外源硫对镉胁迫下马齿苋光合性状和矿质元素吸收的影响

doi:10.13560/j.cnki.biotech.bull.1985.2019-0672

摘要/Abstract

摘要： 从光合反应系统揭示外源硫（S）诱导马齿苋镉（Cd）耐受性的生理机制,为外源S缓解重金属毒害提供理论依据。采用营养液培养,研究外源S供体（NH₄）₂SO₄对100 mg/L Cd胁迫下马齿苋叶片光合色素、光合特性、叶绿素荧光参数和矿质营养元素的影响。结果表明,Cd胁迫可显著降低马齿苋叶片中叶绿素a和叶绿素b含量;净光合速率、蒸腾速率、气孔导度均显著降低,而胞间二氧化碳浓度上升,表明非气孔因素是Cd胁迫诱导马齿苋光合抑制的主要因素;同时,PSⅡ实际光化学效率（Ф_PSII）、电子传递效率（J）、化学猝灭系数（q_P）显著下降,而非化学猝灭系数（q_N）显著上升,表明Cd胁迫影响马齿苋PSⅡ反应系统的正常运行。外施400 mg/L（NH₄）₂SO₄显著提高马齿苋叶片叶绿素a含量、叶绿素b含量和叶绿素a/b比值,增强马齿苋叶片光合作用和PSⅡ原初光化学反应量子效率。对5种与光反应系统密切相关的矿质元素含量进行分析发现,Cd处理显著增加马齿苋叶片中的Ca和Fe含量,显著抑制马齿苋对Mg、Mn和Cu的吸收。Cd胁迫下马齿苋叶片的变黄与Mg、Mn的亏缺有关,而与Fe缺乏无关;添加外源S可显著提升马齿苋叶片中Ca、Mg、Fe、Cu和Mn含量,从而增强Cd胁迫下马齿苋叶片的PSII反应系统功能。

关键词: 硫, 镉胁迫, 马齿苋, 光合性状, 矿质元素

Abstract: Uncovering the physiological mechanism of exogenous sulfur inducing cadmium（Cd）tolerance in Portulaca oleracea from the aspect of photosynthetic reaction system may provide a theoretical foundation for application of S in alleviating the toxicity of heavy metals in plants. A hydroponic experiment was conducted to investigate the effects of exogenous（NH₄）₂SO₄,an S donor,on the photosynthetic pigments,photosynthetic characteristics,chlorophyll fluorescence parameters,and mineral element contents in P. oleracea treated with 100 mg/L CdCl₂. The results showed that Cd stress resulted in the significant decrease of chlorophyll a and b,also the net photosynthesis rate transpiration rate,and stomatal conductance,while the increase of intercellular concentrations of carbon dioxide（Ci）;these results indicated that nonstomatal factor was the dominant one that induced photosynthetic inhibition under Cd stress. Meanwhile,PSII actual photochemical efficiency（Ф_PSII）,electron transfer efficiency（J）,and chemical quenching coefficient（q_P）all significantly decreased,whereas nonchemical quenching coefficient（q_N）significantly increased;these results implied that Cd stress disturbed proper function of PSII in P. oleracea. However,the application of 400 mg/L（NH₄）₂SO₄ significantly increased the content of chlorophyll a and b,ratio of chlorophyll a/b,meanwhile enhanced both of the photosynthesis and quantum yield of PSII photochemistry. Furthermore,Cd treatment significantly increased content of calcium（Ca）and iron（Fe）,while inhibited absorption of magnesium（Mg）,manganese（Mn）,and copper（Cu）;these results implied that the cadmium-incited etiolation of the leaves was related to the deficiency of Mg and Mn in P. oleracea,but not to Fe. In sum,adding surplus S may significantly increase the content of Ca,Mg,Fe,Cu and Mn and therefore enhance PSII system in the leaves of P. oleracea under Cd stress.

Key words: sulfur, cadmium stress, Portulaca oleracea, photosynthetic characteristics, mineral element

王竹承, 刘辉, 李荣华. 外源硫对镉胁迫下马齿苋光合性状和矿质元素吸收的影响[J]. 生物技术通报, 2020, 36(3): 133-140.

WANG Zhu-cheng, LIU Hui, LI Rong-hua. Effects of Exogenous Sulfur on Photosynthetic Characteristics and Mineral Elements Absorption in Portulaca oleracea Under Cadmium Stress[J]. Biotechnology Bulletin, 2020, 36(3): 133-140.

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