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.
Taking the twisted tortuous branch segment and twisted straight branch segment of annual branches in Ziziphus jujuba Mill. var. tortuosa as experimental materials,the morphological,anatomical and vessel characteristics of its branches were observed and compared by xylotomy and wood segregation techniques. The differences of anatomical structures between twisted tortuous branch segment and twisted straight branch segment were mainly manifested in the number,shape and distribution of abnormal secondary structures. Compared with the twisted straight branch segment,the number of auxillary bundles in twisted tortuous branch segments was more,and there were three auxillary bundles adjacent to each other,which were relatively concentrated in the inner bend of the segments;The number of interxylary phloem was about the same as that of the twisted straight branch segment,and its end expanded,which was different from the slightly curved elliptic columnar shape of the twisted straight branch segment,and relatively concentrated in the outer bend of the segments;The number of medullary vascular bundles was slightly reduced. At the cellular level,the vessel elements at the inner and outer bends of the twisted tortuous branch segments of the variety were all reticulate vessels with single perforation and various shapes. Among them,the number of vessel elements with tails at both ends and sloped at both ends at the inner bend were 28.0% and 20.2% less than those at the outer bend,respectively. The number of vessels without tails at either ends,sloped at one end and horizontal at both ends were 17.9%,375.0% and 200.0% more,respectively. The number of vessels with one tail at one end was the same. The end wall slope of end wall was 10.1% larger than that at the outer bend,and the length of vessel element was 16.4% shorter than that at the outer bend,while the diameter was 18.6% smaller than that at the outer bend. The hypothesis of “abnormal structure-spatial difference-coordination”was put forward. The tortuous branch traits of Z. jujuba var. tortuosa may be the result of the unbalanced growth rates and forces at different locations of the branches caused by the spatial difference and coordination of the number,the mechanical tension,the transport and utilization of the assimilated products of the three abnormal secondary structures,namely the auxillary bundle,interxylary phloem and medullary bundle.
Based on the amino acid sequence of Arabidopsis SKP1-like,the SKP1-like members were identified in the longan genome database to explore the molecular characteristics and its expression patterns during early somatic embryogenesis in Dimocarpus longan. In the meanwhile,bioinformatics methods were used to analyse the physical and chemical properties of its protein,system evolution characteristics,chromosome positioning,collinearity and selective pressure,gene structure,conserved motifs,protein structure,protein interaction network,promoter cis-elements. The results showed that there were 14 SKP1-like family members in longan,which were named as DlSKP1-1-DlSKP1-14. The number of amino acids,molecular weight and isoelectric point of proteins encoded by the family genes were 75 to 399 aa,8.29 to 45.34 kD,and 4.44 to 5.76,respectively. They did not contain signal peptides and might be mainly located in chloroplast. There were one pair of tandem repeat genes and four pairs of fragment repeat genes in the DlSKP1 family. The protein interaction prediction results suggested that DlSKP1 family members might interact with multiple proteins（especially F-Box family proteins）. The results of the promoter cis-acting elements showed that the promoters of DlSKP1 family members contained more abscisic acid（ABA）and methyl jasmonate（MeJA）response elements. In addition,longan DlSKP1 members had five different expression patterns during early somatic embryogenesis,among which three members（DlSKP1-6,DlSKP1-8,DlSKP1-13）had higher expression levels than other members at each stage. The results of the study indicated that DlSKP1 family members might interact with the F-Box proteins,participate in the regulation of ABA and MeJA,and also play an important role in the morphogenesis of longan somatic embryos.
