Triterpenoids are important, pharmacologically active substances in jujube (Ziziphus jujuba Mill.), and play an important role in the plant’s resistance to abiotic stress. However, regulation of their biosynthesis, and the underlying mechanism of their balance with stress resistance, remain poorly understood. In this study, we screened and functionally characterized the ZjWRKY18 transcription factor, which is associated with triterpenoid accumulation. The transcription factor is induced by methyl jasmonate and salicylic acid, and its activity was observed by gene overexpression and silencing experiments, combined with analyses of transcripts and metabolites. ZjWRKY18 gene silencing decreased the transcription of triterpenoid synthesis pathway genes and the corresponding triterpenoid content. Overexpression of the gene promoted the biosynthesis of jujube triterpenoids, as well as triterpenoids in tobacco and Arabidopsis thaliana. In addition, ZjWRKY18 binds to W-box sequences to activate promoters of 3-hydroxy-3-methyl glutaryl coenzyme A reductase and farnesyl pyrophosphate synthase, suggesting that ZjWRKY18 positively regulates the triterpenoid synthesis pathway. Overexpression of ZjWRKY18 also increased tolerance to salt stress in tobacco and Arabidopsis thaliana. These results highlight the potential use of ZjWRKY18 to improve triterpenoid biosynthesis and salt stress tolerance in plants, and provide a strong basis for metabolic engineering to improve the content of triterpenoids and breeding of jujube varieties that are resistant to stress.

Jujube (Ziziphus jujuba Mill.) is a fruit tree that is gaining increasing importance in drought-affected regions worldwide. The fruit size is an important quantitative agronomic trait that affects not only the fruit yield and attractiveness but also consumer preference. Genetic enhancement of fruit appearance is a fundamental goal of jujube breeding programs. The genetic control of jujube fruit size traits is highly quantitative, and development of high-density genetic maps can facilitate fine mapping of quantitative trait loci (QTLs) and gene identification. However, studies regarding the construction of high-density molecular linkage maps and identification of quantitative trait loci (QTLs) targeting fruit size in jujube are limited. In this study, we performed whole-genome resequencing of the jujube cultivars “JMS2” and “Xing16” and their 165 F₁ progenies to identify genome-wide single-nucleotide polymorphism (SNP) markers and constructed a high-density bin map of jujube that can be used to assist in the selection of multiple traits in jujube breeding. This analysis yielded a total of 116,312 SNPs and a genetic bin map of 2398 bin markers spanning 1074.33 cM with an average adjacent interval of 0.45 cM. A quantitative genetic analysis identified 15 QTLs related to fruit size and the observed phenotypic variation associated with a single QTL ranged from 9.5 to 13.3%. Through the screening of overlapping and stable QTL regions, we identified 113 candidate genes related to fruit size. These genes were ascertained to be involved in cell division, cell wall metabolism, synthesis of phytohormones (ABA, IAA, and auxin), and encoding of enzymes and transcription factors. These candidate genomic regions will facilitate marker-assisted breeding of fruits with different sizes and shapes and lay a foundation for future breeding and manipulation of fruit size and shape in jujube.

The aim of this study was to establish a standardized and unified method for identifying and evaluating jujube fruit texture quality and to provide a theoretical basis for determining the texture quality of jujube germplasm resources. The texture of 56 jujube germplasms was characterized via the texture profile analysis (TPA) method, and the texture and anatomical structure of three each of the hard- and soft-fleshed germplasms were analyzed. Cluster analysis was used to categorize the 56 germplasms into hard- (17) and soft-fleshed jujubes (39). Significant positive correlations were found between all other textural parameters of jujube fruits except adhesiveness. The hardness, springiness, and chewiness of the full-red period hard- and the soft-fleshed jujube fruit were lower than those of the half-red period. The hardness, adhesiveness, and chewiness of the hard-fleshed jujube fruits in the full-red period were 2.13–3.57, 3.00–4.99, and 4.39–9.58 times higher than those of the soft-fleshed jujube fruits, respectively. The findings of this study provide a theoretical foundation for the evaluation and classification of the texture and quality of jujube fruits and a basis for the breeding of new, high-quality jujube varieties with distinctive characteristics.

