Symbiotic responsivity of garden pea (Pisum sativum L.): history of study and current state of the art (review)

The ability of legume plants (family Fabaceae ) to biological nitrogen fixation (BNF) is a well-known phenomenon in which atmospheric nitrogen (N2) is converted into a form accessible to living systems (“fixed”) as a result of symbiosis of the plant with nitrogen-fixing bacteria collectively known as rhizobia (I.A. Tikhonovich et al., 2009, J. Yang et al., 2022). Thanks to BNF, legume crops do not require intensive treatment with nitrogen fertilizers, which reduces financial costs, has a positive effect on the environment and allows ensuring food security while adhering to the principles of sustainable agriculture (S.M.F. Bessada et al., 2019). Scientifically based attempts to improve the effectiveness of BNF in legumes have been made for a long time, but a large number of external and internal factors affecting the outcome of nitrogen-fixing symbiosis hamper this work. Researchers of ARRIAM (St. Petersburg, Russia) proposed a new criterion for the selection of symbiotically active legumes, which takes into account the interaction with a complex of beneficial microorganisms that are always present in the soil (rhizobia, arbuscular mycorrhiza fungi, growth-promoting bacteria) (O. Shtark et al., 2012). The degree of positive influence of beneficial microorganisms on the agriculturally important characteristics of plants (increase in seed weight, green mass weight, and protein content in seeds) relative to control conditions varies among different plant genotypes and can be quantified. This quantitative feature has been called “efficiency of interaction with beneficial soil microorganisms” (EIBSM), or “symbiotic responsivity” (O. Shtark et al., 2006). This review sums up the results of the work aimed at establishing the molecular and genetic basis of the EIBSM trait, or symbiotic responsivity, with an emphasis on the study of this trait in pea. Over the past ten years, the study of this trait on garden pea ( Pisum sativum L.) using modern “omics” approaches has yielded significant results (T. Mamontova et al., 2019; A. Afonin et al., 2021; E. Zorin et al., 2024; D. Kuzmina et al., 2025). The following factors tied to the plant genome were shown to contribute to the EIBSM trait: control by the plant over the spread of microsymbionts in root tissues; secretion of flavonoid molecules that attract nodule bacteria while playing a role in protecting against pathogens; prolongation of the seed filling phase under the influence of microsymbionts. Currently, a search is underway for transcriptomic markers of the EIBSM. One such a marker, the PsGLP2 gene, has been converted into a DNA marker of symbiotic responsivity (E. Zorin et al., 2024). Further study will be aimed at identifying genetic markers of EIBSM during the analysis of recombinant inbred lines, as well as evaluating the possibility of increasing EIBSM through genetic transformation and genome editing.