Abiotic stress and response of peanut-rhizobia

DARDANELLI M.S., BUSTO V., PEREIRA P., BUENO M., GARCÍA M.

Organic Farming and Peanut Crops

Nova Publishers

Lugar: Huntington; Año: 2010; p. 153 - 162

Peanut (Arachis hypogaea L.) is a regional crop of Argentina. It is located in the centre-south of Córdoba province, where almost 96% of the national production and all its industrial processing are concentrated (Fernandez and Giayetto, 2006). Peanut is an important subsistence and cash crop in the semi-arid tropics where it often suffers from drought or saline stress. Little is known about the molecular events involved in its adaptive responses to stress and about the biochemical and physiological basis of tolerance by rhizobia nodulating peanut roots and their symbiosis. The aim of the present chapter was to contribute with the knowledge of physiological and biochemical response (trehalose content; lipids and periplasmic glucans) of peanut microsimbionts under different types of stress. This response will be compared between rhizobia, and it probably will contribute in the selection of a great tolerant strain for future essays of inoculation. Results indicate that there are different responses of peanut-rhizobia to abiotic stress, indicating variability genetic in tolerance to these environmental constraints. Trehalose accumulation is strain dependent. However other parameters were similar in different strains. Thus the polymerization degree of periplasmic glucans was affected under the stress conditions applicated, this was evidenced in its molecular weight profile. Also phospholipids increased under hypersaline and hyperthermic condition. Results suggest that periplasmic glucans and phospholipids would be implicated in the adaptive response of peanut strains. Further analysis of these molecules in peanuts rhizobia must be carried out to select tolerant bacteria to stress for inoculants formulations.