Prunasin and amygdalin are important factors that influence the kernel taste of apricots, however, the regulatory mechanisms underlying this are unclear. In this study, we analyzed the phenotype and transcriptome of kernels during development in Prunus sibirica (bitter kernels) and Prunus armeniaca × Prunus sibirica (kernel consumption apricot, sweet kernels). Prunasin and amygdalin content was significantly higher in bitter kernels compared with that in sweet kernels. Prunasin content exhibited a decreasing trend in both bitter and sweet kernels. The fastest decline was observed in bitter and sweet kernels during S3–S4 (82.21%) and S2–S3 (59.65%), respectively. The amygdalin content in the bitter kernels exhibited the fastest increase between 45–60 d after flowering, and reached a peak at 6.22% on 60 d after flowering. In contrast, the peak in sweet kernels occurred at 60 d after flowering, with a much lower content of 0.18%. Transcriptome analysis revealed 6,942 differentially expressed genes (DEGs), with a subset of 38 DEGs specifically enriched in the cyanoamino acid metabolic pathway. Among these, the ten candidate genes, including CYP79, CYP71, UGT1, AH, and PH, were identified as crucial in regulating prunasin and amygdalin metabolism. Furthermore, a weighted gene co-expression network analysis (WGCNA) unveiled two modules that exhibited significant correlation with prunasin and amygdalin content. Five DEGs were located at the center of the co-expression network, and were identified as hub genes, with four positively regulating prunasin content and one negatively regulating amygdalin content. Our results provide novel insights into the molecular-level regulation of the apricot kernel taste.

Studying the evolutionary history of plants in the Qinghai-Tibetan Plateau region provides a theoretical basis for the conservation and use of plant genetic resources. In this study, we analyzed five chloroplast gene fragments to examine the genetic diversity and phylogeography of Prunus mira in 577 individuals from 32 populations. The results indicated that P. mira populations exhibit high genetic diversity and significant phylogeographic structure (NST > GST). High genetic differentiation (FST = 0.979) and limited gene flow were detected among populations, likely due to geographic isolation. Neutrality tests and mismatch analysis indicated that the P. mira population has not experienced significant expansion during the historical period and remains relatively stable. Additionally, based on haplotype distribution and genetic diversity levels, we propose that P. mira had three refugia during the glacial period. Considering the genetic diversity of P. mira populations, we propose dividing all populations into two conservation units and prioritizing in situ conservation of populations with high genetic diversity within each unit. Furthermore, ex situ conservation of specific populations could prevent the loss of unique genes, such as those in populations with low genetic diversity but distinct haplotypes.

The production and quality of apricots in China is currently limited by the availability of germplasm resource characterizations, including identification at the species and cultivar level. To help address this issue, the complete chloroplast genomes of Prunus armeniaca L., P. sibirica L. and kernel consumption apricot were sequenced, characterized, and phylogenetically analyzed. The three chloroplast (cp) genomes ranged from 157,951 to 158,224 bp, and 131 genes were identified, including 86 protein-coding genes, 37 rRNAs, and 8 tRNAs. The GC content ranged from 36.70% to 36.75%. Of the 170 repetitive sequences detected, 42 were shared by all three species, and 53–57 simple sequence repeats were detected with AT base preferences. Comparative genomic analysis revealed high similarity in overall structure and gene content as well as seven variation hotspot regions, including psbA-trnK-UUU, rpoC1-rpoB, rpl32-trnL-UAG, trnK-rps16, ndhG-ndhI, ccsA-ndhD, and ndhF-trnL. Phylogenetic analysis showed that the three apricot species clustered into one group, and the genetic relationship between P. armeniaca and kernel consumption apricot was the closest. The results of this study provide a theoretical basis for further research on the genetic diversity of apricots and the development and utilization of molecular markers for the genetic engineering and breeding of apricots.