Heat Stress Promotes Nitrogen Accumulation in Meristems via Apical Blade Erosion in a Brown Macroalga With Intercalary Growth
Heat Stress Promotes Nitrogen Accumulation in Meristems via Apical Blade Erosion in a Brown Macroalga With Intercalary Growth
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DOI：
10.3389/fmars.2020.575721
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发表时间：
2020-09-25
影响因子：
3.7
通讯作者：
Agatsuma, Yukio
中科院分区：
文献类型：
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作者：
Endo, Hikaru;Inomata, Eri;Agatsuma, Yukio
众所周知，热应激会在顶端生长的陆地植物中引起光抑制、叶片衰老和养分再利用，然而，在海带等居间生长的海洋大型藻类中，很少研究其对叶片侵蚀和化学成分相关变化的影响。本研究考察了海洋变暖（23和26摄氏度）、辐照度（30和180 mu mol m(-2)s(-1)）和营养富集（富集和非富集）对海带双环爱胜蚓光系统II最大效率（F-v/F-m）的综合影响。它还根据五个形态参数和三种化学成分（碳、氮和草单宁）研究了海洋变暖对海带相对生长率的影响。仅在较高辐照度和营养富集条件下才检测到对光抑制的变暖效应（即 F(v)/F-m 下降）。在此条件下，升高的温度将相对生长率降低至负值，表明发生了顶端叶片侵蚀。温度升高还导致全身内氮和叶皮单宁含量增加，但碳含量没有增加。此外，26℃时分生组织中的氮含量高于23℃时的分生组织中的氮含量，但叶皮单宁含量没有观察到这种差异。这些结果表明，热诱导的顶端叶片侵蚀促进了位于叶片下部的分生组织中的氮积累。自行车。
Heat stress is known to induce photoinhibition, leaf senescence, and nutrient remobilization in terrestrial plants with apical growth, however, its effect on blade erosion and associated-changes in chemical compositions has rarely been studied in marine macroalgae with intercalary growth such as kelp. The present study examined the combined effects of ocean warming (23 and 26 degrees C), irradiance (30 and 180 mu mol m(-2)s(-1)), and nutrient enrichment (enriched and non-enriched) on photosystem II maximum efficiency (F-v/F-m) in the kelpEisenia bicyclis. It also investigated the effect of ocean warming on the kelp's relative growth rates based on five morphological parameters and three chemical compositions (carbon, nitrogen, and phlorotannnins). A warming effect on photoinhibition (i.e., decline inF(v)/F-m) was only detected under the higher irradiance combined with nutrient-enrichment condition. Under this condition, elevated temperature decreased relative growth rates to negative values, indicating occurrence of apical blade erosion. Temperature elevation also caused increases in nitrogen and phlorotannin contents within the whole body, but not carbon content. Moreover, nitrogen content in the meristems at 26 degrees C was higher than that at 23 degrees C, although such a difference was not observed with phlorotannin content. These results suggested that heat-induced apical blade erosion promoted nitrogen accumulation in the meristems, located in the lower part of the blade, inE. bicyclis.