油茶幼苗对不同浓度锰离子的早期生理响应及其耐锰能力初探

Early physiological response to manganese ion with different concentrations and manganese tolerance of Camellia oleifera seedlings

关键词:  高锰胁迫  表观变化  生理响应  耐受能力  油茶幼苗

Key words:  high manganese stress  apparent change  physiological response  tolerance ability  Camellia oleifera seedlings

摘要:

油茶是一种重要的木本油料作物,为了解油茶幼苗对不同浓度锰离子的早期生理响应规律及其对高锰的耐受能力,该研究以油茶幼苗(湘林7号)将其放于0.005(CK)、0.1、1、4、8、10、12、14、16 mmol·L^-1 共9个不同锰浓度的霍格兰氏营养液中培养,研究不同供锰水平短期处理下水培油茶幼苗的表观及生理变化。测定叶片中超氧化物酶(SOD)与过氧化物酶(POD)活性,丙二醛(MDA)与可溶性糖以及叶绿素的含量。结果表明:(1)锰浓度达到4 mmol·L^-1后,幼苗出现叶片失绿、褐斑、脱落现象; 浓度超过8 mmol·L^-1后,植株出现死亡; 锰浓度越高上述现象越明显;(2)随锰浓度增加,叶片中SOD、POD活性及叶绿素含量呈先增后减的变化趋势,MDA与可溶性糖的含量则持续增加且在浓度超过8 mmol·L^-1后增加更明显;(3)随培养天数(0、20、50 d)增加,8 mmol·L^-1组可溶性糖与MDA含量持续增加,叶绿素含量持续减少; POD与SOD的酶活在前阶段(0～20 d)呈增加趋势,后期(20～50 d)则相反; 低于8 mmol·L^-1各组,浓度越低各指标随时间变化幅度越小;(4)处理过程中,各组抗氧化酶活性变化率SOD均大于POD(Paired t-Test, P<0.01)。这说明油茶幼苗生理响应可有效抵御锰胁迫的毒害效应,植株表现出了较高的锰耐受能力(≤8 mmol·L^-1),SOD与POD等抗氧化酶在抵御锰胁迫过程中发挥了重要作用。

Abstract:

Camellia oleifera is an important woody oil crops in china. In hydroponic conditions, apparent and related physiological indexes changes responding to short-term treatment of manganese ion with different concentrations were tracking analyzed in the present research in order to understand the early physiological response rules and tolerance ability to high manganese stress of C. oleifera seedlings. Seedlings(Xianglin No.7)for researching were provided by the C. oleifera breeding base of Hunan University of Science and Engineering. Seedlings were cultured in Hoagland's nutrient solution with different manganese concentrations of 0.005(CK), 0.1, 1, 4, 8, 10, 12, 14, 16 mmol·L^-1. Then the apparent changes with treating day were observed, and the activities of superoxide dismutase(SOD)and peroxidase(POD), the content of malondialdehyde(MDA), soluble sugar and chlorophyll were determinated by methods from references. The results were as follows:(1)Leaves appeared chlorosis, brown spot, shedding when manganese concentration reached 4 mmol·L^-1 and part of the plants died when concentration exceeded 8 mmol·L^-1; the symptoms became more serious with concentration came to a higher level;(2)With the increasing of manganese concentration, the activity of superoxide dismutase(SOD)and peroxidase(POD)and the chlorophyll content increased first and then reduced in leaves, and the enzymes activity dropped more dramatically when manganese concentration reached 8 mmol·L^-1; the content of MDA and soluble sugar kept increasing and showed more significantly as the concentration exceeded 8 mmol·L^-1;(3)With the increasing of culturing days, soluble sugar and MDA content in 8 mmol·L^-1 group kept increasing while the chlorophyll content decreased continuously, POD and SOD enzyme activity increased in initial stage(0-20 d)and turned into opposite later(20-50 d); in these groups with concentration lower than 8 mmol·L^-1, the variation amplitude of each indexes was more gentle with the concentration decreased.(4)The change degree of SOD activity was always greater than that of POD during the whole treatment process(Paired t-Test, P<0.01). These results indicate that effective physiological responses reduce the toxic effects of manganese stress making C. oleifera seedlings show a good tolerance to manganese(≤8 mmol·L^-1), the antioxidant enzymes such as SOD and POD play an important role in this process.