Genetic & Breeding · Germplasm Resources · Molecular Biology

• Cloning and Function Analysis of Ubiquitin-conjugating Enzyme Gene CrUBC2 in Citrus reticulata‘Wuzi Shatangju’
• WU Xiulan, LI Guihua, TANG Wenwu
• Acta Horticulturae Sinica. 2023, 50(10): 2069-2078. DOI:10.16420/j.issn.0513-353x.2022-1185
• Abstract ( 435 ) HTML ( 266 ) PDF (2052KB) ( 266 ) 　　　

• Ubiquitin-conjugating enzyme E2 is a key enzyme for substrate ubiquitination reaction，which plays an important role in the mechanism of self-incompatible by S-RNase degradation via ubiquitin-proteasome system. An E2 gene was cloned based on EST sequence（EY715921）of Citrus sinensis using the flower buds from‘Wuzi Shatangju’and‘Shatangju’，named as CrUBC2. The full-length cDNA sequence of the CrUBC2 was 965 bp，encoding 152 amino acids. There was one base difference （C/T）in the coding sequence of CrUBC2 between‘Wuzi Shatangju’and‘Shatangju’，which resulted in the conversion of threonine to isoleucine. Multiple sequence alignment showed that only one amino acid difference（Thr/Ile）was found between CrUBC2 and orthologs. Therefore，CrUBC2 protein was highly conservative during the evolution process. qRT-PCR showed that the highest expression level of the CrUBC2 was detected in anthers，and the expression level of the CrUBC2 after cross-pollination was 2.22-5.36 fold higher than that of self-pollination，indicating obvious expression specificity in different pollination. Pollen germination experiment in vitro showed that CrUBC2 protein of‘Wuzi Shatangju’inhibited significantly the growth of pollen tubes of self-pollination，but it had no effect on the growth of cross-pollination pollen tubes，which may be related to its involvement in S-RNase ubiquitination and resulting in cross-compatibility.

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• Analysis of Circadian Clock Genes SlLNK1，SlEID1，and SlELF3 Response to Photoperiod in Tomato
• LIU Hui, HUANG Ting, TAO Jianping, ZHANG Jiaqi, ZHANG Rongrong, SONG Liuxia, ZHAO Tongmin, YOU Xiong, XIONG Aisheng
• Acta Horticulturae Sinica. 2023, 50(10): 2079-2090. DOI:10.16420/j.issn.0513-353x.2022-0627
• Abstract ( 289 ) HTML ( 190 ) PDF (2211KB) ( 190 ) 　　　

• Circadian clock genes play important roles in the regulation of plant growth，development and metabolism. LNK1，EID1 and ELF3 are important circadian clock genes in tomato. In this study，orthologous genes of SlLNK1，SlEID1 and SlELF3 were identified by BLAST software in 35 species. The phylogenetic analysis found these genes were originated from land plants. qRT-PCR experiments showed that the three genes responded to photoperiod and different light intensities with different expression patterns. During two photoperiods（48 h），the net photosynthetic rate，intercellular CO₂ concentration，stomatal conductance，and transpiration rate changed rhythmically. Transcriptome analysis of temporal and spatial expression patterns of clock genes SlLNK1，SlEID1，and SlELF3 in tomato showed differences in different tissues.

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• Root Architecture Alteration by Down-regulation of the StIAA22 Gene Using Artificial MicroRNA in Potato
• YANG Jiangwei, DUAN Xiaoqin, ZHANG Feiyan, ZHANG Li, DENG Yurong, WANG Xiaofeng, ZHENG Zhiyong, ZHANG Ning, SI Huaijun
• Acta Horticulturae Sinica. 2023, 50(10): 2091-2103. DOI:10.16420/j.issn.0513-353x.2022-0761
• Abstract ( 186 ) HTML ( 77 ) PDF (2969KB) ( 77 ) 　　　

• Quantitative real-time PCR（qRT-PCR）were used to analyze the expression levels of 26 StIAA genes during potato root development，the results showed that 18 StIAAs were obviously up-regulated between the early period and the mature period of potato development，expression level of other eight StIAAs are not obvious. In addition，artificial microRNA（amiRNA）were used to futher functional study of StIAA22 that is one of the most significant up-regulated StIAAs. Interference vector of pBI121-amiRIAA was constructed，and transferred into the potato genome mediated by Agrobactium tumefacienses to obtain the transgenic plants. The qRT-PCR analysis showed that the expression of StIAA22 was obviously restrained in all transgenic plant lines. Also，the transgenic lines showed a drastic change in root architecture compared with that in control plants by suppressing StIAA22 expression，such as severe reduction in the length of root，an increase in number of lateral roots，and a decrease in biomass of potato roots. The results showed that StIAA22 had a key role in modulating potato root architecture.

