摘要
Arbuscular mycorrhizal fungi(AMF)enhance plant tolerance to abiotic stresses like salinity and improve crop yield.However,their effects are variable,and the underlying cause of such variation remains largely unknown.This study aimed to assess how drought modifed the effect of AMF on plant resistance to high calcium-saline stress.A pot experiment was performed to examine how AMF inoculation affects the growth,photosynthetic activity,nutrient uptake and carbon(C),nitrogen(N)and phosphorus(P)stoichiometric ratio(C:N:P)of maize under high calcium stress and contrasting water conditions.The results showed that high calcium stress signifcantly reduced mycorrhizal colonization,biomass accumulation,C assimilation rate and C:N stoichiometric ratio in plant tissues.Besides,the adverse effects of calcium stress on photosynthesis were exacerbated under drought.AMF inoculation profoundly alleviated such reductions under drought and saline stress.However,it barely affected maize performance when subjected to calcium stress under well-watered conditions.Moreover,watering changed AMF impact on nutrient allocation in plant tissues.Under well-watered conditions,AMF stimulated P accumulation in roots and plant growth,but did not induce leaf P accumulation proportional to C and N,resulting in increased leaf C:P and N:P ratios under high calcium stress.In contrast,AMF decreased N content and the N:P ratio in leaves under drought.Overall,AMF inoculation improved maize resistance to calcium-salt stress through enhanced photosynthesis and modulation of nutrient stoichiometry,particularly under water defcit conditions.These results highlighted the regulatory role of AMF in carbon assimilation and nutrient homeostasis under compound stresses,and provide signifcant guidance on the improvement of crop yield in saline and arid regions.
丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)能够提高植物对非生物胁迫(如盐碱)的耐受性,并改善作物产量。然而,这种影响是不稳定的,导致这种变异的原因仍不清楚。本研究旨在评估干旱如何改变AMF对植物抵抗高钙盐胁迫的影响,采用盆栽实验探究AMF接种如何影响玉米在高钙胁迫和两种水分条件下的生长、光合、养分吸收以及C:N:P化学计量比。结果显示,高钙胁迫显著降低了菌根侵染率、生物量积累、C同化速率以及植物组织中的C:N化学计量比。此外,干旱进一步加剧了钙胁迫对光合作用的抑制。在干旱和钙盐胁迫下,AMF接种在很大程度上缓解了这些负面效应。然而,在充足灌溉条件下,当受到高钙胁迫时,AMF几乎不影响玉米的生长。此外,水分影响了AMF对植物组织中养分分配的调控。在充足水分条件下,AMF刺激了根部的P积累和植物生长,但未造成叶片P与C/N比的增长,导致在高钙胁迫下叶片C:P和N:P增加。相反,在干旱条件下,AMF降低了叶片N含量和N:P比。总体而言,AMF通过增强光合作用和调节养分化学计量,提高了玉米对钙盐的抵抗力,这种效应在水分亏缺条件下更为显著。该研究结果强调AMF在复合胁迫下碳同化和养分稳态调控中的调节作用,并为在盐碱和干旱地区作物产量提升提供了科学依据。
基金
supported by China Postdoctoral Science Foundation(2021M703137)
Chongqing Postdoctoral Science Foundation(cstc2021jcyj-bshX0195)
Postdoctoral Foundation of Jiangsu Province of China(1501014B)
Education Department of Sichuan Province(17ZB0211),the Ecological Security and Protection Key Laboratory of Sichuan Province(07144812)
the Scientifc Research Foundation of Chongqing University of Technology(2021ZDZ022).
