Background: Prunus armeniaca, Prunus divaricata, Prunus tianshanica, and Prunus domestica are valuable ancient tree species that have persisted since the end of the Tertiary period within the Tianshan wild fruit forest. However, the evolutionary relationships among Prunus species in the Tianshan wild fruit forest have long posed a challenge. Methods: We sequenced and assembled the chloroplast genomes of P. armeniaca, P. divaricata, and P. tianshanica, and incorporated the chloroplast genome data of P. domestica for comparative analysis to elucidate their phylogenetic positions within the genus Prunus. Results: The lengths of these chloroplast genomes ranged from 157,395 bp to 158,090 bp, with a total of 130 to 131 genes annotated, comprising 85 to 86 protein-coding genes, 8 rRNA genes, and 35 to 36 tRNA genes. Notably, the four wild Prunus species predominantly used high-frequency codons ending in A/U. Additionally, we identified 300 simple repetitive sequences and 166 long repetitive sequences across the four wild Prunus species. The mutation sites were mainly found in the non-coding regions, with seven regions of high mutation frequency identified. The phylogenetic tree revealed five branches: subgenus Armeniaca, subgenus Microcerasus, subgenus Prunus, subgenus Amygdalus, and subgenus Cerasus. The estimated deviation time for the crown group of Prunus is roughly 61.41 million years ago. Conclusions: This study provides exhaustive genetic evidence for the classification and systematic relationships of the four wild Prunus species and establishes a crucial foundation for subsequent research into the diversity and evolutionary history of the Prunus genus.

Salt stress severely affects the growth of turnips (Brassica rapa subsp. rapa), leading to a decline in quality and a reduction in yield. Methyl jasmonate is an endogenous plant hormone that plays a role in regulating plant responses to salt stress. However, its role and mechanism in regulating the response of turnip salt stress remain unclear. Herein, exogenous 100 μM MeJA was applied to four-leaf turnip seedlings subjected to 100 mM NaCl stress to investigate the changes in growth parameters, plant physiology, gene expression, and hormone accumulation after treatment for 3, 5, and 7 days. The results indicated that exogenous spraying of MeJA restricted the growth of turnip seedlings, but enhanced the activity of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX), while reducing the generation of hydrogen peroxide (H₂O₂). Additionally, RNA-seq data showed that exogenous MeJA significantly up-regulates the expression of genes associated with resistance to abiotic stress, specifically those involved in sulfur metabolism, phytohormone signaling, glutathione metabolism, and phenylpropanoid biosynthesis. This up-regulation improved the activity of antioxidant enzymes in vivo, facilitated the scavenging of accumulated reactive oxygen species, and strengthened the plant’s defense mechanisms. In summary, exogenous application of MeJA inhibited the growth of turnip seedlings, but enhanced the plant’s physiological responses to salt stress.