A squalene synthase（SQS）gene was isolated from 18 citrus accessions,and its sequence and expression characteristics were analyzed. The roles in the biosynthesis of limonoids were identified by genetic transformation. The results showed that the full length of SQS ORF（open reading frame）in citrus is 1 242 bp,coding 413 amino acids except in the accessions of Rongan Kumquat（Fortunella classifalia）and Xiaoguo Kumquat（F. margarita）. Clustal analysis showed that the deduced amino acids of SQS shared from 97.1% to 100% homology among the 18 citrus accessions. SQS in Xiaoguo kumquat,Rongan kumquat,and No.4 Ichang Papeda（Citrus ichangensis）shared a G/C nonsynonymous mutation at the fourteenth nucleotide of CDS region. Phylogenetic analysis result of SQS proteins showed that the SQS of those accessions clustered together. qRT-PCR analysis showed that the highest expression of SQS was observed in flower,followed by that in stem,root,leaf,and young fruit. The expression level of SQS gene is positively correlated with the limonoids contents in seeds of Guanxi Mi You（C. grandis）variety at different development stages. Four positive SQS interference transgenic citrus plants（SiN-1-SiN-4）were obtained via citrus genetic transformation. The expression levels of SQS gene in four transgenic lines were 61.00% to 79.00% of the control plants. Obvious deduction on limonin content was observed in all the four transgenic lines（about 35.83% to 81.56% of the control plants）. The contents of nomilin in SiN-1 and SiN-2 lines were decreased to 80.11% and 94.94% of the control,respectively. However,the nomilin content increased by 52.76% and 35.30% in SiN-3 and SiN-4 lines,respectively. The expression levels of genes belonging to oxidosqualene cyclase（OSC）superfamily involved in triterpenoids and sterol biosynthesis were down-regulated in SQS interference transgenic citrus plants. This may due to the reduced supply of precursor for triterpenoids and sterol biosynthesis. This study indicated that SQS gene contributed greatly to the production of limonoids in citrus.

In order to explore the role of heat shock protein(HSP90)gene family members in heat tolerance of apple(Malus × domestica Borkh.),bioinformatics method was used to identify the apple HSP90 gene family members,and their physicochemical properties,gene structure,cis elements,phylogenetic relationship and expression characteristics of HSP90 gene family under high temperature stress as well as in different tissues were analyzed. The results showed that a total of 11 HSP90 family members were identified in apple genome,which were distributed on 10 chromosomes. The amino acid sequence size was ranged from 104 to 818 aa,and molecular weight of protein ranged from 11.81 to 93.58 kD. Transcriptome analysis showed that four genes(MdHSP90-1,MdHSP90-3,MdHSP90-5and MdHSP90-11)of the 11 members were significantly up-regulated under high temperature stress. Subcellular localization analysis showed that MdHSP90-1,MdHSP90-3 and MdHSP90-5 proteins were located in the cell cytoplasm and nucleus,whereas MdHSP90-11 was targeted to the nucleus. Subsequent qRT-PCR analysis showed that the expression trend of the four genes in the two kinds of apple rootstocks were similar,the expression level increased greatly in the early stage of high temperature stress,and decreased in the middle and late stage. Four genes were also detected in different apple tissues,and the expressions of fourHSP90 genes were induced by heat stress to varying degrees,which indicated that the above four HSP90 genes may play an important role in the heat tolerance of apple.

