Research Papers

• Studies on the Regulation of Anthocyanin Accumulation by Apple Sucrose Transporter MdSUT2
• LU Jing，MA Qijun，LIU Xiao，KANG Hui，LIU Yajing，HAO Yujin，and YOU Chunxiang*
• Acta Horticulturae Sinica. 2019, 46(1): 1-10. DOI:10.16420/j.issn.0513-353x.2018-0501
• Abstract ( 439 ) HTML ( 1148 ) PDF (1920KB) ( 1148 ) 　　　

• A gene named MdSUT2（MDP0000277235）was cloned from‘Gala’apple（Malus × domestica Borkh.）. Sequence analysis showed that this gene contained 1 704 bp nucleotides，and encoded a protein of 566 amino acids. Overexpression vector of MdSUT2 was constructed and transformed into Arabidopsis seedlings via Agrobacterium-mediated method. Semi RT-PCR analysis indicated that MdSUT2 was genetically transformed into Arabidopsis. In addition，the transient expression vectors were constructed and transformed into apple fruits. We found that overexpression of MdSUT2 in apple fruits significantly increased the anthocyanin content，whereas suppression of MdSUT2 decreased the anthocyanin content.

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• Effects of Exogenous Glucose Treatment on Soluble Sugar and Expression of Related Genes During Floral Bud Differentiation Stage in Terminal Spur Buds of‘Nagafu 2’Apple
• ZHANG Lizhi，ZHANG Xin，ZUO Xiya，XING Libo，FAN Sheng，LI Youmei，ZHAO Caiping，HAN Mingyu，and ZHANG Dong*
• Acta Horticulturae Sinica. 2019, 46(1): 11-24. DOI:10.16420/j.issn.0513-353x.2018-0173
• Abstract ( 342 ) HTML ( 774 ) PDF (547KB) ( 774 ) 　　　

• ‘Nagafu 2’apple trees were sprayed with 1.5% and 3% glucose solutions at 25 days and 30 days after full bloom，respectively. Bud growth，endogenous sugar levels，starch content and activities of related enzymes in terminal spur buds were examined. Genes associated with sugar metabolism and flowering were studied by quantitative real-time PCR. The results revealed that glucose treatments increased bud size and fresh weight. The contents of sucrose，glucose and sorbitol were significantly higher than in the control during early stage of floweral bud differentiation，while starch increased generally，but the content of fructose significantly decreased during the whole period. The activities of sorbitol dehydrogenase，sorbitol oxidase，synthesis direction of sucrose synthase and sucrose phosphate synthase increased at different stages，while acid and neutral invertases，decomposition direction of sucrose synthase decreased. Carbohydrate accumulation in leaves was evident，and the activities of enzymes involved in sugar metabolism also changed similarly. Genes associated with sugar metabolism and two MdTPS genes in terminal buds all responded to glucose treatment. Furthermore，flowering genes like MdFT 1，MdFD，MdLFY，MdSOC 1，and MdAP 1 were significantly up-regulated，while the suppressor MdTFL 1 was down-regulated from beginning of floral induction.

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• Cloning and Functional Analysis of the Promoter of PbTMT4 Gene Related Sugar Transport in Pear
• CHENG Yinsheng1,2,*，CHEN Jianqiu1,*，CHEN Dan1，Lü Jiahong1，ZHANG Jun1，ZHANG Shaoling1，WU Tao2,**，and ZHANG Huping1,**
• Acta Horticulturae Sinica. 2019, 46(1): 25-36. DOI:10.16420/j.issn.0513-353x.2017-0786
• Abstract ( 292 ) HTML ( 803 ) PDF (2651KB) ( 803 ) 　　　

• The 2 211 bp CDS sequence of PbTMT4 gene（Pbr032130.1）and the promoter sequence of 1 220 bp upstream of the transcription initiation site were obtained using Pyrus bretschneideri‘Dangshan Suli’as the material based on the pear genome database. When the PbTMT4 gene was introduced into Arabidopsis by Agrobacterium-mediated method，the growth rate of transgenic Arabidopsis was faster，and the flowering time was earlier than the wild type. At the same time，the amount of sugar accumulation in transgenic Arabidopsis was significantly higher than that in wild type. Bioinformatics analysis indicated that the promoter contains multiple cis-acting elements associated with stress response，hormone signals and light signals. To further analyze the promoter function of PbTMT4 gene，a promoter-reporter vector was constructed and transformed into Arabidopsis. Analysis of T3 transgenic Arabidopsis tissues with histochemical staining and semi-quantitative analysis showed that GUS gene was expressed in roots，stems，leaves，flowers and fruit pod. And sodium chloride（NaCl），drought，gibberellin（GA3），methyl jasmonate（MeJA）and light intensity can induce the transcription level of GUS gene in Arabidopsis to some extent. Stress treatment revealed that the PbTMT4 gene overexpression transgenic line had less damage than the wild type plants. The results of the study preliminarily suggest that PbTMT4 gene can promote the development of transgenic plants and increase sugar accumulation，and may play an important regulatory role in the abiotic stress.

