Journal of Energy Bioscience 2025, Vol.16, No.5, 248-262 http://bioscipublisher.com/index.php/jeb 253 flower at the right time. In Arabidopsis thaliana, plants lacking the ability to synthesize T6P do not flower, which indicates that T6P is very important in flowering regulation (Xing et al., 2015; Cho et al., 2018; Fichtner and Lunn, 2021; Wang et al., 2021b; Wingler and Henriques, 2022; Gobel and Fichtner, 2023). During the seed development stage, sugar signals help seeds accumulate nutrients. As the seeds mature, the contents of sucrose and T6P increase, promoting the utilization of carbon and the development of endosperm. T6P can also inhibit the activity of SnRK1, regulate ABA signals, and ensure normal seed development (Wang et al., 2021b). In fruits, sugar not only determines the sweetness but also affects genes related to ripening, pigment formation and hormone activity. Sugar interacts with ABA, auxin and ethylene to jointly control the time and process of fruit ripening (Robert, 2019; Duran-Soria et al., 2020; Rashid et al., 2022; Rossouw et al., 2024). 6 Environmental Regulation of Sugar Biosynthesis and Metabolism 6.1 Effects of light, temperature, and water supply Light gives energy for photosynthesis and also controls sugar-related genes. These genes regulate enzymes that make sucrose and starch. Changes in light strength, time, or color affect enzymes like UDP-glucose pyrophosphorylase and glucan synthase, which then change sugar types and amounts. Light signals through photoreceptors and redox factors help plants adjust sugar production and storage under different light conditions (Borbély et al., 2022; Wu et al., 2025). Temperature affects enzyme activity and respiration. Heat speeds up sugar breakdown, while cold slows it, causing sugar buildup that protects cells from freezing. When water is low, plants collect sugars like sucrose, trehalose, and raffinose to keep water and protect cells. Sugar transporters and starch-degrading enzymes become more active to help plants survive drought (Dong and Beckles, 2019; Gurrieri et al., 2020; Saddhe et al., 2020; Nägele et al., 2022). 6.2 Responses under abiotic stress (drought, salt stress, low and high temperature stress) Drought, salinity, low temperatures and high temperatures can all slow down plant growth and reduce yields. Under these pressures, plants usually change the way they use sugar. For instance, under drought or salt stress, plants accumulate soluble sugars such as glucose, fructose, sucrose, trehalose and raffinose. These sugars can help cells retain water, protect proteins and membrane structures, and eliminate reactive oxygen species (ROS) (Kosar et al., 2018; Nagele et al., 2022). To ensure the supply of sugar, plants make the enzymes and transport proteins involved in sugar synthesis more active, while releasing sugar by breaking down starch. For instance, in arid environments, plants enhance the activities of sucrose synthase and glucan hydrolase to convert stored carbohydrates into energy and maintain cellular water balance (Dong and Beckles, 2019; Gurrieri et al., 2020). At low temperatures, plants convert starch into soluble sugar, which can lower the freezing point of the cell fluid and prevent it from being damaged by freezing (Thalmann and Santelia, 2017; Dong and Beckles, 2019). When under salt stress, plants tend to accumulate more starch to support growth and enhance salt tolerance. High-temperature stress, especially when drought coexists, can disrupt the sugar balance and eventually lead to a reduction in biomass and yield (Das, Rushton and Rohila, 2017; Wang and Wang, 2023). 6.3 Role of sugars in biotic stress resistance Sugars act as both energy and defense signals. Pathogens take sugars through transporters like SWEETs, but plants reduce sugar loss by changing transporter and enzyme activity (Tauzin and Giardina, 2014; Bezrutczyk et al., 2018; Breia et al., 2021). During infection, invertase increases glucose, which moves to the infected area to support defense compounds (Wingler and Roitsch, 2008).
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