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Fruit color is an important factor that affects its quality. The red-skinned cultivars of Japanese apricot (Prunus mume Sieb. et Zucc.) have high medicinal economic benefits and are mainly used for deep-processed products because of their eye-catching red pigmentation. In contrast, molecular markers related to the red color trait in Japanese apricot fruit haven't been reported. This study identified twenty-eight SNPs markers based on genome resequencing data. The average number of alleles per SNP marker site in red and green-skinned groups of Japanese apricot cultivars was 1.9643, with heterozygosity ranging from 0.02 to 0.75, and an average Shannon index of 0.517 and 0.4420, respectively, indicating high dispersion and diversity. The total germplasm was divided into two (K = 2) clusters, including 10 and 34. Most red-skinned Japanese apricot cultivars were classified as cluster I, showing the significant genetic difference between the two cultivar groups (Fst = 0.54). According to PIC values, a total of seven SNPs markers showed high polymorphism (PIC > 0.5), including PmSNP_1 (4-CL), PmSNP_4 (WD40), PmSNP_5 (MYB29), PmSNP_18 (UFGT6) and PmSNP_27 (UFGT3) that were highly correlated with red color trait. Among them, PmUFGT3 exhibited the highest polymorphism, which is significant for future research on developing and utilizing germplasm resources related to red fruit skin. [ABSTRACT FROM AUTHOR]

Indole-3-acetic acid (IAA) is an important plant hormone required for various plant growth and developmental activities. YUCCA proteins are the enzymes for IAA synthesis that catalyze the rate-limiting step. However, the YUCCA gene family in Japanese apricot has not been thoroughly characterized. Here, we investigated the effect of rootstocks on scion growth of Japanease apricot and genes involved in auxin biosynthesis (YUCCA). Growth characteristics revealed that the height of 'Longyan' [Prunus mume Sieb. et Zucc] plants with P. mume rootstock were significantly shorter than 'Longyan' plants with P. persica rootstock. This study isolated 13 PmYUCCA genes from the Japanese apricot genome. Bioinformatics and expression studies were undertaken to investigate the functions and characteristics of YUCCA genes. The physicochemical properties, gene structure, conserved domains, conserved motif, and phylogenetic relationships of YUCCA genes were determined using bioinformatics analysis. Likewise, we analyzed the expression of PmYUCCA genes in Japanese apricot's leaf and stem-bark (scion). The expression levels of PmYUCCA3 and PmYUCCA5 genes were noticeably lower in the leaves of 'Longyan'/P. mume graft combination than that of the 'Longyan'/P. persica graft combinations, suggesting their distinct roles in regulating growth vigor. This research explores the genome-wide identification, characterization, and possible relationship between growth vigor and expression profile analysis of the YUCCA gene family in Japanese apricot. [ABSTRACT FROM AUTHOR]

Flower development exists as a key period in the angiosperms life cycle and the proper development is considered with its reproductive success. Pistil abortion is one of the widely distributed aspects of berry plants and its basic mechanism in Japanese apricot is quite unclear and needs thorough investigation. The present study was carried out to get a deep insight into the pistil abortion mechanism in Japanese apricot using a transcriptomic approach. A large number of DEGs were identified from different development stages of normal and abortive pistils. Pair-wise comparison analysis was performed as LY1 vs DQD1, LY2 vs DQD2, and LY3 vs DQD3 and produced 3590, 2085, and 2286 transcripts, respectively. The Gene Ontology (GO) showed that different metabolic processes, plant hormones, developmental processes, and photosystem-related genes were involved in pistil abortion. The pathway analysis revealed significant enrichment of plant hormone's signal transduction and circadian rhythm pathways. Furthermore, transcription factors such as MYB, MADS-box, and NAC family showed lower expression in abortive pistils. The current study presents a new strategy for advanced research and understanding of the pistil abortion process in Japanese apricot and provides a possible reference for other deciduous fruit trees. [ABSTRACT FROM AUTHOR]

