盐碱胁迫下AMF对羊草的离子吸收和分配作用

Effects of arbuscular mycorrhizal fungi on ion absorption and distribution in Leymus chinensis under saline-alkaline stress

丛枝菌根真菌(AMF)通过影响植物地上及地下离子吸收分配来增强植物耐盐碱能力的机理尚不明确,采用盆栽试验,选取松嫩草地的优势种羊草作为试验材料,研究不同盐碱梯度下接种AMF对羊草体内无机阳离子吸收、运输和分配的影响。试验结果表明:1)盐碱胁迫会增加羊草体内Na^+含量,减少K^+、Ca^2+和Mg^2+含量,增强地下到地上部分Na+的运输,抑制K^+、Ca^2+和Mg^2+的运输,改变羊草体内地上和地下的离子分配;2)盐碱胁迫条件下,AMF抑制了羊草对Na^+的吸收,促进了其对K^+、Ca^2+和Mg^2+的吸收,同时提高了根系对Na^+的截留能力,通过调节羊草体内的无机离子运输比和阳离子运输选择比,维持其体内的离子平衡,从而提高耐盐碱性;3)盐碱胁迫程度增加改变了AMF的盐碱适应性,使其菌丝侵染率及菌丝密度显著降低,泡囊侵染率显著升高,AMF可以利用泡囊存储更多的盐碱离子来减轻盐碱胁迫对羊草根系的破坏作用。可见,在盐碱胁迫下,AMF能够通过抑制羊草吸收Na^+,利用泡囊结构帮助其根系截留Na^+,以及促进K^+、Ca^2+和Mg^2+的吸收来调节羊草体内地上和地下的离子分配,进而增强羊草的盐碱耐受性。由此,可以利用羊草-AMF共生体改良草地盐碱化,同时为研究AMF对其他植物的耐盐碱机理提供了有效参考。

To explore the mechanism by which arbuscular mycorrhizal fungi(AMF)improve plants’tolerance to saline-alkaline stress,we determined their effects on ion absorption and distribution in above-and below-ground plant parts in a pot experiment.The dominant species in Songnen grassland,Leymus chinensis,was used as the experimental material.Saline-alkaline stress increased the Na^+content and reduced the contents of K^+,Ca^2+,and Mg^2+in above-ground parts,enhanced Na^+transport from below-ground to above-ground parts,inhibited the transport of K^+,Ca^2+,and Mg^2+,and altered above-and below-ground ion distribution in L.chinensis.Under salinealkaline stress,AMF inhibited the absorption of Na^+,promoted the absorption of K^+,Ca^2+,and Mg^2+,and improved the ability of L.chinensis roots to retain Na^+.The ion balance was maintained by the ion transport ratio and the cation transport selection ratio,and this improved the salt and alkali tolerance of L.chinensis.With increasing saline-alkaline stress,the hyphal colonization rate and hyphal density of AMF decreased significantly,but vesicle colonization increased.This helped the AMF store more saline-alkaline ions in the vesicles,thereby reducing the damage caused by saline-alkaline stress to L.chinensis roots.Therefore,under saline-alkaline stress,AMF enhanced the salt-alkali tolerance of L.chinensis by inhibiting absorption of Na^+,by using the vesicle structure to help the root intercept Na^+,and by promoting the absorption of K^+,Ca^2+,and Mg^2+.The results suggest that the L.chinensis-AMF symbiosis has the potential to improve the health of grasslands affected by salinizationalkalization.In addition,these results provide insights into the mechanisms by which AMF enhance plants’saltalkali tolerance.