Spermidine Enhances Heat Tolerance of Rice Seeds by Modulating Endogenous Starch and Polyamine Metabolism

Abstract

Polyamines have been reported to be involved in grain filling and they might contribute to the construction of heat resistance of some cereals. In this study, the hybrid rice ‘YLY 689’ was used to explore the possible effects of exogenous spermidine (Spd) on seed quality under high temperature during the filling stage. Rice spikes were treated with Spd or its synthesis inhibitor cyclohexylamine (CHA) after pollination, and then the rice plants were transferred to 40 °C for 5-day heat treatment. The results showed that, compared with the control under high temperature, Spd pretreatment significantly improved the germination percentage, germination index, vigor index, seedling shoot height, and dry weight of seeds harvested at 35 days after pollination, while the CHA significantly decreased the seed germination and seedling growth. Meanwhile, Spd significantly increased the peroxidase (POD) activity and decreased the malondialdehyde (MDA) content in seeds. In addition, after spraying with Spd, the endogenous content of spermidine and spermine and the expression of their synthetic genes, spermidine synthase (SPDSYN) and spermine synthase (SPMS1 and SPMS2), significantly increased, whereas the accumulation of amylose and total starch and the expression of their related synthase genes, soluble starch synthase II-3 (SS II-3) and granules bound starch synthase I (GBSSI), also increased to some extent. The data suggests that exogenous Spd pretreatment could alleviate the negative impacts of high temperature stress on rice seed grain filling and improve the rice seed quality to some extent, which might be partly caused by up-regulating endogenous polyamines and starch metabolism.

GABA-Alleviated Oxidative Injury Induced by Salinity, Osmotic Stress and their Combination by Regulating Cellular and Molecular Signals in Rice

“…In the present study, GABA induced starch catabolism, which is of primary importance for providing available carbohydrates for seed germination and growth under osmotic stress, salinity and the combined stress. These findings are consistent with previous studies, which found that environmental stresses such as osmotic stress, salt and heat stress decreased seed germination due to the inhibition of starch catabolism under these conditions [29,36,37]. It has been found that the metabolite mobilization of starch and soluble sugars is critical for the maintenance of cell turgor and energy sources when seeds are subjected to salinity and osmotic stress [36].…”

Dynamic Transcriptome Analysis of Anther Response to Heat Stress during Anthesis in Thermotolerant Rice (Oryza sativa L.)

“…Phenolamine, as a substrate of peroxidase, also participates in the scavenging of hydrogen peroxide and strengthening of the extraplastid cell wall, so it functions as an antioxidant and free radical scavenger, which can improve the ability of plants to resist abiotic stress [37]. The most important is that spermidine, a precursor in phenolamine synthesis, can enhance thermotolerance in rice seeds by modulating endogenous starch and polyamine metabolism [38]. Therefore, to characterize the possible role of the OsACT in thermotolerance of rice anther at anthesis, this gene was cloned and sequenced from SDWG005, 9311 and N22.…”

Mechanisms and Adaptation Strategies to Improve Heat Tolerance in Rice. A Review

“…Application of spermidine also increased soluble sugars content, photosystem II (FPSII), photosynthetic electron transport rate (ETR), photochemical reaction of light energy ratio (Pr), variable fluorescence/maximum fluorescence ratio (Fv 0/Fm 0), stomatal conductance, and ultimately improved the photosynthesis and transpiration rate [68]. Fu et al [70] reported that exogenously applied spermidine increased rice tolerance to heat by modulating the antioxidants, polyamine metabolism, and starch accumulation.…”