In order to investigate the structure and function of Chalcone Synthase from Clivia miniata,members of CHS gene family were screened and identified based on the previously constructed transcriptome database. The results showed that four CmCHSs（CmCHS1,CmCHS2,CmCHS3 and CmCHS4）genes were cloned in C. miniata. The open reading frames of the four CmCHSs were 1 173,1 170,1 173 and 1 173 bp and encoding 390,389,390,390 respectively. Amino acid sequence that CmCHSs had typical the conserved domains. Phylogenetic tree analysis showed that the four CmCHS genes clustered with the bona-fide CHSs from other plants and belonged to type Ⅲ polyketide synthase（PKS）super family. The results of subcellular localization showed that they were localized in the cytoplasm and nucleus. Gene expressionanalysis showed CmCHS1 and CmCHS2 were highly expressed at the late stage of flower development process,and the transcripts of CmCHS1,CmCHS2 and CmCHS3 were confirmed to the extensively detected in pigmented leaves and red fruit peels. In contrast,the expression level of CmCHS4 gene was relatively low. In order to firmly verified the roles of CmCHSs in the biosynthesis of anthocyanins,prokaryotic expression vectors,pET-32-CmCHS,were constructed and recombinant proteins were prepared and purified,which were subjected to in vitro enzyme activity analysis. Results showed that the four CmCHS recombinant proteins could catalyze coumarinyl-CoA and malonyl-Coenzyme A into naringenin chalcone. This study explored the bioinformatics analysis,gene expression analysis,and functional analysis of CmCHS genes,and laid a theoretical foundation for the genetic transformation and flower color improvement of C. miniata.

The sexual propagation of Hemerocallis citrina‘Datong Huanghua’was determined by the flowering characteristics and breeding system. To promote the process of hybrid breeding,we investigated the flowing traits including the morphological characteristics of flowers,blooming process,pollen vitality changes under varied storage temperatures,stigma receptivity,breeding system types,and hybrid seed setting rate. The results showed that：（1）The flowering period of‘Datong Huanghua’started from mid-to-late June and ended at the end of July or early August. Flower buds at maturity show yellow-green color and turn bright yellow when opened;the florescence last about 12 hours. The pollen grains are oval with clear and deep net-like carvings on the outer wall.（2）With the extension of storage period,the pollen viability exhibited consistent decreasing trends at varied storage temperatures. During the 60-day storage period,the pollen viability was the highest under-80 ℃ storage condition among 25,4,-20 and-40 ℃.（3）After the petals opening,the stigma receptivity increased firstly and reached its maximum at 3 hours;then it started to decrease and lost the receptivity at 30 h.（4）The out crossing index（OCI）of‘Datong Huanghua’was 4 and the ratio of pollen and ovule（P/O）was 2 446.22. The fruit setting rate of natural cross-pollination was significantly higher than that of artificial self-pollination. Therefore,the breeding system of‘Datong Huanghua’is defined as facultative outcrossing type.（5）The multiple parental hybridization experiments revealed that the seed setting rate of‘Datong Huanghua’as male parent was higher than that of female parent.

The variety of ornamental flower colors are due to the diversity of reproductive systems that co-evolved with pollinators,and tightly connected to the evolution of the pollination systems. For human production or aesthetic,plants domestication,cultivation,hand-pollination,and the abuse of chemical insecticides have led to insect pollinators habitat loss and food chain disruption,and the population of insect pollinators decline in agricultural areas,urban green areas and gardens. Therefore,people have begun to pay more attentions to the mechanisms of the adaptation between flower colors and pollinators. In this review,insect perception with flower color,flower epidermal structure and color pattern,flower color polymorphism and regionality driven by insect pollinators,flower color changer and its pollinator attract,imitation and deception of flowers were reviewed. Finally,we briefly summarized the research on the mutualistic and antagonistic interactions of flower color and the insect pollinators,and put the suggestions on how to scientific attract pollinators base on flower color on the construction of wildflower strips and urban garden,improve the breeding efficiency of ornamental plants and cultivating more colorful flowers.

Twenty-seven lily cultivars of seven colour group were used to analyze the lily tepal structure,the pigments exist in upper and lower epidermis of lily tepals. The upper and lower epidermal cells are irregular rectangular in most of the lily cultivars while some epidermal cells present closely regular polygon that contain anthocyanin. At the same time,tepal spots contained anthocyanins. Sixty-one lily cultivars and two wild species of seven colour group were used to analyze the tepal pigment composition,twenty-three kinds of flavonoid compounds,one kind of anthocyanin （ cyaniding-3-O- rutinoside ） and ten carotenoids （ 9Z-violaxanthin,antheraxanthin,9Z-antheraxanthin,mutatoxanthin,capsanthin,lutein,zeaxanthin,β-cryptoxanthin,β-carotene,and 9Z-β-carotene ） were identified by HPLC-QTOF-MS from lily tepal. The lily tepal all contained flavonoids. White tepal mainly contained flavonoids and some cultivars had a tiny amount of carotenoids. Red tepal contained anthocyanins,carotenoids and flavonoids while carotenoids and anthocyanins were the main pigment,flavonoids served as co-pigment. Purple-red and pink tepal contained anthocyanins and flavonoids while yellow and orange tepal mainly contained carotenoids.

