Construction of the microbial protein metabolism map of tea rhizosphere soil in acidified plantations

Abstract

Soil plays a crucial role in tea tree growth, however, only few studies have reported the responses of soil microorganisms to soil acidification in tea plantations and the negative regulation of soil acidification on tea tree growth. In this study, the soil samples from Tieguanyin tea tree plantation with different acidities were used as a material for rhizosphere soil microbial protein extraction. Data dependent acquisition (DDA) was used to establish the soil microbial protein data, whereas Data independent acquisition (DIA) was used for quantitative analyses to obtain the reduced abundance of soil protein in tea rhizosphere soil. Furthermore, the functional analysis of the obtained proteins was conducted, and the regulation map of microbial protein metabolism of rhizosphere soil was constructed. The results showed that a total of 2,741 microbial proteins were detected in the tea tree rhizosphere soil, and the molecular weight ranged from 2.64 to 338.33 kD, whereas the range of pI was from 3.78 to 12.15. Quantitative analyses of soil proteins showed that the abundance of 54 microbial proteins, including genetic signaling proteins, energy metabolism signaling proteins, soil antioxidant signaling proteins, and soil nutrient cycling signaling proteins, which are named according to their functions, was decreased. Based on these analyses, a metabolic regulation map of soil microbial proteomes was constructed, and the results suggested that as tea soil acidity increased, soil microbes released quorum-sensing proteins to trigger signaling proteins for survival. Under the regulation of signaling pathway proteins, signaling proteins activated the expression of specific signaling proteins in different metabolic pathways and then regulated the expression of proteins in different metabolic pathways, demonstrating a downregulated expression trend. Finally, this regulation resulted in a decrease of microbial energy metabolism and circulation capacity as well as the reproduction capacity and quantity. The change in microbial quantity and function led to the weakening of soil nutrient cycling capacity, the blocking of the absorption of nutrients in tea trees, and the stunting of the growth and the declining of the yield and quality of tea trees.