枫香叶片变色期全长转录组测序及分析

枫香因其树形优美,入秋后叶色红艳或橙黄,极具观赏价值,是优良的景观生态树种。为了解枫香叶片变色及其次级代谢过程的遗传基础,该文以枫香5个叶片变色期叶片混合样品为材料,利用单分子实时测序技术(PacBio平台)对其进行全长转录组测序。结果表明:(1)全长转录组测序共获得41.04 Gb的高质量数据,从中鉴定出全长非嵌合序列563 180条,通过聚类和去冗余,获得27 269条高质量全长转录本。在27 269条全长转录本中预测到2 035条长链非编码RNA(lncRNA),并检测出14 892个简单重复序列(SSR)位点和1 856个转录因子。(2)基因注释结果表明,NR、GO、COG、KEGG 等8个数据库共注释了24 857条转录本,KEGG数据库共获得了124个条代谢途径,主要有核糖体、碳代谢、氨基酸生物合成等,在类黄酮和叶绿素代谢途径中分别有49和71个转录本参与。上述结果初步揭示了枫香叶片变色期转录组信息以及功能特性,为后续研究枫香叶片变色分子机制、色素代谢合成途径和调控、相关功能基因克隆以及叶色改良提供基础数据。     

Studies on leaf spot disease of <Emphasis Type="Italic">Withania somnifera</Emphasis> and its impact on secondary metabolites

During an investigation of the disease profile of Withania somnifera, it was observed that leaf spot is the most prevalent disease. Repeated isolations from infected leaf tissues and pathogenicity tests showed the association of fungal pathogen identified as Alternaria alternata (Fr.) Keissler. Scanning electron microscopy showed various histological changes in the leaf tissues of infected plants. A decrease in total content of reducing sugars (20%) and chlorophyll (26.5%) was observed in diseased leaves whereas an increase was noticed in proline (25%), free amino acids (3%) and proteins (74.3%). High performance thin layer chromatography (HPTLC) analysis of secondary metabolites viz. withanolides, withaferin-A and total alkaloids of the diseased leaves vis-à-vis control revealed reduction in withaferin-A and withanolides contents by 15.4% and 76.3% respectively, in contrast to an increase in total alkaloids by 49.3%, information hitherto unreported in W. somnifera.     

Expression of <Emphasis Type="Italic">Withania somnifera</Emphasis> Steroidal Glucosyltransferase gene Enhances Withanolide Content in Hairy Roots

In Withania somnifera, sterol molecules of immense medicinal value are diversified by means of glycosylation. Identifying sterol glycosyltransferases provides an imperative insight of diverse sterol modifications, thereby helping to comprehend the underlying plant mechanisms. In the present study, one of the W. somnifera sterol glycosyltransferase-4 (Ws-Sgtl4) gene was transformed into the W. somnifera leaf explant through Agrobacterium rhizogene. Transformed W. Somnifera Ws-Sgtl4 leaf explants were subjected to hairy root induction and analyzed for biomass accumulation. The analysis of Ws-Sgtl4 gene expression was performed at different time exposures with the application of salicylic acid and methyl jasmonate. The elicitation of W. somnifera hairy root expressing the Ws-Sgtl4 gene was also evaluated for the enhancement if any, in the total withanolide yield as well as the withanolides-A contents. The results suggested that Ws-Sgtl4 gene expression enhanced the production of total withanolide yield and withanolides-A in the hairy root culture of W. somnifera in the response to the elicitors.     

Biotransformation of withanolides by cell suspension cultures of Withania somnifera (Dunal)

The biotransformation potential of cell suspension cultures generated from Withania somnifera leaf was investigated, using withanolides, i.e. withanolide A, withaferin A, and withanone as precursor substrates. Interestingly, the cell suspension cultures showed inter-conversion of withanolides, as well converted to some unknown compounds, released to the culture media. The bio-catalyzed withanolide was detected and quantified by TLC and HPLC, respectively. There is noticeable conversion of withanolide A to withanone, and vice versa though at a lower level. The type of reaction of this biotransformation appears to be substitution of 20-OH group to 17-OH in withanolide A. In this paper, we present for the first time the possibility of biotransformation by inter-conversion of withanolides of pharmacological importance through cell suspension culture of W. somnifera. The possible role of putative cytochrome P₄₅₀ hydroxylases is implicated in the conversion.     