The study compared the low temperature response mechanism of loquat（Eriobotrya japonica Lindl.）flowers and fruits at different developmental stages. Flower buds,fully open flowers and young fruits were used as the experimental materials,treated at-3 ℃ for 12 h,and samples without low temperature treatment were used as controls. The relevant physiological and biochemical indexes,as well as transcriptome were determined both in control and treated samples. Low temperature stress led to the destruction of cell membranes,the generation rate of superoxide anion,the content of malondialdehyde and proline,and the activity of antioxidant enzymes were dramatically increased. In general,the low temperature resistance ability was flower bud > flower > young fruit. Transcriptome sequencing analysis obtained a total of 6 987 differentially expressed genes（DEG）. A large number of metabolic pathways related to low temperature stress were found,including glycolysis/gluconeogenesis,glyoxylic acid and dicarboxylic acid metabolism and phosphoinositol metabolism pathways in carbohydrate metabolism,tryptophan metabolism and tyrosine metabolism pathways in amino acid metabolism,glycerol phospholipid metabolism,α-linolenic acid metabolism and glyceride metabolism pathways in ester metabolism,isoquinoline alkaloid biosynthesis pathway in secondary metabolism,as well as thiometabolism pathway in energy metabolism,were significantly enriched in all comparison groups of low temperature and control at three flower and fruit development stages,which indicated that these pathways were important metabolic pathways in response to low temperature stress in loquat. The phenylpropanoid biosynthesis pathway was significantly enriched in both flower bud and flower comparison groups,and more amino acid metabolism pathways were enriched in young fruit comparison group after low temperature treatment. In addition,53 AP2-EREBP genes,14 WRKY genes and 15 NAC genes were screened from the differentially expressed genes related to low temperature treatment,and 12 low temperature response-related transcription factor genes were analyzed by qRT-PCR,which further confirmed the accuracy of transcriptome data.
In this study,combined with bioinformatics,biochemistry and genetics methods,the biological function of the evolutionary conserved site T111 of tryptophan transaminase TAA1（Tryptophan aminotransferase of Arabidopsis 1）in strawberry（Fragaria vesca）were studied. Though gene expression analysis,it was found that strawberry FveTAA1 was up-regulated during fruit expansion and fruit ripening stages,suggesting that it may have important biological function during fruit development. Based on bioinformatics analysis,it was found that the 111th threonine（T111）of FveTAA1 protein,which is highly evolutional conserved,may have an important biological function. Through biochemical detection,it was found when T111 was mutated to alanine T111A,a simulated non-phosphorylation version,or aspartic acid T111D,a simulated phosphorylation version,FveTAA1 will lose its tryptophan aminotransferase activity,which suggests that this site maybe significant for its function. Using genetic methods,it was found that FveTAA1 WT could complement the genetic phenotype of TAA1/TAR mutant in Arabidopsis whereas FveTAA1 T111A / T111D could not,which further proved that FveTAA1 T111 site plays a key role for its biological function. Overall,these results not only support the evolutionary conservative regulation mechanism of auxin synthesis,but also provide a theoretical basis for the study of the regulation mechanism of auxin synthesis in fruit development and ripening process in strawberry.
In order to understand the sequence characteristics of circadian clock-related genes REVEILLEs（RVEs）in garlic and their roles in osmotic stress response,AsRVE1 and AsRVE2 genes were isolated from garlic,and their expression patterns under salt stress and simulated drought stress were analyzed by qRT-PCR. Sequence analysis showed that the open reading frames of AsRVE1 and AsRVE2 genes were 1 050 and 975 bp in length,encoding 349 and 324 amino acids,respectively. In terms of evolutionary relationship,AsRVE1 and AsRVE2 were relatively close to ZmRVE2 in corn and AcRVE2 in pineapple. The RVE amino acid sequences of different plants had low homology,but showed high consistency in the conserved domain at the N-terminus. Both AsRVE1 and AsRVE2 genes can respond to changes in circadian rhythms,and their expression can be detected in different tissues;the expression of AsRVE1 in different tissues was not obviously different,the expression of AsRVE2 in the roots was relatively high. Both drought stress and salt stress induced the altered expression of AsRVE1 and AsRVE2 genes in different tissues. These results indicated that AsRVE1 and AsRVE2 genes may be involved in drought- and salt-stress response in garlic. The AsRVE1 and AsRVE2 genes cloned in this study laid a foundation for further identification of the biological functions and regulatory mechanisms of RVE.
