Species-specific regulatory pathways of small RNAs play sophisticated roles in flower development in Dimocarpus longan Lour.

Flower development plays vital role in horticultural plants.Post-transcriptional regulation via small RNAs is important for plant flower development.To uncover post-transcriptional regulatory networks during the flower development in Dimocarpus longan Lour.‘Shixia’,an economically important fruit crop in subtropical regions,we collected and analyzed sRNA deep-sequencing datasets and degradome libraries Apart from identifying miRNAs and phased siRNA generating loci(PHAS loci),120 hairpin loci,producing abundant sRNAs,were identified by in-house protocols.Our results suggested that 56 miRNA-target pairs,2221-nt-PHAS loci,and 111 hairpin loci are involved in posttranscriptional gene silencing during longan reproductive development.Lineage-specific or species-specific post-transcriptional regulatory modules have been unveiled,including miR482-PHAS and miRN15.miR482-PHAS might be involved in longan flower development beyond their conserved roles in plant defense,and miRN15 is a novel miRNA likely associated with a hairpin locus(HPL-056)to regulate strigolactone receptor gene DWARF14(D14)and the biogenesis of phasiRNAs from D14.These small RNAs are enriched in flower buds,suggesting they are likely involved in post-transcriptional regulatory networks essential for longan flower development via the strigolactone signaling pathway.

Research Progress on Structure and Bioactivity of Longan Polysaccharide

Longan originates from southern China and has high nutritional and health value.Recent phytochemistry and pharmacology studies have shown that polysaccharides are a main bioactive component of longan.Longan polysaccharides possess antioxidant,anti-aging,anti-tumor,immunomodulatory,and other bioactivities.Hot-water extraction,ethanol precipitation,and ultrasonic extraction are generally used to extract water-soluble longan polysaccharides.However,the relationship between the structure and bioactivity of longan polysaccharides remains unclear,requiring further investigation.The aim of this review is to evaluate the current literature focusing on the extraction,purification,structural characterization,and biological activity of longan polysaccharides.We believe that this review would provide a useful bibliography for further innovation and a basis for using longan polysaccharides in functional food.

泸州市与广州市龙眼核不同极性部位体外抗氧化活性的比较研究

比较研究四川省泸州市和广东省广州市两个主产区的龙眼(Dimocarpus longan)核不同极性部位的体外抗氧化活性。以泸州张坝、泸州黄舣和广州荔湾产地的龙眼核为研究对象,经5种不同极性的溶剂提取其抗氧化活性物质,通过DPPH法和ABTS^(+)·法比较各提取物的抗氧化能力。结果表明,各极性部位3个产地(除泸州张坝外)龙眼核干膏质量的大小均表现为正丁醇>乙酸乙酯>无水乙醇>去离子水>石油醚。体外抗氧化试验结果表明,在DPPH法中,除广州荔湾产地龙眼核的石油醚部位外,其余产地的各极性部位均具有较高的自由基清除率,其中广州荔湾、泸州张坝产地乙酸乙酯部位的抗氧化能力最佳,IC_(50)分别为0.021、0.022 mg/mL。在ABTS^(+)·法中,各产地龙眼核的石油醚部位清除ABTS^(+)自由基能力最强、乙酸乙酯部位次之,且在乙酸乙酯提取部位中以泸州张坝龙眼核的抗氧化能力最佳,其IC_(50)为0.023 mg/mL。

