Nitrate availability regulated leaf anatomical structure to prevent ammonium toxicity on photosynthetic rate of Brassica napus

文献类型： 外文期刊

第一作者： Hu, Wenshi

作者： Hu, Wenshi;Zhang, Shanshan;Dai, Jing;Gu, Chiming;Yang, Lu;Li, Yinshui;Qin, Lu

作者机构：

关键词： Nitrate; Ammonium; Photosynthesis; Mesophyll conductance; Anatomical traits

期刊名称：ENVIRONMENTAL AND EXPERIMENTAL BOTANY （ 影响因子：4.7； 五年影响因子：5.4 ）

ISSN： 0098-8472

年卷期： 2025 年 237 卷

页码：

收录情况： SCI

摘要： Ammonium (NH4+-N) is the predominant form of nitrogen (N) fertilizer, but poses a risk of NH4+ toxicity, adversely affecting plant growth. Photosynthesis, which is closely linked to biomass and yield, is inhibited by NH4+ toxicity, but this effect is alleviated with increasing supplied nitrate (NO3--N) fraction. To understand the mechanism behind NO3--N's alleviation of NH4+-N inhibition on photosynthesis, limiting factors for photosynthetic rate (A) and anatomical characteristics of Brassica napus, an essential oil crop that heavily relies on N fertilizer, were measured. Results revealed that the inhibition of NH4+-N toxicity on A and growth was aggravated under NO3--N deprivation. When the proportion of NO3--N was lower than that of NH4+-N, the decrease of A was dominated by mesophyll conductance (g(m)), with its reduction strongly correlated with increased distance between two neighbouring chloroplasts (Dchl-chl) and decreased chloroplast surface area exposed to intercellular airspace per unit leaf area (Sc). NO3--N supply promoted volume fraction of intercellular air space (f(ias)) and mesophyll surface area exposed to intercellular airspace per unit leaf area (S-m), furtherly enhancing Scand facilitating higher gm. Additionally, Dchl-chl, f(ias), and S-m were more closely related to leaf NO3--N concentration than to NH4+-N. Thus, NO3--N plays a crucial role in mitigating NH4+-N toxicity on A by regulating leaf mesophyll arrangement and morphology. Increasing the proportion of NO3--N in fertilizers provides a strategy for crops at the risk of soil NH4+-N toxicity to maintain high A, furtherly promoting yield and N use efficiency.

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