Abstract:Nod factors are a novel general class of signal molecules produced by rhizobia,which play a key function in the initial steps of nodulation.Research has shown that different substitutions on a lipochito oligosacchride(LCO)backbone play a role in deciding the specificity between bacteria and the host plants.The nod genes of rhizobia,which contain the genetic basis for this structural variety,include a set of nodulation genes encoding the enzymes that synthesize LCOs.