Citrus genetic improvement has achieved a great progress during the last six decades in China. A repository harboring more than 1 700 accessions of Rutaceae in Chongqing and an embryogenic callus collection including more than 100 varieties in Wuhan have been established,respectively. Continuing exploration of citrus germplasm resulted in the identification of wild Daoxian tangerine,Honghe papeda and the mini-citrus,a mono-embryonic Hongkong kumquat for functional genmics research. A new type of rootstock,Ziyang Xiangcheng（Citrus junos）has been utilized in Chinese citrus industry. A total of 122 citrus varieties including 121 for scion and one for rootstock have been registered or protected by PVP. Out of the scion varieties,88.5% is from the natural mutation including the bud-sport and chance seedling variation,and the rest from artifically created mutants,such as the irradiation,hybridization and protoplast fusion etc. These varieties covered nearly all types of citrus,including loose-skin mandarin,sweet orange and pummelo etc,with improved seedlessness,mature season and fruit color etc. The omics technologies have been widely used in citrus genetic improvement in China. Genomes including sweet orange and other main citrus species have been sequenced and assembled during the recent decade,as has accelerated cloning of the key genes controlling import agronomic traits,such as the polyembryonic related gene CitRWP etc. Genetic transformation and gene editing are also setup in Citrus. These achievments have laid a solid base for citrus genome-design breeding for the future.

Flower color is one of the most obvious ornamental character for lotus（Nelumbo Adans.）. The flavonoids are the dominant pigments in lotus petals. A series of key enzyme genes and transcription factors related to the biosynthesis of flavonoids regulate flower color. However,lotus is not rich in flower color and the innovation of which has been a bottleneck in lotus breeding. Elucidating the mechanism of flower color formation is of great significance for molecular color breeding. This paper will review and summarize researches on flower color breeding of lotus,the chemical and molecular mechanism for the formation of lotus flower color,which will serve as significant theoretical basis for breeding of lotus cultivars with novel and excellent flower color.

To evaluate the effect of apple dwarfing rootstocks on the scion growth and drought resistance,we used four-year-old apple trees with different scion-rootstock combinations（‘Fuji’/G935,‘Fuji’/M9-T337 and‘Fuji’/SH6）. Morphology analysis of these three apple trees showed that‘Fuji’scion grown on SH6 exhibited significantly reduced leaf thickness,palisade tissue thickness and stomatal density compared with the‘Fuji’grafted on G935 and M9-T337. Furthermore,three kinds of apple trees were exposed to drought stress treatment for determining their drought tolerance and recovery feature after re-watering. The analysis of drought-related physiology parameters indicated that compared with the other two grafted combinations,the‘Fuji’/SH6 combination displayed enhanced water use efficiency（WUE）,osmoregulation substance content,superoxide dismutase（SOD）activity and ABA content,and the reduced malondialdehyde（MDA）content,net photosynthetic rate（P_n）,transpiration rate（T_r）and stomatal conductance（G_s）under drought stress. The results of membership function analysis showed that‘Fuji’/SH6 had the optimal drought resistance,followed by‘Fuji’/G935,and‘Fuji’/M9-T337 had the worst drought resistance. Overall,‘Fuji’/SH6 grafted combination showed excellent drought resistance.

