Nitrogen Addition Increases the Sensitivity of Photosynthesis to Drought and Re-watering Differentially in C-3 Versus C-4 Grass Species
Nitrogen Addition Increases the Sensitivity of Photosynthesis to Drought and Re-watering Differentially in C-3 Versus C-4 Grass Species
复制标题
添加氮可提高 C-3 与 C-4 草种光合作用对干旱和补水的敏感性
DOI：
10.3389/fpls.2019.00815
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发表时间：
2019
影响因子：
5.6
通讯作者：
Wei Sun
中科院分区：
文献类型：
--
作者：
Shangzhi Zhong;Yueqiao Xu;Bo Meng;Michael E. Loik;Jian-Ying Ma;Wei Sun
全球变化因子，如降水制度和氮沉降的变化，可能同时发生，并可能对不同功能性状的草的相对丰度产生深远的影响，如C3和C4种。为了解不同N沉降情景下C3和C4禾草的抗旱性和恢复能力的差异，进行了极旱复水试验。选择生长在东北地区的一种C3多年生牧草羊草（Leymus chinensis）和两种C4禾草（一年生植物Chloris virgata和多年生植物hemimha altissima）作为实验植物。对C3和C4禾本科植物而言，N的添加均引起生物量的显著增加，干旱胁迫更为严重，导致干旱期优势光合限制发生变化。虽然氮素增加了抗氧化酶活性和保护性溶质浓度，但在复水期结束时，固碳能力并未完全恢复到干旱前水平。施氮降低了干旱条件下的抗逆性，也降低了复水结束时的抗逆性。然而，氮的添加导致光合作用恢复速度更快，特别是在C3草中，这表明干旱时期氮添加对光合作用的影响是不对称的，特别是在不同光合氮利用效率（PNUE）的植物中。这些结果表明，氮沉降可能显著改变C3和C4禾草对干旱胁迫和再浇水的敏感性，突出了抗性和恢复力之间的不对称性，并提高了我们对植物对气候变化响应的认识。
Global change factors, such as variation in precipitation regimes and nitrogen (N) deposition, are likely to occur simultaneously and may have profound impacts on the relative abundance of grasses differing in functional traits, such as C3 and C4 species. We conducted an extreme drought and re-watering experiment to understand differences in the resistance and recovery abilities of C3 and C4 grasses under different N deposition scenarios. A C3 perennial grass (Leymus chinensis) and two C4 grasses (annual species Chloris virgata and perennial species Hemarthria altissima) that cooccur in Northeast China were selected as experimental plants. For both C3 and C4 grasses, N addition caused a strong increase in biomass and resulted in more severe drought stress, leading to a change in the dominant photosynthetic limitation during the drought periods. Although N addition increased antioxidant enzyme activities and protective solute concentrations, the carbon fixing capacity did not fully recover to predrought levels by the end of the re-watering period. N addition resulted in lower resilience under the drought conditions and lower resistance at the end of the re-watering. However, N addition led to faster recovery of photosynthesis, especially in the C3 grass, which indicate that the effect of N addition on photosynthesis during drought was asymmetric, especially in the plants with different photosynthetic nitrogen use efficiency (PNUE). These findings demonstrated that nitrogen deposition may significant alter the susceptibility of C3 and C4 grass species to drought stress and re-watering, highlighting the asymmetry between resistance and resilience and to improve our understanding about plant responses to climate change.