The cytokinin response regulator VlRRA1 and its promoter were cloned from‘Kyoho’grape. The expression characteristics of VlRRA1 and the activity of VlRRA1 promoter were analyzed. The results showed that the full-length cDNA of VlRRA1 was 666 bp and encoded 221 amino acids. Conservative domain analysis showed that the gene contained only one phosphoacceptor receiver domain（REC），which belongs to type-A RR genes and can only accept phosphate groups;phylogenetic relationships showed that VlRRA1 was closely related to type-A RR in other species. The yeast self-activation assay illustrates that VlRRA1 has no transcriptional activation activity in agreement with other A-type RR genes and does not have a function similar to that of the B-type RR transcription factor. The results of qRT-PCR showed that VlRRA1 had tissue-specific expression and was mainly expressed in stems，leaves and young fruit，slightly lower expression in inflorescence and ripe fruit，suggesting that VlRRA1 may play an important role in the process of fruit set;exogenous cytokinin forchlorfenuron（CPPU）can promote VlRRA1 expression，while the cytokinin biosynthesis inhibitor lovastatin（LOV）inhibits VlRRA1 transcription. Many elements related to abiotic stress and hormone response were found in VlRRA1 promoter. The results of GUS tissue staining showed that VlRRA1 promoter had promoter activity and could respond to a variety of hormone signals，including three plant hormones related to fruit setting，cytokinin，auxin and gibberellin. These results suggest that VlRRA1 plays an important role in grape fruit setting and young fruit development mediated by cytokinin.

In this study，ninety apple cultivars were used as experimental materials to evaluate cold tolerance by a relative electrical conductivity test. Genome-wide association analysis was conducted on 1 247 162 SNPs detected in apple accessions by genome resequencing technology，and candidate genes significantly associated with cold tolerance were selected. Three cultivars with the strongest cold tolerance were identified，and their relative electrical conductivity was all less than 40%，which were‘Jinhong’，‘Ederbostdorf’and‘Haralson’. Based on the association analysis using 1 247 162 high-quality SNPs and index of relative electrical conductivity characterizing cold tolerance，five significant correlated loci related to cold tolerance were identified，which were distributed on chromosome 4，15，and 16，respectively. Three candidate genes TIF3B1（MD04G1241100），COR47（MD15G1003900），and MD16G1069900 closely related to cold stress tolerance were identified.

In this study，a total of 296 pear germplasms from National Horticulture Germplasm Resources Center Pear Branch Center（Zhengzhou）were collected for fruit spots observation，data collection and photography. During fruit harvesting period，the indicated pear germplasms were sampled and different fruit spot traits，including fruit spots size，fruit spots density，fruit spots height，and the fruit spots area in unit area were comprehensively analyzed. Additionally，sensory evaluation of fruit appearance quality associated with fruit spots in different pear germplasms was performed，and the apperance quality of different pear germplasms was evaluated by grey relation analysis（GRA）and cluster analysis（CA）to establish a comprehensive evaluation model for pear fruit spot traits. The results showed that the relative correlation degree of fruit spots of 296 pear resources ranged from 0.3158 to 0.6526，and the 296 resources were classified into five grades：excellent，good，medium，poor，and extremely poor. Pear varieties including‘Autumn Red’‘Silk Red’‘Red Sensatian’‘Zhongli Meicui’‘Barlett’and‘Dabali’were screened out with excellent fruit spot traits，which have good appearance quality and were consistent with the actual production fruit exterior. On the contrary，pear varieties including‘Puguali’‘Xihuamake’‘Chili’and‘Enli’were screened out with extremely poor fruit spot traits，which have poor appearance quality. Furthermore，the fruit spot traits of 296 pear germplasm resources were divided into five grades by cluster analysis，including excellent，good，medium，poor and extremely poor，which accounted for 7.8%，8.8%，37.1%，34.1% and 12.1% of the tested materials，respectively. Above all，the germplasm resources with excellent fruit spot traits will lay the foundation for the improvement of pear appearance quality，and the germplasm resources with poor fruit traits will be helpful for the investigation of the formation and regulation mechanism underlying pear fruit spots.

In China，there are four kinds of important deciduous fruit trees with a cultivation area of over 666 700 hm²：apple，pear，peach and grape. According to the quality and maturity，several generations of domestic genetic breeders，after decades of collaborative innovation and joint research，created a high-quality and efficient breeding technology system on the basis of excellent germplasm evaluation and creation，and bred a series of high-quality new cultivars of apples and pears with high quality，storability，different maturity and diverse characteristics，and bred high-quality new cultivars of peaches and grapes in early，middle and late maturity. A high-quality and efficient supporting cultivation technology system for new cultivars has been developed，which has promoted the large-scale popularization and application of independent research and development of new cultivars and the high-quality and efficient development of the industry，and provided important support for ensuring the annual demand for high-quality fruits.