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• Genetic Performance of Photoreaction Cycle in F₁ Generation of Cut Chrysanthemum
• YUAN Chucong, SU Jiangshuo, JIANG Jiafu, DENG Bo, ZHANG Fei, GUANG Zhiyong, FANG Weimin, CHEN Fadi
• Acta Horticulturae Sinica. 2023, 50(10): 2104-2116. DOI:10.16420/j.issn.0513-353x.2022-0465
• Abstract ( 170 ) HTML ( 113 ) PDF (1927KB) ( 113 ) 　　　

• The photoreaction cycle，a very important trait in the production of cut chrysanthemums（Chrysanthemum morifolium Ramat.），refers to the number of days for them to start from short sunshine and to reach the initial blooming state. Six chrysanthemum cultivars with larger differences in photoreaction cycle were selected as parents and produced 3 hybrid combinations，namely：‘Q-17’בLühuang Hongbian’（combination Ⅰ），‘Nannong Luhuo’בMini Huang’（combination Ⅱ），‘Q1-39’בHeixinhuang’（combination Ⅲ），386，208 and 181 F₁ offspring were obtained from the three combinations，respectively. In the three combinations，the coefficient of variation of the photoresponse cycle was 5.85%，10.94% and 8.76%，and the coefficient of variation of the 5 traits of budding period，color developing period，plant height，internode length and number of leaves was from 6.27% to 27.21%，the mid-parental dominance of the photoreaction cycle in the three combinations of F₁ populations were 5.81，6.88 and 9.69，respectively；while the other 5 traits，except for the insignificant high-to-high parental dominance of the combination Ⅲ，all were extremely significant. Positive and negative pro-predominance. The mixed genetic model analysis revealed that there were differences in the genetic models of the photoreaction cycle，the budding period and the color developing period among the three combinations. The photoreaction cycle conformed to the A-1 model in the combination I，and the heritability of the main gene is 50.4%；in the combination Ⅱ，it conforms to the A-0 model，without the control of the main gene；in the combination Ⅲ，it conforms to the B-1 model，and the heritability of the main gene It is 84.93%，which belongs to high heritability. Taken together，the photoreaction cycle is a complex quantitative trait，and its heritability varies greatly among different combinations.

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• Cloning and Functional Analysis of LlLBD18 in Lilium lancifolium
• YIN Xiaoyu, HE Guoren, BI Mengmeng, TANG Yuchao, HAO Chunlian, QU Yuxiao, HAO Zehui, XU Leifeng, HU Fengrong, YANG Panpan, MING Jun
• Acta Horticulturae Sinica. 2023, 50(10): 2117-2127. DOI:10.16420/j.issn.0513-353x.2022-0766
• Abstract ( 229 ) HTML ( 86 ) PDF (2493KB) ( 86 ) 　　　

• In this study，a LBD transcription factor gene，named LlLBD18（GenBank accession number ON455210）was cloned from Lilium lancifolium. Its open reading frame was 684 bp，which encoded 227 amino acids，and contained a typical LOB domain. The phylogenetic tree analysis showed that LlLBD18 had the highest homology with Zingiber officinale ZoLBD18. Subcellular localization results showed that LlLBD18 was localized in the cytoplasm and nucleus. Quantitative real-time PCR analysis showed that the expression of LlLBD18 was the highest in primary bulbils，followed by roots，and the lowest in leaves. In the process of bulbil formation，the overall expression of LlLBD18 was first increased，then decreased，and then increased，and the highest expression was at the early stage of bulbil primordium initiation（the 4th day）. Functional studies found that overexpression of LlLBD18 in L. lancifolium can promote bulbil formation，while the formation of bulbils after VIGS silencing of LlLBD18 was significantly inhibited. This research suggested that LlLBD18 plays a positive regulatory role in bulbil formation of L. lancifolium.

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• Construction of Core Collection of Nymphaea Based on SSR Fluorescent Markers
• SU Qun, WANG Hongyan, LIU Jun, LI Chunniu, BU Zhaoyang, LIN Yuling, LU Jiashi, LAI Zhongxiong
• Acta Horticulturae Sinica. 2023, 50(10): 2128-2138. DOI:10.16420/j.issn.0513-353x.2022-0902
• Abstract ( 236 ) HTML ( 159 ) PDF (5429KB) ( 159 ) 　　　

• The genetic diversity of 240 accessions of water lily germplasm resources was analyzed using fluorescent SSR marker；the population structure of water lily resources was analyzed using Structure software and validated by the principal component analysis and cluster analysis. The core germplasm of water lilies was constructed based on the minimum distance step-sampling method and validated by a t-screen. The results showed that a total of 205 alleles were detected in 16 pairs of fluorescent SSR primers，with an average Shannon information index（I）of 0.2036，an average Nei genetic diversity index（H）of 0.1168，and an average effective number of alleles（N_e）of 1.1697，showing rich genetic diversity. The K-value of the optimal number of populations was three，with a small amount of germplasm mixing between populations；the population structure analysis divided the 240 accessions of water lily into three taxa. The method of LDSS was used to sample at percentage of 70%，65%，60%，55%，50%，45%，40%，35%，30%，25%，20%，15%，and 10% of the core subsets，with no significant overall variation in genetic diversity indices. Thirty-six accessions of core germplasm of Nymphaea were finally constructed，accounting for 15% of the initial collection，with the retention rates of I，H and N_e were 117%，118% and 102%，respectively. The t-test showed that the genetic parameters of the core germplasm containing 36 accessions of water lilies were not significantly different from the original germplasm and adequately represented the diversity of the original germplasm.

