Table_2_Glomus mosseae improved the adaptability of alfalfa (Medicago sativa L.) to the coexistence of cadmium-polluted soils and elevated air temperature.docx

The coexistence of heavy metal-polluted soils and global warming poses serious threats to plants. Many studies indicate that arbuscular mycorrhizal fungi (AMF) can enhance the resistance of plants to adverse environments such as heavy metals and high temperature. However, few studies are carried out to explore the regulation of AMF on the adaptability of plants to the coexistence of heavy metals and elevated temperature (ET). Here, we investigated the regulation of Glomus mosseae on the adaptability of alfalfa (Medicago sativa L.) to the coexistence of cadmium (Cd)-polluted soils and ET. G. mosseae significantly enhanced total chlorophyll and carbon (C) content in the shoots by 15.6% and 3.0%, respectively, and Cd, nitrogen (N), and phosphorus (P) uptake by the roots by 63.3%, 28.9%, and 85.2%, respectively, under Cd + ET. G. mosseae significantly increased ascorbate peroxidase activity, peroxidase (POD) gene expression, and soluble proteins content in the shoots by 13.4%, 130.3%, and 33.8%, respectively, and significantly decreased ascorbic acid (AsA), phytochelatins (PCs), and malondialdehyde (MDA) contents by 7.4%, 23.2%, and 6.5%, respectively, under ET + Cd. Additionally, G. mosseae colonization led to significant increases in POD (13.0%) and catalase (46.5%) activities, Cu/Zn-superoxide dismutase gene expression (33.5%), and MDA (6.6%), glutathione (22.2%), AsA (10.3%), cysteine (101.0%), PCs (13.8%), soluble sugars (17.5%), and proteins (43.4%) contents in the roots and carotenoids (23.2%) under ET + Cd. Cadmium, C, N, G. mosseae colonization rate, and chlorophyll significantly influenced shoots defenses and Cd, C, N, P, G. mosseae colonization rate, and sulfur significantly affected root defenses. In conclusion, G. mosseae obviously improved the defense capacity of alfalfa under ET + Cd. The results could improve our understanding of the regulation of AMF on the adaptability of plants to the coexistence of heavy metals and global warming and phytoremediation of heavy metal-polluted sites under global warming scenarios.

重金属污染土壤与全球变暖的共存态势，对植物构成了严峻的生存威胁。诸多研究表明，丛枝菌根真菌（arbuscular mycorrhizal fungi, AMF）能够增强植物应对重金属、高温等逆境环境的抗性。然而，目前鲜有研究探讨AMF对植物适应重金属与升温（elevated temperature, ET）双重胁迫的调控作用。本研究以摩西球囊霉（Glomus mosseae）为供试菌种，探究其对紫花苜蓿（Medicago sativa L.）适应镉（Cd）污染土壤与升温双重胁迫的调控效应。在Cd+ET处理组中，摩西球囊霉可使紫花苜蓿地上部分的总叶绿素与碳（C）含量分别显著提升15.6%与3.0%，并使根系对镉、氮（N）、磷（P）的吸收量分别显著增加63.3%、28.9%与85.2%。在ET+Cd处理组中，摩西球囊霉可显著提升地上部分的抗坏血酸过氧化物酶活性、过氧化物酶（POD）基因表达量与可溶性蛋白含量，增幅分别为13.4%、130.3%与33.8%；同时显著降低地上部分的抗坏血酸（AsA）、植物螯合肽（PCs）与丙二醛（MDA）含量，降幅分别为7.4%、23.2%与6.5%。此外，在ET+Cd处理组中，摩西球囊霉定殖还可使根系的过氧化物酶（POD）与过氧化氢酶活性分别提升13.0%与46.5%，铜/锌超氧化物歧化酶基因表达量提升33.5%；同时使根系的丙二醛（MDA）、谷胱甘肽、抗坏血酸（AsA）、半胱氨酸、植物螯合肽（PCs）、可溶性糖与可溶性蛋白含量分别提升6.6%、22.2%、10.3%、101.0%、13.8%、17.5%与43.4%，并使地上部分的类胡萝卜素含量提升23.2%。研究发现，镉、碳、氮、摩西球囊霉定殖率与叶绿素显著影响植物地上部分的防御能力；而镉、碳、氮、磷、摩西球囊霉定殖率与硫则显著调控根系的防御系统。综上，摩西球囊霉可显著提升紫花苜蓿在ET+Cd双重胁迫下的防御能力。本研究结果有助于加深我们对AMF调控植物适应重金属与全球变暖共存胁迫的认知，以及全球变暖背景下重金属污染场地的植物修复实践。