*4.1. Plant Material*

*Dendrobium* plants were cultivated artificially in a greenhouse located in Anhui Tongjisheng Biotechnology Company, Lu'an, China. Seed germination, the growth of protocorm-like bodies protocols and the condition of pots used for planting were described by our previous study [15]. Two-year-old *D. huoshanense*, *D. o*ffi*cinale,* and *D. moniliforme* were selected to provide three replicates of each sample. Stems, leaves, and roots were collected from three different kinds of *Dendrobium* plants for RNA extraction. Then, after drying, they were used to determine polysaccharide and total

alkaloid contents in March, 2017. The same samples were used for transcriptome sequencing and polysaccharide and total alkaloid contents determination.
