Research Papers

• Cloning and Expression Analysis of the Cytokinin Response Regulator VlRR5 in Kyoho Grapevine
• BIAN Lu, GUO Dalong, YU Keke, WEI Tonglu, PEI Maosong, LIU Hainan, YU Yihe
• Acta Horticulturae Sinica. 2021, 48(8): 1437-1445. DOI:10.16420/j.issn.0513-353x.2020-0668
• Abstract ( 929 ) HTML ( 567 ) PDF (1742KB) ( 567 ) 　　　

• 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.

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• Functional Analysis of Sucrose-phosphate Synthase Genes（SPS）in Sweet Cherry
• QI Xiliang, LIU Congli, SONG Lulu, LI Ming
• Acta Horticulturae Sinica. 2021, 48(8): 1446-1456. DOI:10.16420/j.issn.0513-353x.2020-0630
• Abstract ( 592 ) HTML ( 414 ) PDF (1594KB) ( 414 ) 　　　

• In order to ascertain the function of sucrose-phosphate synthase genes（SPS）in the regulation of sweet cherry ripening,four full-length cDNA of sweet cherry SPS genes（PavSPSA1,PavSPSA2,PavSPSB,and PavSPSC）were cloned in sweet cherry genome. Gene expression analysis showed that the expression levels of PavSPSA1 was the highest,followed by PavSPSC,whereas PavSPSA2 and PavSPSB were relatively weakly expressed during the fruit growth and development,and ripening using quantitative real-time PCR. The expression levels of PavSPSA1 and PavSPSA2 coincided with fruit ripening and softening. Furthermore,we used TRV-mediated virus-induced gene silencing（VIGS）to evaluate the function of PavSPSA1,PavSPSA2,PavSPSB,and PavSPSC in the regulation of ripening. The results showed that silencing PavSPSA1 gene decreased sucrose content,delayed fruit coloring,ripening and softening. However,The fruit phenotypes for the PavSPSA2,PavSPSB,and PavSPSC-silenced fruits showed no visible defects when compared with the control fruits. Taken together,our findings determined that PavSPSA1 may be a key gene regulating sucrose synthesis and accumulation in sweet cherry fruit and play an indispensable role in the regulation of sweet cherry fruit ripening and softening.

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• Changes of Fruit Abscission and Carbohydrate,ABA and Related Genes Expression in the Pericarp and Fruit Abscission Zone of Longan Under Starvation Stress
• YANG Weihai, ZENG Lizhen, XIAO Qiusheng, SHI Shengyou
• Acta Horticulturae Sinica. 2021, 48(8): 1457-1469. DOI:10.16420/j.issn.0513-353x.2020-0538
• Abstract ( 543 ) HTML ( 251 ) PDF (799KB) ( 251 ) 　　　

• In order to explore the regulation mechanism of longan fruit abscission induced by “starvation stress”,a treatment of girdling and defoliation was made on the bearing shoots of longan cultivar‘Chuliang’at the early stage of fruit development,simulating starvation stress induced by interrupting carbon supply to fruit cluster,and the levels of carbohydrate,abscisic acid（ABA）and related genes expression in the pericarp and the pedicel abscission zone were investigated at 0,1,3,5 and 6 d after treatment,respectively. The results showed that a severe fruit drop occurred at 5-6 d after starvation stress treatment,the contents of total soluble sugar and its components（glucose,fructose,sucrose）in pericarp were significantly decreased,and the reduction was relatively large during 3 d after treatment,with the decreases of sucrose and glucose significantly larger than fructose. Meanwhile,the similar changes in the levels of total soluble sugar and sucrose also occurred in abscission zone. After being treated,ABA content did not change obviously in pericarp,while increased significantly in abscission zone. Starvation stress generally decreased the expression of genes related to carbohydrate and ABA in the pericarp and abscission zone,the expressions of genes involved in sugar metabolism（NI,SS1,SPS1）,sugar signaling（HXK2,TPS1,SnRK2）and ABA metabolism（AAO3,NCED,BG）were significantly decreased during the early stage of fruit shedding,whereas NI,SS1,HXK2,SnRK2,AAO3 and NCED genes were expressed with up-regulation in the period of severe fruit drop,resulting in the sharply decreased sucrose,occurring of sugar signal and ABA accumulation. These results suggested that a crosstalk between sugar and ABA may be related to longan fruitlet abscission induced by carbohydrate starvation.

