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Members of the GOLVEN (GLV) gene family encode small secreted peptides involved in important plant developmental programs, including meristem maintenance and gravitropic responses. However, research on the functions of peptide hormones has mainly focused on various model plants, and little is known about their possible roles in peach fruit. Here, we identified eight PpGLV genes and analyzed their expression patterns in peach. PpGLV family genes share some similarities with Arabidopsis GLV family genes. PpGLV4 is responsive to 1-MCP and naphthalene acetic acid treatment. To investigate the role of PpGLV4 in detail, we treated peach callus with a synthetic PpGLV4 peptide. The upregulation of auxin and ethylene biosynthesis and signal transduction pathway genes in response to these treatment and the expression patterns of PpGLV family genes suggest that PpGLV4 may be involved in the crosstalk between auxin and ethylene signaling. The comprehensive data generated in this study improve our understanding of the roles of PpGLV peptides in peach.

The plant hormone ethylene regulates ripening in climacteric fruits. The phytohormone abscisic acid (ABA) affects ethylene biosynthesis, but whether ethylene influences ABA biosynthesis is unknown. To explore this possibility, we investigated the interactions between the ABA biosynthesis genes PpNCED2/3 and the ethylene response transcription factor PpERF3 in peach fruit. The ABA content increased during fruit maturation and reached a peak at stage S4 III. The increase was greatly inhibited by the ethylene inhibitor 1-MCP, which also suppressed PpERF3 expression. PpERF3 shared a similar expression profile with PpNCED2/3, encoding a rate-limiting enzyme involved in ABA biosynthesis, during fruit ripening. A yeast one-hybrid assay suggested that the nuclear-localized PpERF3 might bind to the promoters of PpNCED2/3. PpERF3 increased the expression of PpNCED2/3 as shown by dual-luciferase reporters, promoter-GUS assays and transient expression analyses in peach fruit. Collectively, these results suggest that ethylene promotes ABA biosynthesis through PpERF3’s regulation of the expression of ABA biosynthesis genes PpNCED2/3., Fruit ripening: Hormones go hand in hand Two hormones that regulate fruit ripening are more closely linked than previously thought, according to a study of ripening in peaches. Ethylene is a key ripening hormone in many fruits, and high ethylene levels turn on ethylene response factors (ERFs), genes that trigger production of sugars, pigments, and flavor compounds associated with ripening. Another hormone, abscisic acid (ABA), has recently been found to affect ripening, but its interaction with ethylene is unclear. Zhiqiang Wang and Guohuai Li at the Chinese Academy of Agricultural Sciences and coworkers investigated how ethylene and ABA interact during ripening. They found that as ethylene levels increased, ABA production was stimulated. Further investigation showed that ethylene directly triggered the ABA increase via ERFs. These results illuminate the fruit ripening process, and may help in finding ways to prolong fruit shelf life.

Peach (Prunus persica) is a typical climacteric fruit that produces ethylene rapidly during ripening, and its fruit softens quickly. Stony hard peach cultivars, however, do not produce large amounts of ethylene, and the fruit remains firm until fully ripe, thus differing from melting flesh peach cultivars. To identify the key proteins involved in peach fruit ripening, an antibody-based proteomic analysis was conducted. A mega-monoclonal antibody (mAb) library was generated and arrayed on a chip (mAbArray) at a high density, covering ~4950 different proteins of peach. Through the screening of peach fruit proteins with the mAbArray chip, differentially expressed proteins recognized by 1587 mAbs were identified, and 33 corresponding antigens were ultimately identified by immunoprecipitation and mass spectrometry. These proteins included not only important enzymes involved in ethylene biosynthesis, such as ACO1, SAHH, SAMS, and MetE, but also novel factors such as NUDT2. Furthermore, protein–protein interaction analysis identified a metabolon containing SAHH and MetE. By combining the antibody-based proteomic data with the transcriptomic and metabolic data, a mathematical model of ethylene biosynthesis in peach was constructed. Simulation results showed that MetE is an important regulator during peach ripening, partially through interaction with SAHH.

Background The green peach aphid (GPA), Myzus persicae (Sülzer), is a widespread phloem-feeding insect that significantly influences the yield and visual quality of peach [Prunus persica (L.) Batsch]. Single dominant gene (Rm3)-based resistance provides effective management of this invasive pest, although little is known about the molecular responses of plants to GPA feeding. Results To illustrate the molecular mechanisms of monogenic resistance in peach to young tissue-infecting GPAs, aphid-resistant/aphid-susceptible peach lines from a segregating population with Rm3/rm3 and rm3/rm3 genotypes were infested with GPAs for 3 to 72 h. Transcriptome analysis of the infested tissues identified 3854 differentially expressed genes (DEGs). Although the majority of the DEGs in the resistant line also responded to aphid attack in the susceptible line, the overall magnitude of change was greater in the resistant line than in the susceptible line. The enriched gene ontology of the 3854 DEGs involved in plant defence responses included redox situation, calcium-mediated signalling, transcription factor (e.g., WRKY, MYB, and ERF), MAPK signalling cascade, phytohormone signalling, pathogenesis-related protein, and secondary metabolite terms. Of the 53 genes annotated in a 460 kb interval of the rm3 locus, seven genes were differentially expressed between the aphid-resistant and aphid-susceptible peach lines following aphid infestation. Conclusions Together, these results suggest that the Rm3-dependent resistance relies mainly on the inducible expression of defence-related pathways and signalling elements within hours after the initiation of aphid feeding and that the production of specific secondary metabolites from phenylpropanoid/flavonoid pathways can have major effects on peach-aphid interactions. Electronic supplementary material The online version of this article (10.1186/s12864-018-5215-7) contains supplementary material, which is available to authorized users.