龙眼体胚CDC48基因的克隆、原核表达及其在体胚发生过程中的表达分析

为探讨龙眼(Dimocarpus longan)体胚CDC48基因的表达方式,采用RT-PCR和RACE方法,从龙眼胚性愈伤组织中克隆得到1条长度为2620 bp、含有完整开放阅读框的DlCDC48基因cDNA序列(GenBank登录号:EU606206)和长度为2418 bp的DNA序列(GenBank登录号:FJ590953)。DlCDC48编码1个含有805个氨基酸的蛋白质。DlCDC48基因不含内含子。生物信息学分析表明:DlCDC48蛋白为不具跨膜结构域的亲水性胞质蛋白,不具有信号肽,定位在细胞核;与其他植物的CDC48有较高的同源性。将DlCDC48基因构建成原核表达载体,经IPTG诱导表达了1个分子量约为89 kD的蛋白。利用实时荧光定量PCR(qPCR)技术,DlCDC48在龙眼体胚发育过程中的各个阶段均有表达,其中球形胚时的表达量最低,胚性紧实球形结构阶段的表达量最高。这为进一步研究CDC48基因在植物体胚发生中的作用奠定基础。

龙眼菠萝复合果酒制备酶解条件的优化

以龙眼(Dimocarpus longan)和菠萝(Ananas comosus)果实为原料制备复合果酒,采用果胶酶酶解处理龙眼菠萝复合果汁以提高果酒的得率和澄清度,通过单因素试验和正交试验优化酶解条件。结果表明,果胶酶添加量对龙眼菠萝果酒的得率和澄清度影响最大,其次是酶解时间和酶解温度,酶解pH的影响最小。酶解处理的最佳条件组合为果胶酶添加量占混合果肉质量的0.4%、酶解时间2.5 h、酶解温度45℃、酶解pH 3.5。在最优条件组合下酶解后龙眼菠萝复合果酒的得率和透光率分别为92.3%和91.9%。

龙眼核活性炭制备工艺及其吸附性能研究

以龙眼(Dimocarpus longan Lour.)核为原料制备活性炭,通过正交试验优化制备工艺。结果表明,氢氧化钾为最适活性剂,龙眼核活性炭的最佳工艺条件为活化时间40 min、活化温度500℃、碳化温度400℃和碱碳比2∶1(质量比),在此工艺条件下制备的龙眼核活性炭的碘吸附值和亚甲基蓝吸附值分别为942.36 mg/g和12.83 m L/0.1 g,采用扫描电镜对产品的表面形态进行分析,发现其具有丰富的不规则孔隙结构。

龙眼核糖化工艺条件分析

以龙眼(Dimocarpus longan Lour.)核为原料,对其液化、糖化工艺进行研究。将干燥的龙眼核粉碎后过40目筛,按料水比1∶4(g∶m L)加水调浆,搅拌均匀后加入1 200 U/gα-淀粉酶,在自然p H,85℃下液化,可显著缩小液化时间。然后再加入糖化酶进行糖化,选取反应温度、糖化酶添加量和p H三个因素为反应因素,以料液中还原糖含量为考察指标进行正交试验,确定最佳糖化工艺条件。试验结果表明,在反应温度为60℃,糖化酶添加量为150 U/g,p H为4.5的条件下糖化,糖化液还原糖含量为16.76%,淀粉转化率达135.51%,葡萄糖收率达150.42%。将糖化液接种0.5%酿酒高活性干酵母,30℃恒温发酵3 d,最终糖化醪液中酒精浓度为5.4%。

MH、CEPA和B_9控制水涨龙眼花芽分化的效应

试验结果表明,MH(250—1000ppm)、CEPA(250—2000ppm)、B_9(750—3000ppm)及B_9(500—1500ppm)+CEPA(250—750ppm)混合液对水涨龙眼花芽分化都有不同程度的影响,花穗抽生率随处理浓度提高而下降。MH和CEPA有摘心作用,但MH250—1000ppm、CEPA750—2000ppm对结果母枝及花穗生长有副作用。CEPA250ppm12月下旬处理的花穗抽生率显著提高,而B_93000ppm11月下旬处理则适量地降低了花穗抽生率,且均不影响花穗的正常生长,对花芽分化具有明显的控制效应。

“控梢灵”对龙眼控梢促花效应的初步研究

用不同浓度"控梢灵"处理龙眼枝梢,并对龙眼枝梢生长情况、成花、产量进行调查.试验结果表明:"控梢灵"控梢作用显著,能提高龙眼的成花率,增加产量.连续喷2次"控梢灵",对适时秋梢,成花率86%～95%,与对照比较增产111 36%～261 02%;对1～5cm的冬梢,成花率80%～90%,与对照比较增产78 41%～296 61%.随着"控梢灵"浓度增加其抑制作用加强,花穗的抑制过强,长度过短,影响产量.冬梢的长度和成熟度对花穗长度、产量有很大影响."控梢灵"的抑制作用受大气温度、湿度的影响,低温、干旱的冬季抑制作用强,高温、多雨的冬季抑制作用弱.

