Sand culture method was used with Malus hupehensis seedlings as tested materials, 15N isotope tracer was used to study the effects of deficient Zn,moderate Zn and excess Zn（0.5,4 and 16 μmol · L-1 Zn2+）and five methods[keeping in deficient Zn（0.5 μmol · L-1 Zn2+ for 30 d）treatment,Zn concentrations ranged from deficient to excess（0.5 μmol · L-1 Zn2+ 15 d + 16 μmol · L-1Zn2+ 15 d）,moderate stable Zn supply（4 μmol · L-1 Zn2+for 30 d）treatment,Zn concentrations ranged from excess to deficient（16 μmol · L-1 Zn2+ 15 d + 0.5 μmol · L-1Zn2+ 15 d）and keeping in excess Zn（16 μmol · L-1 Zn2+ 30 d）] on the growth,nitrogen absorption and utilization. The results of the two consecutive years of testing showed that at the 30th day after the treatment,the plant dry matter,total length and total surface area of root under moderate stable Zn supply treatment were the largest,and root activity was significantly higher than that under other treatments. Nitrate reductase（NR）activity was the highest in moderate stable zinc supply treatment during the whole treatment period. The results of 15N isotope tracer showed that the 15N absorption and 15N utilization under moderate stable zinc supply treatment were the highest,followed by keeping in excess Zn and Zn concentrations ranged from deficient to excess treatment,and the lowest value was founded in keeping in deficient Zn treatment. All these results indicated that insufficient and excessive zinc supply inhibited root growth and nitrogen assimilation,limited nitrogen absorption,and was not conducive to the growth and development of seedlings. Sustained and stable zinc supply can improve root activity and maintain nitrate reductase activity,so as to achieve efficient absorption and utilization of nitrogen,thus promoting the growth of apple rootstock seedlings.
In this study,a WRKY transcription factor gene,named MdWRKY74（XM_029090147.1）was obtained from apple rootstock M9T337（Malling 9 NAKBT337）. The open reading frame of MdWRKY74 was 939 bp,which encoded 312 amino acids,and contained a typical WRKY domain. Amino acid sequence alignment and phylogenetic tree analysis showed that MdWRKY74 had the highest homology with Pyrus bretschneideri WRKY74. Subcellular localization assays showed that MdWRKY74 was located in the nucleus. Quantitative real-time PCR analysis showed that MdWRKY74 was expressed in different apple tissues. Overexpression of MdWRKY74 in Arabidopsis could improve the salt resistance of plants,and promote the expression of SOS1 and NHX1. The results showed that MdWRKY74 can be induced by salt stress,so it may participate in the regulation of salt resistance in apple.
An early-maturing pear‘Sucui 1’was developed by crossing ‘Huasu’and‘Cuiguan’. The‘Sucui 1’produces fruit with sweet taste,crisp texture and low level of stone cells,so it is well accepted by consumers. To explore biochemical and molecular mechanisms that establish the characteristics of the ripening fruit in‘Sucui 1’,we carried out the metabolic and transcriptomic analysis using UPLC-MS,HPLC,and an amino acid analyzer and RNA-seq approach. The results from the metabolic analysis showed that metabolites such as sugars,organic acids,amino acids and lipids were significantly different between‘Sucui 1’and its parents. Although the total soluble sugar content was similar between‘Sucui 1’and‘Cuiguan’,and the total organic acid content was similar between ‘Sucui 1’and‘Huasu’,the level of sucrose,malate,Asp,Phe,Met,glycerophospholipids and palmitaldehyde was significantly higher in the ripening fruit of‘Sucui 1’. On the other hand,the level of sorbitol and chlorogenic acid was significantly lower in the ripening fruit of‘Sucui 1’compared to ‘Cuiguan’. Differentially expressed genes involved in the biosynthesis pathways of these metabolites were further identified using RNA-Seq. The results from the transcriptomic analysis showed that GO terms such as organic acid biosynthesis,organic substance catabolic process,carbohydrate metabolic process,carboxylic acid biosynthetic process,lipid biosynthetic process and polysaccharide metabolic process were significantly enriched in the comparison of‘Sucui 1’to‘Cuiguan’and‘Huasu’. The higher accumulation of SPS transcripts might be related to the higher level of sucrose in‘Sucui 1’. The higher transcript accumulation of S6PDH and SDH might contribute to its more active sorbitol metabolism. Additionally,the upregulation of FUM1,ICDH,PDH,OGDHL might be related to metabolite accumulations in the TCA cycle. Moreover,differential expression of GAT,GLSN,LASPO,SAMS and DGK1,ACCA,KASC2,ADH2 and PLDA might be related to the higher amino acid and lipid contents in ‘Sucui 1’. These findings provide a foundation for pear quality improvement.