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• Genome-wide Identification and Abiotic Stress Response Analysis of PP2C Family Genes in Rosa chinensis‘Old Blush’
• SHEN Yuxiao, ZOU Jinyu, LUO Ping, SHANG Wenqian, LI Yonghua, HE Songlin, WANG Zheng, SHI Liyun
• Acta Horticulturae Sinica. 2023, 50(10): 2139-2156. DOI:10.16420/j.issn.0513-353x.2022-0752
• Abstract ( 246 ) HTML ( 164 ) PDF (6182KB) ( 164 ) 　　　

• A total of 69 members of the PP2C family were identified from the genome of Rosa chinensis‘Old Blush’using bioinformatics techniques. The majority of the proteins were hydrophilic，and the amino acid lengths ranged from 122 to 1 082 amino acids，with isoelectric points ranging 4.03 and 9.34. Phylogenetic analysis indicated that PP2Cs were divided into 12 subfamily groups，and the genetic structure and conserved motif of the same subfamily had a high similarity. Segmental duplication events were the main reason for the expansion of PP2C family genes. A significant function for the PP2C family of genes in response to stress may be inferred from the prediction of the cis-elements of promoters，which revealed that nearly 85% of PP2Cs had stress response elements and phytohormone response elements. The expression of rose PP2Cs was specific in tissue and developmental stage，and some genes were involved in the response to drought and high-temperature stress. Among them，three members of subgroup A were significantly responsive to drought stress，one member of subgroup A and two members of subgroup G were significantly responsive to high-temperature stress. Using qRT-PCR，the expression patterns of 11 PP2Cs genes under ABA and dehydration treatment were examined. Six subgroup A genes （RC0G0099200，RC1G0458700，RC1G0569200，RC2G0066800，RC2G0089100 and RC5G0571100）and a subgroup G gene（RC3G0083700）showed significantly higher expression levels following two treatments，suggesting that these genes may be activated by ABA and take part in the dehydration response.

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• Statistics and Phenotypic Traits Analysis of Camellia reticulata Registered Cultivars
• WU Guijin, CHEN Longqing, WEI Qiuyu, HU Yunchong, XU Jian, LI Dongxue, CHEN Shengtong, WANG Zhonglang, GENG Fang
• Acta Horticulturae Sinica. 2023, 50(10): 2157-2170. DOI:10.16420/j.issn.0513-353x.2022-1192
• Abstract ( 231 ) HTML ( 99 ) PDF (4125KB) ( 99 ) 　　　

• Based on the World Camellia Plant Variety Registry，823 cultivars of Camellia reticulata that had been registered in 2021 and before were analyzed for the resources and biological characteristics，and traits diversity analysis，principal component analysis and cluster analysis were carried out for 213 cultivars whose morphological characteristics were well documented. The results showed that Camellia reticulata cultivars are rich in resources，and China，the United States and Australia are the main sources of their cultivars. The flower color is mainly red，followed by pink，rare compound color and white. The flower types are mainly semi-double petals and double petals，and there are few single-petal groups. The leaf shape is mainly elliptic，followed by round，ovate and lanceolate. The leaf tip is mainly tapering，and the leaf base is mainly wedge-shaped. The phenotypic diversity index（H）of 213 cultivars was 0.41-1.91，among which the H value of leaf width was the largest（1.91）. The coefficient of variation（CV）was 15.16%-49.08%，among which the leaf length was the smallest（15.16%）and the largest number of petals（49.08%）. Through principal component analysis，it was shown that the characteristics of leaves played an important role in the classification of Camellia reticulata cultivars. Clustered by leaf size and number of petals，the 213 cultivars can be divided into three groups. GroupⅠcan be used as breeding materials for single-petal flower breeding，and group Ⅲ has a large number of petals and leaves，which can be used as breeding materials for the selection and breeding of double-petal flower cultivars.

