Effects of Gibberellic Acid/Cytokinin Treatments on Berry Development and Maturation in the Yellow-green Skinned ‘Shine Muscat’ Grape

Abstract

Phytohormones play major roles in the berry maturation process. Gibberellic acid (GA) and cytokinin (CK) are phytohormones used in seedless table grape production. Several studies have been conducted on the effects of GA and CK application on berry development. However, the detailed mechanisms underlying their physiological effects on berry maturation after the veraison stage have not been clarified. Skin browning during maturation is a major commercial problem in yellow-green skinned grape cultivars including 'Shine Muscat', and expanding our knowledge of these mechanisms is a necessary step towards addressing this problem. In this study, we investigated the effects of GA and CK treatments from the veraison stage to the subsequent developmental stages of this grape berry. Both treatments resulted in enlarged berries and the suppression of increases in sugar content. Chlorophyll in the berry skin was less decomposed after GA/CK treatment, and the occurrence of skin browning in the maturation stage was reduced, as expression of the VvPP2Cs gene decreased. GA/CK treatment at the veraison stage (45-50 DAFB) reduced the expression levels of phytohormone-related genes, particularly those of VvGID1 and VvCHKs, which are involved in GA and CK signaling, respectively. These similar changes in gene expression patterns suggest phytohormonal crosstalk and a common expressional regulatory mechanism. VvACO2 and VvYUC1 expressions were significantly increased in skin browning samples, regardless of treatment, indicating involvement of the ethylene and auxin biosynthesis pathways in skin browning. Therefore, GA/CK treatment at the veraison stage may broadly affect phytohormone biosynthesis and signaling pathways in subsequent developmental stages, although the effect size greatly differs depending on the experimental conditions, including year and plant.

Effects of Gibberellin and Abscisic Acid on Fruit Quality and Aromatic Compound Formation during Fruit Development in ‘Kyoho’ Grapes (<i>Vitis vinifera</i> L.×<i>Vitis labrusca</i> L.)

“…Effect of GA 3 and ABA on fruit quality GA 3 significantly increased berry size and weight (Fig. 1), consistent with the results of Suehiro et al (2019). In terms of TSS (Fig.…”

“…Based on the differences in biosynthesis precursors, the biosynthesis pathway of aroma compounds in grapes can be divided into many components, including isoprene pathways, fatty acid pathways and amino acid pathways (Zhou, 2013). The formation and biogenesis of grape aroma compounds are affected by many factors, including grape variety (Ghaste et al, 2015;Wu et al, 2016), fruit maturity (Vilanova et al, 2012), growth environment (Arias et al, 2019;Yu et al, 2015), cultivation management technology (Bouzas-Cid et al, 2018;Ji et al, 2019), and use of plant growth regulators (Gao et al, 2020;Ju et al, 2016;Suehiro et al, 2019;Xi et al, 2020;Zhang et al, 2020).…”

Gibberellic Acid Modifies the Transcript Abundance of ABA Pathway Orthologs and Modulates Sweet Cherry (Prunus avium) Fruit Ripening in Early- and Mid-Season Varieties

“…Regarding the hormonal regulation of these genes, the transcript abundance of PavPP2C3 , PavSnRK2.1 and PavSnRK2.2 was decreased upon IAA treatment, while PavPP2C4 was not affected [ 20 ]. In grapevine, downregulation of an ABA putative negative regulator, PP2Cs , was produced by GA 3 treatment at fruit color change [ 45 ]. Therefore, it seems plausible that these genes are modulated by GA 3 in sweet cherry.…”

“…GA perception and signaling components are expressed when strawberry fruits are red [ 58 ]. In grapevine, GA 3 applied at veraison modifies ripening parameters and the expression of several genes involved in hormone biosynthesis and signaling, including PP2Cs [ 45 ]. In sweet cherry, GA 3 treatment modifies the ABA accumulation pattern [ 17 ].…”

“…The molecular mechanisms by which GA controls fruit ripening are poorly understood. In grapevine ( Vitis vinifera L.), PP2Cs and SnRK2s ABA pathway orthologs express during fruit ripening [ 44 ], and GA 3 treatment modifies the expression of PP2Cs [ 45 ], which code for putative negative regulators of ABA pathway. In sweet cherry, orthologs of ABA signaling pathway, PP2Cs and SnRKs , express during fruit ripening [ 20 , 46 ], though their modulation by gibberellin at the onset of fruit ripening had not been evaluated in sweet cherry fruits.…”