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• Metabolic Characteristics of Interspecific Allotetraploid Somatic Hybrid Between‘Newhall’Navel Orange and‘Eureka’Lemon
• SONG Xin，TAN Fengquan，ZHANG Miao，CAI Yuankang，GUO Dayong，XIE Kaidong，WU Xiaomeng，and GUO Wenwu*
• Acta Horticulturae Sinica. 2019, 46(1): 37-46. DOI:10.16420/j.issn.0513-353x.2018-0547
• Abstract ( 313 ) HTML ( 822 ) PDF (1055KB) ( 822 ) 　　　

• The levels of primary metabolite in the fruit pulp of somatic hybrid [Citrus sinensis Osbeck‘Newhall’+ Citrus limon（L.）Burm. F.‘Eureka’] and both parental species were quantitatively evaluated by GC–MS（gas chromatography-mass spectrometry）and flavonoid contents were investigated by LC–MS（Liquid chromatography-mass spectrometry）. The results indicated the allotetraploid was closer to the lemon parent in the accumulation of primary metabolites. The levels of malic acid，citric acid and four fatty acids were higher than those of the diploid parents，while the contents of most amino acids in the allotetraploid showed an additive manner. Additionally，a total of 48 flavonoids were detected in the allotetraploid. The contents of 33 flavonoids were intermediate between both parents. Meanwhile，the levels of 15 flavonoids were transgressive. The allotetraploid was closer to the lemon parent in flavonoid composition.

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• Mineral Nutrients Distribution in Leaf Different Parts in Navel Orange Plant
• LIU Guidong，HU Ping，ZENG Yu，ZENG Zijun，GUAN Guan，YAO Fengxian，and ZHOU Gaofeng*
• Acta Horticulturae Sinica. 2019, 46(1): 47-56. DOI:10.16420/j.issn.0513-353x.2018-0205
• Abstract ( 478 ) HTML ( 811 ) PDF (1029KB) ( 811 ) 　　　
• To explore the leaf partitioning of essential mineral elements in Newhall navel orange plants grafted on trifoliate orange and citrange，ten elements（N，P，K，Ca，Mg，Fe，Mn，Cu，Zn and B）in leaf tip，leaf margin，leaf middle，leaf base，and winged petiole of the new leaves and old leaves were determined by ICP-MS and Kjeldahl apparatus，and analyzed using multivariate analysis and principal component analysis（PCA）. The PCA results showed that the first two principal components could explain 43.4% and 21.1% of the total variables，respectively. The first component separated new leaves from old leaves，the second component generally discriminated the different leaf parts，especially the winged petiole of new leaves from other leaf parts. For the new leaves，in both rootstock，showed a steep gradient in the K concentrations（winged petiole > leaf base > leaf middle > leaf margin ≈ leaf tip）and Mg concentrations（leaf tip ≈ leaf margin > leaf middle > leaf base > winged petiole）；and the old leaves showed a steep gradient in the Mn concentrations（leaf tip ≈ leaf margin > leaf middle > leaf base > winged petiole）and B concentrations（leaf tip > leaf margin > leaf middle > leaf base > winged petiole）. There was no significant difference in the contents of N，P and B among the different leaf parts of the new leaf blade and the contents of P and Ca among the different leaf parts of the old leaf blade. The contents of Mn，Cu and Zn in the new leaf petiole wing of Newhall navel orange plants grafted on trifoliate orange were not significantly different from those of the other new leaf parts，while the contents of Mn，Cu and Zn in the new leaf petiole wing of Newhall navel orange plants grafted on citrange were significantly lower than those of the other new leaf parts. These results suggest that there are obvious differences in the element distribution characteristics of leaf partitioning，and the element concentrations and ion composition in the leaf petiole wing are very different from other leaf parts.
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• Targeted Editing of BoaZDS by CRISPR/Ca9 Technology in Chinese Kale
• ZHENG Aihong*，ZHANG Fen*，JIANG Min，YUAN Qiao，JIANG Leiyu，CHEN Qing，TANG Haoru，and SUN Bo**
• Acta Horticulturae Sinica. 2019, 46(1): 57-64. DOI:10.16420/j.issn.0513-353x.2018-0426
• Abstract ( 312 ) HTML ( 828 ) PDF (2177KB) ( 828 ) 　　　