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• Accumulation of Anthocyanins in Red-flowered Strawberry‘Meihong’Petals and Expression Analysis of MYB Gene
• HONG Yanhong, YE Qinghua, LI Zekun, WANG Wei, XIE Qian, CHEN Qingxi, CHEN Jianqing
• Acta Horticulturae Sinica. 2021, 48(8): 1470-1484. DOI:10.16420/j.issn.0513-353x.2020-0477
• Abstract ( 488 ) HTML ( 505 ) PDF (3736KB) ( 505 ) 　　　

• ‘Meihong’which is a red-flowered strawberry variety was dynamically observed the anthocyanin contents during petals development. Moreover,we performed transcriptome sequencing on four development periods of petals for screening key functional genes and transcription factors in the anthocyanin synthesis pathway. The results showed that：(1) During the lifecycle of petal,the content of anthocyanin is sharply increased and reached the highest at the petal half-open period,and then decreased;(2) The key functional genes of the anthocyanin synthesis pathway,FaPAL,Fa4CL-1,Fa4CL-2,FaDFR,and Fa3GT,were positively correlated with the accumulation of anthocyanins in their expression patterns;(3) FaMYB6 and FaMYB90 were performed positively correlation with anthocyanin content;(4) Pearson correlation analysis showed that FaMYB6 was significantly positively correlated with FaPAL and FaDFR;FaMYB90 had a significant positive correlation with FaPAL,Fa4CL-1,Fa4CL-2,FaDFR and Fa3GT;FaMYB82 was significantly negatively correlated with FaPAL,Fa4CL-1,Fa4CL-2,FaDFR and Fa3GT. In summary,FaMYB82,FaMYB6,FaMYB90 regulate the transcriptional of anthocyanin synthesis genes facilitated the accumulation of anthocyanin caused the color formation of the petals in‘Meihong’strawberry.

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• Bioinformatic Identification and Expression Analysis of Candidate Genes of LIM Protein Family in Strawberry Under Abiotic Stresses
• ZHANG Zhiqiang, LU Shixiong, MA Zonghuan, LI Yanbiao, GAO Caixia, CHEN Baihong, MAO Juan
• Acta Horticulturae Sinica. 2021, 48(8): 1485-1503. DOI:10.16420/j.issn.0513-353x.2020-0595
• Abstract ( 731 ) HTML ( 346 ) PDF (6985KB) ( 346 ) 　　　

• In this paper,NCBI and GDR database were used to analyze the candidate genes of LIM family in strawberry genome,and 37 LIM genes could be divided into four subgroups,nine LIM genes were identified from Fragaria vescaL. and 28 LIM genes were identified from cultivated strawberry（F. ananassaDuch.）. The LIM family candidate genes were mainly expressed in the nucleus. Their codon bias were less preferred and tended to use the synonymous codon ending in A/T. The upstream 2 kb region of promoter sequences of FvLIM and FaLIM contained a large number of hormone response elements and abiotic stress elements. The expression levels of LIM family candidate genes under 200 mmol · L^-1 NaCl,10% PEG,and 4 ℃ low temperature,FaLIMwere more significantly up-regulated than FvLIM with the treatment time. Under 4 ℃ low temperature treatment,FvLIM5（12 h）and FvLIM7（24 h）were significantly up-regulated in F. vesca,FaLIM25（12 h）and FaLIM18（24 h）significantly up-regulated in F. ananassa‘Benihoppe’,the overall response to low temperature is obvious. The results of qRT-PCR showed that most of LIM family candidate genes were highly expressed in roots and flowers,their diverse and specific expression could be detected in five tissues. Based on the above analysis results,it was speculated that the LIM family candidate genes of strawberry might play an important role in abiotic stress and in roots and flowers development.