滇产龙眼叶挥发油化学成分的分析

采用水蒸气蒸馏法从龙眼(Dimocarpus longan)叶中提取挥发油,用气相色谱-质谱联用法分析其成分,共鉴定出39个化学成分,占挥发油总量的88.35%,滇产龙眼叶挥发油的主要成分为萜类,其中含量较高的成分为β-石竹烯(24.03%)、α-石竹烯(15.35%)、反式角鲨烯(13.93%)、δ-荜澄茄烯(5.75%)和2,6-二叔丁基-4-甲基苯酚(5.48%),这些成分可能是龙眼的主要释香成分。

龙眼果肉自溶与部分氧化还原酶同工酶变化的关系

以‘石硖’龙眼果肉为材料,在(4±0.5)℃条件下贮藏,并将贮藏后期不同状态果肉分为自溶与未自溶2部分,对其中的乙醇脱氢酶(ADH)、抗坏血酸过氧化物酶(APX)、过氧化氢酶(CAT)、细胞色素氧化酶(COD)、苹果酸脱氢酶(MDH)、多酚氧化酶(PPO)、过氧化物酶(POD)、超氧物歧化酶(SOD)8个酶进行同工酶电泳检测,以果肉在贮藏过程中的变化为参照,对龙眼果肉自溶与同工酶变化的关系进行探讨。结果表明:"石硖"龙眼低温贮藏过程中,整果果肉除POD外其余7个酶同工酶酶谱变化不大;但贮藏后期自溶果肉与未自溶果肉酶谱差异显著,其中未自溶果肉与刚采收果肉(第0天)酶谱差异不大。说明即使在同一果实中,自溶与未自溶果肉生理状况明显不同,龙眼采后果肉的生理变化主要集中在自溶果肉部分,未自溶的果肉基本维持与刚采收时相近的生理状态。自溶与未自溶果肉中,APX、CAT、MDH、COD、PPD和POD酶谱条带数目、种类以及表达量间差异显著,这几种酶可能与龙眼果肉的自溶有密切关系。

龙眼果皮干燥前后挥发性化学成分的GC-MS分析

采用同时蒸馏萃取与GC-MS联用技术对龙眼(Dimocarpus longan Lour.)果皮干燥前后的挥发性化学成分进行分析和鉴定。鲜果皮中共鉴定出35种成分,相对含量前5位的有罗勒烯异构体混合物(35.44%)、3-甲基-2-丁烯-1-醇(26.14%)、ɑ-古芸烯(11.33%)、δ-榄香烯(4.54%)、角鲨烯(6.29%);干燥后果皮中共鉴定出34种成分,相对含量前5位的有ɑ-古芸烯(24.54%)、3-甲基-2-丁烯-1-醇(17.21%)、棕榈酸(8.07%)、罗勒烯异构体混合物(5.55%)、δ-榄香烯(4.15%)。龙眼果皮干燥前后共有成分有13种,但含量不同。独有成分新鲜组22种,干燥组21种。

龙眼越冬期间冠层温度与大气温度关系的初步分析(英文)