• The ζ-carotene desaturase（ZDS）gene was selected as the target gene to establish the CRISPR/Cas9 genome editing system in Chinese kale. The target site，near the 5′ end of the coding region of the BoaZDS，was selected，and the CRISPR/Cas9 expression vector was constructed. As a result，a total of 19 transgenic plants were obtained through Agrobacterium-mediated genetic transformation. Sanger sequencing analysis revealed that 13 of them were mutated. The mutation efficiency was 68.42%，and all mutants showed a clear albino phenotype.

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• Effects of Rootstock and Scion Interactions on Ascorbate-Glutathione Cycle in Tomato Seedlings Under Low Temperature Stress
• HAN Min1,2，CAO Bili2，LIU Shusen3，and XU Kun2,*
• Acta Horticulturae Sinica. 2019, 46(1): 65-73. DOI:10.16420/j.issn.0513-353x.2018-0110
• Abstract ( 404 ) HTML ( 701 ) PDF (723KB) ( 701 ) 　　　
• In order to investigate the effect of tomato rootstock，scion and their potential interaction on chilling tolerance，the approach grafting between chilling-sensitive tomato cultivar‘060911’（S）and chilling-resistant tomato cultivar‘060112’（R）was proceeded to generate grafted seedlings RS/RS with double rootstocks and scions. By selectively detaching one rootstock or scion from RS/RS，newly formed seedlings of six combinations with different rootstock and scion，i.e.，R/R，R/RS，R/S，S/R，S/RS，S/S were raised in the growth chamber with light intensity of 22 klx and photoperiod of 12 h/12 h. Seedlings were treated with low temperature at 10 ℃ in the day and 3 ℃ at night for 9 days and recovered at 25 ℃ in the day and 15 ℃ at night for 3 days. The level of reactive oxygen species（ROS），and the key enzymes and antioxidants in AsA-GSH cycle in leaves and roots of grafted seedlings were measured after the chilling treatment and recovery. The content of hydrogen peroxide and production rate of superoxide anion in leaves and roots of grafted tomato seedlings were significantly increased under low temperature stress. The ROS level in grafted seedlings with R rootstock or R scion was significantly lower than that with S rootstock or S scion，respectively. The decrease of ROS level between R and S rootstock was more significant than that between R and S scion，indicating that rootstock conferred more chilling resistance than scion. Low temperature stress increased the accumulation of AsA，DHA，GSH and GSSG，and enhanced the activities of APX，MDHAR，DHAR and GR. Moreover，enzyme activities and the content of antioxidants except for DHA and GSSG were highest in grafted seedlings with R rootstock or R scion，lowest in those with S rootstock or scion，and intermediate in those with RS rootstock or scion，indicating that the ability of anti-oxidation in grafted seedlings with R rootstock or R scion under cold stress was significantly higher than that in grafted seedlings with S rootstock or S scion. In addition，the ability of anti-oxidation in leaves of RS-R grafted seedling was significantly higher than that in RS-S grafted seedlings. Statistical analysis showed that probability（P）values of interaction between rootstock and scion were less than 0.01（or 0.05），indicating that rootstock and scion posses significant interaction effects on the chilling tolerance of grafted tomato seedlings.
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• Cloning and Expression Analysis of GA20ox Gene in Lilium Oriental Hybrids‘Sorbonne’
• ZHANG Xuhong1,2，SUN Meiyu1，LI Jingrui1，WANG Di1，ZHANG Jinzheng1，and SHI Lei1,2,*
• Acta Horticulturae Sinica. 2019, 46(1): 74-86. DOI:10.16420/j.issn.0513-353x.2018-0142
• Abstract ( 435 ) HTML ( 742 ) PDF (2289KB) ( 742 ) 　　　
• We cloned a cDNA encoding GA20ox from Lilium Oriental Hybrids‘Sorbonne’using rapid amplification of cDNA ends（RACE）. The bioinformatics and expression patterns of GA20ox were analyzed in our study. Sequences analysis showed that the cloned GA20ox was 1 502 bp in length with an open reading frame（1 167 bp），which encoded 388 amino acids. The putative protein had many glycosylation，phosphorylation and N-myristoylation sites. Alignment of amino acid sequence showed that GA20ox of‘Sorbonne’shared a PLN02276 binding domain like the GA20ox in other species. Phylogenetic analysis revealed that GA20ox of‘Sorbonne’was highly homologous to GA20ox of other monocots，including Phalaenopsis equestris，Dendrobium catenatum，Phoenix