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• Effects of Supplemental Lighting at Different Positions on Tomato Plant Morphology,Photosynthesis and Endogenous Hormone Biosynthesis Under Low-light Environment
• QI Zhenyu, WANG Ting, SANG Kangqi, LIU Yue, WANG Mingqin, YU Jingquan, ZHOU Yanhong, XIA Xiaojian
• Acta Horticulturae Sinica. 2021, 48(8): 1504-1516. DOI:10.16420/j.issn.0513-353x.2021-0216
• Abstract ( 494 ) HTML ( 463 ) PDF (2492KB) ( 463 ) 　　　

• Greenhouse tomato production is often limited by insufficient light. It is of great significance to use LEDs for improvement of light environment. However,considering the cost and efficient use of resources,development and optimization of LED supplemental lighting technology are urgently required. In this study,the tomato plants were supplemented with top-lighting and inter-lighting using LEDs in a low-light environment,and the effects on plant morphology,photosynthetic efficiency and hormone metabolism were studied. Top-lighting promoted the photosynthetic efficiency of leaves at different positions,and led to an overall increase in the leaf area,a shorter plant height,smaller leaf angles,and an increase in the number of flowers. Changes in plant morphology were accompanied by reduced auxin （IAA）content,increased cytokinin（CK）content and down-regulation of brassinosteroid（BR）synthesis genes. Inter-lighting mainly promotes the photosynthetic efficiency and leaf area of the middle and lower leaves,significantly increased plant height and slightly increased the leaf angles of upper leaves. However,it had no effect on flower number,and in general had less effects on hormone metabolism as compared with top-lighting. Taken together,the top-lighting facilitates the formation of a better plant architecture,and promotes the photosynthesis and growth of tomato plants as a whole,and is a promising technology with potential application in the future.

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• Improvement of Photosynthetic Capacity and Lycopene Content of Tomatoes by Covering with Light Conversion Plastic Films
• FENG Qian, DONG Lingdi, YIN Yilei, JIAO Yonggang, GUO Jinghua, LI Qingyun, LIU Bingwei, YU Xianchang, SUN Mintao, HE Chaoxing, LI Yansu, WANG Jun, YAN Yan
• Acta Horticulturae Sinica. 2021, 48(8): 1517-1530. DOI:10.16420/j.issn.0513-353x.2021-2002
• Abstract ( 605 ) HTML ( 263 ) PDF (2731KB) ( 263 ) 　　　

• The light conversion plastic film is formed by adding different light conversion agents into ordinary EVA（ethylene-vinyl acetate）copolymer film. In this study,we compared the effects of different plastic films on plant growth,leaf photosynthesis,yield,and fruit quality of tomato 'Jinpeng 8' in a solar greenhouse. The optical and mechanical properties（such as thickness,tensile strength,elongation at break,and right-angle tearing strength）of EVA film（control）,light conversion film C-RBI-2（EVA film plus light conversion agent VTB470）,and C-RBI-3（EVA plus light conversion agent VTB450）were measured by using a fluorometer,infrared spectrometer,and dual-beam UV-visible spectrophotometer,respectively. Our results demonstrated that C-RBI-2 film converted ultraviolet light into blue light with emission spectrum at 470 nm. Covering C-RBI-2 film increased the net photosynthetic rate（P_n）by upregulating the expression of the the small subunits of ribulose 1,5-bisphosphate carboxylase/oxygenase（RbcS）,improving the tightness of the leaf tissue structure and the leaf tissue porosity values,and increasing the thickness of fence cells,sponge cells,and leaves. Additionally,Covering C-RBI-3 film promoted the root absorption of nitrogen（N）,phosphorus（P）,and potassium（K）,increased tomato yields,and raised the lycopene content by upregulating the gene expressions of phytoene synthase 1（PSY1）,phytoene desaturase（PDS）,and ζ-carotene desaturase（ZDS）during the ripening stage. By contrast,the C-RBI-3 film converted ultraviolet light into blue light with an emission spectrum at 450 nm,inhibited the gene expressions of RbcS and RbcL,reduced the activity of P_n and Rubisco in tomato leaves,reduced the content of lycopene,and clarified the fact that the ultraviolet-to-blue light convertion with the emission spectrum at 470 nm can improve the photosynthetic capacity and lycopene content of tomato leaves. Taken together,covering C-RBI-2 is a better choice to effectively promote the photosynthetic capacity of tomato leaves and improve the fruits’ quality in the solar greenhouse when growing plants during the autumn and winter.

