Abnormal pollen development has a significantly deleterious impact on commercial peach yields, warranting studies on peach pollen fertility.In this study,cytological observations indicated that the tapetum cells of pollen-sterile ''Jiushuo'' (JS) failed to condense or degenerate compared with pollen-fertile ''Jiucui'' (JC) at the S4 mononuclear microspore stage, resulting in the inability to form fertile pollen microspores. Differentially expressed genes (DEGs) during the S2(tetrad stage), S3(from tetrad to mononuclear microspore stage), and S4 (mononuclear microspore stage) stages were significantly enriched in Ubiquinone and other terpenoid-quinone biosynthesis,oxidoreductase activity and ascorbate and aldarate metabolism pathways. The H2O2 content in JS flower buds was higher than those in JC in S2 and S3 periods,the glutathione(GSH) level of JS was significantly lower than that of JC during the S2 period, while it was significantly higher than that of JC during the S3 period. However, during the S2 and S3 stages, the enzymatic activities of Ascorbate Peroxidase(APX) and the other three antioxidant enzymes showed no significant differences. Therefore, the balance of reactive oxygen species in the JS flower buds has been affected. Based on the premise that the pollen fertility gene is located on chromosome 6, combined with the analysis of DEGs, the PpMED15A gene was finally selected.Complementation in the Arabidopsis med15a mutant indicated that the gene drove fertility, making it crucial for normal pollen development. The salicylic acid content in JS flower buds is significantly lower than that in JC, and SA may affect pollen development through ROS.Our findings provide a foundation for future studies on the mechanism by which PpMED15A regulates pollen fertility.

Low-temperature stress limits peach (Prunus persica) cultivation and productivity. Although exogenous abscisic acid (ABA) enhances cold tolerance in peach, its underlying molecular regulatory mechanism remains unclear. Here, time-course RNA-seq analysis (0, 1, 2, and 4 h) under 0 °C cold stress and ABA treatments identified 2,659 cold-responsive and 3,664 ABA-responsive differentially expressed genes (DEGs), with 1,105 DEGs co-responsive to both treatments. Functional enrichment revealed significant crosstalk with distinct temporal dynamics across key pathways, including flavonoid and phenylpropanoid biosynthesis, hormone signal transduction, and transcriptional regulation. qRT-PCR validated the cold-induced upregulation of six co-responsive transcription factors (PpERF48, PpERF017, PpMYB6, PpWRKY46, PpWRKY40, and PpbHLH35). Functional characterization demonstrated that overexpressing PpMYB6 in peach calli enhanced cold tolerance at -5 °C while repressing callus growth, exemplifying a growth–defense trade-off. Yeast two-hybrid screening identified 24 candidate interacting proteins of PpMYB6, including NCED1, PpSRC2, and DWARF8, elucidating a potential mechanism balancing cold resistance and growth. Overall, this study clarifies an ABA-mediated molecular network and provides valuable targets for breeding cold-tolerant peach cultivars.