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• Expression and Functional Identification of Magnesium Transporter Gene CsMGT6 in Camellia sinensis
• WEN Ting, LI Jing, ZHANG Jiaqi, WEI Yi, ZHU Wenrui, NI Dejiang, WANG Mingle
• Acta Horticulturae Sinica. 2023, 50(10): 2171-2182. DOI:10.16420/j.issn.0513-353x.2022-0506
• Abstract ( 191 ) HTML ( 160 ) PDF (2950KB) ( 160 ) 　　　

• To understand how magnesium transporters regulate the uptake and translocation of magnesium，a magnesium transporter gene CsMGT6（GenBank Accession No. ON934629）was cloned from Camellia sinensis cultivar‘Echa 10’，which was distributed on the third chromosome of C. sinensis genome. The open reading frame of CsMGT6 gene was 1 368 bp，encoding 455 amino acids. Multiple alignment analysis indicated that CsMGT6 contained two transmembrane domains and a conserved GMN motif. Phylogenetic tree analysis showed that CsMGT6 belonged to the five subfamily，which had the highest homology with Actinidia rufa ArMGT6. Subcellular localization assays confirmed that CsMGT6 was located in the plasma membrane in tobacco epidermal cells. Moreover，quantitative real-time PCR analysis indicated that CsMGT6 showed various response to magnesium deficiency in roots and leaves among five different tea plant cultivars. In addition，functional complementation tests in Salmonella typhimurium mutant strain MM281 proved that CsMGT6 was a low-affinity magnesium transporter，which might mediate the uptake and translocation of magnesium under high concentration of magnesium. These results implied that the expression of CsMGT6 could be induced by magnesium deficiency，and CsMGT6 might be involved in the maintenance of magnesium homeostasis in tea plant plasma membrane.

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Cultivation Physiology & Biochemistry

• Effects of Different Growth Type Scions on Root Architecture of Self-rooted Young Apple Trees
• ZHU Jie, LI Lu, SUN Mingfei, GAO Meina, LIANG Bowen, XU Jizhong, LI Zhongyong
• Acta Horticulturae Sinica. 2023, 50(10): 2183-2191. DOI:10.16420/j.issn.0513-353x.2022-0771
• Abstract ( 245 ) HTML ( 175 ) PDF (878KB) ( 175 ) 　　　

• One-year-old apple seedlings with different scion-rootstock combinations，marked as‘Tianhong 2’（spur type）/‘Jizhen 2’，‘Tianhong 1’（standard type）/‘Jizhen 2’and‘Jizhen 2’/‘Jizhen 2’were used as experimental materials. The differences of root architecture and endogenous hormone content were measured to explore the effect of scion-rootstock combinations on root characteristics. The results showed that the shoot length，fresh weight of the aboveground and root system，and root-shoot ratio of‘Tianhong 1’/‘Jizhen 2’were the highest. The root activity of‘Tianhong 1’scion plants was significantly higher than that of‘Tianhong 2’scion plants and control plants. The root volume and root tip number of‘Tianhong 1’scion plant were the largest. The root length，surface area，average root diameter and root bifurcation number of the control plants were the largest. The content of IAA in leaves and the content of IAA，ZR and GA₃ in roots of‘Tianhong 1’scion plants were the highest. The relative expression levels of MdPIN1a，MdAUX1，MdARF7 and MdYUCCA10 in roots of‘Tianhong 1’/‘Jizhen 2’were higher than those of‘Jizhen 2’/‘Jizhen 2’and‘Tianhong 2’/‘Jizhen 2’. In conclusion，standard type Red Fuji‘Tianhong 1’grafted on the self-rootstock of‘Jizhen 2’had more vigorous tree growth than that of the spur type Red Fuji‘Tianhong 2’. The differences in the amount of auxin produced by the shoot tips of different growth types and the physiological and biochemical mechanisms of transport to the base are the main reasons for the differences in the root architecture of the same self-rooted rootstock. Moreover，ZR and GA₃ were involved in the formation process of apple root architecture.

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• Interaction of Different Concentrations of Salt and Nitrogen Treatment on Fruit Quality Formation of Ziziphus jujuba‘Dongzao’
• PENG Ling, FENG Lu, SONG Aiyun, DONG Linshui, LI Qingjun, LIU Jingtao
• Acta Horticulturae Sinica. 2023, 50(10): 2192-2206. DOI:10.16420/j.issn.0513-353x.2022-0740
• Abstract ( 206 ) HTML ( 179 ) PDF (1771KB) ( 179 ) 　　　