[Objective] The study aimed to provide supports for developing chilling and freezing injury monitoring and disaster damage assessment of longan(Dimocarpus Longan Lour.).[Method] Based on field observation data,the relationships between longan canopy temperature and air temperature under different weather types(sunny,cloudy to sunny,cloudy,rainy,radiation chilling injury and advection chilling injury)in 2007-2008 winter were analyzed.[Result] Diurnal variations of longan canopy temperature under sunny and radiation chilling injury weather conditions were most dramatic,followed with those under cloudy to sunny condition,while variations under cloudy,rainy and advection chilling injury conditions were mild.Diurnal variations of orchard air temperature were also closely related to weather types.By using linear and curvilinear regression methods,the relationship models between longan canopy temperature and observation station air temperature were established.The models for cloudy,rainy and advection chilling injury had better effects than those for sunny,cloudy to sunny and radiation chilling injury;the models for night were better than those for daytime and the whole day.[Conclusion] To some extent,applying the relationship models between longan canopy temperature and observation station air temperature could make up the shortcoming of meteorological data which were higher than the real values.

Phytochemical constituents and biological activities of longan (Dimocarpus longan Lour.) fruit: a review

Longan(Dimocarpus longan Lour.),as an edible fruit and traditional Chinese medicine,has been consumed for thousands of years.Longan pulp has abundant nutritional phytochemicals such as protein,carbohydrate,vitamin C,polysaccharides,polyphenols,which shows multiple biological activities including antioxidant,immunomodulatory and antitumor effects.Longan pericarp also demonstrates biological activities because of its rich content of polysaccharides and polyphenols.This review summarizes the bioactive compounds and bioactivities of longan pulp and aims to provide comprehensive information for future development of longan as a functional health food.

Genome-wide identification and expression analysis of Argonaute gene family from longan embryogenic callus

Argonaute(AGO)proteins are the core of the RNA-induced gene silencing complex which regulate a wide variety of processes in plants,from organ development to abiotic stress responses.They have been identified in many plants,but little is known in longan(Dimocarpus longan Lour.),and how AGO functions in the signaling pathways in plant embryos in response to changing environmental stimuli remains unclear.In the present research,a genome-wide analysis of the AGO gene family members and their roles in somatic embryogenesis(SE),zygotic embryogenesis(ZE),tissue developmental processes,and responses to hormones,light and abiotic stress in longan were conducted.Ten longan AGO genes were identified genome-wide and divided into four clades.They were distributed on chromosomes 1,4,8,10,12,13,14,and 15,and had 2–23 introns.The expression profiling implied that DlAGOs regulated early and middle embryogenesis,as well as developmental processes of seed,flower,and stem in longan.In addition,the transcript levels of DlAGOs in response to exogenous hormones,light and abiotic stress showed differences in expression patterns.These results provide the useful information for further elucidation of RNAi-mediated gene silencing in longan embryogenic callus(EC).

Absorption and Transfer of Exogenous Selenium in Longan(Dimocarpus longan Lour.) and Its Effect

Different concentrations of sodium selenite and sodium selenate were applied to leaves and roots of longan( Dimocarpus longan Lour.) to study the absorption and transfer characteristics of exogenous selenium in longan,and the effects of nitrogen and phosphorus fertilizers on the absorption of selenium in longan were discussed. This study provides a theoretical basis and reference for the research and influence on the absorption and transfer mechanism of selenium in longan and the production of selenium-enriched longan.

Genome-wide analysis of the CCCH zinc finger family in longan:Characteristic identification and expression profiles in Dimocarpus longan Lour