VaSTS19 and VdSTS19 were cloned from Vitis amurensis Rupr.‘Tonghua 3’and V. davidii Foex.‘Tangwei’. Sequence analysis showed that the open reading frame of VaSTS19 and VdSTS19 were 1 179 bp，encoding 392 amino acid，and they were located on chromosome 16. The identity between VaSTS19 and VdSTS19 nucleotide and amino acid was 98.81% and 98.21%，respectively. Both VaSTS19 and VdSTS19 are located on the cytomembrane，cytoplasm and nucleus. The expression of STS19 gene and the synthesis and accumulation of resveratrol were significantly promoted when VaSTS19 and VdSTS19 were transferred into tomato by Agrobacterium-mediated method. The promoters of VaSTS19 and VdSTS19 were cloned from‘Tonghua 3’and‘Tangwei’，respectively. cis-Acting elements analysis showed that both promoters contained stress-related elements，hormone-related elements and light-related elements. A sequence alignment showed that the VaSTS19 promoter was demonstrated 60% homology with the VST2 promoter cloned from V. vinifera. The promoters of VaSTS19 and VdSTS19 and their fragments were significantly responsive to SA and MeJA induction in transgenic tobacco leaves. The results indicated that the expression pattern of STS19 and the production of resveratrol may be related to the regulation of the upstream region.

To explore the regulation of MADS-box family transcription factors on carotenoid metabolism in yellow fleshed peach, two MADS genes named as PpMADS2（PRUPE_5G208500）and PpMADS3（PRUPE_5G208400）were cloned. The open reading frames of PpMADS2 and PpMADS3 were 768 bp and 756 bp，encoding 255 and 251 amino acids, respectively. Bioinformatics analysis revealed that the N-terminus of both proteins contained typical characteristic domains of MADS-box family. Subcellular localization showed that both PpMADS2 and PpMADS3 were located at the nucleus. The results showed the gene expression levels of PpMADS2，PpMADS3 as well as carotenoid biosynthetic genes such as PpPSY and PpCHYB increased during fruit ripening，which was consistent with the carotenoid accumulation in yellow fleshed peach. Furthermore, the results demonstrated that PpMADS2 could interact with PpMADS3 then synergistically activate the promoters of PpPSY and PpCHYB genes. Therefore，it is speculated that PpMADS2 and PpMADS3 promoted the accumulation of carotenoids in yellow fleshed peach fruit cooperatively through transcriptional activation of PpPSY and PpCHYB. These research provided a theoretical basis for further exploring the regulatory mechanism of MADS-box transcription factors on carotenoid accumulation in peach fruit.

The differentiation period of flower buds in different horticultural plants is slightly different，and the differentiation time is different. The internal factors affecting flower bud differentiation include endogenous hormones and nutrients. Endogenous hormones mainly include auxin，gibberellin，abscisic acid and cytokinin. Light，temperature，moisture and mineral nutrition can affect the flowering of horticultural plants by regulating hormone levels. Flower bud differentiation mechanism includes the C/N ratio theory，hormone balance hypothesis，hormone signal regulation hypothesis and nutrition hypothesis. At the same time，with the further study of flower bud differentiation in horticultural plants，researchers have found that the process of flower bud differentiation is related to the expression of related genes. This paper reviewed the research progress on flower bud differentiation of horticultural plants in recent years， and looked forward to the main research directions in the future.

The new cultivar‘Zixia'is derived from the cross Dendrobium Ekapol‘Big Panda'and Dendrobium‘Yuki'. The flower color is purple and bright and the average single branch has 5.3 flowers with flower diameter of 6.8 cm and the branch length is 35.0 cm. The beginning flower of this cultivar is in October and full bloom is November and December when cultured in greenhouse of guangzhou，and can be widely planted in South China.

Fruit ripening has always been the focus of horticultural plant research. Plant hormone abscisic acid（ABA）plays an irreplaceable role in fruit ripening. This review summarizes the recent advances in the regulation of ABA on fruit ripening，providing reference for further improvement of the regulation network of fruit ripening.

The F2 genetic segregating population was constructed via using high ascorbic acid（AsA）tomato accession TS-226 and low ascorbic acid tomato accession TS-228 as parents. The high-ascorbic acid and low-ascorbic acid pools were constructed respectively. Through bulked segregant analysis sequencing analysis（BSA-seq），the main QTL related to ascorbic acid was found，and the candidate gene related to ascorbic acid was located in the 58.00–60.15 Mb region of tomato chromosome 8. Furthermore，the ∆SNP-index data were analyzed to determine the main candidate gene SlPPO（Polyphenol oxidase）that controls the ascorbic acid content of tomato fruit. Using TS-228 as the background plant，transgenic lines with SlPPO overexpression and silencing were obtained by Agrobacterium-mediated transformation. Compared with the wild type，the total ascorbic acid content in the red ripe fruits of the overexpression lines OE-3 and OE-18 decreased by 18.89% and 26.56%，respectively. The total ascorbic acid content in the red ripe fruits of the silenced lines Ri-9 and Ri-16 increased by 37.53% and 63.93% relative to wild type，respectively. Taken together，SlPPO is the key gene to control the ascorbic acid content of tomato red ripe fruit，and plays a negative role in regulating fruit ascorbic acid content.

