铝胁迫下一氧化氮对巨尾桉生长及生理的影响

酸铝抑制植物生长是全球关注的热点。以往关于酸铝胁迫的研究主要在禾本科和豆科植物上,而对经济用材林木较少。为此,本研究以巨尾桉广林9号为供试材料,在无铝（0 mmol/L）和铝胁迫（5 mmol/L）2种情况下,设置一氧化氮（NO）3个水平（0、10、500 μmol/L）,以期探究铝胁迫下外源施加NO对巨尾桉生长和生理方面的影响。试验结果表明：（1）5 mmol/L铝处理下的巨尾桉根、茎、叶生物量分别显著减少了11.57%、12.04%和37.37%,叶片叶绿素a、叶绿素a+b和类胡萝卜素含量积累也受抑制;（2）铝胁迫下叶片细胞膜透性显著增大,膜脂过氧化的产物丙二醛（MDA）显著增加了43.12%,细胞可溶性糖和蛋白含量分别显著减少了9.43%、42.27%;（3）适量添加NO （10 μmol/L）可提高铝胁迫下光合色素含量,提高最大的叶绿素a达41.23%,MDA含量明显降低了27.66%,提高可溶性糖和可溶性蛋白含量,以达到调节活性氧代谢来维持细胞膜结构稳定的效果,从而使生物量显著提高了10.19%;（4）NO浓度过高（500 μmol/L SNP）时反而对巨尾桉有毒害作用,生物量下降了15.17%,说明NO具有双重性。综上所述,铝胁迫对巨尾桉生长、渗透调节物质和抗氧化酶等生理特性均产生了抑制作用,而适当添加外源NO可以缓解铝对巨尾桉的毒害作用。

Effects of Nitric Oxide on Growth and Physiology of Eucalyptus under Aluminum Stress

Acid aluminum inhibiting plant growth is a global concern.Previous studies on acid and aluminum stress were mainly focused on gramineae and leguminous plants,less on economic timber species.In order to investigate the effects of exogenous application of nitric oxide on the growth and physiology of E.grandis×E.urophylla Guanglin No.9 under aluminum stress,three concentrations of nitric oxide(NO)were applied in the absence of aluminium(0 mmol/L)and aluminium stress(5 mmol/L).The results showed that:(1)the biomass of the roots,stems and leaves of E.grandis×E.urophylla treated with 5 mmol/L Al significantly decreased by 11.57%,12.04%and 37.37%,respectively,and the accumulation of chlorophyll a,chlorophyll a+b and carotenoids in the leaves was also inhibited.(2)Under Al stress,the cell membrane permeability of the leaves increased significantly,the product of membrane lipid peroxidation,malondialdehyde(MDA)increased by 43.12%,and the content of soluble sugar and protein decreased by 9.43%and 42.27%,corresspondingly.(3)The content of photosynthetic pigments increased by 41.23%under Al stress by adding NO(10μmol/L).The content of MDA reduced by 27.66%and the content of soluble sugar and protein increased to regulate the metabolism of reactive oxygen species(ROS)to maintain the stability of cell membrane structure,thus the biomass significantly increased by 10.19%.(4)NO concentration increased by 10.19%.Over-high NO(500μmol/L)was toxic to E.grandis,and the biomass decreased by 15.17%.This indicated that NO had dual characteristics.The results showed that:(1)5 mmol/L Al significantly inhibited the root and above-ground biomass,and inhibited the accumulation of Chl a,Chl a+b and Car.(2)Al stress significantly increased cell membrane permeability and MDA(the product of plasmalemma peroxidation),decreased soluble sugar and soluble protein content in Eucalyptus leaves.(3)Addition of exogenous nitric oxide(10μmol/L)could alleviate the effect of aluminum stress on photosynthetic pigments,significantly reduce MDA content,and increase the content of soluble sugar and soluble protein in order to regulate the metabolism of reactive oxygen species and maintain the stability of cell membrane structure,thus significantly increasing the biomass of E.grandis×E.urophylla Guanglin No.9.(4)When nitric oxide concentration was higher than 500μM SNP,it was toxic to E.grandis×E.urophylla Guanglin No.9.It showed that NO had dual nature.In conclusion,aluminum stress inhibited the growth and physiological characteristics of osmoregulation substances and antioxidant enzymes on E.grandis×E.urophylla Guanglin No.9,and the toxic effect of aluminum on Eucalyptus could be alleviated by appropriate addition of nitric oxide.