Abstract：
The anomalies of cadmium (Cd) in karst region pose a severe threat to plant growth and development. In this study, the responses of Rhododendron decorum to Cd stress were investigated at physiological, molecular, and endophytic microbial levels, and the potential correlation among these responses was assessed. The Cd stress impeded R. decorum growth and led to an increase in malondialdehyde (MDA) and hydrogen peroxide (H2O2) levels, as well as enhanced superoxide dismutase (SOD) and catalase (CAT) activities. Meanwhile, Cd stress increased the Cd (up to 80 times compared to the control), sodium (Na), aluminum (Al), and zinc (Zn) contents, while decreased the magnesium (Mg) and manganese (Mn) contents in R. decorum leaves. Transcriptome suggested that Cd significantly regulated the pathways including \"protein repair\", \"hormone-mediated signaling pathway\", and \"ATP-binding cassette (ABC) transporters\". Additionally, q-PCR analysis showed that Cd stress significantly up-regulated the expressions of ABCB19-like and pleiotropic drug resistance, while down-regulated the expressions of indole-3-acetic acid-amido synthetase and cytokinin dehydrogenase. The Cd stress influenced the composition of endophytic microbial communities in R. decorum leaves and enhanced the interspecific bacterial associations. Furthermore, the bacterial genera Achromobacter, Aureimonas and fungal genus Vishniacozyma exhibited a high degree of connectivity with other nodes in networks constructed by the metal element contents, differentially expressed genes (DEGs), and microbial communities, respectively. These findings provide a comprehensive insight into the response of R. decorum to Cd-induced stress, which might facilitate the breeding of the Cd-tolerant R. decorum.
摘要：
喀斯特地区镉(Cd)异常对植物生长发育构成严重威胁。在这项研究中,研究了杜鹃花对Cd胁迫的生理响应，分子，和内生微生物水平，并评估了这些反应之间的潜在相关性。Cd胁迫阻碍了R.decorum的生长，并导致丙二醛（MDA）和过氧化氢（H2O2）水平增加，以及增强的超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性。同时,Cd胁迫增加了Cd（比对照增加了80倍），钠（Na），铝(Al),和锌(Zn)含量，同时降低了R.decorum叶片中的镁（Mg）和锰（Mn）含量。转录组表明Cd显着调节包括“蛋白质修复”在内的途径，“激素介导的信号通路”，和“ATP结合盒(ABC)转运蛋白”。此外,q-PCR分析表明Cd胁迫显著上调ABCB19样和多效性耐药的表达,同时下调吲哚-3-乙酸-酰胺基合成酶和细胞分裂素脱氢酶的表达。Cd胁迫影响了R.decorum叶片中内生微生物群落的组成，并增强了种间细菌的关联。此外，细菌无色杆菌属，Aureimonas和真菌属Vishniacozyma与由金属元素含量构成的网络中的其他节点表现出高度的连通性，差异表达基因（DEG），和微生物群落，分别。这些发现提供了一个全面的了解R.decorum对Cd诱导胁迫的反应，这可能有助于耐镉的R.decorum的育种。
