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Japanese apricot is an important subtropical deciduous fruit tree in China, widely distributed in different altitude areas. How does it adapt to the different temperature environments in these areas? In this study, we identified a low‐temperature transcription factor PmCBF03 on chromosome 7 through adaptive analysis of populations at different altitudes, which has an early termination single nucleotide polymorphism mutation. There were two different types of variation, PmCBF03A type in high‐altitude areas and PmCBF03T type in low‐altitude areas. PmCBF03A gene increased the survival rate, Fv/Fm values, antioxidant enzyme activity, and expression levels of antioxidant enzyme genes, and reducing electrolyte leakage and accumulation of reactive oxygen species in transgenic Arabidopsis under low temperature and freezing stress. Simultaneously, PmCBF03A gene promoted the dormancy of transgenic Arabidopsis seeds than wild‐type. Biochemical analysis demonstrated that PmCBF03A directly bound to the DRE/CRT element in the promoters of the PmCOR413, PmDAM6 and PmABI5 genes, promoting their transcription and enhanced the cold resistance and dormancy of the overexpressing PmCBF03A lines. While PmCBF03T gene is unable to bind to the promoters of PmDAM6 and PmABI5 genes, leading to early release of dormancy to adapt to the problem of insufficient chilling requirement in low‐altitude areas. Summary statement: The PmCBF03 allele variation is involved in regulating the low‐temperature adaptability of Japanese apricots at different altitudes. [ABSTRACT FROM AUTHOR]

The Knotted1-like Homeobox gene is crucial for plant morphological development and growth. Physicochemical characteristics, phylogenetic relationships, chromosomal localization, cis-acting elements, and tissue-specific expression patterns of the 11 PmKNOX genes found in the Japanese apricot genome in this study were examined. Proteins of 11 PmKNOX were soluble proteins with isoelectric points between 4.29 and 6.53, molecular masses between 15.732 and 44.011 kDa, and amino acid counts between 140 and 430. The identified PmKNOX gene family was split into three subfamilies by jointly constructing the phylogenetic tree of KNOX proteins in Japanese apricot and Arabidopsis thaliana. Combined outcomes of the analyzed conserved motifs and gene structures of the 11 PmKNOX genes from the same subfamily displayed comparable gene structure and motif patterns. The 11 PmKNOX members were distributed across six chromosomes, while two sets of PmKNOX genes were found to be collinear. Analysis of the 2000 bp promoter upstream of the coding region of the PmKNOX gene revealed that most PmKNOX genes might be involved in the physiological metabolism, growth and development processes of plants. The PmKNOX gene expression profile revealed that these genes were expressed at varying levels in different tissues, and most of them were linked to the meristems of leaf and flower buds, suggesting that PmKNOX may be involved in plants' apical meristems. In Arabidopsis thaliana, functional validation of PmKNAT2a and PmKNAT2b revealed that these two genes might be involved in regulating leaf and stem development. In addition to laying the groundwork for future research on the function of these genes, understanding the evolutionary relationships between members of the PmKNOX gene family provides opportunities for future breeding in Japanese apricots. [ABSTRACT FROM AUTHOR]

Background: Chloroplast (cp) genomes are generally considered to be conservative and play an important role in population diversity analysis in plants, but the characteristics and diversity of the different germplasm populations in Japanese apricot are still not clear. Results: A total of 146 cp genomes from three groups of wild, domesticated, and bred accessions of Japanese apricot were sequenced in this study. The comparative genome analysis revealed that the 146 cp genomes were divided into 41 types, and ranged in size from 157,886 to 158,167 bp with a similar structure and composition to those of the genus Prunus. However, there were still minor differences in the cp genome that were mainly caused by the contraction and expansion of the IR region, and six types of SSR in which mono-nucleotide repeats were the most dominant type of repeats in the cp genome. The genes rpl33 and psbI, and intergenic regions of start-psbA, rps3-rpl22, and ccsA-ndhD, showed the highest nucleotide polymorphism in the whole cp genome. A total of 325 SNPs were detected in the 146 cp genomes, and more than 70% of the SNPs were in region of large single-copy (LSC). The SNPs and haplotypes in the cp genome indicated that the wild group had higher genetic diversity than the domesticated and bred groups. In addition, among wild populations, Southwest China, including Yunnan, Tibet, and Bijie of Guizhou, had the highest genetic diversity. The genetic relationship of Japanese apricot germplasm resources in different regions showed a degree of correlation with their geographical distribution. Conclusion: Comparative analysis of chloroplast genomes of 146 Japanese apricot resources was performed to analyze the used to explore the genetic relationship and genetic diversity among Japanese apricot resources with different geographical distributions, providing some reference for the origin and evolution of Japanese apricot. [ABSTRACT FROM AUTHOR]