Low temperatures are a major environmental factor limiting the growth and productivity of peaches (Prunuspersica). U-box E3 ubiquitin ligases (PUBs) are known to play a role in plant responses to abiotic stresses; however, their role in cold tolerance of peaches is unclear. In this study, transcriptome data revealed that a U-box E3 ubiquitin ligase gene, PpPUB20, was significantly activated by low temperatures. Expression analysis showed that PpPUB20 was rapidly upregulated under cold stress, with a more pronounced early response in cold-tolerant cultivars than in the cold-sensitive cultivars. Phylogenetic analysis revealed that PpPUB20 is evolutionarily conserved across plant species, and domain prediction identified a highly conserved U-box domain. Functional assays demonstrated that overexpressing PpPUB20 gene significantly enhanced low-temperature tolerance in Arabidopsis thaliana, whereas silencing it reduced low-temperature tolerance in peach calli. Physiological studies suggested that PpPUB20 positively regulates cold tolerance by enhancing antioxidant enzyme activity and minimizing membrane damage. Yeast two-hybrid screening identified sorbitol dehydrogenase (PpSDH) as a potential PpPUB20-interacting protein, which was further confirmed by luciferase complementation and co-immunoprecipitation assays. In vitro ubiquitination assays demonstrated that PpPUB20 functions as an E3 ubiquitin ligase mediating the polyubiquitination of PpSDH. This study found that an alternatively spliced transcript of PpPUB20 was present in the non-cold-resistant variety ‘21 Shiji’ but absent in the cold-resistant variety ‘Shijizhixing’. These splicing variants show functional deficiencies in their response to low-temperature stress and its substrate protein interaction due to an absent ARM domain. Full-length and structurally intact PpPUB20 was ubiquitinated by targeting PpSDH, thereby regulating sorbitol metabolism and enhancing the low-temperature tolerance of peaches. This study reveals a new molecular mechanism of peach response to low-temperature stress and further emphasizes the important role of ubiquitination-mediated post-translational regulation in the environmental adaptability of fruit trees.

Peach (Prunus persica) production and the northward expansion of its cultivation boundaries are severely constrained by recurrent extreme climatic events. Based on time-series transcriptomic analysis of two independent parallel treatments (cold stress and ABA application) and qRT-PCR validation, multiple candidate transcription factor genes co-responsive to both cold stress and ABA were identified (PpERF48, PpERF017, PpMYB6, PpWRKY46, PpWRKY40, and PpbHLH35). Among these, PpMYB6 was further characterized through bioinformatic analysis, and transgenic peach callus and Arabidopsis thaliana lines overexpressing PpMYB6 were generated, revealing its dual role in modulating plant growth and conferring low-temperature stress tolerance. Yeast one-hybrid and dual-luciferase reporter assays confirmed that PpMYB6 directly binds to and activates the PpCBF2 promoter. Yeast two-hybrid library screening identified DWARF8 as a candidate interacting protein, pointing to a working hypothesis by which PpMYB6 may negatively regulate vegetative growth via the gibberellin pathway. Together, this study characterizes a novel molecular module associated with cold tolerance and growth balance in peach, providing a promising candidate gene for molecular breeding of cold-resistant cultivars and rootstocks.

Mancheng and Shunping counties, located in the central region of Hebei Province, are major peach-producing areas within the province. These regions encompass a substantial cultivation area of approximately 13 000 hectare. The main cultivated varieties in this region include Okubo, Yanhong, Honggangshan, Dajinghong, etc. The fruit harvesting season extends from early July to late August. Notably, the peak maturity of these peach varieties aligns with the rainy season, which markedly influences fruit quality. Consequently, the peaches exhibit a flat flavor and reduced resistance to storage and transportation. Currently, this region lacks late-maturing and high-quality peach varieties. Considering the existing gaps in the peach varieties, Hebei Normal University of Science and Technology has engaged in a collaborative breeding initiative with the Mancheng District Nursery in Baoding City, aiming to develop a peach variety characterized by late maturity and exceptional quality. Ultimately, the novel variety Jiushuang was successfully identified and developed from the natural progeny of Okubo. This variety is distinguished as a high-quality honey peach. The cultivar Jiushuang, originally identified as 28-19, was subjected to a rigorous and refined breeding regimen. In 2001, the breeding team at Hebei Normal University of Science and Technology harvested natural hybrid seeds from the Okubo peach orchard in the Changli region, which were subsequently subjected to in situ sand storage. In the spring of 2002, the seeds were sown within the greenhouse facilities at the Tangshan breeding station. Following extensive monitoring and assessment, the superior individual designated as 28-19 was identified as the primary candidate for cultivation, prompting the immediate initiation of seedling propagation efforts. By 2007, extensive multi-site trials in locations such as Qinhuangdao, Baoding, Tangshan, and Beijing, alongside the control variety, were conducted to assess the adaptability and stress resistance of 28-19, as well as to monitor the consistency and stability of its desirable traits. The trial outcomes indicated that the fruit of the 28-19 line matures approximately 25 days later than the control variety Okubo peach. Notably, the fruit from 28-19 is larger, exhibits vibrant coloration, a round shape, and superior quality, while also demonstrating good adaptability, high yield potential, and resistance to storage and transportation, with stable excellent traits. In 2022, DNA molecular analysis was performed on the superior line, confirming its status as a novel genotype. In September 2022, the Hebei Provincial Forest Variety Approval Committee convened a panel of experts for an on-site evaluation, which concluded that the superior line excelled in fruit traits, botanical features, and biological properties, displaying consistent performance across generations. In comparison to the control variety, 28-19 trees displayed distinct characteristics in terms of fruit maturity and morphological features, suggesting promising market potential. In April 2023, the Hebei Provincial Forest Variety Approval Committee officially designated this exceptional line as Jiushuang. The fruits of Jiushuang cultivar are spherical in morphology, featuring a flat and even apex along with a fruit suture of moderate depth. The fruits exhibit a basal color of milky white, and the surface is red- colored, with a coloration coverage of 60%. The average single fruit weight is 300 g, featuring white flesh with a concentration of red pigments near the stone. The fruit possesses a firm and soluble texture, accompanied by a cling stone. The soluble solids content is 13.5%, manifesting an optimally palatable sweet- tart flavor profile. The fruit development period spans 140 days, exhibiting the capability of self-fertilization. In the Mancheng District of Baoding City, the Jiushuang fruits ripen between late August and early September. In April 2023, this cultivar was officially endorsed by the Hebei Provincial Forest Tree Variety Appraisal Committee, and it was assigned the premium variety designation with the code: Ji S-SV-AP-009-2023.

