环境中镧对水稻叶绿体功能元素的影响

Effects of Environmental Lanthanum Ion on Functional Elements in Chloroplast of Rice

以水稻为研究对象,利用CIRAS-1系统和配有能量色散X光谱扫描电镜(SEM-X-EDS)研究不同浓度镧(La3+)处理下幼苗期和灌浆期水稻净光合速率和叶绿体功能元素及La含量变化。实验结果表明,La3+浓度在0.08 mmol·L-1时,幼苗期水稻叶片叶绿体Ca、Mg、K、Mn、Fe含量和灌浆期Ca、Mg、K含量增加,其余元素未发生明显变化,两生育期净光合速率均上升;当La3+浓度达到1.20 mmol·L-1后,幼苗期和灌浆期水稻叶绿体功能元素含量均呈下降趋势,净光合速率下降。La3+处理下,幼苗期水稻净光合速率对La响应比灌浆期更敏感,净光合速率与叶绿体各功能元素均呈正相关关系。La可以在叶绿体中富集,且与处理La3+浓度呈明显剂量-效应关系,随着处理时间的延长,叶绿体内的La含量越高。总之,1.20 mmol·L-1是La3+引发水稻净光合速率和叶绿体功能元素含量降低的临界点,环境中累积的La3+能影响水稻叶片叶绿体功能元素含量,并通过改变叶绿体元素含量而影响水稻光合作用的正常进行。

The wide applications of rare earth led to the accumulation of rare earth in soils and crops, and enter the body through food chain and endanger human health. Using CIRAS - 1 system and scanning electron microscopy with energy disper- sive X - ray spectroscopy （ SEM - X - EDS ） , net photosynthetic rate and the chloroplast functional elements and lanthanide （La） content in rice chloroplast under different La^3＋ concentrations were studied. Results showed that the contents of Ca, Mg, K, Mn and Fe increased during seedlings stage and Ca, Mg and K also increased during filling stage of rice under 0.08 mmol · L^- 1 La^3＋ ; The net photosynthesis increased during two stages and the net photosynthesis was positively correlated with the contents of functional elements ; The functional elements and the net photosynthesis decreased when treated with 1.20 mmol·L-1 and 2.40 mmol ·L-1La^3 ＋ ; Besides, La enriched in chloroplast and increased with the concentration increasing and growing in treatment, showing significant dose - effect relationship. In a word, 1.20 mmol ·L-1 is the critical point of La to trigger the net photosynthesis and the functional elements decrease in chloroplast. The accumulation of environmental La ion influences the functional elements contents which affect the photosynthesis.