giacomelli et al 2013), A. thaliana with at least five (Yamaguchi 2008) and cucumber with five (Lange et al 2013), suggest that other functional GA20-oxidase genes remain to be cloned. However, the expression profile of these genes found to be predominant in green vegetative organs in the current study corresponds with numbers of GA20-oxidase isoforms expressed in such organs of other species.…”

The KNOTTED-like genes of peach (Prunus persica L. Batsch) are differentially expressed during drupe growth and the class 1 KNOPE1 contributes to mesocarp development

“…6A) recalled that of GA3ox1 of plum and tomato [73,74]. The PpGA20ox1 undetected mRNA in drupe was consistent with RNA-seq data (Table 4) and recalled the absence of GA20ox1 expression in silique (Arabidopsis eFP Browser) and grape berry [75]; however, the tomato GA20ox1 transcription in pericarp [73,76] implies the occurrence of species-related regulatory mechanisms. KNOPE1 and PpGA3ox1 showed opposite expression trends along with 'Chiripa' drupe growth (Fig.…”

Chemical Regulators of Gibberellin Status and Their Application in Plant Production

“…Different from applying the relatively persistent GA 3 , this effect will be relatively short-lived and will not cause negative effects for the following season. This explanation corresponds well with the detailed analytical data on the presence of different GAs in developing grape berries (Giacomelli et al, 2013): GA 1 and GA 4 , which are both biologically active, give a clear peak at anthesis and decline sharply thereafter. Prohexadione-calcium is likely to inhibit the hydroxylation of these GAs via GA 2-oxidase into inactive GA 8 and GA 34 , respectively.…”