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.

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。