Data_Sheet_1_Microbial Communities and Functions in the Rhizosphere of Disease-Resistant and Susceptible Camellia spp..docx

Oil tea (Camellia spp.) is endemic to the hilly regions in the subtropics. Camellia yuhsienensis is resistant to diseases such as anthracnose and root rot, while Camellia oleifera is a high-yield species but susceptible to these diseases. We hypothesize that differences in the rhizosphere microbial communities and functions will elucidate the resistance mechanisms of these species. We used high-throughput sequencing over four seasons to characterize the rhizosphere microbiome of C. oleifera (Rhizo-Sus) and C. yuhsienensis (Rhizo-Res) and of the bulk soil control (BulkS). In Rhizo-Res, bacterial richness and diversity (Shannon index) in autumn and winter were both higher than that in Rhizo-Sus. In Rhizo-Res, fungal richness in autumn and winter and diversity in summer, autumn, and winter were higher than that in Rhizo-Sus. The seasonal variations in bacterial community structure were different, while that of fungal community structure were similar between Rhizo-Res and Rhizo-Sus. Gram-positive, facultatively anaerobic, and stress-tolerant bacteria were the dominant groups in Rhizo-Sus, while Gram-negative bacteria were the dominant group in Rhizo-Res. The significant differences in bacterial and fungal functions between Rhizo-Sus and Rhizo-Res were as follows: (1) in Rhizo-Sus, there were three bacterial and four fungal groups with plant growth promoting potentials, such as Brevibacterium epidermidis and Oidiodendron maius, and one bacterium and three fungi with pathogenic potentials, such as Gryllotalpicola sp. and Cyphellophora sessilis; (2) in Rhizo-Res, there were also three bacteria and four fungal groups with plant-growth-promoting potentials (e.g., Acinetobacter lwoffii and Cenococcum geophilum) but only one phytopathogen (Schizophyllum commune). In summary, the rhizosphere microbiome of disease-resistant C. yuhsienensis is characterized by a higher richness and diversity of microbial communities, more symbiotic fungal communities, and fewer pathogens compared to the rhizosphere of high-yield but disease-susceptible C. oleifera.

油茶（Camellia spp.）为亚热带丘陵区域的特有物种。攸县油茶（Camellia yuhsienensis）对炭疽病、根腐病等多种病害具有抗性，而普通油茶（Camellia oleifera）虽为高产品种，却易受此类病害侵染。本研究提出假说：两种油茶的根际微生物群落组成与功能差异，可阐明二者的抗病机制。我们采用高通量测序（high-throughput sequencing）技术，在四个季节中分别对普通油茶根际土壤（Rhizo-Sus）、攸县油茶根际土壤（Rhizo-Res）以及非根际土壤对照（BulkS）的根际微生物组进行表征分析。相较于普通油茶根际（Rhizo-Sus），抗病油茶根际（Rhizo-Res）在秋季与冬季的细菌丰富度及香农多样性指数（Shannon index）均更高；其真菌丰富度在秋、冬两季，以及真菌多样性在夏、秋、冬三季，亦均高于普通油茶根际（Rhizo-Sus）。二者的细菌群落结构季节变化模式存在显著差异，而真菌群落结构的季节变化则较为相似。普通油茶根际（Rhizo-Sus）的优势菌群为革兰氏阳性、兼性厌氧且耐胁迫细菌，而抗病油茶根际（Rhizo-Res）的优势菌群则为革兰氏阴性细菌。普通油茶根际（Rhizo-Sus）与抗病油茶根际（Rhizo-Res）的微生物功能存在显著差异，具体如下：（1）在普通油茶根际中，存在3类具备植物生长促进潜力的细菌类群与4类真菌类群（如表皮短杆菌Brevibacterium epidermidis与大团囊菌Oidiodendron maius），另有1类致病细菌与3类致病真菌类群（如蝼蛄菌属Gryllotalpicola sp.与杯状暗梗孢Cyphellophora sessilis）；（2）在抗病油茶根际中，同样存在3类具备植物生长促进潜力的细菌类群与4类真菌类群（如罗威不动杆菌Acinetobacter lwoffii与土生空团菌Cenococcum geophilum），但仅含1种植物病原菌——裂褶菌Schizophyllum commune。综上，相较于高产且易感病的普通油茶根际微生物组，抗病攸县油茶的根际微生物组具有更高的微生物群落丰富度与多样性、更丰富的共生真菌类群以及更少的病原菌类群。