College of Biological Science and Technology, Shenyang Agricultural University, Shenyang, Liaoning, China.
Shenyang Key Laboratory of Maize Genomic Selection Breeding, Shenyang, Liaoning, China.
PLoS One. 2020 Dec 11;15(12):e0243835. doi: 10.1371/journal.pone.0243835. eCollection 2020.
Sucrose metabolism contributes to the growth and development of plants and helps plants cope with abiotic stresses, including stress from Cd. Many of these processes are not well-defined, including the mechanism underlying the response of sucrose metabolism to Cd stress. In this study, we investigated how sucrose metabolism in maize varieties with low (FY9) and high (SY33) sensitivities to Cd changed in response to different levels of Cd (0 (control), 5, 10, and 20 mg L-1 Cd). The results showed that photosynthesis was impaired, and the biomass decreased, in both varieties of maize at different Cd concentrations. Cd inhibited the activities of sucrose phosphate synthase (SPS) and sucrose synthase (SS) (sucrose synthesis), and stimulated the activities of acid invertase (AI) and SS (sucrose hydrolysis). The total soluble sugar contents were higher in the Cd-treated seedlings than in the control. Also, Cd concentrations in the shoots were higher in SY33 than in FY9, and in the roots were lower in SY33 than in FY9. The decreases in the photosynthetic rate, synthesis of photosynthetic products, enzyme activity in sucrose synthesis direction, and increases in activity in hydrolysis direction were more obvious in SY33 (the sensitive variety) than in FY9 (the tolerant variety), and more photosynthetic products were converted into soluble sugar in SY33 than in FY9 as the Cd stress increased. The transcript levels of the sugar transporter genes also differed between the two varieties at different concentrations of Cd. These results suggest that sucrose metabolism may be a secondary response to Cd additions, and that the Cd-sensitive variety used more carbohydrates to defend against Cd stress rather than to support growth than the Cd-tolerant variety.
蔗糖代谢有助于植物的生长和发育，并帮助植物应对非生物胁迫，包括 Cd 胁迫。这些过程中的许多过程尚未得到很好的定义，包括蔗糖代谢对 Cd 胁迫响应的机制。在这项研究中，我们研究了对 Cd 敏感程度不同的玉米品种（FY9 和 SY33）的蔗糖代谢如何响应不同水平的 Cd（0（对照）、5、10 和 20 mg L-1 Cd）而变化。结果表明，在不同 Cd 浓度下，两种玉米品种的光合作用均受到抑制，生物量减少。Cd 抑制了蔗糖磷酸合酶（SPS）和蔗糖合酶（SS）（蔗糖合成）的活性，刺激了酸性转化酶（AI）和 SS（蔗糖水解）的活性。Cd 处理的幼苗中的总可溶性糖含量高于对照。此外，SY33 中的 Cd 浓度高于 FY9，而在 SY33 中的 Cd 浓度低于 FY9。在 SY33（敏感品种）中，光合速率、光合产物合成、蔗糖合成方向的酶活性以及水解方向的活性降低比 FY9（耐Cd 品种）更明显，随着 Cd 胁迫的增加，更多的光合产物转化为可溶性糖。不同浓度 Cd 下两种品种的糖转运基因的转录水平也存在差异。这些结果表明，蔗糖代谢可能是对 Cd 添加的次级响应，Cd 敏感品种比 Cd 耐受品种更倾向于利用更多的碳水化合物来抵御 Cd 胁迫，而不是支持生长。