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• Characterization of the Subcellular Localization and Pathogenicity of P6 Encoded by Cucurbit Chlorotic Yellows Virus
• TU Liqin, GAN Shexiang, WU Shuhua, REN Chunmei, CHENG Zhaobang, ZHANG Songbai, ZHU Yuelin, ZHOU Yijun, JI Yinghua
• Acta Horticulturae Sinica. 2021, 48(8): 1531-1540. DOI:10.16420/j.issn.0513-353x.2020-0914
• Abstract ( 352 ) HTML ( 169 ) PDF (1847KB) ( 169 ) 　　　

• Cucurbit chlorotic yellows virus（CCYV）is an important whitefly-transmitted Crinivirus,which has become an emerging infectious agent of cucurbits leading to severe disease and significant economic losses. P6 is a small protein encoded by ORF2 of RNA1,one segment of CCYV,and its functions still remains unknown. In this study,P6 was cloned from an isolate of CCYV from Shouguang,Shandong Provience using specific primers by RT-PCR. The results of sequence analysis revealed that P6 gene was 159 bp in length,encoding a protein of approximately 6 kD with a transmembrane domain. To clarify the subcellular localization of P6,a YFP-tagged P6（P6-YFP）was constructed using a 35S:YFP vector and transiently expressed in the Nicotiana benthamiana by agrobacterium infiltration. Fluorescence signal was observed in the cytoplasm and nucleus of the epidermal cells of infiltrated N. benthamiana leaves,which indicated that P6-YFP was distributed in the cytoplasm and nucleus. To test the pathogenicity of P6,a potato virus X（PVX）-based vector was introduced and PVX-P6 was constructed. Chlorotic,crumple and necrosis symptoms were observed in the emerging leaves of N. benthamiana plants inoculated by PVX-P6 and only slight mosaic symptoms was observed in the plant inoculated by PVX, which showed that heterologous expression of P6 in N. benthamiana enhanced the pathogenicity of PVX,indicating that P6 might be an important protein involved in the pathology of CCYV.

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• Studies on Flowering Characteristics and Breeding System of Hemerocallis citrina‘Datong Huanghua’
• LI Sen, LIU Juan, GONG Feifei, WANG Nan, DU Wei, ZHANG Lingling, KANG Xiuping, XING Guoming
• Acta Horticulturae Sinica. 2021, 48(8): 1541-1551. DOI:10.16420/j.issn.0513-353x.2020-1024
• Abstract ( 554 ) HTML ( 877 ) PDF (2690KB) ( 877 ) 　　　

• 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.

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• Determination of Leaf Volatile Components from Five Phoebe Species
• CHU Sasa, FAN Xiangzhen, QIU Zhaokai, YANG Qi, ZHANG Yuting, WANG Yang, XU Xiaoshan, TONG Zaikang, ZHANG Junhong
• Acta Horticulturae Sinica. 2021, 48(8): 1552-1564. DOI:10.16420/j.issn.0513-353x.2020-0987
• Abstract ( 518 ) HTML ( 229 ) PDF (2292KB) ( 229 ) 　　　

• The Phoebe species are valuable ornamental trees,with abundant volatile compounds in the leaves. In order to determine the dynamic changes of volatile compounds in the leaves of five Phoebe species,the headspace-solid phase microextraction（SPME）,separated and analyzed by gas chromatography-mass spectrometry（GC-MS）. A total of 80 volatile compounds were identified from five Phoebe species,and 52,55,41,56,and 46 compounds were detected from P. chekiangensis,P. bournei, P. sheareri,P. zhennan f. oblong,and P. zhennan f. elliptical,respectively. A total of 70 and 64 volatile compounds were identified from four directions of P. chekiangensis leaves in summer and autumn,respectively. In summer,the maximum variety of compounds was detected in western leaves,while in the autumn the maximum variety was detected in northern leaves. Further,OPLS-DA analysis showed that the volatile compounds were differed between northern and southern leaves,while the western and eastern leaves shared similar compounds. Moreover,we identified six major components,including α-copaene,and α-humulene significantly diverged in leaves grown under four temperatures. In particular,the compound contents under 45 ℃ significantly differed from the other three temperatures. Additionally,the volatile components showed diurnal variation in P. chekiangensis leaves. Eight compounds including α-copaene,β-cadinene and γ-muurolene peaked at 12：00 or 14：00,while ten compounds such as β-caryophyllene,(+)-germacrene D and β-elemene had the lowest content at 12：00 or 14：00. These results provided theoretical guidance on developing and utilizing essential oils from the leaves of P. chekiangensis and other Phoebe species,and the forest rehabilitation at the Phoebe principal stand.

