Tree Genetics and Molecular Breeding 2025, Vol.15, No.2, 62-69 http://genbreedpublisher.com/index.php/tgmb 62 Feature Review Open Access Key Genes Regulating Fruit Size and Sugar Content in Grapevine Wenzhong Huang Hainan Provincial Key Laboratory of Crop Molecular Breeding, Sanya, 572025, Hainan, China Corresponding email: wenzhong.huang@hitar.org Tree Genetics and Molecular Breeding, 2025, Vol.15, No.2 doi: 10.5376/tgmb.2025.15.0008 Received: 25 Feb., 2025 Accepted: 28 Mar., 2025 Published: 05 Apr., 2025 Copyright © 2025 Huang, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Huang W.Z., 2025, Key genes regulating fruit size and sugar content in grapevine, Tree Genetics and Molecular Breeding, 15(2): 62-69 (doi: 10.5376/tgmb.2025.15.0008) Abstract This study explains the key genes that affect the size and sugar content of grape fruits and their regulatory patterns, and analyzes genes such as VvGH9, VvSK1, and VvHB58, which are crucial in the process of fruit enlargement and sugar increase and play an important role in fruit development and sugar accumulation. This study also mentioned the influences of epigenetics, small RNAs and environmental conditions on grape traits, as well as the application of new gene editing technologies in grape breeding. This study aims to provide new ideas and genetic targets for improving the quality of grapevines and propose useful strategies for future breeding work. Keywords Grapevine; Gene regulation; Sugar accumulation; Fruit size; Gene editing 1 Introduction Grapevine (Vitis vinifera L.) is a very important fruit crop. It can be used for winemaking, eaten as a fruit, or dried into fruits. It has high economic value and a wide range of cultivation. Vineyards can be seen in different climate zones. It is necessary to understand its genetic characteristics and physiological responses in different environments in order to grow grapevines better. The quality of grape fruits is a key factor determining whether they sell well, can be used for winemaking or eaten directly (Lecourieux et al., 2009; Li et al., 2021; Zinelabidine et al., 2021). Genes such as VvGH9 are related to sugar accumulation and their effects are more obvious under conditions of low sugar content. Xu et al. (2021) found that its expression is affected by sucrose, fructose and glucose, and the accumulation of sugar in grape callus tissue significantly increases when this gene is overexpressed. Huang et al.’s research in 2023 suggests that potassium content affects the accumulation of sugar and anthocyanins in fruits, and genes related to sugar metabolism such as GST, AT, UFGT, and SPS play significant roles in this process. Lecourieux et al. demonstrated in their early research, in 2009, that the sugar-regulated protein kinase gene VvSK1 regulates hexose transport and sugar accumulation in grape cells. Its expression is influenced by sugar and abscisic acid, enabling the fruit to better absorb and accumulate glucose. VvHB58 is a homologous box gene that can regulate fruit size and seed development through multiple hormone signaling pathways, indicating that the genetic regulation of this type of trait is very complex (Li et al., 2019). Large-sized grapevines are more popular in the fresh food market because they are good-looking and have a good appearance, and consumers are more willing to buy them (Li et al., 2019; Rossmann et al., 2020; Zinelabidine et al., 2021). Grimplet et al. (2017) and Rossmann et al. (2020) found that the size of the fruit would affect the structure of the entire bunch of grapevines, the ability to resist pests and diseases, and the uniformity of ripening. Xu et al. (2021) demonstrated in their study that the sugar content determines the flavor of grapevines, which is crucial for both edible grapevines and those used for winemaking. High sugar content determines the alcohol content, which will affect the overall taste and aroma of wine (Castellarin et al., 2017; Zhong, 2024). This study summarized the known key genes that regulate the size and sugar content of grape fruits and their regulatory pathways, identified which genes mainly control them, and analyzed their mechanisms of action. This study also screened out specific genes related to the size of grape fruit and sugar content, revealed their specific
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