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.

‘Zhongtaohuangjinmi No. 5’is a new cultivar of late-ripening yellow flesh peach bred by artificial pollination. The flower is bell-shaped，pollen-rich，with high natural fruit set rate. The fruit is round. The weight of single fruit is 281–392 g. More than 80% of the fruit surface is yellow at maturity. The flesh is yellow，melting，sweet，with soluble solids content of 14.5%–15.5% and clingstone. Fruit development period is about 142 d. It is very productive，yielding about 37 500 kg · hm-2 at full fruit stage.

MLO is a plant specific recessive resistance gene family. It is widely believed that it has a negative regulatory effect on powdery mildew. Many powdery mildew resistance MLO genes have been found in both monocotyledon and dicotyledon. However，there are few studies on the mechanism of upstream regulator of MLO genes. In this study，a cDNA library of apple rootstock‘Qingzhen 1’leaf was constructed with a titer of about 4 × 10⁹ cfu · mL^-1，and the recombination rate was 100%. Bioinformatics analysis of apple MLO gene family promoter region showed that there were 38 kinds of cis-acting elements，including hormone，stress defense response as well as growth and development response elements，etc. TCA and TC-rich repeats cis-acting elements were selected as bait sequences and constructed bait vectors named Bait-TCA and Bait-TC for yeast one-hybrid，respectively. The results showed that the Bait-TCA had self-activation and could not be used for screening. Among the Bait-TC obtained 30 sequences，six sequences were involved in plant anti-stress defense response. It suggested that they might be involved in the response of apple to powdery mildew through regulating the expression of MLO genes.

‘Chutian 1’is a new early-ripenging nectarine cultivar with small fruit and high sweetness，which is derived the cross of‘Fengguang’and‘070507’（Tianxianhong × Zhongyou 5）. The fruit shape is round，and the average fruit weight is 82 g，the maximum single fruit weight is 130 g. The flesh is white，crisp and very sweet，with 12%–14% soluble solids content and 0.22%–0.29% titratable acid content. The stone is freestone and has nonshowy flowers，with high and steady yield. The maturity date is early-June in Wuhan area，the average yield is 30 000 kg · hm-2. 

To study the change of freezing tolerance and its physiological basis of annual shoots of ‘Taishanhong’‘Luqing 1’and‘Tunisian Soft Seed’pomegranates during overwintering，the cold hardiness was estimated by the semi-lethal temperature（LT₅₀），which was assessed by electrolyte leakage rate with Logistic quation，the content of relative water，soluble protein，soluble sugar，malondialdehyde（MDA），activities of peroxidase（POD）and superoxidase（SOD），field overwintering rate，botanical characteristics of shoots，and the recovery ability of branches after freezing stress were measured. The results showed that the significant differences in cold resistance among three pomegranate cultivars. The overwintering rate of‘Luqing 1’was much higher than those of‘Taishanhong’and‘Tunisian Soft Seed’，and‘Tunisian Soft Seed’was the worst. Compared with‘Tunisia Soft Seed’，the shoots of‘Luqing 1’ were thick，hard，with short internodes，the spiness were also strong and hard. Sealing layers of lenticle were rich and tight. The changes of physiological indexes of‘Luqing 1’were relatively small after low temperature treatment. MDA content was low，soluble proteins content and POD activity were high. The osmotic pressure and redox balance of‘Luqing 1’could be maintained well，so its cold resistance much better than that of‘Tunisan Soft Seed’.

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.

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.

In order to construct a CRISPR/Cas9 system for multiplex gene editing in tomato，Arabidopsis U6 promoters in pKSE401 and pCBC-DT1T2 vectors were replaced with SlU6-2p，SlU6-3p，SlU6-7p，SlU3-5p，SlU3-9p and SlU6-5p，respectively. Accordingly，a binary vector（pMGET），two intermediate vectors（pKC-S2M and pKC-S3M），and three gRNA module vectors（pCBC-S1，pCBC-S2 and pCBC-S3）were constructed. In order to test the system for multiplex gene editing in tomato，multiplex gene editing vectors pMGET-OYGTULC and pMGET-TULCOYG were constructed by aggregating sgRNA expression cassettes containing the target sequences of six tomato fruit trait-related genes Green flesh（GF），Ovate（O），Locule number（LC），SlMYB12（Y），Tangerine（T）and Uniform ripening（U），through PCR amplification，Golden gate cloning and isocaudamer technique，and the editing efficiency of six genes at the same time of the two vectors was 44.00% and 11.76%，respectively. The tomato material was transformed by Agrobacterium tumefaciens carrying pMGET-OYGTULC vector to obtain two plants with six genes edited. The sequence variations were in the form of single base insertion，single or multiple base deletion and large fragment deletion. In this study，the CRISPR/Cas9 system can be efficiently used for multiplex gene editing in tomato，and stable genetic mutants can be obtained，which can provide a versatile toolbox for basic research and genetic improvement in tomato.