• The combined effects of sodium chloride（NaCl）and nitrogen fertilizer on the fruit quality formation of Ziziphus jujuba‘Zhanhua Dongzao 1’were studied，which will provide a theoretical basis for nitrogen management and the improvement of fruit quality under saline alkali environment. In the greenhouse，the solutions of different NaCl concentrations（0，1，3 and 5 g · L^-1）and nitrogen concentrations（0，2，4 and 8 g · L^-1）were used as irrigation water for potted seedlings of‘Dongzao’jujube. The results showed the leaf nitrogen content，chlorophyll content and net photosynthetic rate（P_n）that treated with 3 g · L^-1 NaCl and 4 g · L^-1 nitrogen fertilizer kept a higher level among all treatments. While 5 g · L^-1 NaCl treatment significantly inhibited nitrogen absorption，resulting in the lowest photosynthetic capacity when it interacted with 8 g · L^-1 nitrogen treatment. Under the same NaCl concentration，4 g · L^-1 nitrogen fertilizer had the best effect on reducing the accumulation of Na⁺ and increasing the content of K⁺ in fruits. When 5 g · L^-1NaCl was added but no nitrogen fertilizer was applied，the K⁺/Na⁺ value of fruit decreased to the lowest among all treatments. With the increase of NaCl concentration，the fruit fructose，glucose and sucrose content increased to the highest value under 3 g · L^-1 NaCl treatment，and then decreased to the lowest value under 5 g · L^-1 NaCl treatment. Under the same NaCl concentration，the addition of 4 g · L^-1 nitrogen fertilizer could significantly increase the content of three sugar components. 5 g · L^-1 NaCl treatment could promote the accumulation of malic acid，while 8 g · L^-1 nitrogen treatment could promote the accumulation of citric acid. Under the treatment of 5 g · L^-1 NaCl，no nitrogen or 8 g · L^-1 nitrogen fertilizer would make the total acid content of fruit very high. To sum up，the combination of 3 g · L^-1 NaCl and 4 g · L^-1 nitrogen fertilizer could improve the photosynthetic capacity of leaves，maintain the balance of mineral elements in cells，promote the accumulation of main sugar components in fruits，and increase the sugar acid ratio，which is most beneficial to the improvement of fruit quality. While，under 5 g · L^-1 NaCl stress，too little（no nitrogen）or too much（8 g · L^-1 nitrogen）nitrogen fertilizer resulted in ion toxicity，damaged the function of leaves，thus caused nutrient deficiency and excessive accumulation of organic acids in the fruits，which is not conducive to quality formation.

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• Effects of Organic Fertilizer Replacement on Soil Nutrients in Tea Garden and Yield-quality of Tea Plant
• SHU Zaifa, JI Qingyong, SHAO Jingna, ZHENG Shenghong, ZHOU Huijuan, HE Weizhong
• Acta Horticulturae Sinica. 2023, 50(10): 2207-2219. DOI:10.16420/j.issn.0513-353x.2022-0481
• Abstract ( 238 ) HTML ( 163 ) PDF (885KB) ( 163 ) 　　　

• The effect of soil nutrients and tea yield and quality to different fertilization structures was studied by using the‘Jingbai 1’tea cultivar as experimental material through five fertilization treatments: no fertilization，conventional fertilization，100% chemical fertilizer fertilization，30% organic fertilizer substitution and 100% organic fertilizer substitution. The results of three-year experiment showed that fertilization treatments significantly increased the contents of soil organic matter，total nitrogen (N)，available phosphorus (P)，available potassium (K) and available magnesium (Mg)，and increased the absorption of N，P，K and Mg. Whereas organic fertilizer substitution treatment showed divergent variation in nutrient absorption. Meanwhile，fertilization treatments displayed a positive effect on tea yield. 30% organic fertilizer substitution treatment revealed the highest increase in tea yield with a 27.28% average increase in the three years. In addition，the components of tea quality showed diverse responses to different treatments. When compared with no fertilization，other fertilization treatments promoted the accumulation of free amino acids，decreased the polyphenol/amino acids. After three years，compared to no fertilization treatment，other fertilization treatments decreased the contents of GA，EC，EGCG，EC，ester catechin，Non-ester catechin and total catechin. Furthermore，conventional fertilization and 30% organic fertilizer substitution treatments increased the caffeine content compared with no fertilization treatment. Meanwhile，fertilization treatment increased the content of umami amino acid，organic fertilizer substitution treatment increased obviously. In summary，the results showed that 30% organic fertilizer substitution treatment can effectively improve the tea yield and quality.

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Plant Protection

• Biological Characteristics and Fungicide Sensitivity of Aureobasidium pullulans var. pullulans Causing Spot Blight of Pear
• XIE Yunye, QIU Guanyu, FANG Li, DAI Meisong, SHI Zebin, WU Jun, WANG Hanrong
• Acta Horticulturae Sinica. 2023, 50(10): 2220-2228. DOI:10.16420/j.issn.0513-353x.2022-0706
• Abstract ( 132 ) HTML ( 63 ) PDF (3378KB) ( 63 ) 　　　

