铀在小麦幼苗中的积累分布及其对叶片光系统活性的影响

Accumulation and Distribution of Uranium in Wheat Seedling and the Effects of Uranium on the Photosystem Activities

分别采用不同浓度的铀[0、5、20、50、100mg.L-1 UO2(NO3)2.6H2O]对五叶期的‘西科麦3号’小麦幼苗于水培条件下处理7d,分析小麦对铀的吸收积累情况,并通过快速叶绿素荧光诱导动力学OJIP曲线及820nm光吸收曲线,分析铀对叶片光系统Ⅱ(PSⅡ)和光系统Ⅰ(PSⅠ)活性的影响。结果表明:(1)小麦对铀的富集系数和转移系数较小,吸收的铀主要集中在根部。(2)铀胁迫显著降低了小麦叶片捕光色素叶绿素b的含量,并显著影响小麦叶片两个光系统的活性;铀显著抑制PSⅡ反应中心的活性,但是对PSⅡ的电子供体侧和受体侧电子传递活性及PSⅠ的活性则表现为促进作用。(3)低浓度的铀处理会影响小麦叶片中两个光合系统之间的平衡,对PSⅠ性能的促进作用显著大于PSⅡ。

Along with the development of the nuclear industry,heavy metal uranium emissions and spread was increasing,and it will bring potential harm to human health. In this study,wheat seedlings （Triticum aestivum L. var. Xikemai No. 3） were cultivated with hydroponic culture system, and were respectively treated with nutrient solution containing 0,5,20,50,100 mg · L-1 UEUO2 （NO3）2 · 6 H2 O] after five-leaf stage. Uptake and distribution of U in the up-ground parts and down-ground parts of wheat, the chloro- phyll fluorescence characteristics and photosystem activity were investigated after 7 days of the U treat- ment. The results showed that： （1）Wheat can absorb the U,but both of the bio-enrichment coefficients and the transfer factors were very low, and the U was mainly accumulated in the roots. （2）The chlorophyll b content of leaves was significantly declined under the U stress,while the chlorophyll a content slightly de- creased,and the carotenoid content maintained stable. After the U treatment,Both of photosystem Ⅱ （PS Ⅱ ） and photosystem I （PSI ） activity were subject to different affects,among them, the PS Ⅱ reactioncenter activity was inhibited,but the electron transport activity of donor and reeeptor side in PS Ⅱ ,as well as PSI activity were promoted. （3）Low concentration of U affected the balance between PS Ⅱ and PS Ⅰ of wheat leaves,and there was stronger promoting on the PSI activity than on the PS Ⅱ activity.