A field experiment was conducted to evaluate the effect of application of liquid Bacillus subtilis micro-fertilizer（BSMF）on nutrient absorption,utilization and fruit quality of citrus at orchard. During two consecutive growing seasons of 2017 and 2018,each plant was applied twice in the late stage of the physiological fruit drop period（June）and fruit expansion period（August）with 200,400,600,800,and 1 000 mL of BSMF solution diluted to 15 L as treatments of BSMF200,BSMF400,BSMF600,BSMF800 and BSMF1000,respectively,and 15 L water for each plant was applied as the control. Soil, leaf,root and fruit samples were collected twice for measuring in late October and late December of the same year. The results showed that the application of BSMF can slow down the decline of P and K content in leaves at the fruit ripening stage by promoting the absorption of available P and K nutrients from soil and the release of soil available P and K,which resulted in maintaining a relatively higher nutrient appropriate level in leaf. At the same time,it not only helps to promote fruit enlargement and increase the weight of single fruit,but also helps to reduce the fruit titratable acidity and improve the solid acid ratio at the fruit mature stage,which makes the fruit bigger and the flavor better. In addition,the fruit juice yield also improved. Considering the cost comprehensively,200 mL · plant-1 of BSMF can promote the release of soil available P and K nutrients and improve the absorption and utilization of soil moisture and nutrients by citrus plants under the experimental conditions,which resulted in maintaining the higher P and K nutrient levels in the fruit ripening stage,and ultimately improving the fruit quality and yield increase.
The whole genome bisulfite sequencing（WGBS）and transcriptome sequencing（RNA-seq）techniques were used to sequence papaya fruit samples at four stages,namely green stage,color break stage,half yellow stage and full yellow stage. The average methylation level of C locus,CG,CHG,and CHH sequence contexts were 17.15%,49.33%,34.30%,and 8.28%,respectively. The level of genome-wide DNA methylation decreased with the ripening of fruit,accompanied by the increased number of differentially expressed genes（DEGs）. Combined analysis of genome-wide DNA methylation and transcriptome data showed that the gene expression presented an obvious positive correlation with promoter and genebody methylation. Four differentially expressed candidate genes possibly responsible for papaya fruit ripening,namely CpACO4,CpPDS,CpXTH30 and CpXTH31,were screened out. Their expression levels and DMRs methylation levels obtained by RT-qPCR and McrBC-PCR matched well with the results of the transcriptome and methylome,respectively. These genes might play an important role in papaya fruit ripening.
The Chinese kale material（14Y12）containing the Ogura CMS fertility restorer gene Rfo was used to introduce the Rfo restorer gene into six excellent Ogura CMS broccoli through cross breeding,and revealed its change characteristics and genetic background from the aspects of agronomic traits,cell level and genetic diversity. The results showed that the agronomic traits of Ogura CMS broccoli hybrids（F1 generation）were biased towards broccoli and genetic segregation was obvious. At the cellular level,there was a significant difference in the pollen viability of Rfo-transformed offsprings（P < 0.05）,and the range was between 70% and 85%. There were abnormal phenomena of unequal division of chromosomes and loss of chromosomes in the late stage of meiosis. The pollen tubes of some Rfo-transformed offspring could be formed normally,while the pollen tube development of some Rfo-transformed offspring was blocked or abnormal. The ploidy identification showed that there were 12 diploids in Rfo-transformed offspring,accounting for 54.55% of the total,and 10 heterozygous ploidy between triploid and tetraploid,accounting for 45.45% of the total. The results of genetic analysis showed that at the genetic similarity coefficient of 0.50. Chinese kale 14Y12,broccoli 17B1253 and their Rfo-transformed offspring could be divided into two categories：A subgroup had 10 copies,with a genetic background biased toward Chinese kale;B subgroup had 22 copies,all of which are broccoli. The genetic similarity coefficient between Rfo-transformed offspring and Chinese kale was from 0.24 to 0.88,among which 19B809-8 had the farthest genetic background to Chinese kale,and the genetic similarity coefficient was 0.24,which could be used as the parent material for the fertility restoration of Ogura broccoli.