• To investigate the biological characteristics and fungicides sensitivity of the newly purified strains of Aureobasidium pullulans var. pullulans，which cause serious spot blight of pears. The effects of different carbon and nitrogen sources，pH values，temperatures and light conditions on the mycelial growth rate and spore productions were evaluated. The indoor toxicity of nine fungicides on the mycelium of A. pullulans var. pullulans was determined by the growth rate method of mycelium. The regression equation of virulence was established by the logarithm of concentration and probability value，the correlation coefficient（r）and estimate concentration of 50%（EC₅₀）btained. The results showed that the suitable temperature for mycelium growth and spore production of the pathogen was ranged from 15 ℃ to 25 ℃，and 20 ℃ was the optimum. When the temperature exceeds 35 ℃，the growth rate of mycelium becomes very slow. PDA was the optimal media for mycelium growth，while OA was the optimal media for spore production. Mannitol and Yeast extract were optimal for mycelium growth and spore production. A. pullulans var. pullulans could grow on the medium of pH 4-10. The optimum pH for mycelium growth and spore production was 5. Light promoted spore production and mycelium growth. The obvious ringlets observed on the colony with the cultural condition of alternating dark and light. The lethal temperature of conidia was 48.9 ℃. The sensitivity of A. pullulans var. pullulans to nine fungicides was evaluated by the growth rate method of mycelium. The results showed that the pathogen was more sensitive to 75% Trifloxystrobin · Tebutazol WDG，EC₅₀ < 0.01 mg · L^-1，followed by 70% Thiophanate-methyl WP，50% Carbrndazim WP，43% Fluopyram · Trifloxystrobin SC and 325 g · L^-1 Difenoconazole ·Azoxystrobin SC，0.01 mg · L^-1 < EC₅₀ < 1 mg · L^-1.

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• Preliminary Study on the Mechanism of Improvement of Resistance to Chinese Bayberry Twig Blight Disease by Brassinolide and Oligosaccharin
• YU Zheping, YAN Xiujuan, ZHANG Shuwen, ZHENG Xiliang, SUN Li, REN Haiying, LIANG Senmiao, QI Xingjiang
• Acta Horticulturae Sinica. 2023, 50(10): 2229-2241. DOI:10.16420/j.issn.0513-353x.2022-0873
• Abstract ( 128 ) HTML ( 45 ) PDF (1296KB) ( 45 ) 　　　

• To explore the mechanism of induced resistance by immune inducers to Chinese bayberry （Myrica rubra）twig blight disease，young plants of‘Dongkui’were used as test materials to study the effects of exogenous inducers on the induction effect，growth index，chlorophyll content，antioxidant enzyme activity and expressions of pathogenesis-related genes in M. rubra after inoculation with twig blight strains. The results showed that 2,4-epibrassinolide（EBR）and oligosaccharins · plant activator protein（OPAP）could significantly reduce the twig blight disease index，with better effects of resistance induction（reaching 47.94% and 39.01%，respectively）. Both EBR and OPAP effectively promoted the growth of M. rubra，including plant height，leaf length and leaf area，which were higher than those of the control. Furthermore，EBR and OPAP significantly improved the contents of chlorophyll a，chlorophyll b and carotenoids on 28-day after inoculation，which were increased by 13.9%-26.8% compared with the control. Under the treatment of EBR and OPAP，the activities of SOD，POD and CAT significantly increased in a short time，and their activities were increased by 87.4%，106.5% and 77.9% compared with the control on 28-day after inoculation，while MDA content was lower than that of control. Both EBR and OPAP could significantly induce up-regulated expressions of M. rubra pathogenesis-related genes during 7-day to 28-day after inoculation，including MrPR1，MrPR2 and MrPR10，and their expressions were maintained at a high level. In conclusion，EBR and OPAP have better effects on the induced resistance to M. rubra twig blight disease，and their potential induction mechanisms may be closely related to the enhancement of antioxidant enzyme activity and the up-regulation of pathogenesis-related genes.

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• Molecular Mechanism of MpICE1 Overexpressing Banana Resistant to Fusarium oxysporum Based on Transcriptome Analysis
• SHI Jingfang, HU Chunhua, LI Haochen, YANG Qiaosong, SHENG Ou, BI Fangcheng, DONG Tao, LI Chunyu, DENG Guiming, GAO Huijun, HE Weidi, LIU Siwen, YI Ganjun, DOU Tongxin
• Acta Horticulturae Sinica. 2023, 50(10): 2242-2256. DOI:10.16420/j.issn.0513-353x.2022-0682
• Abstract ( 220 ) HTML ( 63 ) PDF (1456KB) ( 63 ) 　　　