The patterns of anthocyanin and ABA accumulation and ethylene production as well as the changes in expression of the key genes associated with their synthesis or regulation during berry development were studied using Kyoho grapes（Vitis vinifera × V. labrusca‘Kyoho’）. Analysis of gene expression，promoter response and relative mRNA abundance showed that exogenous ABA treatment upregulated the expression level of VlMybA1 and VlMybA2，in which VlMybA1 was significantly expressed and promoted berry skin pigmentation；In contrast，exogenous ACC treatment increased the VlMybA2 expression and anthocyanin accumulation. The interaction between ABA and ethylene was found，100 μmol · L^-1 ABA largely induced the production of endogenous ethylene，and 500 μmol · L^-1 ACC significantly increased ABA content. Additionally，exogenous ABA treatment increased the relative mRNA abundance of VlMybA2 via ethylene. Collectively，ABA promoted berry skin pigmentation by upregulating the VlMybA1 expression directly and the VlMybA2 expression indirectly via ethylene.

In this study，the role of MhCLE8（CLAVATA3/EMBRYO SURRSURROUNDING REGION 8）peptide hormone gene in regulating anthocyanin accumulation was investigated using the meterials Arabidopsis and apple calli. The results showed that the accumulation of anthocyanin in Arabidopsis seedlings and apple calli was significantly inhibited when treated with MhCLE8 peptide （referred to as MhCLE8p）which was synthesised in vitro. Phylogenetic analysis and multiple protein sequences alignment showed that MhCLE8 and its homologues in other plant species contain a highly conserved CLE-motif，and MhCLE8 showed high homology with Prunus armeniaca（CAB4276204.1）and Malus baccata（TQE01035.1）. The MhCLE8 gene was cloned to binary vector pRI，and transferred to Arabidopsis and apple calli to obtain the stable overexpression materials by Agrobacterium-mediated transgenic technology. The transgenic Arabidopsis seedlings and apple calli showed decresed accumulation of anthocyanin. The qRT-PCR analysis showed that the expression of anthocyanin biosynthesis structural genes in MhCLE8 overexpressed plant materials was inhibited to varying degrees. In summary，all the results suggested that the peptide encoding gene MhCLE8 was a negative regulator of anthocyanin accumulation.

To explore the effect of exogenous melatonin on the growth of Malus hupehensis seedlings under saline-alkali stress and its mechanism，M. hupehensis seedlings with 94% apomixis rate were selected as test materials. The control group was irrigated with Hoagland’s nutrient solution（groupⅠ）;The saline-alkali treatment group was irrigated with nutrient solution containing 100 mmol · L^-1 NaHCO₃︰NaCl = 1︰1（groupⅡ）. The group Ⅲ was added with 0.1 mmol · L^-1 melatonin on the basis of groupⅡ. The fresh weight，dry weight，chlorophyll content，photosynthetic rate，mineral element content，antioxidant enzyme activity，osmotic substance content，organic acid content，endogenous hormone content and saline-alkali related gene expression were detected after saline-alkali stress and exogenous melatonin treatment for 15 days. The results showed that application of 0.1 mmol · L^-1 melatonin could significantly enhance the tolerance of M. hupehensis to saline-alkali stress. At first，exogenous melatonin treatment could significantly reduce the wilting rate，and effectively improve the biomass and photosynthesis of M. hupehensis seedlings under salt-alkali stress. Meanwhile，it also increased the content of soluble sugar，soluble protein and proline in seedlings so as to alleviate osmotic stress. In addition，melatonin increased intracellular organic acid content and the expression of AHA family genes to enhanced the saline-alkali tolerance of plants. Moreover，exogenous MT could regulate the expression of Na⁺ transporter genes（MhCHX15 and MhSOS1）and K⁺ transporter genes（MhSKOR，MhNHX1，MhNHX2 and MhNHX4），and enhance the ratio of K⁺/Na⁺ in cytoplasm to maintain ion homeostasis. Melatonin could enhance the activities of POD and CAT and regulate the expressions of antioxidase genes（MhGPX6，MhpoxN1 and MhPER65）to alleviate oxidative damage under saline-alkali stress. Furthermore，exogenous MT could cooperate with gibberellin，auxin，cytokinin and methyl jasmonate responding to saline-alkali stress. In conclusion，exogenous 0.1 mmol · L^-1 melatonin alleviated the damage of saline-alkali stress on M. hupehensis seedlings by regulating ion balance，osmotic substances，antioxidant enzyme activities and coordinating with other endogenous hormones.