dactylifera，Elaeis guineensis and Cocos nucifera. Quantitative Real-time PCR（qRT-PCR）analysis showed that GA20ox was highly expressed in stem root after germination，stem of squaring stage，leaf of germination stage and leaf expansion stage，and terminal bud of germination stage，implying the temporal and special regulation of GA20ox. The application of high GA3 concentration in germination stage had great influence on plant growth as plant height and biomass of underground were promoted by 200 mg ? L-1 and 400 mg ? L-1 of GA3 treatment，respectively. After treatment of GA3 at 200 mg ? L-1，the expression of GA20ox was significantly suppressed in all tissues（except for bulb scale）and fell to their lowest level at 12 h，especially in the stem and root with decreasing by 96.79% and 94.65% respectively. These results suggest that the expression of GA20ox may be regulated by active gibberellins with a potential feedback mechanism，thus the GA20ox may play a key role for the maintenance of endogenetic active gibberellins homeostasis in lily.
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• Studies on the Flower Bud Differentiation of Four Species of Clematis
• YANG Yi，WANG Na，WANG Kuiling，LIU Qinghua，and LIU Qingchao*
• Acta Horticulturae Sinica. 2019, 46(1): 87-95. DOI:10.16420/j.issn.0513-353x.2018-0268
• Abstract ( 283 ) HTML ( 672 ) PDF (6075KB) ( 672 ) 　　　
• A natomic observation was made in the terminal bud of Clematis heracleifolia，C. terniflora var. mandshurica，C. hexapetala and C. fusca during flower bud differentiation with the paraffin-cut section. The results showed that flower bud differentiation of the four species of Clematis could be divided into five stages. The primordia of all floral organs initiated and developed centripetally without differentiation or degradation of calyx or petal obviously. It also included the whole inflorescence formation during the flower bud differentiation of C. heracleifolia，C. hexapetala and C. terniflora var. mandshurica. After the complete morphology differentiation of floral organ，it took about 10–12 d for the flowers of C. terniflora var. mandshurica and C. fusca，12–14 d for that of C. hexapetala and 15–17 d for that of C. heracleifolia to develop from the initiation to the end.
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• Cloning and Profiles Analysis of CsCIPK Gene from Tea Plant
• LIU Hao，WANG Wenli，TENG Ruimin，LI Hui，WANG Yu，WANG Yongxin，and ZHUANG Jing*
• Acta Horticulturae Sinica. 2019, 46(1): 96. DOI:10.16420/j.issn.0513-353x.2018-0225
• Abstract ( 214 ) HTML ( 679 ) PDF (3252KB) ( 679 ) 　　　
• In this experiment，a CIPK gene was cloned from tea plant（Camellia sinensis）cultivar‘Longjing 43’by RT-PCR，and named CsCIPK. Sequence analysis showed that the open reading frame of CsCIPK is 1 341 bp and encoded 446 amino acids with molecular weight of 414 234. The prediction of protein functional domain showed that the CsCIPK protein contains a conserved N-terminal kinase domain and a relatively unconserved C-terminal regulatory domain，namely the serine/threonine kinase domain and the NAF domain. CsCIPK is a hydrophobic protein and theoretical pI is 7.04. CsCIPK contains four unordered regions，and mainly composed of α-helix and irregular coils. The expression profile of CsCIPK gene in tea plant cultivars‘Longjing 43’and‘Anjibaicha’was analyzed by real-time quantitative PCR. The results showed that the relative expression of CsCIPK in‘Longjing 43’reached its highest level at high temperature，drought，salt treatment for 4 h，and low temperature treatment for 24 h. The relative expression of CsCIPK in‘Anjibaicha’was highest at high temperature and salt treatment for 4 h，and at low temperature and drought treatment for 1 h. In different tea tree tissues，the expression of CsCIPK was highest in the root of‘Longjing 43’，and in the stem of‘Anjibaicha’. Different concentrations of GA and IBA treatment showed that the expression level first increased and then decreased under 0.2 mmol ? L-1 GA，and reached the highest level at 6 days. After treatment with 0.6 mmol ? L-1 IBA，the expression level was significantly higher than the control at 3 days. After treatment with different concentrations of different hormones，the expression level of CsCIPK on the 9 days in the treatment was significantly lower than the control.
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Research Notes