To deepen the understanding of peach aroma, we investigated the changes of volatile organic compound (VOC) profiles during fruit development in three fresh peach cultivars: 'Jiucui (JC)', 'Zhongyoupan No. 9 (ZYP9)' and 'Zhongyou No. 8 (ZY8)'. The classes and contents of VOCs changed significantly during fruit ripening. The representative VOC changes were categorized into three developmental stages, with the lowest volatile content observed during the middle stage. At maturity, ester-related volatiles increased significantly, dominating the VOC profiles and accounting for 78 %, 82 % and 88 % in JC, ZYP9 and ZY8, respectively, while alcohols decreased dramatically. Multivariate analysis identified 23, 21 and 20 potential volatile markers in JC, ZYP9 and ZY8, respectively, with 9 shared markers distinguishing the different developmental stages. Odor activity values (OAVs) and olfactometry analysis highlighted 36, 29, and 26 aroma-active compounds (OAV > 1) across the cultivars, with key contributors to the mature peach aroma including hexyl acetate (OAV 860-2896), (E)-2-hexenyl acetate, (Z)-3-hexenyl acetate, (E)-3-hexenyl acetate, linalool, and gamma-decalactone. The fruity aroma intensified as ripening progressed, with ZY8, a cultivar with a longer maturation cycle, exhibiting the highest odor intensity. This study offers insights into the dynamic changes in VOC profiles during peach development, highlighting key aroma-active compounds and their stage-specific variations.

The changes in volatiles during postharvest storage of three peach cultivars (JC, ZYP9 and ZY8) were tracked under two temperature conditions (25 °C and 4 °C). Overall volatile content significantly decreased during storage over time, specifically with a marked decrease in ester levels, while the relative proportions of alcohols, aldehydes, and ketones increased during cold storage. These changes in volatile composition revealed three distinct storage stages across the cultivars, with the middle stage marking a critical turning point in volatile flavor quality. Among the cultivars, ZYP9 and ZY8 exhibited better adaptability to cold storage than JC. The reduction in key esters, coupled with the increase in alcohols and aldehydes, led to altered aroma profiles and the development of off-flavors in cold-stored peaches. Overall, this study provides valuable insights into the dynamic changes in flavor volatiles during postharvest storage and contribute to a deeper understanding of aroma quality in stored peaches.