CCCH(C3 H) Zinc finger(Znf) transcription factors(TFs), as a novel type of Znf gene, regulate the expression of genes by binding to their mRNAs and play important roles in plant growth and development and abiotic stress resistance.Longan(Dimocarpous longan) is a tropical/subtropical fruit tree of great economic importance in Southeast Asia.However, genomic information on C3 H and their functions in longan are still unknown. In this study, a comprehensive analysis of the longan C3 H(DlC3 H) gene family was carried out. A total of 49 DlC3 H genes in three clades were identified from the longan genome database. Characteristics of the genes were analyzed with respect to gene structure,motif composition, phylogenetic tree and potential functions. The analysis of alternative splicing(AS) events suggested that AS events in DlC3 H genes were related to the transformation from longan non-embryonic to embryonic cultures.Promoter analysis indicated that most of the DlC3 H genes included cis-acting elements associated with hormones and stresses responses. Quantitative real-time PCR(qRT-PCR) analysis indicated that 26 of the 49 DlC3 Hs, which possess methyl jasmonate(MeJA) and abscisic acid(ABA) responsive cis-acting elements, showed differential expression patterns under treatment with ABA, MeJA and their endogenous inhibitors, suggesting that DlC3 Hs might be involved in the ABA and MeJA signaling pathways. The expression profiles of 17 of the 49 DlC3 Hs in non-embryonic callus and three tissues of embryonic cultures showed that only five of the 17 DlC3 Hs had the same expression trends as the FPKM trends in transcriptome data;the expression levels of DlC3 H07/14/16/36/49 in embryogenic callus and DlC3 H04/38 in globular embryos were high, suggesting that they have different functions in embryonic development. Further, we verified that DlC3 H01/03/05/11/19/39 were regulated by sRNAs by a modified 5’ RLM-RACE method. This study provides the first systematic analysis of C3 H genes in longan, and found that C3 H genes may be involved in hormone and stress responses, and somatic embryogenesis. Our preliminary investigation may provide clues to further studies on the characteristics and functions of this family in longan.

Analysis of Carbon Content in Off-season Flowering and Non-flowering Longan Trees

After flower induction, some longan trees can successfully blossom and bear fruit, while others with similar tree body status can only sprout leaf buds. In order to investigate the main reason for these differences, in this study, off-season flowering and non-flowering longan trees were used as experimental materials to analyze the changes of carbon content in mature leaves, tender leaves, mature shoots, tender shoots and terminal buds of longan trees after flower induction by potassium chlorate. The result showed that carbon content played an important role in flowering process. Off-season longan trees with carbon content in mature leaves reached 50.93 mg/g could successfully blossom, but those with carbon content in mature leaves lower than 37.40 mg/g were usually difficult to blossom. In addition, the maturity of tender leaves posed great influence on flowering. Specifically, tender leaves with a higher maturity contained higher carbon content and could easily blossom, which could be used as a new indicator to evaluate flower induction in off-season longan trees.

Differences in Carbon Nutrition between On-season and Off-season Longan during the Flowering Process

Flower-bud differentiation is the most critical stage of fruit yield formation, as well as a complicated carbon transfer process. To understand the changes of carbon during the flower bud differentiation process of longan, it is very important to adopt suitable planting measures and control flowering time. This study fo- cused on the changes of sugar and starch content of on-season and off-season longan during the flowering process. The results showed that the accumulation and transformation of carben differed between on-season and off-season longan during flower-bud differentiation process ; to be specific, sugar and starch content in tissues differentiated from apical buds of on-season longan were reduced at the late flower-bud physiological differentiation stage except in leaf buds ; on the contrary, sugar and starch content in off-season longan increased at the late flower-bud physiological differentiation stage： specifically, total sugar content increased from 15.43 （ - 7 d） to 31.38 mg/g （7 d） ; starch content increased from 5.42 to 8.31 mg/g during this time, which may be relevant to the external environment or tree original metabolism damaged by potassium chlorate.

Potential roles of longan flower and seed extracts for anticancer

Polyphenol-rich plants are known to possess benefits to human health. Recent studies have revealed that many Traditional Chinese Medicines(TCMs) are rich sources of polyphenols and exhibit antioxidant and anti-inflammatory activities, and these TCMs have been shown experimentally to overcome some chronic diseases, including cancer. Longan flowers and seeds, two TCMs traditionally used for relieving pain and urinary diseases, have been revealed in our recent reports and other studies to possess rich amounts of polyphenolic species and exhibit strong anti-oxidant activity, and these could be applied for the treatment of diabetes and cancer. Herein, we review the recent findings regarding the benefits of these two TCMs in the treatment of humancancer and the possible cellular and molecular mechanisms of both substances.