Sinomonas gamaensis NEAU-HV1 remodels the IAA14-ARF7/19 interaction to promote plant growth

Sinomonas species typically reside in soils or the rhizosphere and can promote plant growth. Sinomonas enrichment in rhizospheric soils is positively correlated with increases in plant biomass. However, the growth promotion mechanisms regulated by Sinomonas remain unclear. By using soil systems, we studied the growth-promoting effects of Sinomonas gamaensis NEAU-HV1 on various plants. Through a combination of phenotypic analyses and microscopic observations, the effects of NEAU-HV1 on root development were evaluated. We subsequently conducted molecular and genetic experiments to reveal the mechanism promoting lateral root (LR) development. We demonstrated that NEAU-HV1 significantly promoted the growth of lettuce, wheat, maize, peanut and Arabidopsis. This effect was associated with multiple beneficial traits, including phosphate solubilization, indole-3-acetic acid and 1-aminocyclopropane-1-carboxylic acid deaminase production and survival ability in the rhizosphere and within the inner tissue of roots. In addition, NEAU-HV1 could secrete metabolites to promote LR development by affecting auxin transport and signaling. Importantly, we found that the influence of auxin signaling may be attributed to the remodeling interaction between SOLITARY-ROOT (SLR)/IAA14 and ARF7/19, occurring independently of the auxin receptor TIR1/AFB2. Our results indicate that NEAU-HV1-induced LR formation is dependent on direct remodeling interactions between transcription factors, providing novel insights into plant-microbe interactions.