Development of Novel Bacteriostatic Agents Derived from Natural Product Formononetin and Their Action Mechanisms in Crop Diseases Management

The present study involved the development of a series of novel antibacterial compounds based on the structure of the natural product formononetin. The <i>in vitro</i> activity experiments demonstrated that compound <b>M34</b> exhibited the most potent inhibitory effects against <i>Xanthomonas oryzae pvoryzae</i> (<i>Xoo</i>) and <i>Xanthomonas axonopodis</i> pv citri (<i>Xac</i>), with EC₅₀ values of 0.9 and 2.4 μg/mL, respectively. Pot experiments verified the excellent curative and protective effects of <b>M34</b> against bacterial leaf blight of rice (<i>BLB</i>) and citrus canker (<i>CC</i>). Furthermore, a series of physiological and biochemical experiments were conducted to investigate the action mechanism exerted by <b>M34</b> against plant pathogens <i>Xoo</i> and <i>Xac</i>. The findings revealed that <b>M34</b> effectively inhibited the expression of multiple pathogenic factors, disrupted their energy metabolism, altered their cell membrane morphology, enhanced the activity of host defense enzymes, and attenuated their virulence toward host cells. Therefore, <b>M34</b> could serve as a promising candidate drug for the inhibition of crop pathogens.