In this study,the cluster analysis,principal component analysis,and multivariate evaluation of 26 phenotypic traits were carried out to evaluate the genetic diversity of 110 cherry tomato germplasm resources in South China. The results showed that high variation,phenotypic diversity,and genetic diversity were assessed in the 110 cherry tomato germplasm resources. The genetic diversity index of 26 phenotypic traits ranged from 0.33 to 2.04. The highest genetic diversity index was detected for the glucose/total soluble sugar（2.04）. The mean value of the variation coefficient of the 19 quantitative indexes was 31.41%,and the highest variation coefficient was observed in lycopene content（80.41%）. The 110 cherry tomato resources were divided into five groups by systematic clustering. The germplasms in groupⅠimplied the good potential for genetic improvement. The germplasms in group Ⅲ could be mainly used for the selection of flavor breeding genotypes of cherry tomato. The germplasms in groupⅤcould be mainly used for the selection of functional breeding genotypes of the cherry tomato. The principal component analysis and comprehensive evaluation indicated that the cumulative contribution rate of the nine main components was 75.512%. The first and third principal components mainly reflected the fruit quality of the cherry tomato. The second and fourth principal components mainly reflected the appearance quality of the cherry tomato fruit. The fifth and sixth principal components mainly reflected the growth characteristics of the cherry tomato plant. The comprehensive score of the germplasms ranged from -1.548 to 1.460. The five germplasms with high comprehensive scores were ct092,ct028,ct018,ct090,and ct017 which could be used as the core breeding resources.
In order to reveal the key factor influencing the regeneration vigor of different cucumber （Cucumis sativus L.）and optimize the cucumber in vitro regeneration system. The effect of endogenous hormone levels and exogenous hormone treatments on the differentiation rate,the number and morphology of adventitious buds were investigated in cotyledon node explants of 10 different genotypes. The results showed that the differentiation rate of the 10 materials was significantly different in the absence of exogenous hormones,and the endogenous CTK level was positively correlated with the differentiation rate,with correlation coefficients were 0.4544 （0 d incubation）and 0.6110（14 d incubation）,respectively. The differentiation rates of different genotypes were increased from 5.95% ~ 20.45% to 42.39% ~ 80.43% by 1.5 mg · L-16-BA treatment. Morphology observation showed there were two different types of adventitious buds,typeⅠbuds：leaf blade stretching and visible culm,typeⅡbuds：deformity bud with leaf blade and no visible culm. The proportion of the formation of typeⅠand typeⅡadventitious buds were significantly different in different genotypes. The regeneration rates of the genotypes with a high ratio of typeⅠ/Ⅱadventitious buds were significantly higher than that of the genotypes with a low ratio. Correlation analysis showed that the typeⅠ/Ⅱexplant ratio was closely correlated with the IAA/ABA ratio（R2= 0.4214）,and the ratio of typeⅠ/Ⅱadventitious buds was obviously positive correlation with the rate of regeneration seedings（R2= 0.5623）. For the genotype C5 and C6,which had a low typeⅠ/Ⅱexplant ratio（0.52 and 0.46）,adventitious buds ratio and low rate of regeneration seedings,different proportion of exogenous NAA and ABA was added to the induction medium,it was found that typeⅠ/Ⅱexplants ratio（1.65 and 1.15）,adventitious buds ratio（1.81 and 1.17）and the regeneration rate（48.57% and 53.33%）were significantly improved when the NAA/ABA ratio was 0.01/0.1.
In order to study the resistant mechanism of Dendrobium catenatum response to temperature stress,the heat shock protein 70（HSP70）gene families were identified using bioinformatics methods. Meanwhile,the expression profiles of HSP70 genes in different tissues and under high（42 ℃）and low（4 ℃）temperatures were assayed by quantitative real time PCR（qRT-PCR）method. The results showed that 10 HSP70 genes were identified from D. catenatum,which encode 628 to 702 amino acids, the molecular weight was between 69.65 to 75.15 kD,and the theoretical isoelectric point ranged from 5.12 to 6.18. The HSP70 proteins were divided into four subgroups by phylogenetic tree analysis,and the conserved motifs of each subgroup were similar. Structural analysis showed that the number of introns in HSP70 gene varied from one to seven. Spatial expression pattern analysis showed that HSP70 gene expression was tissue specific and the highest expression was found in gynostemium. The expression levels of DcHSP7-1 and DcHSP70-7 increased after low temperature treatment,which indicated that DcHSP70-1 and DcHSP70-7 responded to cold stress. While the relative expression of DcHSP70-2,DcHSP70-3,DcHSP70-5 and DcHSP70-7 was up-regulated obviously under high temperatuer,then we can speculate that these genes play key roles in response to heat stress.
