Transcriptional analysis reveals new insights into the different light intensities of red and blue light on the growth and synthesis of medicinal ingredients in Dendrobium denneanum

The intensity of red-blue light has important impacts on plant growth and medicinal ingredients. To identify the key genes of Dendrobium denneanum responsive to red-blue light intensity, and to reveal the regulatory mechanism of red-blue light intensity on the growth, development and medicinal quality in D. denneanum. In this experiment, D. denneanum was treated with red-blue light (2R/3B) under various light intensity (50, 100, 200, 400, 800 μmol•m−2•s−1), while the control group was white light, the photoperiod was 8/16 h (day/night). And the changes of plant growth, development, and medicinal components were studied by physiological, biochemical and transcriptome analysis. The results demonstrated that the light intensity of 400 μmol•m−2•s−1 was most conducive to the growth, development, and accumulation of the medicinal ingredients in D. denneanum. Transcriptome analysis revealed that the difference genes between the 400 μmol•m−2•s−1 treatment and CK (white light) were mostly enriched in the metabolic pathways of MAPK signaling, phenylpropanoid biosynthesis and flavonoid biosynthesis. Among them, CAM, PP2C, PYR1 may be the critical genes regulating the growth and development of D. denneanum. The combination of CAM and Ca2+ activates MPKs to maintain ROS homeostasis in D. denneanum. PP2C and PYR1 induced ABA synthesis to control the growth, development, and resistance of D. denneanum. Moreover, 4CL, CAD, BGLU, CCoAOMT and CHI may be the hub genes involved in regulating the synthesis of its key medicinal ingredients. This experiment provides scientific evidence for the application of red-blue light in the artificial cultivation in D. denneanum, and offers the mechanism of in-depth research foundation.