• DNA Methylation in Red Fuji Apple Bud Sports Lines
• DU Xiaoyun1，SONG Laiqing1，ZHAO Lingling1,3，LIU Meiying1，TANG Yan1，SUN Yanxia1，JIANG Zhongwu1,3,*，and SHU Huairui1,2,*
• Acta Horticulturae Sinica. 2019, 46(1): 107-120. DOI:10.16420/j.issn.0513-353x.2018-0313
• Abstract ( 262 ) HTML ( 762 ) PDF (2033KB) ( 762 ) 　　　

• To understand the mechanism of bud mutation in Malus × domestica Borkh.‘Fuji’，DNA methylation patterns and epigenetic variations were identified using MSAP（Methylation Sensitive Amplified Polymorphism）molecular marker analysis and UPGMA cluster analysis in a population of 35 ‘Fuji’bud sports lines（Red Fuji）. Results indicated that：(1) MSAP amplication pattern varied among different bud sports lines. Total methylation was ranged from 27.90% to 36.16%，and 32.87% in average. Inner-methylation of double-stranded DNA was the main pattern in a primary‘Fuji’cultivar and its bud sports lines. (2) The CCGG sites remained primary methylation patterns during the occurrence of bud sports together with‘Fuji’. (3) In total，12 methylation variation patterns were detected from 68.57% Red Fuji lines. The frequence of hypomethylation was significantly higher than that of hypermethylation. Moreover，CG hypomethylation was significantly higher than that of CHG（P < 0.01）. (4) Average similarity coefficience among 36 bud sports lines was 0.89，ranging from 0.79–0.92. In the UPGMA dendrogram，the primary Fuji cultivar fell out of the group of bud sports lines. Most recently bud spot lines had tendency to cluster together；typeⅠ（flushed-skin color pattern）and typeⅡ（striped-skin color pattern）bud sports lines were mixed into differents. In summary，DNA methylation and demethylation happened at the same time，demethylation was the main methylation pattern. CG hypomethylation plays an important role in the occurrence of Red Fuji. Our results would be great help in future epigenetic study of‘Fuji’sports lines，and CG hypomethylation would be as an emphysis to explore the mechanism of sports line occurence.