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• Expression Pattern and Regulation Mechanism of ApSK₃ Dehydrin （Agapanthus praecox）Response to Abiotic Stress and Hormone Signals
• YANG Tianchen, CHEN Xiaotong, LÜ Ke, ZHANG Di
• Acta Horticulturae Sinica. 2021, 48(8): 1565-1578. DOI:10.16420/j.issn.0513-353x.2020-0660
• Abstract ( 337 ) HTML ( 154 ) PDF (2000KB) ( 154 ) 　　　

• This study cloned the dehydrin ApSK₃（Agapanthus praecox）2 195 bp promoter sequence of ApSK₃-P using real-time PCR technology to analyze tissue specificity of ApSK₃ gene,and gene expression pattern response to various abiotic stress and ABA signal. Expression vectors with five promoter deletion fragments of ApSK₃-P were constructed and transformed into Arabidopsis thaliana,in order to reveal the response pattern of ApSK₃ gene to different stress and hormone signals and the regulatory function of cis-acting elements. Bio-informatic analysis showed that the ApSK₃-P contained many typical cis-acting elements related to plant stress,hormone response and plant development. ApSK₃ gene was tissue-specific expression,the highest expression was found in fruits,followed by leaves and roots,and the lowest value was shown in flowers. ApSK₃ is more sensitive to ABA and salt signals,followed by drought and low temperature,and no obvious response to high temperature. ApSK₃-P::GUS were transformed into A. thaliana and it showed that ApSK₃-P presented strong activity in seedlings of A. thaliana,GUS activity of roots was stronger than that of leaves,and the activity gradually increased in the developing fruits. Different promoter deletion fragments of ApSK₃-P test results showed that-2 175 to-950 bp fragment played an important role in the regulation of promoter activity,multiple cis-acting elements responsed to drought stress,two tandem ABRE elements participated in response to ABA signals,and ApSK₃-P can be activated by ERE（-526 to-533 bp）and P-box（-561 to-567 bp）under ethylene and gibberellin signal,respectively. These results indicated that ApSK₃-P can be activated by drought,cold,salt,ABA,GA and ethylene,and ABRE,ERE and P-box elements of ApSK₃-P play important roles in response to abiotic stress and hormone signals.

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Research Notes

• Leaf Cytological Characteristics and Resistance Comparison of Four Citrus Rootstocks Under Drought Stress
• ZHONG Zaofa, ZHANG Lijuan, GAO Sisi, PENG Ting
• Acta Horticulturae Sinica. 2021, 48(8): 1579-1588. DOI:10.16420/j.issn.0513-353x.2020-0502
• Abstract ( 1084 ) HTML ( 430 ) PDF (2650KB) ( 430 ) 　　　

• Mature leaves from two-year-old Sanhu red tangerine（Citrus reticulata Blanc.）,Chongyi wild mandarin（C. reticulata‘Chongyi’）,Poncirus trifoliata and Carrizo citrange（C. sisensis × P. trifoliata‘Carrizo’）were detached and dehydrated for 0,3,and 6 h. The results of relative water loss and electrolyte leakage indicated that the leaves of Sanhu red tangerine had the best water retention capacity and suffered the least cell membrane damage under dehydration. Stomatal density of the lower epidermis was counted via blotting,indicating that Sanhu red tangerine had the lowest stomatal density（325 · mm^-2）,significantly lower than the other three varieties（P < 0.05）. Moreover,blotting using the dehydrated leaves showed that the stomatal aperture area of Sanhu red tangerine decreased more promptly in response to dehydration. In addition,leaf anatomical structure was compared via paraffin sectioning. The palisade parenchyma of Sanhu red tangerine was completely differentiated into two layers,but palisade parenchyma of the other three materials were relatively underdevelopped. The ratio of palisade parenchyma thickness and the sponge parenchyma thickness of Sanhu red tangerine was 0.56,which was significantly higher than that of the other three materials. Finally,principal component analysis indicated that the capacity of the four citrus germplasms tolerant to drought was: Sanhu red tangerine > P. trifoliata > Chongyi wild mandarin > Carrizo citrange. In conclusion,Sanhu red tangerine was the most drought-tolerant one among the four tested varieties,which could be used for drought-tolerant citrus breeding in the future.