Background: Japanese apricot (Prunus mume Sieb. et Zucc.) is popular for both ornamental and processing value, fruit color affects the processing quality, and red pigmentation is the most obvious phenotype associated with fruit color variation in Japanese apricot, mutations in structural genes in the anthocyanin pathway can disrupt the red pigmentation, while the formation mechanism of the red color trait in Japanese apricot is still unclear. Results: One SNP marker (PmuSNP_27) located within PmUFGT3 gene coding region was found highly polymorphic among 44 different fruit skin color cultivars and relative to anthocyanin biosynthesis in Japanese apricot. Meantime, critical mutations were identified in two alleles of PmUFGT3 in the green-skinned type is inactivated by seven nonsense mutations in the coding region, which leads to seven amino acid substitution, resulting in an inactive UFGT enzyme. Overexpression of the PmUFGT3 allele from red-skinned Japanese apricot in green-skinned fruit lines resulted in greater anthocyanin accumulation in fruit skin. Expression of same allele in an Arabidopsis T-DNA mutant deficient in anthocyanidin activity the accumulation of anthocyanins. In addition, using site-directed mutagenesis, we created a single-base substitution mutation (G to T) of PmUFGT3 isolated from green-skinned cultivar, which caused an E to D amino acid substitution and restored the function of the inactive allele of PmUFGT3 from a green-skinned individual. Conclusion: This study confirms the function of PmUFGT3, and provides insight into the mechanism underlying fruit color determination in Japanese apricot, and possible approaches towards genetic engineering of fruit color. [ABSTRACT FROM AUTHOR]

SUMMARY: Japanese apricot (Prunus mume) is an attractive fruit tree originating from China, and its cultivation history dates back 7000 years. In this study, we investigated the genetic diversity, population structure, and genetic relationship of Japanese apricots in different regions of China and Japan. The analyses of the genetic variation between wild and cultivated populations improved our understanding of the general mechanisms of domestication and improvement. A total of 146 accessions of Japanese apricot from different geographic locations were sequenced. The genetic diversity of wild and domesticated accessions (3.60 × 10−3 and 3.51 × 10−3, respectively) from China was high, and the effect of artificial selection pressure on domesticated accessions was small; however, the genetic diversity of artificially bred accessions decreased significantly (2.68 × 10−3) compared to domesticated accessions, which had an obvious improvement bottleneck effect. The chloroplast genome results showed that 41 haplotypes were detected, and Japanese apricots from the Yunnan region had the most haplotypes and the highest genetic diversity. The results revealed the dissemination route of Japanese apricot, not only along the Yangtze River basin system (from southwest China to Hunan, Jiangxi, and Anhui, and finally to the Jiangsu, Zhejiang, and Shanghai areas). Additionally, we discovered a second route for Japanese apricot dispersion, which was mostly in the Pearl River basin system, from southwest China to Libo of Guizhou and then to the Guangdong, Fujian, and Taiwan areas. This also showed that Japanese‐bred accessions originated from Zhejiang, China. In addition, selective sweep analysis showed that most of the high‐impact single nucleotide polymorphisms were identified in genes related to glucose metabolism, aromatic compound metabolism, flowering time, dormancy, and resistance to abiotic stress during the domestication and improvement of Japanese apricot. Significance Statement: Japanese apricot was widely distributed in different regions of China. As for how to disseminate in different regions, there has been a great controversy in the academic circles. This study provided novel insight into the evolution and dissemination of Japanese apricot and a greater number of valuable genome resources for the genetic improvement and effective utilization of Japanese apricot. [ABSTRACT FROM AUTHOR]

• Dwarfing rootstocks are a valuable genetic resource for managing high-density plantations because it decreases the vegetative growth of scion and minimizes labor expenditures. • This study was undertaken to explore the dwarfing mechanism in Japanese apricot using RNA- sequencing. • Approximately, 1827 DEGs were found, and a comparison analysis between dwarfing and vigorous graft combinations was performed. • Alterations in the activity of hormones including IAA, ZR, GA 3 , ABA and BR contribute significantly to scion dwarfing. • Our research provides a foundation for the molecular mechanism of size reduction, as well as a reference for future studies related to size control of fruit crops. Dwarfing rootstocks are a valuable genetic resource for managing high-density plantations because it decreases the vegetative growth of scion and minimizes labor expenditures. The scion architecture of grafted Japanese apricot (Prunus mume) is affected by various characteristics of the rootstocks. A leaf and root RNA-Sequencing of the two scion/rootstock combinations (LY/PM and LY/PP) was conducted to explore molecular mechanisms underlying the effect of rootstock on scion vigor and dwarfing related genes. The phenotypic observations showed that size reduction in p. mume (PM) rootstock is due to lower node number, reduced internode length, and decreased trunk diameter of the scion, while trees grafted with P. persica (PP) rootstock increased all the values of morphological index. After cutoff and pairwise comparison analysis, we retrieved 1827 differentially expressed genes (DEGs) in LY/PM and LY/PP graft combinations. The KEGG pathway analysis revealed that the most DEGs were found predominantly enriched in complex plant hormone transduction networks involving the auxin (IAA), cytokinin (CK), abscisic acid (ABA), jasmonic acid (JA), brassinosteroid (BR) and gibberellic acid (GA) pathways. Several transcription factor families, such as WRKY, NAC, LBD and bZIP , might be involved in the complicated growth induction process. These findings provide a framework for exploring the molecular mechanisms underlying differential scion growth mediated by rootstock. [ABSTRACT FROM AUTHOR]