Effect of Exogenic IAA and BAP on Metabolism in a Rhizobia-Sensitive Pea Root Zone (Pisum sativum L.) in the Initial Period after Inoculation

• Published in: Russian journal of plant physiology 2022-04, Vol.69 (2), Article 28
• Main Authors: Makarova, L. E., Akimova, G. P., Sokolova, M. G., Petrova, I. G.
• Format: Article
• Language: English
• Subjects: Acetic acid; Antioxidants; Biomedical and Life Sciences; Cell division; Cell walls; Elongation; Ethyl acetate; Filter paper; Indicators; Inoculation; Life Sciences; Mathematical analysis; Meristems; Nodulation; Peas; Phenolic compounds; Phenols; Pisum sativum; Plant growth; Plant hormones; Plant Physiology; Plant Sciences; Research Papers; Root zone; Roots; Salicylic acid; Seedlings
• ISSN: 1021-4437; 1608-3407
• DOI: 10.1134/S1021443722010113

The response to the action of exogenous IAA and BAP was studied and nodulation was monitored in the rhizobia-susceptible region of the root of pea seedlings ( Pisum sativum L.). The pro/antioxidant activities of “soluble” and ionic and covalently bound peroxidases to the cell walls, the content of soluble phenolic compounds (PCs) extracted with ethyl acetate, their antiradical activity with DPPH, the content of PCs bound to cell walls, and the content of salicylic acid (SA) were the reaction indicators. Etiolated pea seedlings grown in a thermostat with a temperature of 21°C in cuvettes on wet filter paper were used for the study. The roots of the original 2-day-old seedlings were marked at a distance of 5–20 mm from its tip (the zone susceptible to rhizobia), and the seedlings were simultaneously inoculated with the bacteria Rhizobium leguminosarum bv. viceae and treated with solutions of 10 –11 M IAA and 10 –9 M BAP. The movement of the marked area was monitored after 24 h. It was excised for biochemical studies, and cytological indicators that characterize the features of growth processes under the action of exogenous phytohormones (PCs) were calculated for the apical part of the root adjacent to the marked area of the root. Some of the seedlings inoculated and exposed to PCs were left to control their nodulation. The action of exogenous PCs led to increased root growth and displacement compared to the control (inoculated roots without PC treatment), the zone susceptible to rhizobia, and to a slight increase in its length. The displacement occurred due to increased elongation of the cells (IAA) that had again switched to this process and increased cell division of the meristem (BAP). Nodulation in the observation area was carried out and even increased under the action of BAP, but it was inhibited under the action of IAA. The presented biochemical parameters suggest that the manifestations of defense reactions in the studied root zone are significantly higher in the variant with IAA, which may explain the negative effect of exogenous IAA on nodulation.