The peach landrace ‘Liuyefeitao’ exhibits the unique reproductive trait of self-compatibility combined with cross-incompatibility, contrasting with typical Prunus species in this way. In preliminary studies involving controlled pollination assays, we showed complete pollen tube arrest in cross-pollinated styles, whereas self-pollination enabled full tube elongation. S-genotyping identified a homozygous S2S2 genotype with intact S2-RNase but a truncated PpSFB2 due to a frameshift mutation. Transcriptome profiling of the styles revealed 7937 differentially expressed genes (DEGs) between self- and cross-pollination treatments, with significant enrichment in plant MAPK signaling, plant–pathogen interactions, and plant hormone signaling transduction pathways (|Fold Change| ≥ 2, FDR < 0.01). Notably, PpSLFL3 (a pollen F-box gene) showed down-regulation in cross-pollinated styles, as validated by means of qRT-PCR. Protein interaction assays revealed direct binding between PpSLFL3 and S2-RNase via Y2H and BiFC analysis, suggesting its role in mediating SCF complex-dependent degradation. We propose that insufficient PpSLFL3 expression during cross-pollination disrupts SCF ubiquitin ligase complex-mediated degradation of non-self S2-RNase, leading to the toxic degradation of RNA in pollen tubes by S2-RNase. This mechanism is mechanistically similar to unilateral reproductive barriers in Solanaceae but represents a novel regulatory module in Rosaceae. Our findings provide critical insights into the evolution of cross-incompatibility systems and molecular breeding strategies for Prunus species.

With global climate change, extremely high temperatures are occurring frequently during summer, seriously affecting development of the apple industry. Heat-shock factors (HSFs) are important signaling proteins for plants to respond to heat stress. However, research on the effects of the apple HSF gene on the regulation of heat-stress tolerance is lacking. In this study, we analyzed the expression and function of MdHSFA2, an HSF, in apples. The MdHSFA2 expression level significantly increased under heat treatment, and Arabidopsis overexpressing MdHSFA2 showed significantly higher tolerance than that in the WT plants. In addition, we found that apple MdGolS4/6 had the highest expression levels among the eight MdGolSs under heat treatment. Using electrophoretic mobility shift (EMSA) and dual-luciferase assays, we found that MdHSFA2 could directly bind to the MdGols4 promoter region thereby promoting transcription. MdGolS4 overexpression in Arabidopsis enhances heat-stress tolerance. Our findings suggest that MdHSFA2 directly promotes MdGolS4 transcription, thereby enhancing heat-stress tolerance in apples. These results enhance our understanding of heat-stress tolerance mechanisms.

BackgroundWith the rising proportion of saline soils in the global irrigated soil area, improving salt stress tolerance in peach is of great significance and value for the development of peach industry. Plant U-box proteins (PUBs) are widely involved in various stress response processes. In this study, genome-wide identification and analysis of PUBs genes in cultivated peach were carried out, and the expression profiles of peach PUB genes in different tissues of peach as well as their responses under salt stress were also investigated.MethodsThe genome-wide identification of PUBs genes in cultivated peach was analysed by gene localisation, gene structure and evolutionary analysis. Subsequently, the expression profiles of PpPUB genes in different tissues of peach and the changes in the relative expression of peach PUB genes under ABA, GA3, IAA, 6-BA treatments, low-temperature stress and salt stress were investigated.Results and discussionIn this study, 51 U-box protein genes (PUB) were identified in the cultivated peach “SJZX” and divided into six groups. Most of the PpPUB were predicted to be located in the nucleus and chloroplasts. Promoter analyses indicated that most members may be associated with lightresponsive processes. Expression analysis based on RT-qPCR showed that most PUB members in peach were highly expressed in a certain tissues or organs. Based on the results of RT-qPCR expression analysis of 18 representative PpPUB after abiotic stress and hormone induction, all detected genes except for PpPUB19 were induced by salt stress, and PpPUB3/20/23/49 were induced by low temperature. Multiple genes were induced or repressed by exogenous hormone treatments. Furthermore, Arabidopsis seedlings heterologously overexpressing PpPUB20 exhibited greater salt tolerance than wild-type seedlings under the same salt stress conditions. These findings provide comprehensive information on the PpPUB family and identify PpPUB members that may be involved in the regulation of hormones and salt stress. Therefore, this study enhances the understanding of potential role of PpPUB in stress adaptation in peach, thereby establishing a foundation for subsequent functional investigations and applications in stress-resistant crop breeding.

