College of Resource and Environment, Qingdao Agricultural University, Qingdao, China.
MOE Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China.
J Sci Food Agric. 2020 Dec;100(15):5412-5421. doi: 10.1002/jsfa.10592. Epub 2020 Jul 23.
Phenolic compounds are phytochemicals present in vegetables which contribute to human health. Although nitrogen deficiency and sucrose (Suc) are linked to phenolic production in vegetables, the relationship between them in the regulation of phenolic biosynthesis remains unknown. This study investigated the potential role of Suc in regulating phenolic biosynthesis of lettuce under low-nitrogen (LN) conditions.
Our results showed that LN treatment significantly increased Suc content in lettuce by inducing rapid increases in activities of sucrose synthesis-related enzymes. Exogenous Suc further stimulated LN-induced phenolic accumulation in lettuce by upregulating the expression of genes (PAL, CHS, F3H, DFR, F35H and UFGT) involved in phenolic biosynthesis. The opposite effects were true for exogenous 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) application. No changes were observed in chlorophyll content in LN-treated lettuce, in either the presence or absence of Suc application. Notably, exogenous DCMU resulted in decreases of maximum quantum efficiency of photosystem II (PSII) photochemistry, actual efficiency of PSII and electron transport rate in PSII and increase of quantum yield of non-regulated energy dissipation in PSII in lettuce under LN conditions, whereas these effects were reversed on Suc application. Exogenous Suc also increased glutamine synthetase and glutamate synthase activities in LN-treated lettuce.
These results suggest that Suc is involved in LN-induced phenolic production in lettuce by enhancing photosynthetic and nitrogen assimilation efficiency to increase the supply of carbon resources and precursors for phenolic biosynthesis. © 2020 Society of Chemical Industry.
酚类化合物是蔬菜中的植物化学物质，对人体健康有贡献。虽然氮缺乏和蔗糖（Suc）与蔬菜中酚类物质的产生有关，但它们在调节酚类生物合成方面的关系尚不清楚。本研究调查了 Suc 在低氮（LN）条件下调节生菜酚类生物合成中的潜在作用。
我们的结果表明，LN 处理通过诱导蔗糖合成相关酶活性的快速增加，显著增加了生菜中的 Suc 含量。外源 Suc 通过上调参与酚类生物合成的基因（PAL、CHS、F3H、DFR、F35H 和 UFGT）的表达，进一步刺激 LN 诱导的生菜中酚类物质的积累。外源 3-(3,4-二氯苯基）-1,1-二甲基脲（DCMU）的相反作用。LN 处理的生菜中叶绿素含量没有变化，无论是存在还是不存在 Suc 应用。值得注意的是，外源 DCMU 导致 LN 条件下生菜 PSII 光化学最大量子效率、PSII 实际效率和 PSII 电子传递速率降低，PSII 非调节能量耗散量子产率增加，而在 Suc 应用时则相反。外源 Suc 还增加了 LN 处理的生菜中谷氨酰胺合成酶和谷氨酸合酶的活性。
这些结果表明，Suc 通过增强光合作用和氮同化效率来增加碳资源和酚类生物合成前体的供应，从而参与 LN 诱导的生菜中酚类物质的产生。 © 2020 化学工业协会。