In this study，apple whole-genome data were used to identify and conduct a biological analysis of the MdTOPP gene family. A total of 44 TOPP genes were systematically identified from apple genome，and they distributed on 15 chromosomes. The phylogenetic tree analysis showed that MdTOPP，PpTOPP and AtTOPP were highly homologous；the gene structure and conserved domain analysis showed that 1-2 exons，0-20 introns and 10 conserved motifs were in MdTOPP genes. The promoter cis-acting element analysis showed that the MdTOPP genes were not only affected by the external environment such as light and heat，but also comprehensively regulated by multiple hormones. All the MdTOPP genes have distinctive expression patterns in different apple tissues. MdTOPP13 and MdTOPP28 were identified from the transcriptome data of exogenous cytokinin（6-BA and TDZ）induced apple axillary bud outgrowth，and cloning sequence alignment showed high homology. Using quantitative real-time PCR，the expressions of MdTOPP13 and MdTOPP28 were upregulated after exogenous 6-BA or TDZ applied on the axillary buds of apple rootstock‘SH40’. In summary，MdTOPP13 and MdTOPP28 may play an important role in mediating cytokinin regulation of axillary bud outgrowth.

Conducted a systematic review on the anthocyanin biosynthesis in horticultural crops regulated by various light factors,e.g. intensity,quality,and photoperiod,based on the literatures in the last three decades. Key transcription factors,their functional mechanism,and the entire molecular regulatory network related to this biological process were summarized.

In order to explore the effects of water stress on volatile compounds of grape berries,the 10-year-old table grape variety ‘Muscat Hamburg’ under three different water states were used as materials. Gas chromatography-mass spectrometry(GC-MS)was employed to analyze volatile composition,the expression of relevant genes of the berries at different development stages were determined by qRT-PCR. The results showed that water stress could reduce 100-berry weight and the content of soluble solids,there was no significant difference on titratable acid and total phenol of berries at harvest stage. In this study,41,43 and 33 volatile compounds were detected in control,light water stress and severe water stress,respectively,in which aldehydes were the main volatile compounds,terpenes were the second,the contents of phenols and esters were at a low level. The total content of volatile compounds in light water stress was 34.74% and 36.92% higher than that in control and severe water stress at ripening stage,respectively. The content of esters,aldehydes and phenols in light water stress was the highest,while the content of alcohols was the lowest. The content of acids and alcohols of severe water stress were significantly higher than that of the other two treatments. The content of terpenes with rose scent increased with the aggravation of water stress. Water stress upregulated the expression of VvTPS of berries,but was not conducive to the expression of VvRiLinNer and VvCCD1. The expression of VvGPPS in light water stress was significantly higher than that in control,but the severe water stress decreased the expression of this gene of berries. In a word,moderate water stress can improve berries quality by increasing the content of volatile compounds of‘Muscat Hamburg’grape.

Malus halliana is a highly saline-alkali-resistant apple rootstock in north-western China. The genes and main pathways which respond to saline-alkali stress were identified by RNA-Seq. This study revealed the mechanism of the response to salt damage and provided theoretical basis for the salt tolerance mechanism of apple rootstocks. Normal water（Hoagland nutrient solution）（Control）supply and mixed saline-alkali stress（Hoagland nutrient solution + 100 mmol · L^-1 NaCl + NaHCO₃）（Treatment）were set up to screen the saline-alkali resistance of each treatment in the growth period. These two samples before and after saline-alkali treatment were analyzed by RNA-seq. The function and pathway enrichment of differentially expressed genes（DEG）were also performed by GO and KEGG analysis. Twenty DEG were randomly selected for further qRT-PCR analysis to verify the RNA-seq data. A total of 16 246 DEGs were determined,7 268 genes were up-regulated and 8 978 genes down-regulated under saline-alkali stress. GO analysis fund that the DEGs were considerably differenct in the biological processes,cell components and molecular functions. KEGG analysis indicated that most enriched saline-alkali-responsive genes were mainly involved in signal transduction,carbon metabolism,biosynthesis of amino acids,and other secondary metabolites. DEG mainly focused on calcium signaling pathway,plant hormone signal transduction,phenylalanine metabolism,and carotenoid biosynthesis. qRT-PCR detection results of 20 DEG expression patterns were similar to those of RNA-seq. Among them,aspartate aminotransferase（GOT1）,monodehydroascorbate reductase（NADH）,chalcone isomerase（CHI,E5.5.1.6）,β-carotene 3-hydroxylase（CrtZ）genes were highly expressed during saline-alkali stress. The results indicated that they might play a role in the leaf response to saline-alkali stress. M. halliana is mainly regulated by calcium signal pathway,plant hormone signal transduction,biosynthesis of amino acids, carotenoid biosynthesis and other secondary metabolites to respond to saline-alkali stress.

