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.

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 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.

A New Diol from Dimocarpus longan Seeds

Objective To investigate the chemical constituents of Dimocarpus longan seeds in Sapindaceae.Methods The chemical constituents were isolated from the ethanol extract of D.longan seeds by silica gel column chromatography.Their structures were identified on the basis of physical and chemical properties and spectral analysis.Results One compound was isolated and identified as 2-methyl-1,10-undecanediol,named longandiol(1).Conclusion Compound 1 is a new compound.

Indicator Analysis of Off-season Longan Flower Reversal

[Objectives] This study was conducted to analyze the internal causes of flower reversal in Longan （ Dimocarpus longan Lour.） trees. [Methods] With flowering trees and flower reversal trees as experimental materials, the variations in sugar and starch in mature leaves, tender leaves, mature branches, twigs and terminal buds after flower forcing were analyzed. [Results] During flowering process, sugar content showed the greatest difference between flowering and flower reversal trees, and the difference was the greatest in mature leaves. Trees with mature leaves having a sugar content above 44.71 mg/g were found to be more prone to flowering, while those with leaf sugar content lower than 27.80 mg/g were susceptible to flower reversal. In addition, longan trees with a higher sugar content in tender leaves were not prone to flower reversal. [Conclusions] In future, whether off-season flower forcing can be performed on longan trees could be judged through the detection of tree leaves, which is of great significance to prevention of flower reversal in off-season longan production.

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.

龙眼DlWRKY25基因克隆及在成花进程中的功能分析

WRKY是植物中一类至关重要的转录因子,其与植物的生长发育过程以及胁迫响应有着密切的关系。从目前研究结果中得到,在龙眼成花诱导进程中部分WRKY基因也参与了其中,比如DlWRKY25。为了对龙眼WRKY基因的功能有更深入的了解,本研究以‘四季蜜’龙眼cDNA为模板克隆了龙眼DlWRKY25基因,同时对该基因的序列特征、成花发育过程与组织表达模式,亚细胞定位及过表达转DlWRKY25基因拟南芥进行研究。结果表明,龙眼DlWRKY25基因的开放阅读框(open reading frame, ORF)全长为1 056 bp,编码355个氨基酸。氨基酸序列显示DlWRKY25含有典型的WRKY结构域与锌指结构,属于Ⅲ型WRKY蛋白。亚细胞定位的结果显示,细胞核处有明显而又集中的荧光信号,表明DlWRKY25定位于细胞核。RT-qPCR结果显示,该基因在茎中有较高的相对表达量,并在‘四季蜜’龙眼的成花诱导阶段,显示特异下调表达。过表达转基因拟南芥植株结果显示,DlWRKY25在拟南芥中的过量表达能够加快植株的成花过程。

龙眼DlWRKY57基因克隆与拟南芥遗传转化

以龙眼成熟叶片为材料,利用实验室构建的龙眼转录组数据库,筛选出Dl WRKY57基因c DNA序列,对其开放阅读框(ORF)进行克隆和生物信息学分析。结果表明,Dl WRKY57基因ORF长度为894 bp,编码297个氨基酸,此蛋白属于WRKY基因家族中的域a类,存在1个WRKY结合位点。通过生物信息学分析表明,该蛋白属于非跨膜亲水蛋白,预测定位于细胞核,存在45个氨基酸磷酸化位点。其二级结构由无规则卷曲、琢-螺旋和延伸链构成,其中无规则卷曲为二级结构中最主要的结构元件,并且二级结构与三级结构预测结果高度一致。同源基因进化树分析表明该基因与木薯亲缘关系最近。以p MD18-T和p BI121载体为基础,成功构建了植物超表达载体p BI121-Dl WRKY57,利用农杆菌花序法转化拟南芥,经PCR分子检测,获得含Dl WRKY57基因的拟南芥植株,该超表达载体的遗传转化为Dl WRKY57基因功能的深入研究提供依据。

龙眼Dlc4h基因组织特异性表达及其生物信息学分析

肉桂酸4-羟化酶(cinnamate-4-hydroxylase,c4h)是合成黄酮类化合物的关键酶之一。为了研究Dlc4h基因的结构及其在龙眼次级代谢产物合成中的功能,本研究采用实时荧光定量PCR (qRT-PCR)技术分析Dlc4h基因在龙眼根、茎、叶组织中的特异性表达,并对该基因进行了生物信息学分析。定量分析结果表明:Dlc4h基因在各组织中均有表达,表达量由高到低依次为根、茎、叶。生物信息学分析结果表明:该基因全长1 611 bp,编码536个氨基酸;蛋白质相对分子质量为61 389.45 Da,等电点(pI)为8.82;它是一种不含信号肽、有跨膜结构、定位于质膜的可溶性亲水蛋白;二级结构主要包括α-螺旋和无规则卷曲,并具有卷曲螺旋结构;采用SWISS-MODEL构建Dlc4h三级结构模型,运用Ramachandran评估表明该模型准确可靠;Dlc4h预测得到的配体结合位点分别为128Arg、145Val、146Phe、153Trp、157Arg、213Met、329Ile、332Ala、333Ala、336Thr、337Thr、340Ser、402His、467Pro、468Phe、473Arg、475Cys和476Pro。本研究的结果为进一步研究Dlc4h基因在龙眼黄酮类化合物生物合成途径中行使的功能提供依据。