Role of molecules involved in peanut-rhizobia

MEDEOT, D.B.; PEREIRA, P; BUENO, MA; GARCÍA, MB

Congreso; XL Reunión anual SAIB; 2004

To improve the yield of peanut crops it is necessary to know the adaptative response of the nitrogen fixer micro-organisms that interact with the crops. There are bacterial components such as LPS, proteins and lipids that take part in peanut-rhizobia interaction. In this work we analysed proteins, phospholipids and fatty acids profiles of peanut-symbiotic rhizobia and also the effect of temperature and salinity on the mentioned molecules. The strains used were Bradyrhizobium USDA 3187 and Rhizobium TAL 1000, both were grown in control and stressed medium. Proteins were subjected to SDS-PAGE. Lipids were separated using TLC plates and the unsaturation degree was analysed in TLC plates impregnated with AgNO3. Under stress there was a change in protein profile, bands of 0.15 and 0.24 Rf were not detected under salinity and bands that belong to 0.16 and 0.50 Rf appeared because of temperature stress. Phospholipids concentration was modified by both kinds of stress recording a 38% increase under saline stress and a 40% decrease under thermal stress. Phospholipids profile was modified mainly because of temperature with which CL increased an 80% and the fraction formed by PE + PG decrease a 37%. Hyperthermic stress reduced the unsaturation degree of fatty acids. These results suggest that lipids and proteins are implicated in the adaptative response of rhizobia that interact with peanut crops.