In this study,the seedlings leaves of‘Jiangnan Yuanbai’radish（Raphanus sativus）were sprayed with 0,50,100,1 000 and 1 500 μmol · L-1 melatonin solution,the effects of exogenous melatonin on plant biomass,total chlorophyll content,APX enzyme activity,content of H2O2,endogenous melatonin and subcellular structures were measured,disease indexes after Alternaria brassicae inoculation were also detected. It was found that within the concentrations of 50,500 μmol · L-1 melatonin increased growth and resistence of seedling with the increase of concentration,and 500 μmol · L-1 treatment showed the best performance,while the indexes of 1 000 μmol · L-1 and 1 500 μmol · L-1 treatments decreased sharply. The results showed that the melatonin influences radish growth and resistence relying on a dose-dependent effect.RNA-Seq based transcriptome analysis was conducted on 0,500 and 1 500 μmol · L-1melatonin treated samples,eight key DEGs were selected,which were Ubr,acting on photosynthetic regulation,and Aos1,Prp1,Zat-like,Jub1-like,Edr1,Usp and Eda,regulating resistence. The expression pattern of DEGs was consistent with the phenotypic changes of all treatments,showed a dose-dependent pattern.
In order to elucidate the heat resistance mechanism of rhododendron seedlings induced by ethylene,in this study two Rhododendron cultivars,‘Yanzhimi’and‘Hongyue’,were used as experimental materials to analyze the effects of heat stress on the ethylene biosynthesis,and the changes of MDA,H2O2 content,the superoxide anion production rate and antioxidant enzyme（SOD,POD and CAT）activities in the leaves induced by spraying ethephon and ethylene synthesis inhibitor（cobalt nitrate）. The results showed that the enzyme activities of ACC synthase（ACS）and ACC oxidase（ACO）and endogenous ethylene release rate increased in the leaves under heat stress. In addition,the enzyme activities of ACO,ACS and ethylene release rate in the heat-resistant cultivar‘Yanzhimi’were higher than those in the heat-sensitive cultivar‘Hongyue’. 100 μmol · L-1 ethephon increased the enzyme activities of SOD,POD and CAT in the leaves under heat stress,reduced H2O2 content,the superoxide anion production rate of‘Hongyue’and degree of lipid peroxidation indicated by MDA. The results of spraying 1 000 µmol · L-1 cobalt nitrate were contrary to those of spraying 100 µmol · L-1ethephon. These results indicated that ethylene played an important role in the heat tolerance of rhododendron seedlings,and exogenous ethylene and ethylene synthesis inhibitors could affect the heat resistance of rhododendron by regulating antioxidant system.
In this study,257 representative lily germplasms were selected as test materials. We used the Royal Horticultural Society Color Comparison Chart（RHSCC）and colorimeter to measure the flower color. Based on the measurement data,systematic clustering was used to classify the sample patterns quantitatively. Combining RHSCC and CIELab parameter values,the result showed that the lily flower colors could be divided into eight major color groups：white,yellow,pink,orange,orange-red,rose-red,red and dark-red. Each color group had correspondence with the lightness（L*）,redness（a*）and yellowness （b*）of CIELab coordinate,which could realize the quantitative description of lily flower color phenotype. Based on the pure-pattern and multi-pattern,the numerical classification phenotype,the spots type and linear,all samples was divided into two groups,eight colors,and six types. This study had completed the numerical classification of flower color phenotype in lily and created a lily flower color classification index,meanwhile providing a reference for the classification and identification of lily varieties.
In this research,five-year Paeonia suffruticosa‘Fengdan’was chosen as an experimental material. On the basis of mastering meiosis process of pollen mother cells,“a non-in-vitro branch bud heat treatment device of trees”（ZL200610113448.X）was used to implement pollen chromosome doubling of P. suffruticosa under high-temperature processing,a suitable technique for high temperature-induced pollen chromosome doubling in P. suffruticosa was established. The findings indicated that meiosis process of pollen mother cells had correlation with the external form of flower buds and anther color changes. When flower buds remained between“small wind bell”stage to“big wind bell”stage,namely the diameter of flower buds was 13 mm,meiosis process of pollen mother cells reached diplonema—metaphaseⅠ. The treatment combination of 40 ℃ for 4 h produced the greatest amount of diploid pollen（up to 21.98% of the total yield）.