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• LncRNA Sequencing Identification of Viruses Infecting Strawberry in Shaanxi
• HUANG Qianru, NIU Yonghao, WU Kuan, LIU Zhanjie, CAO Mengji, ZHAO Lei, WU Yunfeng
• Acta Horticulturae Sinica. 2021, 48(8): 1589-1594. DOI:10.16420/j.issn.0513-353x.2020-0675
• Abstract ( 466 ) HTML ( 244 ) PDF (691KB) ( 244 ) 　　　

• In order to clarify major virus species on strawberry and their geographical distribution in main strawberry areas in Shaanxi,this study collected and detected strawberry samples from seven districts or counties in Xi’an,Xianyang and Baoji through LncRNA sequencing and reverse transcription PCR （RT-PCR）. Results showed that strawberry mottle virus（SmoV）and strawberry vein band virus（SVBV）were identified in all of the seven districts or counties,but strawberry mild yellow edge virus（SMYEV）,spinach latent virus（SpLV）and Lycopersicon esculentum nepovirus（LENV）were only identified in parts of the seven districts or counties. SpLV and LENV were firstly identified in strawberry.

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• Preliminary Study on the Role of sly-miR166b and Its Target Genes in Tomato Resistance to Late Blight
• ZHANG Xiaoyi, HONG Yuhui, ZHANG Yuanyuan, LUAN Yushi
• Acta Horticulturae Sinica. 2021, 48(8): 1595-1604. DOI:10.16420/j.issn.0513-353x.2020-0730
• Abstract ( 347 ) HTML ( 217 ) PDF (1349KB) ( 217 ) 　　　

• To investigate the function of sly-miR166b in tomato resistance to late blight,the vectors that overexpressing and silencing sly-miR166b were constructed and transiently expressed in tomato plants respectively. The results showed that transient overexpressing sly-miR166b（TO）reduced its target genes expression. The ratio of lesion area to leaf area on TO leaves was much lower than that in control leaves upon inoculation. On the contrary,transient silencing sly-miR166b（TS）increased its target genes expressions. The ratio of lesion area to leaf area on TS leaves was much higher than that in control leaves upon inoculation. This study preliminarily showed that overexpression of sly-miR166b enhanced plant resistance to late blight,while silencing sly-miR166b enhanced plant susceptibility to late blight,laying a foundation for comprehensively revealing the sly-miR166b mechanism in disease resistance.

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• Embryogenesis Pathway of Chinese Kale Isolated Microspore and the Effect of 2,4-D on Embryo Formation
• LI Zhijun, ZENG Jing, TAN Mingxi, XIE Jing
• Acta Horticulturae Sinica. 2021, 48(8): 1605-1618. DOI:10.16420/j.issn.0513-353x.2020-0699
• Abstract ( 313 ) HTML ( 150 ) PDF (1982KB) ( 150 ) 　　　

