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Gibberellin (GA) is a crucial hormone that drives parthenocarpy and fruit set progression. However, it remains unknown whether GA participates in the parthenocarpy and fruit set in jujube (Ziziphus jujuba Mill.). In this study, we observed the morphology and effect of parthenocarpy in jujube flowers with GA3 treatment. Liquid chromatography tandem-mass spectrometry analysis was performed to detect the levels of endogenous hormones in sepal spread (H), filament wilting (S), and ovary inflation (G) stages of jujube flowers, and the GA3-induced differentially expressed genes (DEGs) were identified by RNA sequencing. We found that GA3 improved jujube parthenocarpic fruit set and that the morphology and size of flowers after GA3 treatment were superior to those in control flowers. GA3 treatment increased the levels of gibberellin, ABA, auxins, and cytokinins in jujube flowers. RNA sequencing revealed that GA3-induced DEGs expressed in the H, S, and G stages. Functional and pathway analyses demonstrated that these DEGs belong to plant development, including glucan metabolic processes and plant hormone signal transduction. Moreover, quantitative reverse transcription polymerase chain reaction validated the reliability of the sequencing data. Fruit set–related genes were significantly induced in the H, S, and G stages of jujube flowers. Our study confirmed that GA3 induced phytohormone production and fruit set by regulating the expression of endogenous hormones and related genes.

Background: Heat stress (HS) is a common stress and influences the growth and reproduction of plant species. We found and bred a putative heat-resistant jujube (Ziziphus jujuba Mill.) cultivar (JHR17) in previous study. Results: In the current study, we made the seedlings of ‘JHR17’ cultivar to be under HS (45°C) for 0, 1, 3, 5 and 7 days, respectively, and the leaf samples (HR0, HR1, HR3, HR5 and HR7) were collected accordingly. Fifteen cDNA libraries from ‘JHR17’ leaves were built with a transcriptome assay. The RNA sequencing (RNA-seq) and transcriptome comparisons were performed, and the results indicated that 1642, 4080, 5160 and 2119 differentially expressed genes (DEGs) were identified in HR1 vs. HR0, HR3 vs. HR0, HR5 vs. HR0 and HR7 vs. HR0, respectively. Gene Ontology (GO) analyses of the DEGs from these comparisons were implemented. Conclusion: It revealed that a series of biological processes, involved in stress response, photosynthesis and metabolism, were enriched successfully, suggesting that lowering or up-regulating these genes of processes might play important roles in response to HS. This study may contribute to understand the molecular mechanism of ‘JHR17’ cultivar response to HS, and be beneficial for developing jujube cultivars to improve heat resistance.

Long non-coding RNA (lncRNA) of plant species undergoes dynamic regulation and acts in developmental and stress regulation. Presently, there is little information regarding the identification of lncRNAs in jujube (Ziziphus jujubaMill.), and it is uncertain whether the lncRNAs could respond to heat stress (HS) or not. In our previous study, a cultivar (Hqing1-HR) ofZ.jujuba were treated by HS (45°C) for 0, 1, 3, 5 and 7 days, and it was found that HS globally changed the gene expression by RNA sequencing (RNA-seq) experiments and informatics analyses. In the current study, 8260 lncRNAs were identified successfully from the previous RNA-seq data, and it indicated that lncRNAs expression was also altered globally, suggesting that the lncRNAs might play vital roles in response to HS. Furthermore, bioinformatics analyses of potential target mRNAs of lncRNAs with cis-acting mechanism were performed, and it showed that multiple differentially expressed (DE) mRNAs co-located with DElncRNAs were highly enriched in pathways associated with response to stress and regulation of metabolic process. Taken together, these findings not only provide a comprehensive identification of lncRNAs but also useful clues for molecular mechanism response to HS in jujube.

Jujube (Ziziphus jujuba Mill.) is an economically and agriculturally significant fruit crop and is widely cultivated throughout the world. Heat stress has recently become a primary abiotic stressor limiting the productivity and growth of jujube, as well as other crops. There are few studies, however, that have performed transcriptome profiling of jujube when it is exposed to heat stress. In this study, we observed the physiochemical changes and analyzed gene expression profiles in resistant jujube cultivar 'HR' and sensitive cultivar 'HS' subjected to heat stress for 0, 1, 3, and 5d. Twenty-four cDNA libraries from 'HR' and 'HS' leaves were built with a transcriptome assay. A total of 6887 and 5077 differentially expressed genes were identified in 'HR' and 'HS' after 1d, 3d, and 5d of heat stress compared with the control treatment, GO and KEGG enrichment analysis revealed that some of the genes were highly enriched in oxidation-reduction process, response to stress, response to water deprivation, response to heat, carbon metabolism, protein processing in endoplasmic reticulum, and plant hormone signal transduction and may play vital roles in the heat stress response in jujube plants. Differentially expressed genes were identified in the two cultivars, including heat shock proteins, transcriptional factors, and ubiquitin-protein ligase genes. And the expression pattern of nine genes was also validated by qRT-PCR. These results will provide useful information for elucidating the molecular mechanism underlying heat stress in different jujube cultivars.