TY - JOUR AU - Belimov, Andrey AU - Shaposhnikov, Alexander AU - Safronova, Vera AU - Gogolev, Yuri PY - 2020/12/30 Y2 - 2024/03/28 TI - Abscisic acid utilizing rhizobacteria disturb nitrogen-fixing symbiosis of pea Pisum sativum L. JF - Biological Communications JA - BioComm VL - 65 IS - 4 SE - Full communications DO - 10.21638/spbu03.2020.401 UR - https://biocomm.spbu.ru/article/view/7566 SP - 283–287 AB - <p>Rhizosphere bacteria are capable of utilizing various phytohormones (particularly auxins) as nutrients and thereby affect plant growth, nutrition and interactions with symbiotic microorganisms. Here, for the first time we evaluated the effects of rhizosphere bacteria <em>Novosphingobium</em> sp. P6W and <em>Rhodococcus</em> sp. P1Y capable of utilizing abscisic acid (ABA) on growth and nitrogen-fixing symbiosis of pea (<em>Pisum sativum</em> L.) line SGE and its Cd-insensitive mutant SGECd<sup>t</sup> using hydroponic culture. The plants were co-inoculated with the ABA-utilizing bacteria and nodule bacterium <em>Rhizobium leguminosarum</em> bv. <em>viciae</em> RCAM1066. Treatment with cadmium (Cd) was applied as an inducer of ABA biosynthesis in plants. In the presence of only nodule bacteria, Cd significantly inhibited the growth of roots and shoots and also decreased the nodule number and nitrogen-fixing activity in SGE peas, but not in the SGECdt mutant. Inoculation with ABA-utilizing bacteria also inhibited biomass production, nodulation and nitrogen-fixation of Cd-untreated SGE plants. This negative effect of bacteria on the SGECd<sup>t</sup> mutant was less pronounced. Contrary to this, ABA-utilizing bacteria had no effect on SGE plants treated with Cd, but decreased shoot biomass and nitrogen-fixing activity of the SGECd<sup>t</sup> mutant. Inoculation with ABA-utilizing bacteria had no effect on shoot Cd and nutrient content of both pea genotypes, suggesting that bacterial effects on plants were not associated with the plant nutrient status. We propose that the bacteria counteracted the increased ABA concentrations in SGE roots caused by Cd due to utilization of this phytohormone. However, opposite processes aimed at inhibiting and stimulating growth and legume–rhizobia symbiosis can be caused by the ABA-utilizing bacteria.</p> ER -