Fruit cracking or splitting is a severe physiological disease that significantly affects appearance and quality, compromising the commodity value of fruit and causing substantial economic losses to the producers of several fleshy fruit crops. The growth-promoting plant hormone gibberellins (GAs) and growth-inhibiting abscisic acid (ABA) antagonistically regulate numerous processes throughout the plant life cycle. The homeostasis of GA and ABA plays a significant role in the normal growth and development of fruits, and the imbalance of them may lead to the occurrence of cracking or splitting during the process of fruit growth, development, ripening and postharvest storage. The pathways of GA and ABA metabolism and signaling have been studied widely, and the major components are well characterized, including the genes encoding major biosynthesis and catabolism enzymes and the key signaling components. Nevertheless, our knowledge of the mechanisms of GA and ABA governing fruit cracking is not comprehensive enough. In this review, we summarize the advances in understanding the effects of endogenous GAs and ABA contents in fruits and exogenous GAs and ABA treatments on fruit cracking, and we endeavor to provide some genetic cues on the function of GAs and ABA responsible for fruit cracking modulation. The progress in understanding the molecular bases underlying the actions of GAs and ABA in fruit cracking coordination control will facilitate breeding strategies of cracking-resistant ideotypes of fruits, and also carry great theoretical significance in guiding the establishment of integrated prevention and control measures in fruit cracking.

Jujube (Ziziphus jujuba Mill.) is one of the three traditional woody crop species in China, where it originated from the middle and lower reaches of the Yellow River. Jujube is considered one of the oldest cultivated fruit trees species in the world, as its utilization can be traced back to more than 7000 years ago. The jujube has important nutritional, economic, and ecological values, hence it is well received by both planters and consumers. At present, jujube cultivation has spread to more than 48 countries and provides a pathway for Chinese farmers to produce a lucrative cash crop. Jujube is regarded as a superfruit of the future due to its excellent nutritional profile. Social progress and economic shifts leading to the improvement of living standards influence the value of jujube to consumers, who have gradually shifted toward functional foods, while at the same time, consumer desires and environmental pressures change the breeding goals for new jujube varieties. In this review, we summarize the origin, classification, and historical, as well as modern, uses of jujube. We also provide some advice on the establishment of breeding objectives in this new period of jujube development. This review aims to provide useful references for researchers new to jujube, to guide shareholders in the jujube industry, and to formulate breeding objectives for the modern development of elite jujube cultivars.

Dehydration response element binding factor (DREB) is a family of plant-specific transcription factors, whose members participate in the regulation of plant responses to various abiotic stresses. Prunus nana, also known as the wild almond, is a member of the Rosaceae family that is rare and found to grow in the wild in China. These wild almond trees are found in hilly regions in northern Xinjiang, and exhibit greater drought and cold stress resistance than cultivated almond varieties. However, the response of P. nana DREBs (PnaDREBs) under low temperature stress is still unclear. In this study, 46 DREB genes were identified in the wild almond genome, with this number being slightly lower than that in the sweet almond (Prunus dulcis cultivar ‘Nonpareil’). These DREB genes in wild almond were separated into two classes. All PnaDREB genes were located on six chromosomes. PnaDREB proteins that were classified in the same groups contained specific shared motifs, and promoter analyses revealed that PnaDREB genes harbored a range of stress-responsive elements associated with drought, low-temperature stress, light responsivity, and hormone-responsive cis-regulatory elements within their promoter regions. MicroRNA target site prediction analyses also suggested that 79 miRNAs may regulate the expression of 40 of these PnaDREB genes, with PnaDREB2. To examine if these identified PnaDREB genes responded to low temperature stress, 15 of these genes were selected including seven homologous to Arabidopsis C-repeat binding factor (CBFs), and their expression was assessed following incubation for 2 h at 25 °C, 5 °C, 0 °C, −5 °C, or −10 °C. In summary, this analysis provides an overview of the P. nana PnaDREB gene family and provides a foundation for further studies of the ability of different PnaDREB genes to regulate cold stress responses in almond plants.

Prunus tenella is a rare and precious relict plant in China. It is an important genetic resource for almond improvement and an indispensable material in ecological protection and landscaping. However, the research into molecular breeding and genetic evolution has been severely restricted due to the lack of genome information. In this investigation, we created a chromosome-level genomic pattern of P. tenella, 231 Mb in length with a contig N50 of 18.1 Mb by Hi-C techniques and high-accuracy PacBio HiFi sequencing. The present assembly predicted 32,088 protein-coding genes, and an examination of the genome assembly indicated that 94.7% among all assembled transcripts were alignable to the genome assembly; most (97.24%) were functionally annotated. By phylogenomic genome comparison, we found that P. tenella is an ancient group that diverged approximately 13.4 million years ago (mya) from 13 additional closely related species and about 6.5 Mya from the cultivated almond. Collinearity analysis revealed that P. tenella is highly syntenic and has high sequence conservation with almond and peach. However, this species also exhibits many presence/absence variants. Moreover, a large inversion at the 7588 kb position of chromosome 5 was observed, which may have a significant association with phenotypic traits. Lastly, population genetic structure analysis in eight different populations indicated a high genetic differentiation among the natural distribution of P. tenella. This high-quality genome assembly provides critical clues and comprehensive information for the systematic evolution, genetic characteristics, and functional gene research of P. tenella. Moreover, it provides a valuable genomic resource for in-depth study in protection, developing, and utilizing P. tenella germplasm resources.