• Based on previous studies，it was found that overexpression of MpICE1 transcription factor in bananas significantly improved the resistance to fusarium wilt. To further reveal the resistance mechanism of MpICE1 to fusarium wilt，the samples from the roots of wild-type and MpICE1 overexpressing bananas before（0 d）and after （7 d and 14 d）Foc TR4 inoculation were collected， and these samples were applied to RNA-sequencing for DEGs analysis. The results showed that the overexpression of MpICE1 could increase the expression of a series of genes before inoculation. These genes were enriched in phenylpropane synthesis，flavonoid synthesis，ABC transporters，MAPK signal transduction，pentose and glucuronic acid conversion pathway，which were related to the structure and function of cell wall. Combined with KEGG pathway analysis，we speculate that overexpression of MpICE1 may elevate the resistance to Foc TR4 by enhancing the basic immunity. In addition，genes higherly expressed in MpICE1 overexpressing bananas began to decline after inoculation，and the interaction between MpICE1 overexpressing bananas and pathogens reached a relatively stable state seven days after inoculation. Compared with the wild type，only a small amount of DEGs were found in MpICE1 overexpressing bananas 7 and 14 days after incolation. The expression dynamic of DEGs revealed that 12-oxophytodienoic acid reductase （Ma06_g18840），which is related to oxidation lipid metabolism （JA and OPDA），may be the target gene of MpICE1. Moreover，the expression of ubiquitin carboxyl-terminal hydrolase 36/42 was also affected by MpICE1 overexpression. However，the specific mechanism was still unknown，and need further study.

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• Screening of Antagonistic Bacteria Against Fusarium spp. Causing Melon Fruit Rot and the Antagonistic Properties
• HE Yafang, BAO Huifang, WANG Ning, ZHAN Faqiang, ZHANG Xuejun, SHI Yingwu, YANG Rong, HOU Xinqiang, LONG Xuanqi
• Acta Horticulturae Sinica. 2023, 50(10): 2257-2270. DOI:10.16420/j.issn.0513-353x.2022-0741
• Abstract ( 160 ) HTML ( 72 ) PDF (7479KB) ( 72 ) 　　　

• In this study，the antagonistic bacteria JS6-1 and JS3-4 against Fusarium solani BM1 were screened from the saline-alkali soil of Jiashi County，Kashgar，Xinjiang by plate confrontation method and the agar diffusion method. The diameters of the inhibition zone of the melon and fruit rot pathogens were 22.90 and 21.05 mm，respectively. JS6-1 and JS3-4 were identified as Bacillus velezensis and Bacillus siamensis by morphological observation，physiological and biochemical tests as well as 16s rRNA gene sequence analysis，respectively. The results of bacteriostatic spectrum showed that the two strains had strong inhibitory effect to nine plant pathogens，such as Fusarium oxysporum KW1，Alternatia alternata HB2，fragrant pear rot pathogen Valsa mali var. pyri FL1 and so on. The results of enzyme activity and iron carrier determination showed that the two strains could produce cellulase，protease，amylase，glucanase and iron carrier. Lipopeptides of two strains were extracted by acid precipitation method，and bacteriostatic experiments were carried out against Fusarium solani BM1. The results showed that the diameters of bacteriostatic zone of the lipopeptides were 20.55 and 19.05 mm，and the inhibition rate against spore germination of pathogenic bacteria were 100% and 93.77%，respectively. In conclusion，JS6-1 and JS3-4 have good antagonistic effect against Fusarium solani and are expected to be used in the biological control of melon fruit rot.

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• Screening and Identification of E3 Ubiquitin Ligase Genes Relate to Bacterial Wilt Resistance in Eggplant
• WANG Yixi, YAN Shuangshuang, YU Bingwei, GAN Yuwei, QIU Zhengkun, ZHU Zhangsheng, CHEN Changming, CAO Bihao
• Acta Horticulturae Sinica. 2023, 50(10): 2271-2287. DOI:10.16420/j.issn.0513-353x.2022-0835
• Abstract ( 192 ) HTML ( 51 ) PDF (3271KB) ( 51 ) 　　　

• Eggplant is vulnerable to bacterial wilt in production. In order to investigate eggplant bacterial wilt resistance genes，previously，the transcriptome of highly resistant inbred line and susceptible inbred line were performed and analyzed. Four E3 ubiquitin ligase genes related to bacterial wilt resistance，including SmSP1，SmSPL2，SmDDA1a1，and SmDDA1a2 were obtained. Sequence analysis showed that the domains of four E3 ligase proteins were conservative among seven species. SmSP1 and SmSPL2 belonged to RING type E3 ligase，SmDDA1a1 and SmDDA1a2 belonged to CRL^DDB type E3 substrate receptor. The subcellular localization results indicated that SmDDA1a2 was localized in the nucleus，and SmSP1，SmSPL2 and SmDDA1a1 were localized in the nucleus and other cell sites. The four genes were expressed in the roots，stems and leaves of eggplant，and the highest expression was found in the leaves. The expression of four genes were induced by Ralstonia solanacearum and exogenous hormones，and higher in resistant materials than in susceptible materials. SmSP1 was induced by salicylic acid，SmSPL2，SmDDA1a1 and SmDDA1a2 were induced by methyl jasmonate，and all four genes were induced by ethephon. Function identification by VIGS demonstrated that silencing of SmSP1 and SmDDA1a2 in resistant materials led to the decline of plant resistance to bacterial wilt，and silencing of SmSPL2 and SmDDA1a1 in resistant materials did not affect the plant resistance to bacterial wilt. These results suggested that SmSP1 and SmDDA1a2 may be involved in the regulation of eggplant bacterial wilt resistance.