Background: Low temperature pose significant challenges to peach cultivation, causing severe damage to peach buds and restricting production and distribution. Ethylene, an important phytohormone, plays a critical role in enhancing plant cold resistance. Structural genes and transcription factors involved in ethylene biosynthesis and signal transduction pathways are associated with cold resistance. However, no research has specifically addressed their roles in peach cold resistance.Methods: In this study, we aimed for cold-resistance gene discovery in cold-sensitive peach cultivar “21Shiji” (21SJ) and cold-resistance cultivar “Shijizhixing” (SJZX) using RNA-seq and gas chromatography.Results: The findings revealed that under cold stress conditions, ethylene biosynthesis in “SJZX” was significantly induced. Subsequently, a structural gene, PpACO1-1, involved in ethylene biosynthesis in peach buds was significantly upregulated and showed a higher correlation with ethylene release rate. To identify potential transcription factors associated with PpACO1-1 expression and ethylene signal transduction, weighted gene co-expression network analysis was conducted using RNA-seq data. Four transcription factors: PpERF2, PpNAC078, PpWRKY65 and PpbHLH112, were identified.Conclusion: These findings provide valuable theoretical insights for investigating the regulatory mechanisms of peach cold resistance and guiding breeding strategies.

To recognize the key ester-related volatile compounds, 5 types of peaches including 54 late-ripening peach materials were examined by headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry and E-nose. Here, a large number of esters were identified to be released by ripe peach fruits and were mainly characterized by fruity, green, and fatty notes. The variety and content of esters had greatly changed within or between cultivars, indicating that the fruit volatiles were highly differentiated depending on the specific genotypes and cultivation conditions. The ester types showed that fatty acid-derived C6 alcohols and methyl-/ethyl- short-chain alcohol were the main ester precursors, which were more likely to be utilized and well selected by alcohol acyltransferases, whereas the preference of acyl donors was not observed. The common peach type, which exhibited a unique volatile profile, displayed broader diversity and more abundant characteristics in ester-related volatiles than the other four types. A total of 19 key esters were identified as the main components and the content of most esters showed no significant difference among different peach types. Some key esters had even been enriched in nectarines. Moreover, the multiple discriminant analysis revealed a possible relationship between peach types and the domestication of the peach evolution. This study investigated ester-related volatiles released by different types of peach fruits and can be further used to evaluate the peach qualities, providing an important reference for peach breeding and processing.

桃(Prunus persica)多数品种可以自花结实,花粉正常发育对产量至关重要,花粉发育异常影响自花授粉受精和坐果.因此,研究桃的花粉育性具有重要的产业和理论意义.本研究以不育品种'久硕'('JiuShuo',JS)与可育品种'久脆'('JiuCui',JC)及其杂交后代为实验材料对花粉育性基因进行研究.花药解剖观察结果表明,JS花粉不育发生在单核小孢子期,绒毡层细胞质不能正常浓缩、退化.RNA测序(RNA sequencing,RNA-seq)分析结果表明,与绒毡层细胞程序性死亡和花粉外壁形成相关的途径-糖代谢、苯丙氨酸代谢、脂肪酸的生物合成和氧化还原反应在四分体和单核小孢子时期被显著富集.qRT-PCR检测可育品种JC、不育品种JS以及JS×JC后代中相关基因表达模式发现,细胞色素P450703A2(cytochrome P450703A2,PpCYP703A2)(GenBank No.XM_007220109)、4-香豆酸-CoA连接酶-1(4-coumarate-CoA ligase-like 1,Pp4CL)(GenBank No.XM_007225695)和ABC转运蛋白G家族成员26(ABC transporter G family member 26,PpABCG26)(GenBank No.XM_020565361)参与了花粉育性的调控.本研究为桃的花粉育性研究挖掘到新的基因,也为进一步揭示桃花粉育性的分子机制提供了新的理论依据.