Flavonoids are a class of secondary metabolites with ‘flavan’ skeleton and thousands of derivatives. The biosynthetic pathways of flavonoids are complicated，and some of them and related enzymes have been analyzed. Flavonoids play important roles in the growth and development of plants and the formation of flowers and fruits. Studies revealed that flavonoids can response to stresses and improve the tolerance and resistance of plants. This article reviews the biosynthetic pathways and molecular regulation mechanism of flavonoids in plants，the response of flavonoid pathways to different stresses，the main roles and mechanisms of flavonoids，and the future research directions. Thus，this article is expected to providing theoretical support for the targeted cultivation of horticultural crop varieties with highly resistant，deep processing，and product development.

A new R2R3-MYB gene AaMYB6 with GenBank accession number MZ171064 was isolated from the spadix of Anthurium andraeanum‘Pink Champion’based on the information from previous transcriptome data for identification of transcription factor genes associated with anthocyanin biosynthesis. The function of AaMYB6 was analyzed through the assays such as amino acid sequence alignment,phylogenetic tree analysis,subcellular localization,overexpression in tobacco,qRT-PCR,yeast two-hybrid assay（Y2H）,and bimolecular fluorescence complementation（BiFC）. The results suggested that AaMYB6 showed homology with previously identified AaMYB1 from anthurium and belong to C1 subgroup R2R3-MYBs,represented by Zea may C1,that regulate anthocyanin biosynthesis in monocots. AaMYB6 was proved to be nucleus-localized protein. Overexpression of AaMYB6 in tobacco markedly activated the expression of the enzyme genes NtF3′H,NtDFR,NtANS,NtUFGT,specifically involved in anthocyanin biosynthesis in filaments and promoted the accumulation of anthocyanin pigments. AaMYB6 was mainly expressed in the spadix of‘Rapido’. And the expression of AaMYB6 was closely linked to anthocyanin accumulation in the spadix of various cultivars. The interaction between AaMYB6 and the AabHLH1 protein,which was identified previously to regulate the biosynthesis of anthocyanin and proanthocyanidin in anthurium,was confirmed by Y2H and BiFC assays. The results indicated that AaMYB6 play a role in the regulation of anthocyanin biosynthesis in anthurium.

There are three fruit-dropping peaks in grape growth and development. Grape fruit-dropping phenomenon is more serious in Kyoho grapevine. In this study,a cytokinin response regulator VlRR5 was cloned from Kyoho grapevine,which has a phosphoric acid receptor domain（REC）and a MYB-like DNA binding domain. Sequence analysis revealed that cDNA of VlRR5 was 2 597 bp in length,encoding 693 amino acids,and located on chromosome 4 of grape. Subcellular localization assay showed that VlRR5 was localized in the nucleus. The yeast transformed into pGBKT7-VlRR5 could grow normally and turn blue on SD/-Trp/-Ade/-His/+X-α-Gal deficient medium,which proved that VlRR5 was a transcription factor with transcriptional activation activity. By quantitative real-time PCR analysis,VlRR5 was characterized by tissue specific expression and showed high expression level in leaf and stem,which was increased and then decreased in the development stage of young fruit. The expression level increased after treatment with exogenous cytokinin,and decreased after treatment with the cytokinin synthesis inhibitor lovastatin. These results indicated that VlRR5 can respond to cytokinin and plays an important role in participating in cytokinin to improve the fruiting rate of grape.

