Molecular, hormonal, and metabolic mechanisms of fruit set, the ovary-to-fruit transition, in horticultural crops

Abstract

Fruit set is the process by which the ovary develops into a fruit and is an important factor in determining the fruit yield. Fruit set is induced by two hormones, auxin and gibberellin, and the activation of their signaling pathways, partly by suppressing various negative regulators. Many studies have investigated the structural changes and gene networks in the ovary during fruit set, revealing the cytological and molecular mechanisms. In tomato (Solanum lycopersicum), SlIAA9 and SlDELLA/PROCERA act as auxin and gibberellin repressors, respectively, and are important regulators of the activity of transcription factors and downstream gene expression involved in fruit set. Upon pollination, SlIAA9 and SlDELLA are degraded, which subsequently activates downstream cascades and mainly contributes to active cell division and cell elongation, respectively, in ovaries during fruit setting. According to current knowledge, gibberellin appears to be most downstream in fruit set induction, and therefore its role in fruit set has been extensively explored. Furthermore, multi-omics analysis has revealed the detailed dynamics of gene fluctuation and metabolites downstream of gibberellins, highlighting the rapid activation of central carbon metabolism. This review will outline the relevant mechanisms at the molecular and metabolic levels during fruit set, particularly focusing on these mechanisms in tomato.

A dynamic epigenetic perspective on above and below-ground phenotypic responses to drought: insights from global DNA methylation inErodium cicutarium

“…As regards the seed production of this autonomous plant, fruit set and seed set probabilities increased under recurrent drought whereas they were negatively impacted by seed demethylation. Such findings suggested that allocation of resources to reproduction could be to some extent upregulated by stress and mediated by DNA methylation, likely through their combined effects on hormones' metabolism (Fleta-Soriano and Munné-Bosch, 2016;Avramova, 2019;Ezura et al, 2023).…”

Variations in Fruit Ploidy Level and Cell Size between Small- and Large-Fruited Olive Cultivars during Fruit Ontogeny

“…Fleshy fruit undergo a precise orchestration of steps, including fruit set, growth, maturation, and ripening, by integrating endogenous signals and various environmental cues [1][2][3][4]. During fruit growth, the final fruit size is a complex trait that results from strict spatiotemporal control and coordination of overlapping and interconnected cellular events, cell division, and cell expansion, beginning at different times and having varying rates as well as duration [5,6].…”

“…During fruit growth, the final fruit size is a complex trait that results from strict spatiotemporal control and coordination of overlapping and interconnected cellular events, cell division, and cell expansion, beginning at different times and having varying rates as well as duration [5,6]. Notable progress has been made in recent years in elucidating the cellular and molecular mechanisms controlling fruit growth [3][4][5][6][7]. Regarding the cell level, previous studies have linked endoreduplication with cell growth, especially in tomato fruit, in which high levels of endopolyploidy occur during fruit growth [8][9][10][11].…”

New Advances in the Study of Regulation of Tomato Flowering-Related Genes Using Biotechnological Approaches

“…The optimal timing of this event from a physiological point of view is a prerequisite for successful reproduction. Flowering and fruit set are initiated and regulated via the combined action of various genetic factors in response to endo- [1,2] and exogenous [3,4] stimuli. Processes, including male and female organogenesis, meiosis, gametogenesis, pollination, and fertilization, occur during the diploid and haploid phases of reproductive development, which are necessary to maintain genetic variability [5].…”