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.

‘Zijin Hongxia’is a new early-ripening table grape cultivar. The berry ripens in late July in Nanjing，Jiangsu. It was selected from progenies of the cross‘Yatomi Rosa’בXiangfei’. The cluster is cone with an average weight 520 g，and single berry is elliptic with average weight 9.2 g. The color of skin is red-violet and thickness of bloom is thick. The flesh is slight crisp and the must is high with particular weak muscat flavor. The soluble solids content is 18.3% and titrate acid content is 0.30%. ‘Zijin Hongxia’is characterized by good berry quality and showed high and stable yield.‘Zijin Hongxia’ performed well in Jiangsu Province and its surrounding area

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.

This study aims to explore the molecular regulation mechanism of flower bud dormancy in sweet cherry cultivars that are suitable for growing in South China. Two sweet cherry cultivars（‘Brooks’and‘Summit’）planted in Hangzhou with different chilling requirements were used as materials. Flower buds were collected at three different dormancy stages，namely pre-dormancy stage（S1），endodormancy stage（S2），and pre-budbreak stage（S3）. Transcriptome sequencing was performed to analyze the gene expression differences between these two cultivars. 343，671，and 1 588 differentially expressed genes （DEGs）were obtained in S1，S2，and S3，respectively，and the number of DEGs in S3 was the largest. GO analysis revealed that the DEGs between the two cultivars were mainly enriched in the processes related to cellular component organization，cellular metabolism，response to stimulus，and transporter activity in the dormancy stages. KEGG analysis showed that the DEGs concentrated in S3，which involved sugar metabolism，protein processing，plant-pathogen interaction，and plant hormone signal transduction. The expression trends of some DEGs suggested their roles in regulating the transition of dormancy state of flower buds in sweet cherry. Forty-two differentially expressed transcription factors including nine families were obtained by predictive analysis of transcription factors. The expression levels of 13 transcription factors belonging to AP2/ERF，MYB，WRKY，C2H2，C3H，and MADS-box family in S2 were significantly higher than those in S1 and S3，suggesting that these transcription factors may be involved in the regulation of flower bud dormancy.

‘Qinfu 1’is a bud sport strain selected and bred from‘Karakida Fuji’. The skin of the fruit is easy coloring；the yield and quality of this cultivar are excellent，and the resistance to apple ring rot disease is very strong. The fruit is oblong with a fruit shape index of 0.88 and an average fruit weight of 320 g. The flesh is milky yellow，fine and brittle，with rich flavor，18% soluble solids content，0.21% titratable acidity，and 8.6 kg · cm-2 of average peeling hardness. It has good compatibility with dwarf intermediate rootstocks such as CG80 and M26，and can bear fruit on long，medium and short branches. It can be cultivated without bagging. It is a new late ripening apple cultivar，matured in early November in Qingdao. The yield is 60 000 kg · hm-2. It is suitable for cultivation in Jiaodong Peninsula and other regions.

MYB gene family members of Agapanthus praecox were identified by bioinformatics methods and the function of key genes that regulate blue flower coloration was verified. In total，123 ApMYBs were identified based on full-length transcriptome sequencing data，including 60 R2R3-MYBs，four 3R-MYBs，two 4R-MYBs and 57 1R-MYBs. Then，the R2R3-MYBs that regulate flavonoid biosynthesis were further analyzed. R2R3-MYBs were divided into 22 subgroups（A1-A22），together with A18（S4），A17（S5）and A16（S7）subgroups were all related to flower coloration，except for S6 subgroup. ApMYB4，ApMYB6，ApMYB7，ApMYB12，ApMYB111 and ApMYB123 were all localized in the nuclei. Whereas，ApMYB123 was especially concentrated in the nucleolus. During blue flower coloration，ApMYB12 was significantly up-regulated，while ApMYB111 was opposite. White flowers showed increased expression of ApMYB4，ApMYB6 and ApMYB7 compared to blue flowers，indicating them as the negative regulators of coloration. A specific expression peak of ApMYB123 was arisen in bloom stage of white flowers，suggesting biosynthesis of proanthocyanidins. Further ectopic expression of ApMYB12 in tobacco found that the petal color turned lighter than wild type plants. In addition，the anthocyanin content reduced by 54.55%-62.50% while the flavonols content increased by 125%-170%. These results demonstrated that ApMYB12 regulated the biosynthesis of auxiliary pigment flavonols，thereby regulating the coloration of blue flower.

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.

