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根系分泌物是植物与土壤间进行物质交换和信息传递的重要载体,是植物响应外界胁迫的重要途径,也是构成根际微生态特征的关键因素。根系分泌物与有机污染物的植物修复密切相关,研究胁迫条件下不同修复潜力植物间根系分泌物的释放特征有助于揭示植物修复的内在机制。该文借助根际袋土培试验研究了苯并[α]芘(Ba P)胁迫下5种羊茅属(Festuca)植物根系不同生长期(30–70天)几种低分子量有机物的分泌特征。结果表明:1)Ba P浓度在10.25–161.74 mg·kg~(–1)范围内时,待试植物能有效地促进土壤中Ba P的去除,其修复潜力依次为苇状羊茅(F.arundinacea)>草原羊茅(F.chelungkiangnica)≥毛稃羊茅(F.rubra subsp.arctica)≥贫芒羊茅(F.sinomutica)>细芒羊茅(F.stapfii)。2)Ba P胁迫增强了植物根系对可溶性糖的分泌:随着胁迫强度的增大、胁迫期的延长,其分泌量变化呈“先升后降”趋势。3)Ba P胁迫促进了植物根系低分子量有机酸的释放,植物的修复潜力越大,有机酸高峰值出现时的胁迫浓度越高;组成成分较稳定,草酸、乙酸、乳酸和苹果酸为主要组分(>97.34%),在修复潜力较强植物的根系分泌物中检测出微量的反丁烯二酸。4)Ba P胁迫对氨基酸种类影响不大,但对分泌量影响较大。其中,苏氨酸、丝氨酸、甘氨酸、丙氨酸的分泌量随Ba P胁迫强度的增强而剧增;脯氨酸、羟脯氨酸和天冬氨酸近乎以加和效应甚至协同效应的形式参与植物对Ba P胁迫的应激反应:参与应激组分的分泌量随胁迫强度的增强而剧增,植物的修复潜力越强,参与的组分越多。可见Ba P胁迫下,5种羊茅属植物根系分泌物中几种低分子量有机物的释放特征与植物自身的修复潜力有关:修复潜力越强,释放量越多且成分也越复杂,并呈现出较强的环境适应性及生理可塑性。
Root exudates are an important carrier of material exchange and information transmission between plants and soil. They are also an important way for plants to respond to external stresses and are also the key factors that constitute the rhizosphere micro-ecological characteristics. Root exudates are closely related to phytoremediation of organic pollutants. Studying the release characteristics of root exudates between plants with different restorative potential under stress can help reveal the intrinsic mechanism of phytoremediation. In this paper, we studied the secretion characteristics of several low-molecular-weight organic compounds in roots of five Festuca plants at different growth stages (30-70 days) with benzo [α] pyrene (Ba P) . The results showed as follows: 1) When Ba P concentration was in the range of 10.25-161.74 mg · kg ~ (-1), the test plants could effectively promote the removal of Ba P in soil. The potential for remediation was Phragmites australis (F. arundinacea> F. chelungkiangnica> F.rubra subsp. arctica> F. somnotica> F. stapfii. 2) Ba stress increased the secretion of soluble sugar in plant roots: with the increase of stress intensity and prolongation of stress period, the change of its secretion showed the tendency of “increasing first and then decreasing”. BaP stress promoted the release of low molecular weight organic acids in plant roots, and the higher the potential for plant remediation, the higher the concentration of organic acids when the peak appeared; the more stable components were oxalic acid, acetic acid, lactic acid and malic acid (> 97.34%). Trace amounts of fumaric acid were detected in the root exudates of plants with high potential for remediation. 4) Ba stress had little effect on the types of amino acids, but had a greater impact on the secretion. Among them, the secretion of threonine, serine, glycine and alanine increased sharply with the increase of BaP stress; the contents of proline, hydroxyproline and aspartic acid were almost in the form of additive effect and even synergistic effect Participation in plant stress response to Ba stress: the secretion of stress components increased sharply with the increase of stress intensity, the stronger the potential of plant repair, the more involved components. It can be seen that the release characteristics of several low molecular weight organic compounds in the root exudates of five species of Fescue are related to the potential of the plant to repair itself under the BaP stress. The higher the potential for repair, the greater the release and the more complex the composition, Strong environmental adaptability and physiological plasticity.