A synthetic cytokinin influences the accumulation of leaf soluble sugars and sugar transporters, and enhances the drought adaptability in rice

Abstract

Oryza sativa cv. PTT1 (Pathumthani1) was treated with phenyl-urea-based synthetic cytokinin under drought stress. Soluble sugar contents were examined in rice flag leaves at tillering and grain-filling stages. The same leaf samples were used to analyze the differential abundance intensities of proteins related to metabolism and transport of soluble sugars, and the process of senescence. The results showed drought-induced accumulation of hexose sugars (glucose and fructose) in rice flag leaves, which could be corroborated with enhanced accumulation of MST8 under drought stress. On the other hand, cytokinin-treated plants maintained the normal contents of hexose sugar in their flag leaves under drought stress, alike wellwatered plants. In the case of sucrose, cytokinin treatment reduced its accumulation at tillering stage, but the results were reversed at the grain-filling stage, where the cytokinin-treated plants maintained significantly higher contents of sucrose under drought stress. Growth stage dependent variations in sucrose contents corroborated with the accumulation of SPS (SPS1, SPS2, and SPS5) proteins, implicated in sucrose biosynthesis. In our study, among the proteins involved in sucrose transport, SUT1 transporter was induced by drought stress at both the growth stages, whereas SUT2 transporter accumulated equally in all the treatments. However, cytokinin treatment reversed the effect of drought on the accumulation of SUT1. Similarly, SWEET5, and SWEET13 proteins, which were induced by drought stress treatment, were inhibited by cytokinin treatment. However, the accumulation SWEET6, SWEET7, and SWEET15 was not influenced by the treatment of cytokinin in the flag leaves of rice. In addition, cytokinin treatment reduced the leaf wilting, enhanced the fresh weight and grain yield, and curtailed the accumulation of proteins involved in drought-induced senescence. In conclusion, the cytokinin treatment had a positive agro-economic impact on the rice plants and provided better drought adaptability.

Journal of Water and Land Development

“…Moreover, the ability of Arabidopsis to cope with the soil salinity was increased via the induction of cytokinin production through the up-regulation of cytokinin biosynthetic gene AtIPT8 (adenosine phosphateisopentenyl transferase 8), which increased the induction of enzymatic antioxidants resulting in increasing the activity of ROS that finally improved the salinity stress tolerance in Arabidopsis [WANG et al 2015]. Moreover, the total soluble sugars and the yield of rice were increased under salt treatment through the application of exogenous phytohormones such as Auxin (indole-3-acetic acid IAA) and kinetin (KIN) [GUJJAR et al 2021].…”

pOsHAK1:OsSUT1 Promotes Sugar Transport and Enhances Drought Tolerance in Rice

“…As a key osmoregulatory substance, soluble sugar enhances rice tolerance to drought by regulating osmotic balance, protecting protein structure, and maintaining membrane integrity [6]. Moreover, soluble sugars (mainly glucose and fructose) are re-transported from old leaves to young leaves to sustain the growth of new tissues under drought stress [7,8]. Drought affects the transportation and distribution of sugar in cellular and subcellular components by reducing the osmotic potential of cells [9].…”

Drought and salinity stresses induced physio-biochemical changes in sugarcane: an overview of tolerance mechanism and mitigating approaches

“…Drought affects nearly 30% of agricultural land globally ( Dinh et al., 2017 ). Drought or water deficit inhibits physiological and biochemical processes such as growth, development, photosynthesis, and respiration, resulting in a loss in total biomass and juice production ( Verma et al, 2019 ; Gujjar et al., 2021 ). According to the Food and Agriculture Organization of the United Nations (FAO) estimates, drought caused an 80% drop in global productivity (FAOSTAT 2019).…”