Data_Sheet_2_Arbuscular Mycorrhizal Fungus Alters Root System Architecture in Camellia sinensis L. as Revealed by RNA-Seq Analysis.xlsx

Arbuscular mycorrhizal fungus (AMF), forming symbiosis with most terrestrial plants, strongly modulates root system architecture (RSA), which is the main characteristic of root in soil, to improve plant growth and development. So far, the studies of AMF on tea plant seedlings are few and the relevant molecular mechanism is not deciphered. In this study, the 6-month-old cutting seedlings of tea plant cultivar “Wancha No.4” were inoculated with an AMF isolate, Rhizophagus intraradices BGC JX04B and harvested after 6 months of growth. The indexes of RSA and sugar contents in root were determined. The transcriptome data in root tips of mycorrhizal and non-mycorrhizal cutting seedlings were obtained by RNA-sequence (Seq) analysis. The results showed that AMF significantly decreased plant growth, but increased the sucrose content in root and the higher classes of lateral root (LR) formation (third and fourth LR). We identified 2047 differentially expressed genes (DEGs) based on the transcriptome data, and DEGs involved in metabolisms of phosphorus (42 DEGs), sugar (39), lipid (67), and plant hormones (39) were excavated out. Variation partitioning analysis showed all these four categories modulated the RSA. In phosphorus (P) metabolism, the phosphate transport and release (DEGs related to purple acid phosphatase) were promoted by AMF inoculation, while DEGs of sugar transport protein in sugar metabolism were downregulated. Lipid metabolism might not be responsible for root branching but for AMF propagation. With respect to phytohormones, DEGs of auxin (13), ethylene (14), and abscisic acid (5) were extensively affected by AMF inoculation, especially for auxin and ethylene. The further partial least squares structural equation modeling analysis indicated that pathways of P metabolism and auxin, as well as the direct way of AMF inoculation, were of the most important in AMF promoting root branching, while ethylene performed a negative role. Overall, our data revealed the alterations of genome-wide gene expression in tea plant roots after inoculation with AMF and provided a molecular basis for the regulatory mechanism of RSA (mainly root branching) changes induced by AMF.

丛枝菌根真菌（Arbuscular mycorrhizal fungus，简称 AMF），与大多数陆地植物形成共生关系，显著调节根系结构（Root System Architecture，简称 RSA），这是土壤中根系的主要特征，从而促进植物的生长与发展。迄今为止，关于 AMF 对茶树幼苗的研究为数不多，其相关的分子机制尚未被破解。在本研究中，选取了6个月大的茶树品种“万岔4号”的扦插幼苗，接种了AMF分离株 Rhizophagus intraradices BGC JX04B，并在生长6个月后进行收获。对 RSA 和根系中糖含量的指标进行了测定。通过RNA测序（RNA-sequence，简称 RNA-Seq）分析获得了共生和非共生扦插幼苗根系顶端的转录组数据。结果显示，AMF 显著降低了植物的生长，但增加了根系中蔗糖的含量以及较高等级的侧根（第三和第四级侧根）的形成。基于转录组数据，我们鉴定了2047个差异表达基因（Differentially Expressed Genes，简称 DEGs），并从中挖掘出参与磷（42个DEGs）、糖（39个）、脂质（67个）和植物激素（39个）代谢的DEGs。变异分解分析表明，这四个类别均调节了 RSA。在磷代谢中，AMF 接种促进了磷酸转运和释放（与紫色酸磷酶相关的DEGs），而糖代谢中糖转运蛋白的DEGs被下调。脂质代谢可能不负责根的分枝，而是负责AMF的传播。至于植物激素，AMF接种对生长素（13个DEGs）、乙烯（14个DEGs）和脱落酸（5个DEGs）的DEGs有广泛的影响，尤其是对生长素和乙烯。进一步的偏最小二乘结构方程模型分析表明，磷代谢途径、生长素以及AMF接种的直接途径在AMF促进根分枝方面最为重要，而乙烯则发挥了负向作用。总体而言，我们的数据揭示了AMF接种后茶树根系基因组范围内基因表达的改变，并为AMF诱导的RSA（主要指根分枝）变化调控机制提供了分子基础。