Dormancy in peach (Prunus persica) flower buds. VI. Effects of gibberellins and an acylcyclohexanedione (trinexapac-ethyl) on bud morphogenesis in field experiments with orchard trees and on cuttings

Abstract

The effects of several gibberellins (GAs), exo-16,17-dihydro GA 5 , 2,2-dimethyl GA 4 , and GA 3 , and trinexapac-ethyl (an acylcyclohexanedione inhibitor of late-stage GA biosynthesis), were assessed for their effects on flower bud development during and after winter dormancy in peach (Prunus persica (L.) Batsch.) in three field trials and one experiment using cuttings. At late developmental stages, GA 3 hastened floral bud development and shortened the time to anthesis, whereas early-stage applications of GA 3 either had no effect or delayed floral bud development. In contrast, an exceptionally growth-active GA, 2,2-dimethyl GA 4 , promoted floral bud development (tested only on cuttings) across a range of application dates. However, it also induced a high percentage of bud abscission and remaining buds had a necrotic gynoecium and alterations in the androecium. Surprisingly, trinexapac-ethyl also promoted floral bud development, although it was not as effective as GA 1 . Trinexapac-ethyl-treated buds also showed morphological alterations and gynoecium necrosis. However, the best and most consistent treatment for enhancing floral bud development and hastening flower anthesis was 16,17-dihydro GA 5 . It stimulated floral bud development in up to 80% of the treated buds. Further, the promotive effect of 16,17-dihydro GA 5 was maintained through to anthesis across three years of field experiments on intact trees, as well as with cuttings. Whether 16,17-dihydro GA 5 , a competitive inhibitor of the 3β-hydroxylation step in GA biosynthesis, acts per se, acts via a metabolite (such as 16,17-dihydro GA 3 ), or acts by modifying endogenous GA metabolism is not yet known.Résumé : Les auteurs ont évalué les effets de plusieurs gibbérellines (GAs), soit l'exo-16,17-dihydro GA 5 , la 2,2-diméthyl GA 4 , et la GA 3 ainsi que le trinexapac-éthyl (un inhibiteur de l'acylcyclohexanedione vers la fin de la biosynthèse des AG, sur le développement du bourgeon floral; ces essais ont été effectué au cours et après la dormance hivernale chez la pêche (Prunus persica (L.) Batsch.), dans le cadre de trois expériences conduites sur le terrain, et une expérience effectuée sur des boutures. Aux dernières étapes du développement, la GA 3 accélère le développement du bourgeon floral et raccourci la durée de l'anthèse, alors que des applications de GA 3 aux premiers stades restent sans effet, ou retardent le développement du bourgeon floral. Au contraire, une GA particulièrement active sur la croissance, la 2,2-diméthyl GA 4 , stimule le développement du bourgeon floral (vérifié uniquement sur boutures) pour un ensemble de dates d'application. Cependant, il induit un fort pourcentage d'abscission des bourgeons, et les bourgeons qui restent montrent des gynécées nécrosés et des altérations de l'androcée. Ce qui est surprenant, le trinexapac-éthyl stimule éga-lement le développement du bourgeon floral, bien qu'il ne soit pas aussi efficace que la GA 1 . Les bourgeons traités avec le trinexapac-éthyl montrent également des altérations morphol...

Distinct gibberellin functions during and after grapevine bud dormancy release

“…S2 ). This inhibitory effect corroborates data reported in peach ( Reinoso et al , 2002 ), kiwi fruit ( Lionakis and Schwabe, 1984 ), and persimmon ( Kang et al , 1998 ). A more complicated scenario has been described in poplar, where GA 3 application led to bud abscission and protrusion of embryonic leaves, whereas GA 4 induced bud burst ( Rinne et al , 2011 ).…”

Regulation of Bud Dormancy and Bud Break in Japanese Apricot (Prunus mume Siebold ^|^amp; Zucc.) and Peach [Prunus persica (L.) Batsch]: A Summary of Recent Studies

“…Seasonal expression analysis suggested that the gene was up-regulated during bud and gas chromatography (Luna et al, 1990); however, conclusive results have yet to be obtained. Several studies have investigated the effects of the external application of phytohormones such as GA (Reinoso et al, 2002) and cytokinin (Campoy et al, 2010) on bud burst in Prunus. As the crucial roles of ABA and GA in seed dormancy regulation become more evident (Finkelstein et al, 2008), it is becoming more important that the association of hormonal content with dormancy regulation is taken into account.…”

Dormancy Behaviors and Underlying Regulatory Mechanisms: From Perspective of Pathways to Epigenetic Regulation

“…In fact, androecium/ stamens were found to slowly develop throughout the entire chilling period while the gynoecium went through clear differentiation in late winter or near the end of dormancy (Luna et al 1991). At the cellular level, the archesporal cells and epidermis, endothecium, middle layers, microsporangium walls and tapetum in the anther become distinct, followed by formation of the pollen mother cells that enter meiosis by later winter (Reinoso et al 2002a;Julian et al 2011). These results indicate that microsporogenesis and microgametogenesis occur during the chilling period, which are otherwise suppressed by warm temperature.…”

“…4.1), consistent with dormancy onset and exit occurring only under low-temperature condition. Second, SVP protein physically interacts with flower whorl B, C and E genes to possibly regulate floral organ formation and development in Arabidopsis (Gregis et al 2009); and such interaction is critical for DAM-mediated arrest of floral organ development prior to winter (Luna et al 1990(Luna et al , 1991(Luna et al , 1993Reinoso et al 2002aReinoso et al , 2002bJulian et al 2011). Third, SVP protein as a master transcriptional regulator can bind and regulate minimally a 1000 genes in Arabidopsis that are involved in an array of biological processes including floral development, growth regulator signaling, basic cellular and metabolic processes, protein modification, reproduction, morphology, and others (Gregis et al 2013).…”