As important silkworm varieties reared on artificial diet, Youshi No. 1 (YS) and Guangshi No. 1 (GS) showed remarkable differences in physiological characteristics. GS had significantly better performance than YS in body weight, cocooning ability, food intake, feed utilization efficiency, and digestive enzyme activities. We further performed metabolomics and 16S rRNA high-throughput sequencing to analyze their metabolic profiles and midgut microbiota. More than 40 differential metabolites were screened out, and four metabolic pathways related to feeding divergence were determined via KEGG enrichment, among which L-valine was enriched in multiple pathways. Significant structural differences were also observed in midgut microbiota, and Bacillus was positively correlated with pantothenic acid and valine metabolism. These correlational results disclosed that differential metabolites and gut microbiota might underlie the phenotypic variations between the two varieties. Integrated analysis combined with functional verification experiments demonstrated that supplementation of 1% L-valine or specific Bacillus strains in an artificial diet was associated with the improvement of the growth performance, cocoon quality, and feed utilization efficiency of the YS silkworm variety.

Colletotrichum gloeosporioides causes anthracnose on a wide range of plants, resulting in serious economic losses worldwide. However, the molecular mechanisms underlying its pathogenicity still remain largely unknown. In the past 20 years, the importance of acetylation/deacetylation modification in the pathogenicity of phytopathogens has already been highlighted, but how it functions in C. gloeosporioides is obscure. Here, we identified and functionally characterized a histone acetyltransferase CgHat1 in C. gloeosporioides. As suspected, CgHat1 is localized to the nucleus and regulates the acetylation levels of histone H4K5 and H4K12. Targeted gene deletion revealed that CgHat1 plays crucial roles in growth, colony pigmentation, and conidiation. Furthermore, we provided evidence showing that ΔCghat1 mutant is defective in conidial germination, appressorial formation, and response to endoplasmic reticulum (ER) stress. These combined effects lead to the decreased pathogenicity of ΔCghat1 mutant. Our studies not only firstly shed light on the pleiotropic roles of histone acetyltransferase in C. gloeosporioides, but also offer a potential fungicide target for anthracnose control.