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• Transcriptome Studies the Effect of Glucose on Carbon Metabolism of Grape Plantlets
• LIANG Guoping，LI Wenfang，MA Zonghuan，ZUO Cunwu，CHU Mingyu，MA Lijuan，HE Honghong，WAN Peng，CHEN Baihong，and MAO Juan*
• Acta Horticulturae Sinica. 2019, 46(1): 121-134. DOI:10.16420/j.issn.0513-353x.2018-0226
• Abstract ( 288 ) HTML ( 1158 ) PDF (2532KB) ( 1158 ) 　　　
• The effects of glucose metabolism and photosynthesis on‘Red Globe’grape plantlets were studied under different concentrations（0，1%，2% and 4%）of exogenous glucose by the transcriptome sequencing. The result showed that the growth status of grape plantlets was the best under 2% glucose treatment，the second was 4% and 1%，the control（0）was the weakest in all treatments. 21.53 Gb Clean Data was obtained by sequencing in 4 different concentrations of glucose，and the base ratio of Q30 was more than 89.49%. Compared with reference genome，the sequence alignment efficiency was between 68.31% and 73.71% in all samples. The transfer efficiency of Single Nucleotide Polymorphisms（SNPs）ranged from 64.73% to 66.76%，and transversion was in 33.24%–35.27%. The most frequent types of mutations were A?G and C?T. The main event that occured in alternative splicing type was that the first and last exon were spliced. By setting a threshold to screening differentially express genes（DEGs），a total of 3 272 DEGs were obtained，including 2 826 down-regulated genes and 446 up-regulated genes. In the COG annotation classification，1%，2% and 4% were compared to the control，and annoted to 1 449，846 and 597 DEGs respectively，most of them are transcriptionally related genes except for general functional prediction. By detecting enzymes related leaf-carbon metabolism，SS and G6PDH activities were decreased first，then increased when the glucose concentration was added more. SS and G6PDH activities reached their peak value at 4% and 0，respectively. NI and SPS had same trend and both of their activity peak approached under the concentration of 2%. There was a consensus between expressional trend and sequenceing of 12 genes among 14 genes，indicating different concentrations of glucose regulate the expression of genes related leaf-carbon metabolism to improve the growth of‘Red Globe’.
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• Different influences of Organic and Inorganic Boron Fertilizers on Citrange Rootstock Growth and Physiology Characters
• ZHANG Lin1,2，LIU Leichao1，WANG Yuhan1，Lü Bo1，YAO Zihan1，and JIANG Cuncang1,*
• Acta Horticulturae Sinica. 2019, 46(1): 135-142. DOI:10.16420/j.issn.0513-353x.2018-0157
• Abstract ( 262 ) HTML ( 693 ) PDF (729KB) ( 693 ) 　　　
• The research has compared the influences of different B fertilizers，sorbitol-boric acid（SB）and boric acid（BA），on citrange rootstock growth and physiology characteristics by means of solution culture. Both fertilizers increased the fresh weight，dry weight and plant height of various parts of the rootstock seedling，and SB played a prominent role in underground growth. The transfer of SB in blades or other parts of the ground was easier than BA. There was no significant difference between the B content of SB and BA in roots and stems，but B content and B accumulation in leaves were significantly higher than BA，and the total B content proportion was significantly higher than BA. Various parts of potassium，calcium and magnesium content in SB were higher than that in the control，while the content of element in different parts of BA was higher than SB. Boron deficiency can lead to carbohydrate accumulation in leaves，and SB was more effective than BA in promoting the transport of polysaccharide substance in leaves. The soluble sugar contents in SB treatment were decreased separately by 26.3% and 11.8% than in the control and BA treatment，and the starch content decreased by 43.5% and 26.1%. SB was better than BA in raising resistance ability. Two B fertilizers were significantly lower than the control in Pro and the damage rate of leaves，SB and BA treatments were decreased separately by 20.6% and 19.6% than the control，and the damage rate was decreased separately by 13.3% and 16.5%，MDA content of SB leaves significantly decreased by 19.4% than BA. SB was better than BA in improving the growth and development of root of trifoliate orange rootstock. Besides，SB can effectively reduce the content of carbohydrates in leaves，and help the transfer of photosynthetic products. However，SB and BA had the same effect on reducing the accumulation of harmful substances，protecting the plasma membrane of leaves.
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• Character Identification of the Short-vegetative-growth-period Mutant ‘14-1’in Ananas comosus var. nanus
• LUAN Aiping1，HE Junhu1,*，LIU Jiarou2，GONG Xue2，FANG Shaoqiu2，XIA Jingxian2，LIN Wenqiu3，XU Wentian3，and HE Yehua2,*
• Acta Horticulturae Sinica. 2019, 46(1): 143-148. DOI:10.16420/j.issn.0513-353x.2018-0378
• Abstract ( 196 ) HTML ( 626 ) PDF (2259KB) ( 626 ) 　　　
• Pineapple（Ananas comosus var. comosus）has a long vegetative growth period，restricting the efficiency of its new cultivar breeding. Collection and selection of germplasm with a short vegetative growth period can create intermediate materials for new short-vegetative-growth-period cultivars of pineapple. We have collected 23 wild germplasm materials from abroad，which are easy to flower. Since 2008，the introduced germplasms have been cultivated，propagated and character identified. Through comparing and observing the vegetative growth period，a short-vegetative-growth-period mutant‘14-1’was discovered，from the somatic embryogenesis seedlings of Ananas comosus var. nanus. This mutant is extremely easy to flower. Compared with the original variety，the mutant has a vegetative growth period as long as about 6 months（original variety is about 12 months），i.e.，it blooms twice a year. The characterization of mutant‘14-1’can be stably inherited in its cloned plants，so it is a scarce parental material for short-vegetative-growth-period pineapple breeding.
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• Development of Genomic SSR and Application in Chinese Bayberry
• ZHANG Shuwen1，LIANG Senmiao1，ZHENG Xiliang1，REN Haiying1，ZHU Tingting1，and QI Xingjiang1,2,*
• Acta Horticulturae Sinica. 2019, 46(1): 149-156. DOI:10.16420/j.issn.0513-353x.2018-0233
• Abstract ( 303 ) HTML ( 641 ) PDF (756KB) ( 641 ) 　　　

