Phytohormones in fruit development and maturation

• Published in: The Plant journal : for cell and molecular biology 2021-01, Vol.105 (2), p.446-458
• Main Authors: Fenn, Matthew A., Giovannoni, James J.
• Format: Article
• Language: English
• Subjects: Abscisic acid; Cell division; Crosstalk; Ethylene; Fertilization; fruit expansion; Fruit set; Fruits; Gibberellic acid; Hormones; Indoleacetic acid; Maturation; Phase transitions; Phytohormones; Plant hormones; Precipitates; Regulators; Ripening; Signaling; Solanum lycopersicum; Tomatoes
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.15112

Summary Phytohormones are integral to the regulation of fruit development and maturation. This review expands upon current understanding of the relationship between hormone signaling and fruit development, emphasizing fleshy fruit and highlighting recent work in the model crop tomato (Solanum lycopersicum) and additional species. Fruit development comprises fruit set initiation, growth, and maturation and ripening. Fruit set transpires after fertilization and is associated with auxin and gibberellic acid (GA) signaling. Interaction between auxin and GAs, as well as other phytohormones, is mediated by auxin‐responsive Aux/IAA and ARF proteins. Fruit growth consists of cell division and expansion, the former shown to be influenced by auxin signaling. While regulation of cell expansion is less thoroughly understood, evidence indicates synergistic regulation via both auxin and GAs, with input from additional hormones. Fruit maturation, a transitional phase that precipitates ripening, occurs when auxin and GA levels subside with a concurrent rise in abscisic acid (ABA) and ethylene. During fruit ripening, ethylene plays a clear role in climacteric fruits, whereas non‐climacteric ripening is generally associated with ABA. Recent evidence indicates varying requirements for both hormones within both ripening physiologies, suggesting rebalancing and specification of roles for common regulators rather than reliance upon one. Numerous recent discoveries pertaining to the molecular basis of hormonal activity and crosstalk are discussed, while we also note that many questions remain such as the molecular basis of additional hormonal activities, the role of epigenome changes, and how prior discoveries translate to the plethora of angiosperm species. Significance Statement Numerous recent discoveries pertaining to the molecular basis of hormonal activity during fruit development provide new insights into the role of hormones in this biological and agriculturally important process and highlight important ongoing questions related to molecular mechanisms and conservation of regulatory phenomena across diverse taxa.