Journal of Tea Science Research, 2024, Vol.14, No.1, 1-9 http://hortherbpublisher.com/index.php/jtsr 3 18 21 8.1 5 14 4 0.2 0.21 0.19 0 5 10 15 20 25 4 10 20 Quantity of bactcria (x109 coloay/g dry soil) Soil fertility and tea age ( a) Fertile soil Medium soil Infertile soil Figure 1 Quantitative difference of bacteria in different tea rhizosphere (Adopted from Sun and Liu, 2004) 1.3 Microbial symbiosis in tea plants To investigate the impact of leaf surface microorganisms on catechin synthesis in tea plants, this study inoculated three high-catechin-producing Biluochun tea plants with Pseudomonas bacteria and utilized tandem MBP-sequencing to identify the composition of the symbiotic community. The results revealed that Pseudomonas effectively enhanced the survival capacity of nitrogen-fixing bacteria such as Bacilli on the leaf surface, becoming the dominant microorganism (Wu et al., 2022). In this study, GFP and RFP dual-labeled Pseudomonas and Bacillus strains were employed for real-time dynamic measurement of GFP and RFP signals on the leaf surface. It was observed that these two strains likely aggregate at the leaf margin, possibly through cell chemotaxis. High-throughput RNA sequencing analysis revealed that Pseudomonas upregulates the expression of genes related to catechin synthesis in Bacillus, and even indirectly affects the expression of metabolic genes in tea plants, such as the PAL gene. At the same time, metagenome technology was used to analyze the coupling relationship between leaf microflora and tea tree catechins. The results showed that Bacilli had significant positive correlation with heavy catechin strain. This lays a foundation for further study of its regulatory mechanism from the perspective of microbiome and epigenetics. The high-quality microflora of tea leaf surface can affect the metabolism of tea tree through multiple ways, and catechin biosynthesis has potential. 2 Microbial Diversity in Tea Tea microorganism is a small ecosystem closely related to tea. There are rich and diverse microbial communities on the surface of tea plants, in the soil of tea gardens and inside tea leaves, which play an important role in the growth, processing and quality formation of tea. 2.1 Microorganisms associated with tea leaves The surface of tea plants serves as an important source of microorganisms associated with tea leaves. Various microorganisms, including bacteria, fungi, and yeasts, inhabit tea leaves and stems (Shan et al., 2011). These microorganisms can be transmitted to tea leaves through wind, water, and insects, influencing the growth and development of tea leaves. The tea garden soil represents another significant habitat for microorganisms. Various types of microorganisms, such as bacteria, fungi, and actinomycetes, exist in the soil. These microorganisms establish symbiotic relationships with the tea plant roots, positively influencing nutrient absorption and disease resistance in tea leaves. The interaction between substances secreted by tea plant roots and rhizosphere microorganisms further promotes the healthy growth of tea leaves. Tea leaves also harbor endophytic microorganisms. These microorganisms coexist with tea leaves and participate in the fermentation and catechin synthesis processes. The types and abundance of endophytic microorganisms in tea
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