• The distribution of simple sequence repeat（SSR）was studied in 1 431 scaffolds of Chinese bayberry（Myrica rubar Sieb. et Zucc.）genome. There were 43 842 SSR loci identified totally. And 194 kinds of repeating motifs that distributed in 623 scaffolds were discovered. The number and frequency of dinucleotide SSR loci were 36 383 and 82.99%. The frequency of AG/CT in dinucleotide was 55.70%，and in all SSR loci was 46.23%. It was indicated that AG/CT was the most common repeat motifs in Chinese bayberry genome. The number of trinucleotide SSR loci was 6 115，accounting for 13.95%. The number of tetranucleotide，pentanucleotide and hexanucleotide were 827，245 and 272 with the frequency 1.89%，0.56% and 0.62%，respectively. Meanwhile，59 pairs of Genomic SSR markers（gSSRs）were developed. After polymorphism analysis，26 gSSRs were highly polymorphic markers and 33 gSSRs were moderately polymorphic markers. In this study，the clustering analysis among the advanced selection Zaoxian 856 and the other 13 main cultivars were identified by all 59 gSSRs. According to the result，14 Chinese bayberry materials were clustered into two groups at the similarity coefficient of 0.56. It was illustrated that Zaoxian 856 was different from the other 13 varieties at the DNA level，and the similarity coefficient between Zaoxian 856 and control‘Zaose’was 0.86.

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Review

• Research Progress on Plant Resistance to Heavy Metal Stress
• WANG Ruonan，NIE Lanchun*，ZHANG Shuangshuang，CUI Qiang，and JIA Mingfei
• Acta Horticulturae Sinica. 2019, 46(1): 157-170. DOI:10.16420/j.issn.0513-353x.2018-0585
• Abstract ( 371 ) HTML ( 1423 ) PDF (795KB) ( 1423 ) 　　　
• Heavy metal contamination in agricultural soil could cause the accumulation of heavy metals in plants. While plants suffer from toxicity of heavy metals，they could also operate avoidance and tolerance mechanisms to resist heavy metal poisoning. This paper reviewed the research progress on plant resistance to heavy metal stress in terms of root exudates，subcellular structures，chelation，osmoregulation，and antioxidant systems，aiming to provide reference for further research in this field.
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• The Research Advance of Plant Circular RNA
• GAO Zhen1，LUO Meng1，WANG Lei1，SONG Shiren1，ZHAO Liping1，XU Wenping1，ZHANG Caixi1，WANG Shiping1,2,*，and MA Chao1,*
• Acta Horticulturae Sinica. 2019, 46(1): 171-181. DOI:10.16420/j.issn.0513-353x.2018-0583
• Abstract ( 349 ) HTML ( 973 ) PDF (1092KB) ( 973 ) 　　　
• Circular RNAs are a class of single-stranded non-coding RNA characterized by the presence of a covalent bond linking the 3′ and 5′ ends generated by backsplicing. Widespread circRNAs were found to be expressed in various organisms. CircRNAs feature stable structure and often show cell-，tissue-，or developmental-stage-specific expression. Some researches showed that circRNAs have been postulated to function as miRNA sponges，to enhance transcription of their host genes，also function as protein decoys and participate in the regulation of pathway. Dramatically increased investigations suggest circRNAs potentially regulate a wide range of biological progresses related to biotic/abiotic responses and plant development. Here，we summarize the features of circRNAs in plant，and their regulatory roles achieved so far. In addition，possible functional mechanism of plant circRNAs is inspired by animals，and the challenges and questions in the research area of plant circRNAs are discussed.
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New Technologies and New Methods

• Development and Application of Quantitative PCR for Detection of Pseudomonas syringae pv. tomato
• CHAI Ali1，Patiguli2，GUO Weitao1，SHI Yanxia1，XIE Xuewen1，XI Xianmei3，and LI Baoju1,*
• Acta Horticulturae Sinica. 2019, 46(1): 182-192. DOI:10.16420/j.issn.0513-353x.2018-0294
• Abstract ( 231 ) HTML ( 791 ) PDF (2449KB) ( 791 ) 　　　
• In the present work，a specific primer pair Pst3F/Pst3R was designed based on the pathogenicity-related gene HrpZ of Pseudomonas syringae pv. tomato（Pst），and a target fragment of 161 bp was specifically amplified from the genomic DNA of Pst. A real-time fluorescent quantitative PCR（qPCR）assay was developed for quantifying Pst in contaminated tomato seeds and infected tissues. The detection sensitivity of qPCR established in this study was 1 000 times higher than that of conventional PCR. The detection threshold was 4.21 cfu per gram of artificially contaminated tomato seeds. The amount of Pst was detected to be 4.15 × 102 cfu per gram of inoculated leaves with disease-grade level 1. For naturally infected tomato tissue samples，PCR，qPCR and classical culture methods were used for determination of Pst. Quantifiable levels of Pst were detected in 54 out of the 63 samples，and the results of the three methods were consistent. These studies showed that qPCR assay is a highly rapid and reliable method to quantify Pst in tomato seeds and infected tissues of leaves，stems and fruits. Application of the assay may potentially improve pathogen identification and disease management.
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New Cultivars