The ISSR and rDNA-ITS sequence analysis were used to identify the genetic relationship of 17 wild species of Clematis L. in Hebei Province. The ISSR amplified result was conducted cluster analysis by UPGMA method. After PCR amplification,the ITS sequence characteristics were compared and analyzed by Clustal X,MEGA and other software. Finally,the results of these two molecular markers method were comprehensively analyzed. The results showed that primer combinations can amplify 104 polymorphism bands with the percentage of polymorphic bands（PPB）of 100.0%. The average observed number of alleles（Na）was 2.00;the number of effective alleles（Ne）was 1.3069;the Nei’s gene diversity（H）was 0.2196;the Shannon’s information index（I）was 0.3675. According to the clustering results,17 species were divided into five groups at a genetic distance of 0.66. Moreover,the length of ITS sequences varied from 543 to 561 bp,including 87 variable sites,37 information sites and 50 singleton specific discrimination sites in the 17 Clematis L. species. The genetic distance between C. macropetala and C. ochotensis,C. kirilowii and C. kirilowii var. chaneti was 0,and the genetic distance between C. acerfolia and others was large and the genetic relationship was far.
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 understand the cracking-resistant mechanism of Ziziphus jujuba,the crisp mature fruits of the cracking-resistant‘Wanzao 3’and cracking-susceptible‘Lifu Gongzao’were used as materials to measure fruit firmness and pericarp microstructure in the shoulder,equator and top,and to detect the expression levels of expansin genes in shoulder pericarp of the two cultivars under irrigation using real time PCR,respectively. The results showed that the shoulder of ‘Lifu Gongzao’was cracked after irrigation 30 h. The fruit firmness of the shoulder,equator,and top of‘Wanzao 3’was significantly higher than that of‘Lifu Gongzao’respectively,and the firmness of the equator and top of‘Lifu Gongzao’was significantly higher than that of the shoulder under irrigation. Pericarp cells of‘Wanzao 3’were arranged more tightly and regularly than those of‘Lifu Gongzao’,and pericarp cells of the equator and top of‘Lifu Gongzao’were arranged more tightly and regularly than the shoulder under irrigation. Pericarp thickness of the equator and top of‘Lifu Gongzao’was more than that in the shoulder,however,the increased thickness of the equator and top was less than that of the shoulder under irrigation. The expression levels of EXPA genes ZjEXPA4,ZjEXPA5-like,ZjEXPA6,ZjEXPA14,and ZjEXPA17 in the shoulder pericarp of‘Wanzao 3’were higher than those of‘Lifu Gongzao’under irrigation.
The cultivation of bayberry under rain shelter decrease the harm of rain,besides different light quality of colored rainproof-film have a great influence on the fruit development and quality formation. In this study,five kinds of colored rain-proof films（red,yellow,green,purple,and white）were used to conduct rain-sheltered cultivation before the rainy season approached,and four fruit quality indexes（soluble sugar,titratable acid,total phenol,anthocyanin and ratio of sugar/acid）were monitored during the fruit maturing stages（i.e. white stage,veraison stage,middle maturity stage and late maturity stage）. The results showed that there were obvious differences in light transmittance and light quality composition among the five kinds of colored rainproof-films. For example,the light transmittance of the yellow and red films decreased by 66.21% and 20.02% of the control respectively,but under the yellow film the ratio of red/blue light increased by four times of the control,and the ratio of red/infrared light was close to that of the control. Under the red film the red/blue light ratio increased by 20 times of the control,and the red/infrared ratio was close to that of the control. The transmittance of the green film was 46.8%,and the ratios of red/blue and red/infrared light were 72% and 60% of the control,respectively. The transmittance of purple film was the lowest,only 7.74% of the control,and the ratio of red/infrared light was the lowest and decreased by 40% of the control. In the ripening process,the influence of the rainproof-film on the fruit was mainly reflected in the veraison,which delayed fruit ripening process. The purple and green film delayed the fruit maturation most obviously（veraison was delayed by about 2 d）,while the yellow and red ones did not. Compared with the control,the contents of soluble sugar and anthocyanin of fruit in late maturity stage of the yellow film increased by 12.05% and 12.21%,respectively,and fruit quality of the red film was close. In contrast,the soluble sugar content of fruit in late maturity stage of purple film decreased by 11.14% compared with the control. This is probably due to the difference in the light transmittance and light quality.