DTBIA and regular PCR were both adopted to identify Huanglongbing（HLB）bacteria in the samples showing symptoms similar to HLB in orchards in Meizhou,Guangdong. Typical purple spots were observed in the phloem of leaf petioles and branches of cocktail grapefruit by DTBIA assay,similar as those produced in HLB positive control. Further analysis with branch,leaf,fruit peduncle,columella,seed coat,and ovary by PCR revealed positive target bands were got from all the above samples. The titer of Candidatus Liberibacter asiaticus in fruit peduncle,columella,and seed coat was relatively higher as compared to other parts. 16S rDNA and efTu gene were both cloned and sequenced. The sequence identity between isolates of CLas deposited in GenBank and the ones from‘Cocktail’grapefruit was 100%. In conclusion,the pathogen infecting‘Cocktail’grapefruit was identified as CLas.
The evolution characteristics of the longan GDSL（DlGDSL）family and their expression patterns during the early stages of somatic embryogenesis were investigated. The results showed the 118 members of DlGDSL family can be divided into 15 subfamilies,and the subcellular localization was mainly distributed in the extracell,a few distributed in other parts such as cell membrane,chloroplast,mitochondria and endoplasmic reticulum. Analysis of chromosomal locations suggests that 111 out of 118 DlGDSLs are distributed unevenly on the 15 longan chromosomes. Analysis of synteny relationships indicates 13 pairs of DlGDSL genes. The genomic structures of those DlGDSL genes indicates that their exon numbers vary between two and twelve. The protein conserved motifs of those DlGDSL suggest motif2 and motif3 are particularly important. The cis-acting elements of DlGDSL promoters contained light responsive elements,hormone response,anaerobic induction,stress responsive and circadian control elements. Besides,three family members（A,B and C）of DlGDSL contains a large number of methyl jasmonate（MeJA）,abscisic acid（ABA）,auxin（IAA）and gibberellin（GA）action elements. In addition,transcriptome data analysis revealed that 26 differential expression genes from embryogenic callus to globular embryo stage,suggesting members of the DlGDSL family may play important roles in the morphogenesis of longan somatic embryos. The results of qRT-PCR analysis in different hormone treatments suggests some members of the DlGDSL family may be related to hormone signal transduction such as ABA and MeJA in longan embryogenic callus. DlGDSL57/69/105 genes showed obvious up-regulation and DlGDSL23/42/50/52/75/80/104 genes demonstrated visible down-regulation in ABA treatment. DlGDSL100 gene revealed obvious up-regulation and DlGDSL23/27/42/50/52/57/69/80/104/105 showed visible down-regulation in MeJA treatment. In summary,the research will provide a reference for the subsequent functional verification of DlGDSL genes in somatic embryogenesis.
Stably genetic purple under the calyx,round eggplant inbred line Y5 was crossed with green under the calyx,round eggplant inbred line Y73. The segregation of fruit color under the calyx of F2 progeny had a normal distribution,which could be analyzed by bulk segregant analysis（BSA）. In the F2 population,30 purple and 30 green under the calyx plants were selected to construct separated mixed pools. Whole-genome resequencing of 30× and 10× coverage was carried out in the mixed pools and parents to locate the correlation interval of fruit color under the calyx. Candidate genes were predicted according to the collinear region and gene annotation information of the eggplant genome. A total of 7 747 547 single nucleotide polymorphisms（SNP）and 569 796 insertion deletion markers（InDel）were obtained from the hybrid pools and parents,which were used for genome-wide mapping of fruit color traits under the calyx. According to pathway enrichment and gene function annotation,candidate genes EGP21397,EGP21400,EGP21491,EGP22288,and EGP22289 were obtained. The five candidate genes were closely related to cell photosynthesis and encoded calmodulin-binding family proteins,the C2H2 zinc finger protein,carotenoid isomerase,2Fe-2S ferredoxin-like superfamily proteins,and the lipid transfer protein. At the same time,six candidate genes related to cytochrome P450 and phytochrome synthesis were predicted,which were located in the association regions of chromosomes 10. These proteins and pigments were related to photosynthesis and stress development,which revealed the molecular mechanism of fruit color in eggplant.