Pollen-pistil interaction plays an important role in evolutionary process of species by influencing pollen affinity and serving as reproductive barriers，which determines the reproductive mode of higher plants. Therefore，on the one hand，cloning of male or female recognition factors is the basis of in-depth understanding of plant reproduction mode，which is of great significance for the analysis of the evolutionary mechanism of species. On the other hand，for crop breeding practices that rely extensively on selfing or hybridization，in-depth analysis of the function and mechanism of male or female recognition factors is also of great breeding value. In this review，the current research progress of pollen-pistil interaction factors were summarized systematically，especially in Arabidopsis thaliana，tomato，torenia and other model crops for pollen-pistil recognition research. The structure of pollen and pollen tube，and the S-locus，which determines self-incompatibility，are firstly introduced. Then，according to the sequence of pollen tube extension on female organs，stigma，style and ovule were introduced，and the correlation and uncorrelation between self-incompatibility and cross-incompatibility were introduced in detail. Finally，the research focus of pollen-pistil interaction was prospected.

The relationship between whole genome duplications（WGD）and new plant phenotypes（morphological organ“gigantism”，flowering stage variation，increased secondary metabolites，optimization of agronomic traits，enhanced stress tolerance，etc.）reviewed and discussed systematically and their contribution to evolution and differentiation，and provide prospects for future polyploidy research，which will be helpful by offering important references for innovative research on polyploid plant evolution and molecular breeding of new polyploid crops.

Ubiquitin-conjugating enzyme E2 is a key enzyme for substrate ubiquitination reaction，which plays an important role in the mechanism of self-incompatible by S-RNase degradation via ubiquitin-proteasome system. An E2 gene was cloned based on EST sequence（EY715921）of Citrus sinensis using the flower buds from‘Wuzi Shatangju’and‘Shatangju’，named as CrUBC2. The full-length cDNA sequence of the CrUBC2 was 965 bp，encoding 152 amino acids. There was one base difference （C/T）in the coding sequence of CrUBC2 between‘Wuzi Shatangju’and‘Shatangju’，which resulted in the conversion of threonine to isoleucine. Multiple sequence alignment showed that only one amino acid difference（Thr/Ile）was found between CrUBC2 and orthologs. Therefore，CrUBC2 protein was highly conservative during the evolution process. qRT-PCR showed that the highest expression level of the CrUBC2 was detected in anthers，and the expression level of the CrUBC2 after cross-pollination was 2.22-5.36 fold higher than that of self-pollination，indicating obvious expression specificity in different pollination. Pollen germination experiment in vitro showed that CrUBC2 protein of‘Wuzi Shatangju’inhibited significantly the growth of pollen tubes of self-pollination，but it had no effect on the growth of cross-pollination pollen tubes，which may be related to its involvement in S-RNase ubiquitination and resulting in cross-compatibility.

Molecular marker-assisted selection was used to improve the drought tolerance of two processing tomato lines（Rigel 87-5 and M3）. In this breeding process，a drought-tolerant tomato line（M1040）was used as the donor，while Rigel 87-5 and M3 were used as the recurrent parents. The drought-tolerant molecular marker ID68 was used to select the backcrossing materials for four backcross generations. The drought tolerance of the improved lines（Rigel 87-5D and M3D）at seedling stage was evaluated in detail. The results showed that the survival rate of 87-5D and M3D was significantly higher than that of the recurrent parent after severe drought and rehydration，which can also be reflected by the curve of injury index. The growth，physiological and biochemical indicators under moderate drought stress showed that the improved lines were clearly better than the recurrent parents. Comparison of agronomic traits suggested that the genetic background of the improved lines was restored.

This review summarizes the molecular mechanisms underlying the roles of abscisic acid，jasmonic acid，ethylene，auxin，cytokinin，brassinolide，gibberellin and strigolactone in regulating the anthocyanin accumulation in the fruit trees based on gene expression regulation of the anthocyanin biosynthesis pathway. The review will provide a theoretic basis for enriching the fundamental researches of anthocyanin regulation and biosynthesis in fruit trees，understanding the critical signal transduction pathways of plant hormones，and rationally applying plant hormones to regulate fruits development. The information provides references for the further study of the nthocyanin metabolic pathways in different types of fruit trees.

Tomato is a model plant for fruit research. The study of fruit shape formation is helpful to understand the regulatory mechanisms of fruit morphogenesis. This review summarizes the progress of fruit shape formation in tomato from the aspects of QTL gene regulation，transcriptional and post-transcriptional regulation，and plant hormones. This work contributes to understanding the molecular mechanisms underlying tomato fruit shape formation，and provides new insights for tomato quality breeding.