Data_Sheet_5_Arbuscular Mycorrhizal Fungus Alters Root System Architecture in Camellia sinensis L. as Revealed by RNA-Seq Analysis.docx

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（AMF）与大多数陆生植物形成共生关系，强烈调节根系结构（RSA），这是根系在土壤中的主要特征，从而促进植物的生长与发展。迄今为止，关于AMF对茶树幼苗的研究尚少，且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“晚茶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指数和根部糖含量进行了测定。通过RNA测序（Seq）分析，获得了菌根和非菌根扦插幼苗根部尖端的转录组数据。结果显示，AMF显著降低了植物的生长，但增加了根部蔗糖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（DEGs），其中涉及磷（42个DEGs）、糖（39个）、脂质（67个）和植物激素（39个）的代谢的DEGs被挖掘出来。变异分解分析表明，这四个类别均调节了RSA。在磷（P）代谢中，AMF接种促进了磷的转运和释放（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系分支，而是负责AMF的传播。就植物激素而言，AMF接种对生长素（13个DEGs）、乙烯（14个DEGs）和脱落酸（5个DEGs）的DEGs产生了广泛的影响，尤其是对生长素和乙烯。进一步的部分最小二乘结构方程模型分析表明，磷代谢途径和生长素途径，以及AMF接种的直接方式，在AMF促进根系分支中最为重要，而乙烯则发挥负作用。总体而言，我们的数据揭示了接种AMF后茶树根部基因组范围内基因表达的改变，并为AMF诱导的RSA（主要指根系分支）变化调节机制提供了分子基础。