High nitrogen inhibits photosynthetic performance in a shade-tolerant and N-sensitive species Panax notoginseng
High nitrogen inhibits photosynthetic performance in a shade-tolerant and N-sensitive species Panax notoginseng
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高氮抑制耐荫和耐氮敏感物种三七的光合作用
DOI：
10.1007/s11120-021-00823-5
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发表时间：
2021-02-15
影响因子：
3.7
通讯作者：
Chen, Jun-Wen
中科院分区：
文献类型：
--
作者：
Cun, Zhu;Zhang, Jin-Yan;Chen, Jun-Wen
氮（N）是限制叶片光合作用的主要因素。然而，在三七等耐荫和氮敏感物种中，高氮驱动抑制光合效率和光保护的机制仍不清楚。对耐阴、氮敏感的三七在中氮（MN）和高氮（HN）条件下生长的叶片叶绿素（Chl）含量、核酮糖-1,5-二磷酸羧化酶加氧酶（Rubisco）活性和含量、光合器官中的氮分配、光合性能和叶绿素荧光进行了比较分析。结果表明，HN个体的Rubisco含量、叶绿素含量和比叶氮(SLN)较高。 HN处理下的Rubisco活性、净光合速率(A(net))、光合氮利用效率(PNUE)、最大羧化速率(V-cmax)和最大电子传递速率(J(max))均低于MN处理下的植物。在MN水平下，大部分叶片N被分配给羧化成分。更多的氮仅作为氮储存的一种形式，对 HN 个体的光合作用没有贡献。与MN植物相比，HN植物的光系统II最大量子产率（F-v/F-m）、PSII非光化学猝灭（NPQ）、有效量子产率和电子传输速率均明显降低。 MN 个体的循环电子流（CEF）显着增强。 HN 和 MN 个体之间的最大光氧化 P700+ (P-m) 没有显着差异。最重要的是，HN个体在快速叶绿素荧光诱导动力学曲线（OJIP动力学曲线）中表现出比MN个体更高的K期。结果表明，HN个体的光合能力可能主要受到失活的Rubisco的抑制，而HN诱导的光保护抑制可能是由于PSII放氧复合物供体侧的光损伤造成的。
Nitrogen (N) is a primary factor limiting leaf photosynthesis. However, the mechanism of high-N-driven inhibition on photosynthetic efficiency and photoprotection is still unclear in the shade-tolerant and N-sensitive species such as Panax notoginseng. Leaf chlorophyll (Chl) content, Ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) activity and content, N allocation in the photosynthetic apparatus, photosynthetic performance and Chl fluorescence were comparatively analyzed in a shade-tolerant and N-sensitive species P. notoginseng grown under the levels of moderate nitrogen (MN) and high nitrogen (HN). The results showed that Rubisco content, Chl content and specific leaf nitrogen (SLN) were greater in the HN individuals. Rubisco activity, net photosynthetic rate (A(net)), photosynthetic N use efficiency (PNUE), maximum carboxylation rate (V-cmax) and maximum electron transport rate (J(max)) were lower when plants were exposed to HN as compared with ones to MN. A large proportion of leaf N was allocated to the carboxylation component under the levels of MN. More N was only served as a form of N storage and not contributed to photosynthesis in HN individuals. Compared with the MN plants, the maximum quantum yield of photosystem II (F-v/F-m), non-photochemical quenching of PSII (NPQ), effective quantum yield and electron transport rate were obviously reduced in the HN plants. Cycle electron flow (CEF) was considerably enhanced in the MN individuals. There was not a significant difference in maximum photo-oxidation P700+ (P-m) between the HN and MN individuals. Most importantly, the HN individuals showed higher K phase in the fast chlorophyll fluorescence induction kinetic curve (OJIP kinetic curve) than the MN ones. The results obtained suggest that photosynthetic capacity might be primarily inhibited by the inactivated Rubisco in the HN individuals, and HN-induced depression of photoprotection might be caused by the photodamage to the donor side of PSII oxygen-evolving complex.