In order to identify the cultivars quickly and accurately,DNA fingerprinting of 18 muskmelon cultivars of Xizhoumi series was constructed by using SSR marker technology. Using 18 cultivars（lines）,highly informative and polymorphic simple sequence repeat（SSR）primers were screened. Out of the 73 SSR primer pairs,nine pairs including SSR12083,MU5554-1,TJ10,PM3,MU5499,SSR04219,SSR04632,SSR22874 and C30 were selected,and they could generate stable,clearly and codominant bands. Each primer pair could generate 3-6 polymorphic bands with an average of 4.33. The average polymorphism information content（PIC）was 0.45 with a range from 0.20 to 0.78. Five selected primer pairs（C30,MU5499,MU5554-1,SSR04219 and SSR12083）had established the fingerprinting of the 18 accessions and their unique fingerprint. We found that the female parent of ‘Xizhoumi 25’was the same as the female parent of‘Xizhoumi 17’. Clustering analysis showed that the similarity coefficient of the 18 accessions ranged from 0.70 to 1.00. They can be divided into three groups at 0.74. Above results indicated that the DNA fingerprinting could provide scientific basis for identification of Xizhoumi muskmelon.
Zucchini yellow mosaic virus is a serious emerging virus that has threatened the economically important cucurbits industry in major production areas worldwide. Watermelon inbred line 938-16-B had been identified as resistance to ZYMV in our previous work. It is characterized by hypersensitive response（HR）after infection by ZYMV. Here,we investigated the inheritance of resistance to ZYMV in 938-16-B. In this study,F2 generation with 310 individuals and BC1 generation were generated through crossing 938-16-B with ZYMV-susceptible inbred line H1. According to the segregation ratio of resistance in BC1 and F2 generation,ZYMV resistance in 938-16-B would be established. During the process of inoculation,we found hypersensitive response（HR）would not be induced when the temperature was over 30 ℃,which suggested the resistant gene was temperature-sensitive. Therefore,identification of resistance in the F2 and BC1 population was carried out under the condition of 23-28 ℃. Results showed that,the segregation ratios of resistance to susceptibility in F2 and BC1 were 3︰1 and 1︰1,respectively,which revealed the resistance to ZYMV in watermelon is controlled by a single dominant gene.
The complete chloroplast（cp）genome of Sorbus koehneana and its phylogenetic relationship with S. unguiculata were analyzed. The complete cp genome of S. koehneana is 159 873 bp in size with 36.60% GC content. It has a typical quadripartite structure including a small single copy（SSC）region of 19 218 bp,a large single copy（LSC）region of 87 899 bp and a pair of inverted repeat regions （IRs）of 26 378 bp. The cp genome encodes 108 genes,comprising 76 protein-coding genes,four rRNA genes and 28 tRNA genes. Additionally,47 simple sequence repeats（SSRs）and 48 interspersed nuclear elements（INEs）were identified. In Sorbus,cp genome is highly conserved in length,gene type,codon number,intron number and GC content. However,the different sequence repeats and 12 highly variable regions located in intergenic spacers may be used for population genetic and phylogenetic studies in future. Phylogenetic analyses revealed that S. koehneana,S. unguiculata and S. helenae are in the same lineage nested within Sorbus subg. Sorbus. However,S. unguiculata is sister to S. helenae instead of S. koehneana. So the treatment of S. unguiculata as a synonym of S. koehneana is not supported and the name S. unguiculata is proposed to be reinstated here.
The survey on virus diseases was carried out and the samples of infected seedlings were collected in Dali,Yunnan,China during 2018—2019. The Reverse Transcription-Polymerase Chain Reaction （RT-PCR）was used to detect the virus. The results showed that total 70 sample were infected by ORSV （odontoglossum ringspot virus）. However,CymMV（cymbidium mosaic virus）was not detected,indicating the major potential infection thread may be from ORSV in Dali. Phylogenetic analysis based on Coat Protein gene（cp）showed that all ORSV clustered into a single clade. The results of protein analysis showed that ORSV coat protein belonged to TMV coat protein family,and the theoretical isoelectric point was 5.01,which was a hydrophilic stable protein. Thus,we confirmed that ORSV had infected in cultivated C. goeringii in Dali. The follow up study should be carried out soon on early diagnosing and screening of anti-virus medicine for orchid viral disease.