• Isolated microspore embryogenesis of Chinese kale was observed by an improved DAPI fluorescence staining technology and the effects of 2,4-D on the embryogenesis of six genotypes were compared. In addition,the ploidy and seed setting of regenerated plant lines obtained were identified. The results showed that B（equal division）pathway was the main pathway of microspore embryogenesis in Chinese kale and A（unequal division）pathway also occurred. Once the microspore nucleus undergoes asymmetrical division or symmetrical division accompanied by unequal division of cytoplasm at first time,its polarity can be established,and the formation of various embryoids seems to have their own developmental routes. The effect of 2,4-D on embryo yield varied with genotype. 0.01-0.1 mg · L^-1 2,4-D had no significant effect on the yields of all type microspore embryos in three genotypes：‘Lubao’,‘Qiancui’and‘Zemei’. 0.1 mg · L^-1 2,4-D significantly reduced the cotyledon embryo yield of ‘Xiacui’,but did not affect the yield of other type embryoids. The addition of 0.05 and 0.1 mg · L^-1 2,4-D significantly increased the yields of globular and torpedo embryo of ‘Shunbao’,respectively,and therefore their total embryo yield increased significantly. For‘Shunbao 2’,which has strong ability of embryo formation,the yields of heart-shaped,globular,other type and total embryos increased significantly with the increase of 2,4-D concentration,in contrast,the yield of cotyledon embryo decreased significantly. The addition of 2,4-D had no significant effect on the microspore initiation division of‘Shunbao 2’,but could maintain or improve the re-division ability of the cells and lead to a reduction of the degradation or abortion during the process of embryogenesis,thus increasing the embryo yield. Flow Cytometry（FCM）detection of 150 regenerated plant lines revealed that 72.7% were haploid lines,22.7% were DH lines,and other lines including aneuploid and chimera only accounted for the remaining 4.6%. DH lines or haploid and diploid chimeras could set seed normally after pollination at bud stage,while other aneuploids（including chimeras）could not produce seeds or had a very low seed setting rate. In order to reduce the cost of FCM detection,haploid,DH and haploid + diploid chimera can be determined according to the presence or absence of pollen,the seed setting after bud pollination,leaf morphology and growth potential,and then the ploidy of other regenerated plants which have pollen but no seed or have poor seed can be identified by FCM.

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• Effect of Creeping Bentgrass Small Heat Shock Protein AsHSP26.8a on Transgenic Photosynthesis in Arabidopsis thaliana
• ZHU Junfei, LI Xin, DONG Kangting, TANG Zhifei, BIAN Xiuju, WANG Lihong, LI Huibin, SUN Xinbo
• Acta Horticulturae Sinica. 2021, 48(8): 1619-1625. DOI:10.16420/j.issn.0513-353x.2020-0967
• Abstract ( 286 ) HTML ( 143 ) PDF (733KB) ( 143 ) 　　　

• In this paper,effects of a creeping bentgrass small heat shock protein,AsHSP26.8a,on photosynthesis in transgenic Arabidopsis thaliana were studied by measuring root length,plant weight,transpiration rate,stomatal conductance,net photosynthetic rate and PSⅡlight energy conversion efficiency of AsHSP26.8 transgenic A. thaliana. Furthermore,the expression of endogenous photosynthesis-related genes（rbcL,psaA,psbA,psaE,clpP,rpoB,rpoA,accD）in A. thaliana were analyzed by qRT-PCR to reveal the regulation pathway of AsHSP26.8a in plant photosynthesis. Results showed that compared with the wild type,the root length of transgenic A. thaliana was significantly shortened,the fresh weight and dry weight decreased,and the photosynthetic rate,transpiration rate,stomatal conductance and photochemical efficiency of transgenic A. thaliana decreased,and the expression of photosynthesis-related genes in transgenic A. thaliana was also down-regulated. It is suggested that AsHSP26.8a inhibits the expression of photosynthesis-related genes in transgenic A. thaliana,which weakened the photosynthesis of transgenic A. thaliana,and subsequently leaded to the inhibition of root growth and dry matter accumulation of transgenic A. thaliana.

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New Technology

• High Efficient Grapevine Growth Monitor and In-lane Deficiency Localization by UAV Hyperspectral Remote Sensing
• WANG Haomiao, SONG Miaoyu, LI Xiang, HU Chaoyang, LU Renxiang, WANG Xiang, MA Huiqin
• Acta Horticulturae Sinica. 2021, 48(8): 1626-1634. DOI:10.16420/j.issn.0513-353x.2021-0441
• Abstract ( 395 ) HTML ( 386 ) PDF (3337KB) ( 386 ) 　　　

