Features of the development of a unique legume-rhizobium symbiosystem under conditions of metal-induced stress

Abstract

The development of legume-rhizobium symbiosystems based on the mutant pea genotype SGECdt (Pisum sativum L.) and its wild line SGE grown on a medium supplemented with toxic concentrations of Cd and Co was evaluated under the conditions of a summer greenhouse experiment. Plants were inoculated with a consortium of endomycorrhizal fungus Glomus sp.1Fo, nodule bacteria Rhizobiom leguminosarum bv. viciae and associative ACC-utilizing rhizobacteria Variovorax paradoxus 5C-2. Heavy metals significantly inhibited the growth of uninoculated and inoculated wild line SGE plants compared to SGECdt plants. The content of Cd in the shoots of plants of both genotypes increased in the presence of a toxic concentration of Co, while the latter, on the contrary, decreased. The same effect persisted after inoculation with microorganisms. The introduction of microbes leveled the toxic effect of heavy metals and increased the biomass in both pea genotypes in the absence of the introduction of heavy metals. The microbial consortium also contributed to an increase in the transport of biophilic microelement antagonists to the aerial organs of the pea. In general, based on the results of fractal calculation, despite growth inhibition, the wild line showed higher values of the degree of organization of microelements inside shoots and seeds than the mutant genotype. The stagnation or decrease in the microelement bioconsolidation indices in the homeostasis of shoots of the mutant line can probably be interpreted by the redistribution of the supply of food sources between the partners of the symbiostem, in favor of microsymbionts. An increase in the indicators of the bioconsolidation index in seeds can be considered a positive effect, since the best mobilization of trace elements in their cotyledons, in addition to increasing the germination energy of the offspring, will favorably affect the increase in the adaptive potential of plants.