两种杨树对高硼胁迫的生理响应

Physiological responses of two poplar species to high boron stress

近年来国外学者发现杨树(Populus spp.)对硼表现出很强的富集能力和极强的耐受能力,但其耐硼胁迫的生理机制和种间差异仍不清楚。该研究通过两年的硼梯度控制试验,探讨了硼胁迫对欧洲黑杨杂交种俄罗斯杨(Populus russkii)和银白杨变种新疆杨(P.bolleca)的生长和生理指标的影响。结果表明,新疆杨的耐高硼能力高于俄罗斯杨,其高硼伤害阈值(EC10)为35 mg·kg–1,俄罗斯杨为19 mg·kg–1。两种杨树的过氧化氢酶(CAT)和愈创木酚过氧化物酶(Gu-POD)活性随硼浓度升高而升高,超过EC10后显著下降。尽管两种杨树的叶绿素含量和光化学效率在硼胁迫下降低,但抗硼胁迫能力较强的新疆杨仍然保持了较高的叶绿素a/b值和热耗散能力(非光化学淬灭升高),因此有效地保护了该树种的光合能力。两种杨树的可溶性糖含量随硼胁迫加重而适应性升高,以维持其抗渗透能力,但其叶片可溶性蛋白含量仅在中低强度的硼胁迫条件下有所升高。该研究明确了两个富集硼的杨树种对高硼胁迫的生理响应及其种间差异。

Aims In recent years, international studies have found that poplar species could accumulate high boron with hy- pertolerance ability. Our objective was to investigate the effect of growth and physiological indicators of Populus russkii and P. bolleca under different boron concentrations, and determine the interspecific difference on boron tolerance, to help explaining and providing certain theoretical basis of phytoremediation technology for boron pollution treatment. Methods Poplar cuttings were grown in potting soil and added boron after three months. Physiological proper- ties tested included plant height, fresh biomass, chlorophyll fluorescence parameters, chlorophyll content, activi- ties of catalase （CAT） and guaiacol peroxidase （Gu-POD）, soluble protein （SP） content and soluble carbohydrate （SC） content. Important findings Boron stress seriously inhibited the growth and affected the chlorophyll fluorescence pa- rameters of the two poplar species. Populus russkii was more sensitive than P. bolleca to boron stress, and P. bol- leca could stand higher boron level than P. russkii. The boron damage threshold （10%） ofP. russkii and P. bolleca were 19 and 35 mg.kg-1, respectively. The plant height, fresh mass and chlorophyll decreased linearly with the increase of soil boron concentrations. For antioxidant parameters analysis, the activities of CAT and Gu-POD in- creased at first, and then decreased with increasing concentration of applied boron. Populus bolleca kept higher chlorophyll a/b and non-photochemical quenching than P. russkii under boron stress. Soluble protein and soluble carbohydrate increased with the increasing concentration of applied boron. These results demonstrated that the two poplar species eased the boron toxicity by strengthen the metabolism of protein synthesis but the capacity of clearing up the harmful peroxide was limited, and the CAT and Gu-POD activities were inhibited under high bo- ron concentrations.