Changes in contents and antioxidant activity of phenolic compounds during gibberellin-induced development in <Emphasis Type="Italic">Vitis vinifera</Emphasis> L. ‘Muscat’

Gibberellic acid (GA₃) is a plant growth regulator commonly used for increasing the productivity of seedless fruit. However, little is known about the effect of GA₃ on phenolic compounds in grapevine. In the present study, the effect of GA₃ application on contents and antioxidant activities of phenolic compounds in different tissues of Muscat grapevine (Vitis vinifera L. cv. Muscat) was investigated. An application of 100 mg/L GA₃ could successfully induce seedless grape berry, enhance berry size and accelerate the development of berries, resulting in earlier ripening of seedless berry. The contents of total phenolics and total flavonoids, and antioxidant activities in leaf, stem and tendril obviously increased, while these remarkably decreased in berry skin and flesh after GA₃ application. In addition, the grapevine leaf, stem, tendril and skin extracts were shown to contain high amounts of phenolics and significant antioxidant activities. Thus, these findings indicate that GA₃ application causes different effect on phenolic compounds and antioxidant activities, depending on grapevine tissues.     

Damage Patterns caused by Lygocoris spinolae (Hemiptera: Miridae) on ‘Campbell Early’ Grapes

The phenology and damage patterns of Lygocoris spinolae (Meyer-Dür) on ‘Campbell Early’ grape were examined in different grape development stage of inflorescence formation, blooming, and berry set. Nymphs fed on newly unfolding leaves of shoot tip before inflorescence formation. As the inflorescences were clearly visible, nymphs on leaves moved to flower clusters. Sting spots with brown color occurred at sucking sites of leaves, then expanded to hole as the leaves developed, and resulted in leaf malformation. The nymphs on flower clusters sucked developing florets, which induced the drying of florets followed by defoliation. After flower caps had fallen, L. spinolae fed on young berries causing blackening of berry skin around the sting. The blackening of berry skin changed to corky-scarred tissue as the berry developed. L. spinolae feeding significantly reduced the number of berries per cluster in all grape stages. A few berries became corky-scarred or shot berries when fed at inflorescence formation period. Feeding at blooming caused shot berries with low rate of corky-scarred berry. Most of the berries were corky-scarred or became shot berries when fed at berry set. Feeding by adults caused the same damage patterns as nymphs. Heavy damages were observed where L. spinolae were introduced after inflorescence formation: reduced number of berries per cluster by 35.0 to 99.1% at blooming and by 80.0% at berry setting depending on L. spinolae densities.     

Translocation and Persistence of 1,2-14C-(2-Chloroethyl)-phosphonic Acid (Ethephon) in Thompson Seedless Grapes

Applications of 1,2^?14C-(2-chloroethyl)phosphonic acid (ethephon) were made to the surface of mature Vitis vinifera cv. Thompson Seedless berries. After 7 days, 62 % of the recovered radioactivity was still on the outside surface and was easily washed off. Within the berry, radioactivity was present only in the carbon-labeled ethephon fraction, as revealed by chromatographic analysis. Similar results were obtained when the compound was injected directly into the berries. Application of ethephon to the first leaf above the cluster, or to a berry pedicel or a peduncle, failed to result in measurable movement of the compound into the berries. Autoradiographic studies with young shoots indicated that ethephon translocated in the phloem in a source to sink relationship.     

Metabolomics approach to investigate phytotoxic effects of Wedelia trilobata leaves,litter and soil

Although release and accumulation of plant metabolites from plant into soil can influence allelopathy, little information is known about metabolite changes that occur in leaf, litter and soil. In this study, seed germination bioassay tests and metabolomics analysis were performed to investigate the phytotoxic effects and metabolic variations (measured as buckets) in the ethanolic extracts of leaf, leaf litter and soil of Wedelia trilobata. Increasing the ethanolic extracts concentration of all extracts significantly inhibited Lactuca sativa germination rate (GR), shoot height (SH) and root length (RL). Soil exerted the strongest inhibition but contained the lowest number of buckets relative to those of leaf and leaf litter extracts. An overlap overview on the metabolome revealed a poor bucket overlap and redundancy among the leaf, leaf litter and soil extracts. Canonical correspondence analysis concluded that the SH of L. sativa was more sensitive to leaf litter extract and the leaf extract exerted a strong influence on the GR and RL of L. sativa. Multivariate analysis suggested that the metabolome of the leaf, leaf litter and soil differ substantially. Finally, putative identification using MS/MS data demonstrated various plant metabolites with phytotoxic effects that can contribute to the allelopathy of W. trilobata.