Based on β-tubulin gene of Ciborinia camelliae L. M. Kohn and related isolates,a pair of specific primers and a TaqMan MGB probe were designed and synthesized. A novel real-time fluorescent PCR was established to detect C. camelliae. The optimized primer and probe concentrations were 0.8 and 0.7 μmol · L-1,respectively. The minimum detection limit of this method is up to 1.0 pg for 10 μL reaction system. The method was specific,sensitive,easily to operate and fast,which provide a valuable tool for early rapid detection and identification of C. camelliae.
Epigenetic modifications occurred at DNA sequence and chromatin,including DNA methylation,histone modifications,chromatin remodeling,and non-coding RNAs,are essential to transcriptional regulation. This study introduces the recent progress on mechanisms of DNA methylation and DNA demethylation,and summarizes the roles and function of DNA methylation,histone modification,histone variants,RNA methylation and non-coding RNAs in the development and ripening of horticultural fruits. In addition,this review highlights the potential and unsolved issues related to investigating fleshy fruits of horticultural crops,and provides the theoretical foundation for the investigation,innovation,and utilization of fruit biology research in the future.
Glycosyltransferases belong to a super gene family that catalyze glycosylation. Glycosylation modifications could enrich the structure of anthocyanidins,regulate its water solubility,stability and transportability,which are considered as important steps for petal color determinant. In this research,we reviewed the categories,biochemical and molecular biology of glycosyltransferases involved in the pigment metabolism in ornamental plants. In addition,the effects of some glycosyltransferases in the pigmentation of differently colored petals,such as blue-violet,orange to purplish red and yellow,are summarized. Finally,further research hotspots of pigmentation related glycosyltransferases are prospected. The results are expected to provide a reference for further understanding of the mechanism of glycosylations,and shed lights to the improvement of ornamental plant flower color through molecular breeding strategy.
A new early-mid ripening nectarine cultivar‘Danxia’is derived from natural hybrid seedling of‘Early Red 2’. It ripens at the early August in Dalian,Liaoning Province. The average fruit weight is 141 g,the biggest one is 234 g. Its fruit is round and all deep red. The flesh is yellow,hard-melting,half-clingstone,sweet. The soluble solids content is 15%-19%. The yield of 5-year-old tree is up to 38 595 kg · hm-2. It has high yield.
‘Yuyan 9’is a new cucumber cultivar developed by crossing CU009-8-2-3-1 as female parent with CU001-3-2-2-2 as male parent. Plant growth potential is strong. It is subgynoecious. The fruit shape is beautiful. The cucumber has glossy dark green skin with little thorn. The flesh is crisp and tender. The fruit is about 15 cm long and 3 cm in diameter,and the average fruit weight is about 120 g. It has excellent quality,strong fruiting ability,resistance to powdery mildew and downy mildew,tolerance to low temperature and low light. It is suitable for protected and open field cultivation in Western Gansu.
Pennisetum alopecuroides‘Lingshan’is a new ornamental culticar which is selected from wild germplasm resources by individual selection and bulk selection methods. The ornamental characteristics of the cultivar is a long green stage from April to October. The plant heights before heading are about 60-70 cm. After heading,the plant heights and crown widths are 100-150 cm and plant shape looks like a‘Fountain’. The new cultivar has significant advantages in the ornamental value,cold resistance,drought tolerance and the low maintenance cost.
The primary material of Polygonatum kingianum‘Linyun 1’was found in the investigation of P. kingianum wild resources. The cultivar was selected through the process of primary selection,re-selection,final selection,clone propagation,clone test and so on. The apex of the plant is cirrose,having leaves in whorls,inflorescences whorled in leaf axils,white and cylindrical flowers,orange and globose berries. The surface of tuber is light yellow,with link wrinkles. The tuber is hard and tough,not easy to break. It has the characteristics of robust growth and vigour,high yield,good quality,strong resistance to diseases,insects,and other adversities.