Abstract:

The Illumina NovaSeq high-throughput sequencing was utilized to characterize the diversity，community structure，differential species and bacterial functional profiles of endophytic microorganisms in peppers with contrasting soluble solids content（SSC）across roots，stems，leaves and red fruits（physiological maturity）. The results showed that compared with low-SSC peppers，high-SSC peppers showed relatively lower richness of bacterial communities in roots，stems，and leaves. Whereas fungal richness showed an inverse pattern across all compartments. In low-SSC peppers，the highest bacterial richness was observed in the leaves，followed by the roots，stems，and fruits. In contrast，high-SSC peppers showed the highest fungal richness in the stems，followed by the roots，leaves，and fruits. In fruit tissues，Enterobacter was the dominant bacterial genus in high-SSC peppers，while Cladosporium was the dominant fungal genus. In low-SSC peppers，Chujaibacter was the dominant bacterial genus. Based on 16S rRNA gene sequencing data，PICRUSt2 functional profiling indicated that stems and leaves hosted the most abundant and diverse predicted bacterial gene functions. Fruit-specific pathway analysis showed enrichment of secondary metabolite biosynthesis，antibiotic biosynthesis and carbon metabolism in low-SSC peppers，while ABC transporter systems were more prevalent in high-SSC peppers.

Key words: pepper, soluble solids content, endophytic microorganisms, community differences, functional prediction