In order to explore the change rule of soil medium elements and trace elements content in the condition of long-term continuous cropping of cucumber in solar greenhouse,soil for continuous cropping of cucumber with 2-26 crops were obtained in the solar greenhouse,and the change characteristics of the medium elements and trace elements in the soil were studied. The management patterns of cucumber varieties,cultivation methods,water and fertilizer management,plant management, environmental management and pest control were adopted in the same way. The results showed that soil exchangeable calcium,exchangeable magnesium and the percentage of exchangeable calcium in total calcium decreased with the increase of continuous cropping of cucumber in solar greenhouse. Compared with the 2nd crop,soil exchangeable calcium,exchangeable magnesium and the ratio of exchangeable calcium in total calcium decreased by 8.5%,25.8% and 53.2% in the 26th crop respectively. Compared with the 2nd crop,the soil total calcium increased by 95.9% in the 26th crop,and total magnesium the ratio of exchangeable magnesium in total magnesium had no significant difference between the 2nd crop and the 26th crop. Soil available copper,zinc and molybdenum were enriched to a certain extent. Compared with the 2nd crop,the 26th crop soil available copper,zinc and molybdenum increased by 33.9%,87.3% and 221.7%,respectively. The contents of soil available iron,available manganese and available boron fluctuated with the increase of continuous cropping,and there was no significant difference between the 26th and the 2nd crop. In general,the comprehensive level of the various medium elements and trace elements in the soil of different continuous cropping cucumber gradually increased from 2-8 crops,and then there was a change cycle of first increasing and then decreasing every six crops in the solar greenhouse.
Floral volatile benzenoids/phenylpropanoids（FVBPs）are the second largest class of plant volatile organic compounds（VOCs）. By serving as biological or abiotic stress signals,FVBPs facilitate interactions between flowers and their environments. FVBPs attract pollinators and natural enemies of herbivores. They also help to protect plants from pathogens,parasites and herbivores. In this review,we largely focused on the genes that encode the enzymes responsible for the biosynthesis of FVBPs,the regulation of FVBP biosynthesis and release,and functions of FVBPs in ornamental flowers.
This paper discusses the obstacle mechanism of distant hybridization of woody ornamental plants. It summarized the applications of distant hybridization in breeding,reviews the ways to overcome the barrier of distant hybrization and the latest progress in the identification of hybrid offspring. It shows the opinion that the distant hybridization breeding of woody ornamental plants is supposed to focus on the molecular mechanism of reproductive isolation,making full use of modern biotechnology to seek the ways to overcome pre-fertilization and post-fertilization barriers to cultivate new resources. In addition,fully exploring the wild woody ornamental plant resources is still one of the effective ways to breed varieties of woody ornamental plants.
‘YR Zhonggan 21’is a new spring cabbage cultivar derived from the cytoplasmic male sterile line CMS87-534 and the inbred line YR01-20. The head is round in shape and green in color,with the weight of around 1.0 kg. The leaf head tastes crisp and tender,with high quality. It has broad adaptability,high resistance to Fusarium wilt and high tolerance to premature bolting. It takes about 52 days from transplantation to harvest when planted in the open field in northern China as the spring cabbage.
‘Jianghuaimi 7’is a new late maturing thick skin netted-melon cultivar which was bred from X-25 as female parent and H-3 as male parent. The cultivar has strong growth potential,oval fruit covered with gray green net. It is easy to bear fruit,especially setting in 8-10 knots. The orange red flesh is tender and crispy,3.0 cm in thickness. The soluble solids content is 11%-17%. The average fruit weight is 2 kg. The whole growth period is 112 d. The fruit development period is about 38 d. The yield is 40 260-45 000 kg · hm-2. The cultivar has strong resistance to heat and moderate resistance to powdery mildew and downy mildew. The cultivar is suitable for protected cultivation in spring and autumn in central and eastern China.
A new Hibiscus moscheutos cultivar‘Coastal Purple’is systematically bred from real seeds. The plants are tall perennial herbaceous flowers. Stem is clustered with racemes. The buds are dark purple red（RHS N79A）and the flowers are deep purplish red（RHS 61A）. And the fruit is capsule and small. The plant has good adaptability,salt and alkali resistance,water logging tolerance,and high ornamental value.