俄罗斯杨水培苗对硼胁迫的生长和生理响应

该研究采用水培试验,分析了俄罗斯杨(Populus russkii)对短期硼胁迫(1、5、10mmol/L硼酸)的生长和生理响应特征,探明其对硼胁迫的耐受范围,初步揭示其耐硼的生理基础。结果显示:(1)与对照相比,1mmol/L硼酸处理俄罗斯杨水培苗的生长情况更优,叶片光合色素含量和净光合速率显著上升,SOD和APX活性及抗坏血酸含量显著上调。(2)5mmol/L硼酸处理幼苗有轻微胁迫受害症状,叶片褪绿变黄,叶绿素b含量比对照显著上升,而Chla/Chlb比值显著下降,其SOD和APX活性显著上调。(3)10mmol/L硼酸处理幼苗表现出严重毒害症状,叶片发黄、茎尖和根尖生长受抑制;叶片PSⅡ原初光能转换效率(F_v/F_m)和Chla/Chlb比值比对照显著下降;其叶片MDA含量、POD活性、抗坏血酸含量以及游离脯氨酸和可溶性糖含量均比对照显著上升。研究表明,在不同浓度硼酸短期胁迫下,俄罗斯杨水培苗能通过上调抗氧化酶活性和抗氧化物质、渗透调节物质含量来有效清除体内胁迫产生的活性氧,减轻膜脂过氧化伤害,使其在低于5mmol/L硼酸胁迫环境下正常生长,表现出较强的耐硼性。

The Growth and Physiological Responses of Hydroponic Populus russkii to Excessive Boron

To disclose the tolerant range of hydroponic Populus russkii to excessive boron and reveal the relative physiological mechanism, the present research studied the growth and physiological responses of hydroponic P. russkii to short term boron stress (1, 5, and 10 mmol/L boric acid). The results showed that: (1) the plants grew better under 1 mmol/L boric acid treatment than CK (1/2 Hoagland solution, 0.05 mmol/L boric acid). The content of leaf photosynthetic pigments, net photosynthetic rate, the activities of SOD and APX, and the content of ascorbic acid increased significantly. (2) P. russkii suffered slight stress under 5 mmol/L boric acid treatment as leaf chlorosis was observed. Compared with CK, the content of Chlb and the activities of SOD and APX increased significantly, while the Chla/Chlb ratio decreased. (3) Serious symptom (growth inhibition of shoots and roots) arose when the plants were treated with 10 mmol/L boric acid, accompanying with decrease of F_v/F_m and Chla/Chlb ratio, and increase of MDA content. The activity of POD, the contents of ascorbic acid, free proline, and soluble sugars increased significantly. The present study showed that hydroponic P. russkii can scavenge ROS effectively by up regulating the activities of antioxidant enzymes and the contents of non enzymatic antioxidants and osmoprotectants under short term stress, resulting in strong tolerance ensuring the plants to grow normally under 5 mmol/L boric acid.