Abiotic stress of plants has serious consequences on the development of the apple industry. Nuclear pore complexes (NPCs) control nucleoplasmic transport and play an important role in the regulation of plant abiotic stress response. However, the effects of NPCs on apple salt and osmotic stress responses have not been reported yet. In this study, we analyzed the expression and function of NUCLEOPORIN 62 ( MdNup62) , a component of apple NPC. MdNup62 expression was significantly increased by salt and mannitol (simulated osmotic stress) treatment. The MdNup62 -overexpressing (OE) Arabidopsis and tomato lines exhibited significantly reduced salt stress tolerance, and MdNup62 -OE Arabidopsis lines exhibited reduced osmotic stress tolerance. We further studied the function of HEAT SHOCK FACTOR A1d (MdHSFA1d), the interacting protein of MdNup62, in salt and osmotic stress tolerance. In contrast to MdNup62 , MdHSFA1d -OE Arabidopsis lines showed significantly enhanced tolerance to salt and osmotic stress. Our findings suggest a possible interaction of MdNup62 with MdHSFA1d in the mediation of nuclear and cytoplasmic transport and the regulation of apple salt and osmotic stress tolerance. These results contribute to the understanding of the salt and osmotic stress response mechanism in apple.

为了确定侵染深州蜜桃的病毒和类病毒种类,利用RT-PCR和qRT-PCR的方法对侵染桃树的7种病毒和类病毒进行了检测.RT-PCR病毒鉴定结果表明,深州蜜桃感染了苹果褪绿叶斑病毒(ACLSV)、李树皮坏死茎纹孔伴随病毒(PBNSPaV)、李属坏死环斑病毒(PNRSV)和啤酒花矮化类病毒(HSVd),在深州蜜桃果实中没有鉴定到李矮缩病毒(PDV)、樱桃绿环斑驳病毒(CGRMV)、杏假褪绿叶斑病毒(APCLSV).qRT-PCR检测结果进一步表明李属坏死环斑病毒(PNRSV)侵染了深州蜜桃,其病毒RNA表达量最低.利用RT-PCR开发出高效的多重检测体系,能够同时检测ACLSV,PBNSPaV和HSVd病毒.

[目的]探明外源ABA处理对桃抗寒性的影响.[方法]以不同质量浓度ABA(0、25、50、75、100 mg·L-1)喷施处理的21世纪和久硕1年生枝条为试验材料,分别进行人工模拟低温(0、-5、-10、-15、-20、-25、-30℃)处理,研究相对电导率和丙二醛(MDA)、可溶性蛋白、可溶性糖及内源激素(ABA、GA、IAA、CTK)含量以及ABA/GA的差异.[结果]在低温胁迫下,外源ABA处理的21世纪和久硕枝条可溶性蛋白、可溶性糖含量较对照均增加,丙二醛(MDA)含量和相对电导率均降低,ABA、GA、IAA、CTK含量及ABA/GA均呈无规律变化.用隶属函数法对低温胁迫下各项抗寒指标进行综合评价,不同ABA质量浓度对21世纪抗寒影响顺序为50＞75＞100＞25＞0 mg·L-1(CK),不同ABA质量浓度对久硕抗寒影响顺序为50＞25＞75＞100＞0 mg·L-1(对照).[结论]50 mg·L-1ABA为最佳质量浓度,能有效缓解冻害,提高抗寒性.