The auxin/indole acetic acid (Aux/IAA) genes encode a large family of short-lived proteins that regulate auxin signaling in plants. Previous attempts to understand the role of auxin during fruit development in peach (Prunus persica) found that expression of the Aux/IAA gene PpIAA19 was upregulated during fruit ripening, but the biological significance of the PpIAA19 protein is still unknown. The current study detected PpIAA19 transcripts in all peach plant tissues but found higher levels of accumulation in fruit S1 and S4II stages. During fruit ripening, the expression level of the PpIAA19 gene in melting flesh (MF) peach fruit was unsurprisingly higher than in stony hard (SH) peach fruit. Tomato (Solanum lycopersicum cv. ‘Micro-Tom’) was used as a model for investigating the phenotypic and molecular changes associated with over-expression of PpIAA19. This revealed that PpIAA19 was involved in regulating tomato lateral root number, stem elongation, parthenocarpy, and fruit shape. Molecular analyses of transgenic tomato plants over-expressing PpIAA19 indicated that the observed phenotypic changes were partially mediated by regulating the expression of auxin response genes. This result extends the functional characterization of PpIAA19 in tomato, and broadens our understanding of the role of auxin signaling in regulating plant growth and development.

The fruit skin pubescence of Prunus persica is an economically important characteristic and comprises the classification criteria. The mapping and identification of a complete linkage marker to the fruit skin trichome trait locus of peach fruit are critical for the molecular marker-assisted selection for peach/nectarine. In this study, the BC1 population was constructed from the parents “Zhongyou No. 4”, the recurrent parent, and “Baihuashanbitao”, the non-recurrent parent. Based on the 38 BC1 individuals’ phenotypes and their genotyping using next-generation sequencing, the G (Glabrous skin) locus of the gene was first identified between 14.099 and 16.721 Mb on chromosome 5. Using other individuals of this population, the gene was fine-mapped in the range of 481 kb with SNP markers. Based on the resequencing data of other cultivars (lines), the candidate SNP in the gene Prupe.5G196400 was obtained. Subsequently, the SNP marker was designed and applied to natural and hybrid peach populations. Via genotyping analysis, we confirmed co-segregation between the peach/nectarine phenotype, which was used in the identification of peach or nectarine with 100% accuracy.

Ethylene is an essential regulator of fruit development. However, the role of this phytohormone in the development and maturation of peach (Prunus persica L. Batsch) fruit has not been systematically examined. In this study, through BLAST analysis of tomato (Solanum lycopersicum) protein sequences against the peach genome database and transcriptome analysis of all APETALA2/Ethylene Responsive Factor (AP2/ERF) genes in peach, we identified 15 ethylene signal transduction genes and 15 AP2/ERF genes and examined their expression levels in SH (stony hard) peaches and MF (melting flesh) peaches during fruit maturation. We investigated the expression patterns of six genes, including one ETR-like gene (Prupe.1G034300) and five AP2/ERF genes (Prupe.1G037700, Prupe.2G289500, Prupe.3G240000, Prupe.5G061800, and Prupe.7G194400), through quantitative RT-PCR expression analysis. The transcript levels of these genes were lower at the early stages of fruit development and increased dramatically at stage S4 in MF peaches, while they remained low in SH peaches, which mirrors the pattern of changes observed in ethylene production. Treatment of MF (‘Zhongyoutao 13’, ‘CN13’) fruit at stage S4 II with 1-MCP was ineffective in blocking ethylene production, and the expression of these genes was inhibited by 1-MCP treatment in ‘CN13’ on day 1, further demonstrating that these genes are closely related to fruit ripening. We detected a slight change in fruit firmness in ‘CN13’ after 1-MCP treatment, whereas ethylene production was not affected. By contrast, the transcript profile of gene Prupe.5G090800 exhibited the opposite trend. The comprehensive data generated in this study will improve our understanding of the ethylene receptor genes and ERF genes in peach and lay the foundation for further exploring the mechanisms underlying peach fruit ripening and softening.