• A New Hot Pepper Cultivar‘Qinjiao 1’
• HUANG Wei，GONG Zhenhui，CHEN Rugang，LI Dawei，and LU Minghui*
• Acta Horticulturae Sinica. 2019, 46(1): 193-194. DOI:10.16420/j.issn.0513-353x.2018-0026
• Abstract ( 1123 ) HTML ( 592 ) PDF (1191KB) ( 592 ) 　　　
• ‘Qinjiao 1’is a new hot pepper hybrid developed by the inbred lines‘R9816-2-1-3’and ‘Z97-2-7-42’. The fruit is long lantern shaped with wrinkle surface. The fruit is 17.1 cm long，4.7 cm wide and 3.1 mm flesh thick. The single fruit weight is 73.5 g and the average yield is 45 062.6 kg ? hm-2. The cultivar has fine commercial and nutritional quality as well as high resistance to viruses，bacterial wilt，and blight disease.
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• A New High Yield and Fracture Resistance Watermelon Cultivar ‘Meisheng’
• WU Yanrong，ZHANG Jingjing，GAO Xiurui，LI Bing，and PAN Xiuqing*
• Acta Horticulturae Sinica. 2019, 46(1): 195-196. DOI:10.16420/j.issn.0513-353x.2018-0731
• Abstract ( 436 ) HTML ( 521 ) PDF (962KB) ( 521 ) 　　　
• ‘Meisheng’is a new watermelon cultivar by crossing‘Huazaolü’as female parent and ‘904-2-1-M’as male parent. It has fracture resistance and high yield. The fruit development period is 30 days. The fruit is round with dark green skin and thin green stripes. The number of stripes is from fourteen to sixteen and clear with waxy cuticle. The pericarp thickness is 1 cm，with good toughness and resistance to storage and transportation. The fruit flesh is red，sandy and juicy with less fiber. The soluble solids content in center is about 11.1%. The average fruit weight is 7.4 kg. The yield is 75 570 kg ? hm-2. It is suitable for early spring protected cultivation area in Hebei Province.
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• New Multiflora Chrysanthemum Cultivars‘Fenglin Huangxing’and‘Fenglin Hongyun’
• ZHANG Mengmeng1，DAI Silan1,*，WANG Qing1，FANG Zhijun2，JI Yushan1，and WANG Shuo2
• Acta Horticulturae Sinica. 2019, 46(1): 197-198. DOI:10.16420/j.issn.0513-353x.2017-0819
• Abstract ( 279 ) HTML ( 681 ) PDF (1491KB) ( 681 ) 　　　
• A new multiflora chrysanthemum cultivar‘Fenglin Huangxing’was selected from‘Branice Sunny’ב183’. The ray floret is light yellow，the diameter of flower head is about 3.7 cm，the flowering crown is 63.8 cm and the average number of flower head per plant is 1 007. Another new multiflora chrysanthemum cultivar‘Fenglin Hongyun’was selected out through nature crossing using‘388’as female parent and many varieties as male parent（introduced from Germany Brandkamp Company）. Middle-upper part of ray floret is pink，and bottom part is white. The diameter of flower head is 3.6 cm，the flowering crown is 60.2 cm and the average number of flower head per plant is 847. Because of the big flowering crown and round plant type，group effect of these two new cultivars is very good. And they are suitable for autumn greening in Beijing area.
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• A New Luculia pinceana Cultivar‘Jinyudian’
• LIU Xiuxian，MA Hong，WAN Youming，ZHAO Zhengang，and LI Zhenghong*
• Acta Horticulturae Sinica. 2019, 46(1): 199-200. DOI:10.16420/j.issn.0513-353x.2018-0066
• Abstract ( 496 ) HTML ( 448 ) PDF (1128KB) ( 448 ) 　　　

• ‘Jinyudian’is a new cultivar which is bred from the natural variant plants of Luculia pinceana. The cultivar is perennial evergreen shrub with erect plant type. Its thin leathery leaf is ovate in shape with leaf index 1.81. The inflorescence type is cyme and the flower type is long-style. The viridescent sepal is half-reversal in shape at anthesis and its abaxial surface is glabrous. The corolla tube is （3.52 ± 0.13）cm in length. The corolla diameter is（2.87 ± 0.27）cm with light pink in color. There are tiny flake attachments between corolla lobes. The cultivar has great ornamental value，which can be planted for domestic decoration and landscape designment widely.

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