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Background: Different mulches have variable effects on soil physicochemical characteristics, bacterial and fungal communities and ecosystem functions. However, the information about soil microbial diversity, community structure and ecosystem function in tea plantation under different mulching patterns was limited. In this study, we investigated bacterial and fungal communities of tea plantation soils under polyethylene film and peanut hull mulching using high-throughput 16S rRNA and ITS rDNA gene Illumina sequencing. Results: The results showed that the dominant bacterial phyla were Proteobacteria, Actinobacteria, Acidobacteria and Chloroflexi, and the dominant fungal phyla were Ascomycota, Mortierellomycota and Basidiomycota in all samples, but different mulching patterns affected the distribution of microbial communities. At the phylum level, the relative abundance of Nitrospirae in peanut hull mulching soils (3.24%) was significantly higher than that in polyethylene film mulching soils (1.21%) in bacterial communities, and the relative abundances of Mortierellomycota and Basidiomycota in peanut hull mulching soils (33.72, 21.93%) was significantly higher than that in polyethylene film mulching soils (14.88, 6.53%) in fungal communities. Peanut hull mulching increased the diversity of fungal communities in 0-20 cm soils and the diversity of bacterial communities in 20-40 cm soils. At the microbial functional level, there was an enrichment of bacterial functional features, including amino acid transport and metabolism and energy production and conversion, and there was an enrichment of fungal functional features, including undefined saprotrophs, plant pathogens and soils aprotrophs. Conclusions: Unique distributions of bacterial and fungal communities were observed in soils under organic mulching. Thus, we believe that the organic mulching has a positive regulatory effect on the soil bacterial and fungal communities and ecosystem functions, and so, is more suitable for tea plantation.

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Drought stress triggers a series of physiological and biochemical changes in tea plants. It is well known that flavonoids, lignin and long-chain fatty acids play important roles in drought resistance. However, changes in proteins related to these three metabolic pathways in tea plants under drought stress have not been reported. We analysed the proteomic profiles of tea plants by tandem mass tag and liquid chromatography-tandem mass spectrometry. A total of 4789 proteins were identified, of which 11 and 100 showed up- and downregulation, respectively. The proteins related to the biosynthesis of lignin, flavonoids and long-chain fatty acids, including phenylalanine ammonia lyase, cinnamoyl-CoA reductase, peroxidase, chalcone synthase, flavanone 3-hydroxylase, flavonol synthase, acetyl-CoA carboxylase 1,3-ketoacyl-CoA synthase 6 and 3-ketoacyl-CoA reductase 1, were downregulated. However, the contents of soluble proteins, malondialdehyde, total phenols, lignin and flavonoids in the tea plants increased. These results showed that tea plants might improve drought resistance by inhibiting the accumulation of synthases related to lignin, flavonoids and long-chain fatty acids. The proteomic spectrum of tea plants provides a scientific basis for studying the pathways related to lignin, flavonoid and long-chain fatty acid metabolism in response to drought stress.