Table 2_Biological control of Botrytis cinerea in tomato and Fusarium graminearum in wheat using the novel species Burkholderia mycopellens and Burkholderia crassaminum.xlsx

The use of beneficial microbes to reduce plant stress upon fungal pathogens is a promising strategy for sustainable crop protection. In this study, we evaluated five novel Burkholderia strains for their capacity to mitigate Botrytis cinerea infection in tomato (Solanum lycopersicum L.) and Fusarium graminearum infection in wheat (Triticum aestivum L.). All strains significantly suppressed B. cinerea infection symptoms in tomato plants, hallmarked by a smaller decrease in photosynthetic activity and chlorophyll content compared to infected control. Using a GFP-tagged F. graminearum strain, we show that the strains reduced fungal biomass accumulation in F. graminearum-infected wheat leaves and mitigated chlorosis. Phytotoxicity assessments revealed no adverse effects in tomato for any strain, while two strains induced a mild reduction in chlorophyll fluorescence in wheat, suggesting potential host-specific phytotoxicity. Whole-genome sequencing of the Burkholderia strains revealed a rich repertoire of biosynthetic gene clusters (BGCs) with conserved replicon positioning. While all strains shared BGCs for known bioactive metabolites such as occidiofungin A, ornibactin, and pyochelin, variation in other clusters did not directly correlate with the phenotypic effects observed. Our results highlight the strong biocontrol potential Burkholderia strains in two economically important crops against two globally important fungal pathounder controlled conditions. Finally, a microbial phylogenomic analysis revealed that the five strains belong to two new and previously uncharacterized species within the Burkholderia cepacia complex, for which the names Burkholderia mycopellens sp. nov. and Burkholderia crassaminum sp. nov. are proposed. These strains hold promise as next-generation biocontrol agents for enhancing crop health and managing fungal diseases sustainably.