• Precise orchard management requires efficient,comprehensive and accurate growth data acquisition from the entire orchard. Traditional methods in such data collection are inefficient and with subjective bias. To solve the problem,we tested the use of unmanned aerial vehicle（UAV）to carry out growth monitoring and in-lane deficiency localization in a vineyard for two consecutive years. The main results go as：a total of 69 296 004 pixels have been obtained over an area of 187 015 m² using a multi-spectral camera carrying by a UAV with a flying height of 70 meters and a speed of 5 m · s^-1. The data was processed with EnsoMOSAIC software to obtain the Normalized Difference Vegetation Index（NDVI）. Taking NDVI > 0.75 as the criterion for good growth,the areas of the vineyard evaluated as“ordinary”,“good”and“excellent”in 2019 were 20.51%,46.15% and 35.90% respectively. Early frost at the beginning of October in 2020 resulted in significant decrease in NDVI and increased standard error,demonstrating that NDVI can be used for timely frost impact assessment. Based on a threshold of continuity < 0.6,in-lane deficiency localization was tested in a Cabernet Sauvignon plot,12 lanes were identified with in-lane deficiency,among of them 10 lanes were located in“ordinary”growth plots,which was in consistent with the evaluation results of the overall growth of the vineyard. Taking together,our results showed that UAV-based hyperspectral remote sensing imaging technology has good application prospects in vineyard plant growth analysis and frost assessment.

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New Cultivars

• A New Pear Cultivar‘Dangshan Jinsu’
• JIA Bing, YE Zhenfeng, LIU Pu, LIU Li, ZHU Liwu, HENG Wei
• Acta Horticulturae Sinica. 2021, 48(8): 1635-1636. DOI:10.16420/j.issn.0513-353x.2020-0032
• Abstract ( 527 ) HTML ( 193 ) PDF (896KB) ( 193 ) 　　　

• ‘Dangshan Jinsu’,a new cultivar,was selected from‘Dangshan Suli’pear bud mutation in Dangshan County,Anhui Province. The shape of the fruit is oblate,and the fruit skin is brown. The average fruit weight is 355.4 g. The soluble solids content is 14.5%,which is significantly higher than that of ‘Dangshan Jinsu’. The soluble sugar content is 11.2%. The titratable acid content is 0.11%. The vitamin C content is 77.0 μg · g^-1. The hardness is 3.74 kg · cm^-2. The sphenological phase is similar to‘Dangshan Suli’.

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• A New Late Ripening Red Pear Cultivar‘Wancuixiang’with a Long Storage Life
• WANG Fei, OU Chunqing, MA Li, ZHANG Yanjie, FANG Ming, JIANG Shuling
• Acta Horticulturae Sinica. 2021, 48(8): 1637-1638. DOI:10.16420/j.issn.0513-353x.2020-0639
• Abstract ( 569 ) HTML ( 156 ) PDF (2996KB) ( 156 ) 　　　

• ‘Wancuixiang’,a new late ripening pear cultivar,was selected from CP10 בDangshan Suli’. The shape of its fruit is oblong. The fruit size is big,and the average fruit weight is 376 g. The ground color of skin is yellow green and the over color is red with dense dots. The stalk cavity and the eye basin is shallow,and the fruit sepals were absent. The color of flesh is white. The flesh is fine,crisp and juicy with good flavor. The core is small. The soluble solids content is 14.4%,and the flesh firmness is 6.4 kg · cm^-2. The fruits ripen in mid October in Xingcheng City,Liaoning Province. The fruit have long storage life. The yield is high and stable,and the yield is about 39 750 kg · hm^-2 at full fruiting period.

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• A New Fingered Citron Cultivar‘Cuizhi’
• WANG Xiaoqing, MEI Yulin, LIU Jinlian, XU Jinjian, LI Yongqiang, CHEN Wenrong, ZONG Yu, SHAO Wenke, LIAO Fanglei, GUO Weidong
• Acta Horticulturae Sinica. 2021, 48(8): 1639-1640. DOI:10.16420/j.issn.0513-353x.2021-0005
• Abstract ( 410 ) HTML ( 170 ) PDF (1067KB) ( 170 ) 　　　

• ‘Cuizhi’is a new fingered citron cultivar selected from a natural bud variant of ‘Qingpi’. The tree posture is upright. The stalk of the top branch appears green and yellow strips evenly. The young leaf is green,yellow or mottled. Mature leaves are primary yellow or green,large,thick,and uneven. The young fruit exocarp is covered by yellow-green longitudinal stripes. However,those green stripes turn yellow gradually. At last,the exocarp becomes the entire flavedo when fully riped. It has high ornamental value and is suitable for making bonsai.

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