Integrated Analysis of Transcriptomic and Proteomics Data Reveals the Induction Effects of Rotenoid Biosynthesis of Mirabilis himalaica Caused by UV-B Radiation.

Li Gu,Wei Huang,Mingjie Li,Jianming Wang,Hong Quan,Yunfang Wu,Fengji Wang,Zhongyi Zhang,Xiaozhong Lan,Weilie Zheng

doi:10.3390/ijms19113324

Abstract

Mirabilis himalaica (Edgew.) Heimerl is one of the most important genuine medicinal plants in Tibet, in which the special plateau habitat has been associated with its excellent medicinal quality and efficacy. However, the mechanisms by which environmental factors affect biosynthesis of secondary metabolic components remain unclear in this species. In this study, RNA sequencing and iTRAQ (isobaric Tags for Relative and Absolute Quantification) techniques were used to investigate the critical molecular “events” of rotenoid biosynthesis responding to UV-B radiation, a typical plateau ecological factor presented in native environment-grown M. himalaica plants. A total of 3641 differentially expressed genes (DEGs) and 106 differentially expressed proteins (DEPs) were identified in M. himalaica between UV-B treatment and control check (CK). Comprehensive analysis of protein and transcript data sets resulted in 14 and 7 DEGs from the plant hormone signal transduction and phosphatidylinositol signaling system pathways, respectively, being significantly enriched. The result showed that the plant hormone signal transduction and phosphatidylinositol signaling system might be the key metabolic strategy of UV-B radiation to improve the biosynthesis of rotenoid in M. himalaica. At same time, most of the DEGs were associated with auxin and calcium signaling, inferring that they might drive the downstream transmission of these signal transduction pathways. Regarding those pathways, two chalcone synthase enzymes, which play key roles in the biosynthesis of rotenoid that were thought as the representative medicinal component of M. himalaica, were significantly upregulated in UV-B radiation. This study provides a theoretical basis for further exploration of the adaptation mechanism of M. himalaica to UV-B radiation, and references for cultivation standardization.

Highlights

Mirabilis himalaica (Edgew.) Heimerl (M. himalaica) is a genuine medicine of Tibet that has been historically employed in nourishing the kidney, regenerating tissue, for diuresis, and in removing kidney stones, with accounts that could be traced back to more than 1300 years ago [1,2]
CAT and POD activities significantly increased after three days of UV-B radiation treatment, and peaked on days 15 and 7, respectively, and POD came to a new balance period
All the results suggest that UV-B radiation improves the biosynthesis of rotenoid, a medicinal active ingredient of M. himalaica, which is mainly achieved by a series of regulatory activities induced by the PI signaling system and hormone signaling to promote the up-regulation of chalcone synthase (CHS)

Summary

Introduction

Mirabilis himalaica (Edgew.) Heimerl (M. himalaica) is a genuine medicine of Tibet that has been historically employed in nourishing the kidney, regenerating tissue, for diuresis, and in removing kidney stones, with accounts that could be traced back to more than 1300 years ago [1,2]. High level of UV-B radiation is a major ecological feature of plateau habitats that largely influence plant growth. Increasing the wax content of the leaf surface is another plant response to UV-B radiation stress [10]. For medicinal plants, in addition to influencing growth and development, UV-B radiation acts as a regulatory factor that increases the production and accumulation of pharmaceutically active ingredients [11]. Increased UV-B radiation can significantly enhance anthocyanin and carotenoid content in chrysanthemum [12]. Many studies have found that UV-B radiation could significantly promoted the accumulation of hydrogen peroxide in cells, further leading to an increasing of free radical levels and producing oxidative stress [15,16,17,18]. The enzyme activities of some representative antioxidant enzymes were frequently used to judge the damage degree and adaptability of plants to UV-B stress, such as catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) [17,18]

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Discussion

Conclusion