Identification of the core c-di-GMP turnover proteins responsible for root colonization of .

Root colonization by beneficial rhizobacteria determines their plant beneficial effects. The messenger c-di-GMP is involved in the bacterial transition process between motility and biofilm, which are crucial to the colonization ability of the rhizobacteria. In this study, we identified three GGDEF domain-containing proteins (YdaK, YhcK, and YtrP) and two EAL domain-containing proteins (YuxH and YkuI) in beneficial rhizobacterium SQR9. We found that deficiency of or in SQR9 led to impaired biofilm formation, while deficiency of led to weakened motility. Further investigation showed that YtrP, YuxH, and YkuI all contributed to the root colonization of SQR9 on cucumber root. Further bioinformatics analysis showed that YtrP and YuxH are conserved in plant beneficial group, while they do not occur in animal pathogenic . This research will be useful for enhancing the beneficial function of spp. in agricultural application.