Pectins are synthesized and secreted to the cell wall as highly methyl-esterified polymers and demethyl-esterified by pectin methylesterases (PMEs), which are regulated by pectin methylesterase inhibitors (PMEIs). PMEs and PMEIs are involved in pectin degradation during fruit softening; however, the roles of the PME and PMEI gene families during fruit softening remain unclear. Here, 71 PME and 30 PMEI genes were identified in the peach (Prunus persica) genome and shown to be unevenly distributed on all eight chromosomes. The 71 PME genes comprised 36 Type-1 PMEs and 35 Type-2 PMEs. Transcriptome analysis showed that 11 PME and 15 PMEI genes were expressed during fruit ripening in melting flesh (MF) and stony-hard (SH) peaches. Three PME and five PMEI genes were expressed at higher levels in MF than in SH fruit and exhibited softening-associated expression patterns. Upstream regulatory cis elements of these genes related to hormone response, especially naphthaleneacetic acid and ethylene, were investigated. One PME (Prupe.7G192800) and two PMEIs (Prupe.1G114500 and Prupe.2G279800), and their promoters were identified as potential targets for future studies on the biochemical metabolism and regulation of fruit ripening. The comprehensive data generated in this study will improve our understanding of the PME and PMEI gene families in peach. However, further detailed investigation is necessary to elucidate the biochemical function and regulation mechanism of the PME and PMEI genes during peach fruit ripening.

Ethylene response factors (ERFs) are known to regulate fruit ripening. However, the ERF regulatory networks are not clear. In this study, we have shown that peach (Prunus persica) PpeERF2 regulates fruit ripening through suppressing the expression of two ABA biosynthesis genes (PpeNCED2, PpeNCED3) and a cell wall degradation gene (PpePG1). The transcript levels of PpeERF2 in fruit were opposite to that of PpeNCED2, PpeNCED3 and PpePG1 during ripening and in response to various ripening treatments. PpeERF2 was found to bind to the PpeNCED2, PpeNCED3 and PpePG1 promotors as demonstrated by yeast one-hybrid (Y1H) and EMSA assays; and further found to repress the promoter activities of the three genes in tobacco leaf tissues after Agrobacterium infiltration. Taken together, these results provide new information for a better understanding of the crosstalk network between ethylene signaling, cell wall degradation and ABA biosynthesis during fruit ripening.

In fleshy fruits, sugars (glucose, fructose, sucrose and sorbitol) are most important for fruit growth and development but also play a central role in fruit quality. In Peach (Prunus persica), we observed the sugars content at six developmental stages through high pressure liquid chromatography (HPLC). There was variation during fruit development and ripening, sucrose first increased then decreased; glucose and fructose first decreased, and then increased while sorbitol always decreased. In past, understanding about the mechanisms which control the sugar metabolism and accumulation in peach remains quite limited. We studied the transcript profiles of total 30 genes encoding key enzymes and transporters, which were involved in sucrose metabolism, resynthesis and transport. 13 putative genes including sucrose phosphatase synthase (PpSPS4 and PpSPS2), Hexokinases (PpHK1 and PpHK3), neutral/natural invertase (PpNINV1and PpNINV2), vacuolar acid invertase (PpVAINV2), sucrose transporter (PpSUT2), vacuolar glucose transporters (PpVGT1, PpVGT2 and PpVGT3) and tonoplast monosaccharides transporters (PpTMT1 and PpTMT2) highly expressed during peach fruit ripening. PpSPS4 had significantly positive correlation with glucose and fructose. Our results suggested that more sucrose accumulated in cytosol because of upregulation of (PpSPS4 and PpSPS2), that sucrose imported into vacuole through upregulation of PpSUT2, PpVGT1, PpVGT2, PpVGT3, PpTMT1 and PpTMT2 transporters, where cleaving of sucrose is done by upregulation of PpVAINV2. Hence, level of sucrose decreased as fruit ripe. As a result, the concentration of glucose and fructose increased at ripening stage (S4 II to S4 III). So, these marker genes can be involved in peach fruit ripening. This study will improve our understanding and lay foundation to explore the function of these genes and improvement of peach fruit quality.

As a key component of tree architecture, plant height is an important agronomic trait in fruit trees. Reducing tree height is beneficial for increasing planting density, allowing higher yields, lowering costs and increasing the orchard’s lifespan. However, the genetic and molecular factors that regulate peach height are unknown. Here, we report a semi-dwarf peach mutant, which exhibits extremely shortened internodes at temperature below 30 °C. Genetic analysis indicated that this trait was controlled by a single dominant gene that we have named as temperature-sensitive semi-dwarf (Tssd). To map the Tssd locus, two DNA pools, each consisting of 50 mutant or wild-type siblings, were subjected to specific length amplified fragment sequencing. SLAF analysis followed by marker validation using Sanger sequencing and high-resolution melting genotyping located the Tssd gene in a region spanning approximately 750 kb between 2.35 and 3.10 Mb in scaffold 3 based on the reference peach genome sequence of ‘Lovell.’ Further SNPs were developed for fine mapping the locus, which spans an interval of 500 Kb and contains 69 predicted protein-coding gene models. The SNP markers flanking this interval can be applied in molecular identification of Tssd individuals. The result will provide information on how temperature regulates internode length in temperate fruit trees.