Search

Phytoalexins play a crucial role in plant immunity. However, the mechanism of how phytoalexin is primed by beneficial microorganisms against broad‐spectrum pathogens remains elusive. This study showed that Bacillus cereus AR156 could trigger ISR against broad‐spectrum disease. RNA‐sequencing and camalexin content assays showed that AR156‐triggered ISR can prime the accumulation of camalexin synthesis and secretion‐related genes. Moreover, it was found that AR156‐triggered ISR elevates camalexin accumulation by increasing the expression of camalexin synthesis genes upon pathogen infection. We observed that the priming of camalexin accumulation by AR156 was abolished in cyp71a13 and pad3 mutants. Further investigations reveal that in the wrky33 mutant, the ability of AR156 to prime camalexin accumulation is abolished, and the mediated ISR against the three pathogens is significantly compromised. Furthermore, PEN3 and PDR12, acting as camalexin transporters, participate in AR156‐induced ISR against broad‐spectrum pathogens differently. In addition, salicylic acid and JA/ET signalling pathways participate in AR156‐primed camalexin synthesis to resist pathogens in different forms depending on the pathogen. In summary, B. cereus AR156 triggers ISR against Botrytis cinerea, Pst DC3000 and Phytophthora capsici by priming camalexin synthesis. Our study provides deeper insights into the significant role of camalexin for AR156‐induced ISR against broad‐spectrum pathogens. Summary statement: Beneficial rhizobacterium AR156 triggered ISR by enhancing camalexin accumulation in Arabidopsis, with WRKY33 acting as a positive regulator. PEN3 and PDR12 are involved in AR156‐induced ISR. Salicylic acid and JA/ET signalling pathways participate in AR156‐primed camalexin synthesis to resist various pathogens. [ABSTRACT FROM AUTHOR]

Application of plant growth‐promoting rhizobacteria (PGPR) has been considered as an environmentally friendly method for crop yield promotion as well as plant disease management. Efforts have been devoted to unraveling mechanisms involved in bacteria–plant and bacteria–pathogen interactions. However, little is known on the effect of the interaction among PGPR, soil, and plant. We compared growth and yield promotion capacity of biofertilizer Ning Shield, a consortium of bacterial preparation used as a biofertilizer (BF), and its mixture with compost of agricultural waste including spent substrate of Pleurotus ostreatus (SSP)/Volvariella volvacea (SSV), chicken manure (CM), and inorganic fertilizer (IOF) in a pepper field, respectively. The disease control efficacy, pepper fruit preservation time, and nutrients were also determined. Soil nutrient parameters including organic matter and available NPK of treatments were assayed before and after one growth season. All of the mixture of BF+organic compost treatment significantly enhanced the yield and quality of pepper fruit. Moreover, disease control capacity was promoted by the mixture of BF+organic compost, with BF+SSV reaching the highest control efficacy of 81% on 60th day after transplanting, and remaining 76% at the 105th day. The BF+SSV treatment showed soil fertility retention ability with higher soil nutrient contents after one growth season of pepper. This study provides evidence that, when combined with organic fertilizers such as spent mushroom substrate compost, beneficial microbes have the ability to promote plant growth and yield as well as suppress plant disease by sustaining soil fertility through complex bacteria–soil–plant interaction. [ABSTRACT FROM AUTHOR]