‘Korla fragrant’ pear has a long history of cultivation in Xinjiang, China, with favorable economic and social benefits. The selection of tree growth has a direct impact on improvements in fruit yield and quality. In order to provide a theoretical basis for the efficient and high-quality cultivation of ‘Korla fragrant’ pear, two ‘Korla fragrant’ pear tree growth forms, namely trunk shape and small-canopy shape, were selected as experimental materials to study the differences in the parameters of different tree growth forms, as well as the effect on photosynthetic activity and fruit quality. The results show that the small-canopy-shape trees exhibited significantly improved photosynthetic activity, with a 60.64% higher net photosynthetic rate (Pn) in the upper canopy compared to the trunk-shape trees. Fruit quality was also superior in the small-canopy-shape trees, with increases in single-fruit weight (29.36–46.91%), soluble solids content (13.51–14.39%), soluble sugar content (25.79–27.56%), and vitamin C content (up to 0.4363 mg·100 g⁻¹ in the upper layer). However, the yield per unit area of the trunk-shape trees was significantly higher than that of the small-canopy-shape trees by 19.32% because of the higher number of short fruit branches and increased prevalence of smaller row spacing. In addition, within the same tree growth forms, photosynthetic activity and fruit quality were improved in the upper layers compared to the lower layers.

To explore the phenotypic diversity of jujube germplasm resources and identify superior genotypes, this study systematically evaluated 150 jujube accessions. Multiple organ-related traits—including branches, thorns, bearing shoots, leaves, flowers, and fruits—were investigated. A comprehensive, multidimensional analysis was conducted to assess phenotypic variation and diversity. The results provide valuable insights for germplasm conservation and the selection of elite jujube varieties. The results showed that the variation coefficient of 18 quantitative traits ranged from 5.07% to 21.43%; the variation coefficient of fruit quality traits ranged from 4.25% to 13.48%; and the results of the cluster analysis showed that the germplasm resources were classified into three categories according to the quantitative traits and four categories according to the fruit quality traits. Principal component analysis extracted six significant components for fruit quality traits, accounting for 86.88% of the total variance. Based on the comprehensive evaluation of factor analysis, Sanlengzao, Linyilajiaozao, Zan 2, Jinmanguo, and Jing 39 performed well and ranked high in the comprehensive ranking, which can be used as an important reference for the evaluation of jujube germplasm resources and the selection and breeding of good varieties.

Jujube is a plant of the genus Ziziphus in the family Rhamnaceae; its fruit has high nutritional value, and it is rich in polyphenols, flavonoids, and other secondary metabolites. The color of its peel is an important indicator for evaluating the appearance of the fruit. However, the mechanism of the difference in color presentation between the seedling offspring of the ‘Red Fruit’ (TLHH) and the ‘Green Fruit’ (TLHL) of the fresh jujube cultivar ‘Tailihong’ is not clear. Therefore, this study used targeted metabolomics techniques to accurately and quantitatively analyze the metabolic pathways of carotenoid and anthocyanin metabolites during the ripening process of two color-presenting types of jujube fruits. Through the analysis of the dynamic changes in the pigment content of the jujube peel, it was found that 30 DAP (days after pollination), 80 DAP, and 110 DAP were the key periods for the development of the color of the peel of ‘TLHL’ and ‘TLHH’ jujube and that the substances responsible for the main differences were chlorophyll, carotenoids, and anthocyanins. Furthermore, we used an LC-MS/MS metabolic analysis to compare the differences in the carotenoids and anthocyanin metabolites between the two color-presenting types of jujube peels at the key periods of 30 DAP, 80 DAP, and 110 DAP. We detected 32 carotene metabolites and 75 anthocyanin metabolites, respectively, among which lutein had the highest content of carotenoids; it reached the maximum value (93.05 µg/g) and was higher than that of ‘TLHH’ (74.14 µg/g) at 30 DAP of ‘TLHL’. Both showed a decreasing trend with fruit ripening. The anthocyanin with the highest content was cyanidin-3-O-(tartaryl)rhamnoside-5-O-glucoside, which reached the maximum value (258.32 µg/g) at 30 DAP of ‘TLHH’ and was 51.6 times that of ‘TLHL’; similarly, both showed a decreasing trend with fruit ripening. These results elucidate the main metabolites of carotenoids and anthocyanins in the two types of jujube peel and their accumulation characteristics, suggesting that the key metabolites of the difference in color between ‘TLHL’ and ‘TLHH’ jujube fruits were lutein and cyanidin-3-O-(tartaryl)rhamnoside-5-O-glucoside, increasing the understanding of the color mechanism of jujube peel and providing a reference for targeted genetic breeding of jujube peel color.