The WRKY genes of carnation（DcaWRKY）were identified from Dianthus caryophyllus genomic database based on the WRKY protein sequences of Arabidopsis thaliana and the conserved domain sequence of WRKY proteins（PF03106）. In total,53 DcaWRKY members were identified in the carnation genome,with the amino acid size,molecular weight of protein（average）,isoelectric point and the gene intron numbers varying from 161-747 aa,18.27-82.58 kD,5.10-10.52 and 1-5 respectively. According to phylogenetic analysis,DcaWRKYs can be divided into three groups and groupⅡcan be further divided into five subgroups. DcaWRKY conserved domain analysis revealed three mutations in the WRKY domain,the WRKYGQK heptapeptide domain in N terminal of DcaWRKY20 were lack of ‘YGQK’and formatted the missing variant WRK,and the K in the heptapeptide domain of WRKYGQK at the C terminal of DcaWRKY39 is mutated to N,forming the heptapeptide domain of WRNYGQK and DcaWRKY48 is the WRKYGKK heptapeptide domain. In addition,Conserved motifs analysis showed that there were at least 10 motifs in DcaWRKY members and they have similar conserved motifs when they are in a closer phylogenetic relationship. Cis-acting element analysis in the promoter region showed that DcaWRKYs contained a large number of functional domains related to light signal,plant hormone,stress and meristem. Based on the transcriptomic data analysis,there were 20 DcaWRKY gene family members up-regulated or down-regulated during adventitious root formation,and we speculated that these genes may play an important role in the formation of adventitious roots in carnations cuttings. And the qRT-PCR analysis revealed that the mRNA expression patterns of DcaWRKY11,DcaWRKY13,DcaWRKY15,DcaWRKY22,DcaWRKY23,DcaWRKY31 and DcaWRKY39 showed a fairly good match to the RNA-seq analysis and showed diversity in the growth process of adventitious roots. In addition,there was no significant difference in the expression of DcaWRKYs between auxin group and control group,indicating that the DcaWRKYs is not sensitive to auxin.

To explore the functions of SAUR（Small Auxin-up RNA）gene family in plant growth and development，bioinformatics methods were used to identify the SAUR genes in peach（Prunus persica）. The chromosome location，gene structure，evolutionary relationship and gene expression were analyzed，and the function of PpSAUR5 was verified through transgenic method. A total of 80 PpSAUR members were identified and divided into 12 subgroups，which were unevenly distributed on the eight chromosomes. The analysis of gene structure showed that 75 PpSAUR genes contained only one exon，and five genes contained two to three exons. Eighteen SAUR genes were found to be associated with tree growth through RNA-seq analysis. These genes exhibited different expression patterns in response to exogenous hormone.Among them，PpSAUR5 was induced by both IAA and GA. PpSAUR5 transgenic Arabidopsis exhibited longer petiole，hypocotyl，root，and less sensitivity to NAA and 2,4-D treatment than wild-type. The results indicated that PpSAUR5 functioned to promote organ elongation.

To survey the effect of calcium treatment on the microstructure,wax composition of the fruit skin and aroma emission of pear cultivar‘Nanguoli',the fruits at 15 d before commercial maturity date were treated by 0.04 kg · L^-1 calcium chloride. As a result,the significant differences of microstructure,cell arrangement and wax composition were observed between the fruit with calcium treatment and control（sprayed water）at commercial maturity and five days during post-maturity. In detail,the abscission of wax layer and the intercellular spaces of epidermal cells were larger in the fruit with calcium treatment compared to the control. However,the intactness of lenticels in the fruit with calcium treatment were better than that in the control fruit. The wax composition of fruit skin of‘Nanguoli'pear comprised by fatty acids,esters,fatty alcohol,aldehydes,alkanes,phenols and alkenes. Of these compounds,fatty acids,Fatty alcohol,alkanes and aldehydes had higher contents than the other compounds. Noteworthy,the contents of esters,fatty acids and aldehydes were increased in the fruits with calcium treatment compared to the control. The total contents of volatile aroma compounds in calcium-treated fruit were 3 959.75 and 6 676.80 ng · g^-1 at commercial ripening stage and five days during post-maturity,respectively,which were 20.92% and 24.16% higher than those of the control. These results suggest that calcium treatment promotes aroma emission by affecting the microstructure and wax composition of the fruit skin of‘Nanguoli'pear.

This paper reviewed the pigment composition,key enzymes and transcription factors involved in flavonoid biosynthesis,flower color genetic characteristics,as well as flower color breeding,and discussed the existing problems and development prospects in the research of flower color of rose. The objective of this work was to provide a reference for flower color breeding of rose.