以3年生设施桃品种为试材,设置4个硫酸钾施用量(67、135、202、269 g/株)处理,以不施肥为对照,探讨了钾肥施用量对设施桃果实品质、产量及经济效益的影响.结果表明:施用钾肥显著提高了桃果实的单果重和纵径,并改善了果实色泽,降低了可滴定酸含量,增加了可溶性固形物、可溶性糖、可溶性蛋白含量;在67 g/株硫酸钾处理下果肉的蔗糖含量增加最明显;在施钾量269 g/株处理下,果肉的柠檬酸、苹果酸和酒石酸含量最低;单位面积产量、经济效益以及大部分品质指标在施用硫酸钾202 g/株处理下表现较好.因此,在本试验条件下,硫酸钾的最佳施用量为202 g/株.

为确定苹果MdGolSs基因在低温和盐胁迫下的潜在功能,对苹果8个MdGolSs进行蛋白结构和进化树等生物信息学分析,并做低温和盐胁迫处理表达分析.结果表明,8个MdGolSs蛋白均具有保守的"PLN00176"结构域;进化树分析发现8个MdGolSs成员可分为3组,且MdGolS4和MdGolS6,MdGolS1和Md-GolS8,MdGolS3和MdGolS7,MdGolS2和MdGolS5进化关系较近;8个MdGolSs成员在低温和盐胁迫条件下均不同程度地受诱导表达,表明MdGolSs可能与苹果抗低温和盐胁迫响应有关.

The carotenoid composition and content in the yellow sarcocarp peach are a direct indicator of quality. Therefore, discoveries regarding the identification of candidate genes related to carotenoid accumulation and their regulatory mechanisms would be beneficial for yellow sarcocarp peach breeding. In this study, the white sarcocarp peach cultivar '21shiji' (21SJ) and its unique yellow sarcocarp bud mutation individual (21BM) were used for carotenoid determination and candidate gene discovery based on UPLC-APCI-MS/MS and RNA-seq. In total, 11 carotenoid compositions showed significant differences between '21SJ' and '21BM', including four carotenes and seven xanthophylls. Furthermore, the accumulation of β-carotene, zeaxanthin, β-cryptoxanthin, antheraxanthin, violaxanthin, and capsanthin showed different tendencies between '21SJ' and '21BM' during the ripening stage and influenced '21BM' yellow sarcocarp formation. Using transcriptome analysis, we found that the differential expression of candidate genes PpZEP, PpVDE1, PpCCD4, and PpCCS were major influencing factors. Two transfactors, PpbHLH14 and PpMYB73, were significantly related to PpZEP, PpVDE1, PpCCD4, and PpCCS expression and carotenoid accumulation after weighted gene co-expression network analysis. The identified structural genes and transcription factors in this study will further enrich carotenoid accumulation regulatory mechanism in peach and will provide an important theoretical reference for yellow sarcocarp peach breeding.

Abnormal pollen development significantly impedes fruit set which has serious implications for commercial peach crop production. Hence, research on peach pollen fertility is of great importance. We analyzed phenotypic patterns and cytological data. We determined that pollen sterility occurred at the mononuclear microspore stage and that the tapetum cells fail to condense or degenerate. We used RNA-Seq to analyze peach varieties that were sterile or fertile based on phenotypic and cytological observations. There were 1,125 differentially expressed genes (DEGs) in the pollen-sterile varieties compared with the pollen-fertile varieties. The DEGs regulated sugar metabolism, phenylpropanoid and fatty acid biosynthesis, and oxidation-reduction. The expression of relevant genes was verified using qRT-PCR for varieties JC, JS, and JC × JS progeny. Two key genes, PpCYP703A2 and Pp4CL, were significantly downregulated in JS, and these two genes were further verified, using gene expression patterns in fertile and sterile parent JS, JC and JC x JS progeny, to be crucial for normal pollen development. The results of the present study helped clarify the mechanisms of pollen abortion in peach. The information herein lays the foundation for future investigations into the molecular mechanisms of pollen sterility in peach.