SignificanceBacterial infection has been extensively investigated; however, little is known about how bacterial pathogens timely shut down infecting machinery after successful infections. Here, a previously unknown sucrose–SghR/SghA–SAG–SA signaling axis was identified which controls the timing to shut off bacterial virulence expression and fine-tune host immune response. Sucrose, salicylic acid (SA), and its storage form SAG are small chemicals produced in plants whereas SghR is a bacterial sensor of sucrose and SghA is a bacterial enzyme that releases SA from SAG. Given that SA is an imperative signaling molecule in defense against a variety of microbial pathogens, these results depict a previously unknown 2-way chemical signaling cross-talk during microbe–host coevolution and shed mechanistic insights into host–bacteria interaction.

The function of SNF2 ATPases, the major catalytic subunits of chromatin remodeling complexes, in plants is not sufficiently understood. Here we identified 39 putative SNF2 genes of rice (Oryza sativa L.) by homology analyses and analyzed the expression profiles of eight of them in response to phytohormones and abiotic stresses. Our results indicated that expression of the SNF2 genes was affected by auxin, gibberellin, cytokinin, abscisic acid, ethylene, and some abiotic stresses such as heat, chilling, darkness, drought and salinity. It suggests that, like Arabidopsis SNF2s, rice SNF2 proteins may function in phytohormone signaling pathways and/or be associated with the resistance to abiotic stresses, but in distinct manners from their Arabidopsis orthologs. Some SNF2 proteins in rice may be involved in cross-talk of the signaling pathways between phytohormones and abiotic stresses.