Metabolite and Gene Expression Analysis Underlying Temporal and Spatial Accumulation of Pentacyclic Triterpenoids in Jujube

Abstract

Jujube (Ziziphus jujuba Mill.) has attracted increasing attention because of its fruits’ high nutritional and medicinal value, which produce pentacyclic triterpenoids with valuable pharmacological activities beneficial to human health. However, the dynamic accumulation and metabolism pathway of triterpenoids remain unknown in jujube. Here, we performed metabolite assays of triterpenoids and expression analysis of genes involved in the corresponding metabolic processes on cultivated jujube (Z. jujuba cv. Junzao) and one type of wild jujube (Z. jujuba var. spinosa cv. Qingjiansuanzao). Our results showed that the triterpenoids accumulate predominantly in young leaves, annual stems, buds, and white-mature and beginning red stage fruit. Besides, the total triterpenoid content, ceanothic acid, oleanonic acid, and 3-ketoursolic acid were higher in ‘Qingjiansuanzao’ than in ‘Junzao’. Moreover, we found 23 genes involved in terpenoids metabolism were expressed in all organs, and the ZjSQS1, ZjCYP450/1, ZjCYP450/3, ZjOSC1, ZjFPS, and ZjAACT2 gene expression patterns were consistent with metabolites accumulation during fruit development. In addition, 100 μM MeJA induced ZjSQS1, ZjFPS, and ZjHMGR3 expression in leaves and enhanced triterpenoids accumulation. These findings will help understand the unique metabolism of terpenoids and will benefit further utilization and breeding of jujube as both edible fruit and functional food.

Methyl Jasmonate- and Salicylic Acid-Induced Transcription Factor ZjWRKY18 Regulates Triterpenoid Accumulation and Salt Stress Tolerance in Jujube

“…Triterpenoids were extracted following Wen et al [ 5 ], using 0.5 mg freeze-dried samples. For triterpenoid content analysis, the extracted material was dissolved in 5 mL 90% MeOH and was analyzed using high-performance liquid chromatography (HPLC), following the method of Wen et al [ 5 ]. The triterpenoid standards were obtained from Sigma-Aldrich and were used for identification and quantification.…”

“…Most identified terpenoids are synthesized by plants and are induced by hormones such as methyl jasmonate (MeJA) and salicylic acid (SA) [ 3 , 4 ]. MeJA treatment can promote the accumulation of triterpenoids [ 5 ]. Triterpenoids play important roles in plant respiration, photosynthesis, growth and development, and regulation.…”

Transcription Factors ZjMYB39 and ZjMYB4 Regulate Farnesyl Diphosphate Synthase- and Squalene Synthase-Mediated Triterpenoid Biosynthesis in Jujube

“…Previous studies have shown that the structural genes ZjHMGR, ZjFPS, ZjSQS, ZjOSC, and ZjCYP450 might be involved in triterpenoid synthesis. 10 Correlation analysis showed that the expression of ZjFPS and ZjSQS were highly correlated with the content of triterpenoids. The expression levels of ZjFPS and ZjSQS were higher in the buds and young leaves than in other tissues in jujube.…”

“…Next, 500 μL of perchloric acid and 2.25 mL of glacial acetic acid were added to the reaction mixtures. The extraction and quantification of pentacyclic triterpenoids via HPLC were performed following the procedure of Wen et al 10 The petroleum ether extract of jujube fruit was analyzed by GC-MS following the method described in Reddy et al 35 with slight changes. Three biological replicates and three technical replicates were performed in all experiments.…”

“…24 We have previously identified several structural genes related to triterpene biosynthesis, but the functions of these genes remain unclear. 10 Triterpenoids accumulation is controlled by multiple regulatory mechanisms, including transcriptional regulation and plant phytohormine signaling. 25 The transcriptional level regulation has been considered a major aspect, and transcription factors (TFs) play vital roles in binding to promoters of triterpenoid-related genes to promote their transcription, which affects triterpenoid accumulation.…”