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Review

• Research Progress on Endogenous Banana Streak Virus
• RAO Xueqin, LI Huaping
• Acta Horticulturae Sinica. 2023, 50(10): 2288-2296. DOI:10.16420/j.issn.0513-353x.2022-0659
• Abstract ( 151 ) HTML ( 97 ) PDF (720KB) ( 97 ) 　　　

• This review summarized the related research on the endogenous banana streak virus（eBSV）and briefly described the reactivation mechanism of homologous recombination，regulation mechanism mainly through epigenetic mechanism and genetic mechanism，and biological significance of eBSV. The research on eBSV was prospected，which would provide a reference for the study of co-evolution and interaction of banana and banana streak virus.

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New Cultivars

• A New Late-ripening Peach Cultivar‘Qiuyi’
• WANG Zhaoyuan, LI Yonghong, CHANG Ruifeng, CHEN Hu, TIAN Qihang, LIU Guojian
• Acta Horticulturae Sinica. 2023, 50(10): 2297-2298. DOI:10.16420/j.issn.0513-353x.2021-0612
• Abstract ( 122 ) HTML ( 66 ) PDF (985KB) ( 66 ) 　　　

• ‘Qiuyi’is a new late-ripening peach cultivar which is derived from the cross of‘Dajiubao’and‘Wanmi’. It has strong tree vigor and semi-open tree appearance. The flower is showy with much pollen. The fruit is nearly round in shape，the average weight is 334 g，and the biggest one is 515 g. The hair of peel is short，more than 90% of the fruit surface is covered by deep red color. The flesh is white，hard-melting，sweet. The soluble solids content is 13.6%，and the stone is cling. It is tolerant to storage and long-distance transportation. The fruit development period is about 150 days. It has high yield，the yield is about 45 700 kg · hm^-2 in the fifth year of planting.

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• A New Watermelon Cultivar‘Fenghua 18’
• HE Yanjun, LI Yulin, WANG Yuhuan, FAN Min
• Acta Horticulturae Sinica. 2023, 50(10): 2299-2300. DOI:10.16420/j.issn.0513-353x.2021-0537
• Abstract ( 133 ) HTML ( 43 ) PDF (953KB) ( 43 ) 　　　

• ‘Fenghua 18’is a new watermelon cultivar crossed by inbred lines S0933 and S1082. The whole growth period is about 109 d and the fruit development period is about 32.6 d. The average weight of single fruit is 6.35 kg. The fruit shape is spherical and the shape index is 1.1. The peel is green，covered with clear blackish green stripes and wax powder. The flesh is red and crisp with good taste. The soluble sugar content is 12.3%. It issuitable for storage and can yield about 65 000 kg · hm^-2. It is middle resistant to Fusarium wilt and anthracnose. It’s well adapted to early spring and autumn plastic house culture and open field culture in Taizhou，Zhejiang Province，Eastern China.

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• A New Cultivar‘Xiaobaima’of Intergeneric Hybridization Between Holcoglossum and Rhynchostylis
• CHEN Heming, LÜ Fubing, XIAO Wenfang, LI Zuo
• Acta Horticulturae Sinica. 2023, 50(10): 2301-2302. DOI:10.16420/j.issn.0513-353x.2021-0294
• Abstract ( 274 ) HTML ( 49 ) PDF (3348KB) ( 49 ) 　　　

• The cultivar‘Xiaobaima’is a new cultivar bred by intergeneric hybridization between Holcoglossum and Rhynchostylis. The plant is small and vigorous，the flower is round with fragrance and the average flower diameter is 2.6 cm，the number of peduncles per plant is 1.8 and the number of flowers per peduncle is 9.5. First flowering is in mid-february and the flowers blossom 40 days in the greenhouse of Guangzhou，and the plants have strong resistance.

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• A New Magnolia Cultivar‘Chang’an Liren’
• YAN Huiling, WANG Yaling, LI Renna, YE Wei, FAN Lu, DING Fangbing, LINGHU Yuwei, LIU Licheng
• Acta Horticulturae Sinica. 2023, 50(10): 2303-2304. DOI:10.16420/j.issn.0513-353x.2021-0823
• Abstract ( 177 ) HTML ( 67 ) PDF (934KB) ( 67 ) 　　　

• The new Magnolia cultivar‘Chang’an Liren’was obtained by artificial hybridization between Magnolia polyphala and M. sprengerii‘High Haven’. Each single flower has the tepals of 9-11 and the shape is obovate. The middle and inner tepal is slanted at the beginning of blooming，with outer surface pink color（RHS 63A-D），and inner surface purple pink color（RHS 186D）.The flower bud has terminal.The flowering period is from late March to early April. The suitable planting range is Xi'an City in Shaanxi Province and the areas with similar climates.

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