干旱胁迫下AMF对云南蓝果树叶片解剖结构的影响

Effects of arbuscular mycorrhizal fungi on anatomical structure of Nyssa yunnanensis leaves under drought stress

关键词:  云南蓝果树, 濒危植物, 干旱胁迫, 叶片解剖结构, 丛枝菌根真菌, 植物保护

Key words:  Nyssa yunnanensis, drought stress, endangered plants, anatomical structure of leaves, arbuscular mycorrhizal fungi(AMF), plant conservation

摘要:

苯菌灵为杀真菌剂,在土壤含水量为32.32%、29.63%、25.86%、19.39%、12.93%和6.46%的条件下,分别添加苯菌灵和不添加苯菌灵,形成“低AMF”和“高AMF”处理。该研究以云南蓝果树幼苗叶片为材料,利用盆栽试验研究了干旱胁迫下丛枝菌根真菌(AMF)对云南蓝果树幼苗叶片解剖结构及抗旱性的影响。结果表明:添加苯菌灵处理显著降低了不同水分处理条件下AMF侵染率,随着干旱胁迫程度加剧,云南蓝果树幼苗根部的AMF侵染率显著降低。轻度胁迫条件下(土壤含水量为29.63%),叶片解剖结构参数未发生显著变化; 土壤含水量低于25.86%,云南蓝果树幼苗表现出较高的抗旱性,苯菌灵处理可以显著影响叶片角质层厚度、栅栏组织厚度和上表皮厚度等7个叶片结构指标,证明了高AMF可以增强代表云南蓝果树幼苗叶片抗旱性的结构性状。土壤含水量为25.86%、19.39%和12.93%时苯菌灵处理的效果较土壤含水量为6.46%时更显著,这是因为6.46%的土壤含水量严重抑制AMF的侵染,说明AMF侵染程度会影响云南蓝果树幼苗的抗旱性。进一步用隶属函数值法对10个叶片性状进行综合评价,发现高AMF处理可增强云南蓝果树幼苗的抗旱性。该研究结果为AMF在濒危物种云南蓝果树保护过程中的合理利用提供了理论依据。

Abstract:

The objective of this study was to verify the effects of arbuscular mycorrhizal fungi(AMF)on drought resistance of Nyssa yunnanensis, and to explore the mycorrhizal ways of plant conservation. A pot experiment was conducted to study the effects of AMF on anatomical structure characteristics of N. yunnanensis seedlings and their drought resistances under different water conditions. Six water conditions(soil water content)were designed in this pot experiment: 32.32%, 29.63%, 25.86%, 19.39%, 12.93% and 6.46%, and at each water treatment, both sterilization(Low AMF)and no sterilization(High AMF)were contained through adding fungicide benomyl to control AMF. The results showed that AMF colonization rate were significantly decreased in “Low AMF” treatment under different water treatments. Moreover, AMF colonization rate of N. yunnanensis roots significantly decreased with the intensity of increased drought. No significant difference was found in anatomical structure characteristics under mild drought stress conditions(soil water content was 29.63%)whereas N. yunnanensis seedlings showed higher resistances under severe drought stress conditions(soil water content was less than 25.86%). Benomyl treatment significantly affected seven leaf structure indices, such as the leaf cuticle thickness, palisade tissue thickness, upside epidermal thickness, plisade tissue / spongy tissue ratio, tightness of leaf tissue structure, sponge tissue thickness and leaf institutions looseness when soil water content was less than 25.86%, suggesting that high AMF could enhance leaf structure traits on behalf of the drought resistance of N. yunnanensis seedlings when under severe drought stress conditions. Effects of AMF on N. yunnanensis seedlings under 25.86%, 19.39% and 12.93% were more significant than under 6.46% water content of soil. That was because AMF colonization was severely restrained by 6.46% water content of soil. Thus, effects of AMF on plant probably positively related to the colonization rate. Based on principal component analysis of N. yunnanensis 10 structure's index of leaves, and the method of membership function value, leaf traits of main structure index were comprehensively evaluated. The results demonstrated that N. yunnanensis seedlings showed stronger drought resistance under high AMF conditions. The experimental results provided the theoretical basis for the reasonable use of AMF in the protection of endangered species N. yunnanensis.