Key message: This study is the first to demonstrate that GA4-induced dormancy release is associated with the NF-Y complex, which interacts with gibberellin inhibitor RGL2 in Japanese apricot. Seasonal dormancy is not only vital for the survival in cold winter but also affects flowering of temperate fruit trees and the dormancy release depends on the accumulation of the cold temperatures (Chilling requirement-CR). To understand the mechanism of dormancy release in deciduous fruit crops, we compared miRNA sequencing data during the transition stage from paradormancy to dormancy release in the Japanese apricot and found that the miR169 family showed significant differentially up-regulated expression during dormancy induction and was down-regulated during the dormancy release periods. The 5′ RACE assay and RT-qPCR validated its target gene NUCLEAR FACTOR-Y subunit A (NF-YA), which exhibited the opposite expression pattern. Further study showed that exogenous GA4 could inhibit the expression of the gibberellic acid (GA) signal transduction suppressor PmRGL2 (RGA-LIKE 2) and promote the expression of NF-Y. Moreover, the interaction between the NF-Y family and GA inhibitor PmRGL2 was verified by the yeast-two-hybrid (Y2H) system and a bimolecular fluorescence complementarity (BiFC) experiment. These results suggest that synergistic regulation of the NF-Y and PmRGL2 complex leads to the activation of dormancy release induced by GA4. These findings will help to elucidate the functional and regulatory roles of miR169 and NF-Y complex in seasonal bud dormancy induced by GA in Japanese apricot and provide new insights for the discovery of dormancy release mechanisms in woody plants. [ABSTRACT FROM AUTHOR]

The abnormal pistils widely occur in Japanese apricot ( Prunus mume Sieb. et Zucc) and seriously affect the fruit production. In this study, a CCoAOMT homologue, PmCCoAOMT, was cloned in Japanese apricot and the bioinformatics software analyzed the structural characteristics. The PmCCoAOMT protein was detected to be located in the cell cytoplasm by onion transient expression experiment. Analysis of the real-time PCR data showed that PmCCoAOMT gene expressed in the prophase development of pistil and the expression level in 'Daqiandi' was higher than 'Longyan.' The expression level in 'Longyan' was higher than 'Daqiandi' in the late period development of pistil, and the expression level of perfect flower (perfect pistil) was higher than imperfect flower (pistil deformity and no pistil). Compared with the control, the over-expression of PmCCoAOMT transgenic tobacco lines showed bigger flowers, darker petals. The lignin monomer composition in transgenic tobacco lines was also measured, and the results showed that transgenic tobacco lines had a higher S (Syringyl)/G (Guaiacyl) ratio (22.3 %) than control lines (11.8 %). Also, the perfect flower buds contained more S/G ratio (92.62 %) than imperfect flower buds (83.55 %) in 'Daqiandi.' Our results indicated that the PmCCoAOMT gene might have function in lignin accumulation, which contributed to pistil development in Japanese apricot. [ABSTRACT FROM AUTHOR]

Dormancy is one of the most important adaptive mechanisms developed by perennial plants. To reveal the comprehensive mechanism of seasonal bud dormancy at four critical stages in Japanese apricot ( Prunus persica), we applied Illumina sequencing to study differentially expressed genes (DEGs) at the transcriptional level. As a result, 19,759, 16,375, 19,749 and 20,800 tag-mapped genes were sequenced from libraries of paradormancy (R1), endodormancy (R2), ecodormancy (R3) and dormancy release (R4) stages based on the P. persica genome. Moreover, 6,199, 5,539, and 5,317 genes were differentially expressed in R1 versus R2, R2 versus R3, and R3 versus R4, respectively. Gene Ontology analysis of dormancy-related genes showed that these were mainly related to the cytoplasm, cytoplasmic part metabolism, intracellular metabolism and membrane-bound organelle metabolism. Pathway-enrichment annotation revealed that highly ranked genes were involved in ribosome pathways and protein processing in the endoplasmic reticulum. The results demonstrated that hormone response genes such as auxin, abscisic acid, ethylene and jasmonic acid, as well as zinc finger family protein genes are possibly involved in seasonal bud dormancy in Japanese apricot. The expression patterns of DEGs were verified using real-time quantitative RT-PCR. These results contribute to further understanding of the mechanism of bud dormancy in Japanese apricot. [ABSTRACT FROM AUTHOR]

As with other self-incompatible Prunus species, cultivars of Japanese apricot ( Prunus mume Sieb. et Zucc.) display the S-RNase-based gametophytic self-incompatibility system. In this study, S-genotypes of ten Japanese apricot cultivars native to China were subjected to polyacrylamide gel electrophoresis (PAGE) analysis using an efficient Prunus S-RNase primer pair, Pru-C2 and PCE-R. In addition, three new S-RNase genes ( S, S and S -RNase) and six new SFB genes ( PmSFB14, PmSFB18, PmSFB22, PmSFB24, PmSFB31 and PmSFB34) were identified and their sequences were characterized and deposited in the GenBank database. [ABSTRACT FROM AUTHOR]