Effective Symbiosis between Rhizobium etli and Phaseolus vulgaris Requires the Alarmone ppGpp

• DOI: 10.1128/jb.187.15.5460-5469.2005
• Publication Date: 2005-07-19T19:33:01Z
• Authors: Martine Moris; Kristien Braeken; Eric Schoeters; Christel Verreth; Serge Beullens; Jos Vanderleyden; Jan Michiels
• Keywords: Stringent response; Sigma factor

ABSTRACT The symbiotic interaction between Rhizobium etli and Phaseolus vulgaris , the common bean plant, ultimately results in formation of nitrogen-fixing nodules. Many aspects intermediate late stages this are still poorly understood. R. relA gene was identified through a genome-wide screening for mutants. RelA has pivotal role cellular physiology, as it catalyzes synthesis (p)ppGpp, which mediates stringent response bacteria. ppGpp abolished an mutant strain under conditions amino acid starvation. Plants nodulated by had strongly reduced nitrogen fixation activity (75% reduction). Also, at microscopic level, bacteroid morphology altered, with size bacteroids being increased compared to that wild-type bacteroids. expression σ N -dependent genes rpoN2 iscN considerably mutant. In addition, negatively regulated RpoN2, symbiosis-specific copy . Therefore, autoregulatory loop controlling seems operative production long- short-chain acyl-homoserine-lactones cinIR raiIR systems decreased Our suggest may play important regulation adaptation physiology.