Abnormal Endogenous Repression of GA Signaling in a Seedless Table Grape Cultivar with High Berry Growth Response to GA Application

Abstract

Gibberellin (GA) application is routinely used in the table grape industry to increase berry size and cluster length. Although grapevine cultivars show a wide range of growth responsiveness to GA3 application, the reasons for these differences is unclear. To shed light on this issue, two commercial grapevine cultivars with contrasting berry response to GA were selected for comparative analysis, in which we tested if the differences in response: (1) is organ-specific or cultivar-related; (2) will be reflected in qualitative/quantitative differences in transcripts/proteins of central components of GA metabolism and signaling and levels of GA metabolites. Our results showed that in addition to the high response of its berries to GA, internodes and rachis of cv. Black finger (BF) presented a greater growth response compared to that of cv. Spring blush (SB). In agreement, the results exposed significant quantitative differences in GA signaling components in several organs of both cultivars. Exceptionally higher level of all three functional VvDELLA proteins was recorded in young BF organs, accompanied by elevated VvGID1 expression and lower VvSLY1b transcripts. Absence of seed traces, low endogenous GA quantities and lower expression of VvGA20ox4 and VvGA3ox3 were also recorded in berries of BF. Our results raise the hypothesis that, in young organs of BF, low expression of VvSLY1b may be responsible for the massive accumulation of VvDELLA proteins, which then leads to elevated VvGID1 levels. This integrated analysis suggests causal relationship between endogenous mechanisms leading to anomalous GA signaling repression in BF, manifested by high quantities of VvDELLA proteins, and greater growth response to GA application.

Distinct gibberellin functions during and after grapevine bud dormancy release

“…Transcript levels in buds exposed to hypoxia, HS, or GA treatments, and the relevant controls, were quantified by qRT-PCR with ABsolute Blue QPCR SYBR Green Low ROX Mix (Thermo Fisher Scientific, Waltham, MA, USA) on a Corbett Rotor-Gene 6000 (Qiagen, Hilden, Germany). VvActin and VvGAPDH primers, characterized and optimized by Reid et al (2006) , were used for normalization, while VvGA2ox , VvGA3ox , VvGA20ox , and VvGASA2 primers were previously optimized by Giacomelli et al (2013) and Acheampong et al (2017) . All the primers are presented in Supplementary Table S2 .…”

Alargamiento del raquis del racimo y modificación de algunas características de los frutos con aplicaciones de ácido giberélico en vid ‘Red Globe’ (Vitis vinifera)

“…Incremento de la longitud del raquis del escobajo. Promedios de épocas de aplicación y concentraciones independientes E1: Inicio de crecimiento de panículas C0: Testigo C1: 10 ppm E2: Panículas totalmente formadas C2: 20 ppm C3: 30 ppm E3: Inicio de aperturas florales C4: 40 ppm El efecto positivo del AG 3 en el alargamiento de los racimos está documentado desde hace varios años, tanto para variedades de mesa como para vino, pero la respuesta varía según las dosis, los cultivares y el momento de aplicación, aunque el mayor crecimiento del raquis y de los pedicelos parece que, como en el presente trabajo, se logra con aplicaciones tardías (Weaver y McCune, 1962;Benavente, 1988;Hernández y Vargas, 1993;Coelho et al, 2004, Koukourikou et al, 2015Acheampong et al, 2017). No obstante, algunas veces, como lo reportado para los cultivares Tokay y Zinfadel por Weaver y Pool (1971), las aplicaciones de giberelinas para ralear frutos no tuvieron influencia en la longitud de los racimos.…”

Isolation and Role of PmRGL2 in GA-mediated Floral Bud Dormancy Release in Japanese Apricot (Prunus mume Siebold et Zucc.)

“…The expression pattern of PmSLY1 was similar to PmRGL2 during the different stages of dormancy ( Supplementary Figure S2 ). Acheampong et al (2017) reported that decreased expression of VvSLY1b may be responsible for inducing a massive accumulation of VvDELLA proteins, which then led to elevated VvGID1 levels. The SLY1 homolog, SLY2 (SNE), directly binds to RGA proteins, suggesting that it negatively regulates a subset of DELLA proteins regulated by SLY1.…”

“…All of these proteins possess an N-terminal DELLA domain containing the conserved amino acid sequence, Asp-Glu-Leu-Leu-Ala (DELLA), VHYNP motifs, a poly (S/T) region, and a C-terminal GRAS functional domain ( Silverstone et al, 1998 ). Inconsistent GA signaling repression has been reported by high levels of VvDELLA proteins in grape, and grapes exhibit a higher growth response to GA application ( Acheampong et al, 2017 ). Previous studies demonstrated that GAI and RGA play a role – GA-regulation of hypocotyl growth and stem elongation in Arabidopsis ( Peng et al, 1997 ; Dill et al, 2004 ).…”