Olive trees, originated from Mediterranean, have been cultivated in China for decades and show great adaption to local environment. However, research on this topic is limited. In this study, the major qualitative characteristics and changes of olive grown in southwest China were investigated. The results showed that oil accumulated during fruit development and reached its maximum value when fruit had fully ripened. Phenolic and flavonoid contents increase rapidly in the early growth stage (0-90 DAFB) and then begin to decrease as fruit ripens. Compared with olive from the Mediterranean, olive from China has special characteristics: higher moisture content in the fruit combined with lower percentages of unsaturated fatty acids and oil content. This is due to southwest China’s climate which is wetter and cooler compared to the Mediterranean. Our study suggests that southwest China’s higher annual rainfall might contribute to higher fruit moisture content while its low temperatures would be conducive to higher unsaturated fatty acid levels in the fruit.

Treatments with abiotic elicitors can efficiently induce the accumulation of specialized metabolites in plants. We used a combined omics approach to analyze the elicitation effects of MeJa, AgNO₃, and PEG on camptothecin (CPT) biosynthesis in Camptotheca acuminata plantlets. Untargeted analyses revealed that treatments with MeJa, AgNO₃, and PEG significantly inhibited the photosynthetic pathway and promoted carbon metabolism and secondary metabolic pathways. The CPT levels increased by 78.6, 73.3, and 50.0% in the MeJa, AgNO₃, and PEG treatment groups, respectively. Using C. acuminata plantlets after elicitation treatment, we mined and characterized 15 new alkaloids, 25 known CPT analogs and precursors, 9 iridoid biosynthetic precursors, and 15 tryptamine biosynthetic precursors based on their MS/MS fragmentation spectra. Using 32 characterized genes involved in CPT biosynthesis as bait, we mined 12 prioritized CYP450 genes from the 416 CYP450 candidates that had been identified based on co-expression analysis, conserved domain analysis, and their elicitation-associated upregulation patterns. This study provides a comprehensive perspective on CPT biosynthesis in C. acuminata plantlets after abiotic elicitation. The findings enable us to elucidate the previously unexplored CYP450-mediated oxidation steps for CPT biosynthesis.

Olive (Olea europaea.L) is an economically important oleaginous crop and its fruit cold-pressed oil is used for edible oil all over the world. The basic region-leucine zipper (bZIP) family is one of the largest transcription factors families among eukaryotic organisms; its members play vital roles in environmental signaling, stress response, plant growth, seed maturation, and fruit development. However, a comprehensive report on the bZIP gene family in olive is lacking. In this study, 103 OebZIP genes from the olive genome were identified and divided into 12 subfamilies according to their genetic relationship with 78 bZIPs of A. thaliana. Most OebZIP genes are clustered in the subgroup that has a similar gene structure and conserved motif distribution. According to the characteristics of the leucine zipper region, the dimerization characteristics of 103 OebZIP proteins were predicted. Gene duplication analyses revealed that 22 OebZIP genes were involved in the expansion of the bZIP family. To evaluate the expression patterns of OebZIP genes, RNA-seq data available in public databases were analyzed. The highly expressed OebZIP genes and several lipid synthesis genes (LPGs) in fruits of two varieties with different oil contents during the fast oil accumulation stage were examined via qRT-PCR. By comparing the dynamic changes of oil accumulation, OebZIP1, OebZIP7, OebZIP22, and OebZIP99 were shown to have a close relationship with fruit development and lipid synthesis. Additionally, some OebZIP had a significant positive correlation with various LPG genes. This study gives insights into the structural features, evolutionary patterns, and expression analysis, laying a foundation to further reveal the function of the 103 OebZIP genes in olive.

Oleuropein was extracted from olive leaves by ultrasonic‐assisted method and purified by silica gel column chromatography. The sample was identified as oleuropein by UV, infrared, mass spectroscopy and nuclear magnetic resonance spectroscopy analysis. Oleuropein and total phenolic contents over a year were determined by high‐performance liquid chromatography and Folin–Ciocalteu methods. The results showed that 13.52% of pure oleuropein was found with a high purity of 96.54% and purification efficiency of 78.49%. Oleuropein and total phenolic contents of different olive varieties were quite different, but both had similar trends over the year. Five methods, including DPPH (2,2‐diphenyl‐1‐picrylhydrazyl), ABST (2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt), ferric reducing antioxidant power, total reducing power and nitrite‐scavenging ability, were used to evaluate the antioxidant activities of oleuropein, and the IC₅₀ were 34.54 ± 0.14 μg/mL, 18.79 ± 0.82 μg/mL, 75.32 ± 1.83 μg/mL, 13.80 ± 0.68 μg/mL and 1.00 ± 0.08 mg/mL, respectively. Practical Applications This study provides information on the changes in contents including oleuropein and total phenolics in a year to help understand the relationship between content of oleuropein and various influencing factors. Currently, the metabolic pathways of oleuropein are not clear. These results provide information for the study of the metabolism of phenolic compounds in olive and promote research at the molecular level. Oleuropein occupies a large proportion of total polyphenols in olive and can be to be purified by silica gel column chromatography with high purification efficiency for industrial production and laboratory production. In addition, the comprehensive evaluation of activity in vitro shows that oleuropein is more useful than BHT (2,6‐di‐tert‐butyl‐4‐methylphenol) for the application in food and human health.