In order to identify the pathogen of Impatiens hawkeri root rot，two pathogenic strains were isolated from diseased roots by tissue separation method. Based on morphological characteristics and ITS and COX II sequences analysis，the pathogen strains were finally identified as Phytopythium helicoides. Inoculating the pathogen on the healthy roots，stems and leaves reproduced the heavy symptoms observed according to the Koch’s rule. The determination of host range showed that P. helicoides could infect not only I. hawkeri，but also I. balsamina，Begonia cucullata，B. elatior，Pelargonium hortorum，Rosa hybrida，R. rugosa，Fuchsia hybrida，Crassula arborescens and Kalanchoe blossfeldiana. In culture tests，the optimum for mycelial growth were at 27-32 ℃ at pH 6-7. Additionally，the toxic effect of ten fungicides against pathogen were evaluated in vitro. Among them 10% oxathiapiprolin OD，98% hymexazol SP，40% dimethomorph WG and 80% mancozeb WP performed good inhibition effects.

Brassica juncea can enrich a variety of heavy metals. Heavy metal transporting ATPase（HMA）plays an important role in the process of transporting heavy metals in plants. Based on genomic and transcriptomic data，the HMA gene family members in B. juncea were identified. A total of 27 HMA genes were found in B. juncea genome. Six of these HMA proteins have instability indexes greater than 40. Twenty-two members are hydrophobic proteins. These genes cluster into three subfamilies，P-1B-1，P-1B-2，and P-1B-4. All the HMAs are membrane proteins containing the E1-E2 ATPase and hydrolase domains. Each HMA protein contains 1-8 motifs. Different subfamilies have unique conserved motifs according to the types of heavy metals transported by them. In the promoter regions of the HMA genes，the cis-acting element TGA related to the regulation of growth and development，the cis-acting elements ABRE，MBS，LTR，and TC related to the regulation of stress response are widely distributed. Under cadmium（Cd）stress，BjuA033764，BjuB019118，BjuB035256，and BjuB045293 were up-regulated in leaves，and BjuA003596，BjuB040613，and BjuA025022 were up-regulated in roots，indicating their involvement in the response to Cd stress.

The antagonistic bacteria against Erwinia amylovorawhich were isolated from plant fermentation were used as the test strains，among which Bacillus velezensis FX1 rescreened out by using perforation-inhibition zone method and co-cultivation method respectively. The results showed that the filtered fermentation broth of FX1 had the strongest antibacterial activity against E. amylovora，and the diameter of inhibition zone was 26.11 mm，after co-culture with the bacteria，the antibacterial rate was 99.99%. The antimicrobial activity of crude extracts from fermentation filtrate of FX1 extracted by different methods were compared. The acid precipitation，ammonium sulphate saturation precipitation and n-butanol extract methods were used for the crude extracts of this strain，and the crude extracts obtained by the acid precipitation and ammonium sulphate saturation precipitation methods exhibited significant antibacterial activity，with the acid precipitation extract showing the strongest antibacterial activity. The biocontrol functional genes were amplified by specific primers，and the gene fragments of bmyB，fenD，ituC，srfAA，srfAB，bioA，yngG，yndJ and TasA were amplified from genomic DNA of the FX1，which showed that the strain may produce lipopetide and antibacterial protein metabolites. The preventive efficacy of spraying FX1 strain lipopeptide crude extract，filtered fermentation broth and fermentation broth in vitro inflorescences of Korla Fragrant Pear for 3-5 d were 79.07%，56.85%，50.02%，respectively. The preventive and therapeutic effects on Pyrus betulaefolia seedlings for 7-15 days were 72.64%，72.85% and 71.54%，61.59%，52.02% and 56.03%，respectively. And the preventive effects was similar to that of agricultural streptomycin（82.33%）. The antibacterial substances of B. velezensis FX1 showed obvious preventive and therapeutic effect on E. amylovora，and has the potential for future in-depth research，development，and application in biocontrol fire blight disease.

‘Yanqingyu’，a new early-ripening green apple cultivar，is derived from the cross between ‘Jinshuai’and‘Lanpengwang’. The fruit is nearly round with the fruit shape index of 0.85 and an average single fruit weight of 226.5 g；The peel is green and smooth without rust. The flesh is yellow white，crisp， rich in flavor. The hardness is 8.4 kg · cm-2，the soluble solids content is 14.2%，the vitamin C content is 31.9 mg · kg-1，and the titratable acid content is 0.28%. In the Yantai area of Shandong Province，the fruit ripens in late August，with a fruit development period of about 120 days and an average yield of 4 000 kg · hm-2. It has strong disease resistance，high resistance to apple trunk ring and rot disease，and is suitable for baggless cultivation.