Effects of Medicago truncatula Genetic Diversity, Rhizobial Competition, and Strain Effectiveness on the Diversity of a Natural Sinorhizobium Species Community

摘要: We investigated the genetic diversity and symbiotic efficiency of 223 Sinorhizobium sp. isolates sampled from a single Mediterranean soil trapped with four Medicago truncatula lines. DNA molecular polymorphism was estimated by capillary electrophoresis-single-stranded conformation restriction fragment length on five loci (IGS(NOD), typA, virB11, avhB11, 16S rRNA gene). More than 90% rhizobia isolated belonged to medicae species (others meliloti), different proportions two among M. The S. meliloti population more diverse that medicae, significant differentiation bacterial populations detected. Single inoculations performed in tubes each genotype plant line showed bacterium-plant interactions for nodulation N(2) fixation levels. Competition experiments within highlighted either strong or weak competition genotypes meliloti, respectively. Interspecies be competitive nodulation. Although not highly divergent at nucleotide level, collected this sample displayed wide both fixation. Each might influence differently via its preferences. Our data suggested did evolve similarly, showing variable selective pressures traces recent demographic expansion. Strain effectiveness have played role proportions, but conjunction strain adaptation environmental factors.