New Alkaloid and Aromatic Glucoside from the Flowers of Cymbidium Lunagrad Eternal Green.

In this paper, we investigated the chemical components of the flowers of Cymbidium Lunagrad Eternal Green for the first time. In the whole post-fertilization, a new alkaloid, named Lunagrad A (1), and a new aromatic glucoside, named Lunagrad B (2), were isolated from the MeOH extract of the flowers of Cymbidium Lunagrad Eternal Green, along with other six known aromatic compounds (3-8) and three flavone glucosides (9-11). These structures were determined on the basis of NMR experiments, as well as chemical evidence.

A new nepovirus identified in mulberry (Morus alba L.) in China.

An isometric virus was identified in mulberry leaves showing symptoms of mulberry mosaic leaf roll (MMLR) disease. Its genome consists of two (+)ssRNAs. RNA1 and RNA2 have 7183 and 3742 nucleotides, excluding the 3'-terminal poly(A) tail. Based on phylogenetic analysis of the RNA1-encoded polyprotein and CP amino acid sequences, the properties of the the 3'-UTR of RNA1 and RNA2, and <75 % identity in the CP amino acid sequence, this virus is proposed to be a new member of the genus Nepovirus, subgroup A. Since a causal relationship between this virus and MMLR has not been established, it is tentatively referred to as MMLR-associated virus.

Complete genome sequence of a novel monopartite geminivirus identified in mulberry (Morus alba L.).

The genome sequence of a novel geminivirus from mulberry samples exhibiting crinkle leaf symptoms is reported. The sequence consisted of 2952 nt, containing four open reading frames (ORFs) in the viral-sense strand and two ORFs in the complementary-sense strand. The size of the genome and the conserved origin of replication are similar to those of members of the family Geminiviridae, but the genomic organization, number of ORFs, and especially five contiguous GAAAAA repeats positioned upstream of ORF1 distinguish it from other geminiviruses. Phylogenetic analysis coupled with ORF analysis suggests that this is a novel virus that does not fit into the established seven genera of the family Geminiviridae. The virus, found in Zhenjiang, Jiangsu province, China, is tentatively named mulberry crinkle leaf virus isolate Jiangsu (MCLV-js).

Rice grassy stunt virus nonstructural protein p5 serves as a viral suppressor of RNA silencing and interacts with nonstructural protein p3.

Rice grassy stunt virus (RGSV), a member of the genus Tenuivirus, causes serious rice disease in Southeast Asian countries. In this study, a green fluorescent protein (GFP)-based transient expression assay was conducted to show that p5, encoded on RNA5 in the viral sense, is a viral suppressor of RNA silencing (VSR). Protein-protein interactions (PPIs) between p5 and all RGSV proteins except pC1 and pC2 were investigated using Gal4-based yeast two-hybrid (Y2H) experiments. The results demonstrated that p5 interacts with itself and with p3 encoded on RNA3 in the viral sense. p5-p5 and p5-p3 interactions were detected by bimolecular fluorescence complementation (BiFC) assay, and the p5-p3 interaction was confirmed by subcellular co-localization and co-immunoprecipitation (Co-IP) assays. Using the Y2H system, we demonstrated that the p5-p3 interaction requires both the N-terminal (amino acid residues 1 to 99) and C-terminal (amino acid residues 94 to 191) domains of p5. In addition, either p5 or p3 could enhance the pathogenicity of potato virus X (PVX) in Nicotiana benthamiana plants. A much more significant enhancement of PVX pathogenicity and accumulation was observed when p5 and p3 were expressed together. Our data also showed that RGSV p3 does not function as a VSR, and it had no effect on the VSR activity of p5 or the subcellular localization pattern of p5 in plant cells from Nicotiana benthamiana.

Plant antifungal proteins and their applications in agriculture.

Fungi are far more complex organisms than viruses or bacteria and can develop numerous diseases in plants that cause loss of a substantial portion of the crop every year. Plants have developed various mechanisms to defend themselves against these fungi which include the production of low-molecular-weight secondary metabolites and proteins and peptides with antifungal activity. In this review, families of plant antifungal proteins (AFPs) including defensins, lectins, and several others will be summarized. Moreover, the application of AFPs in agriculture will also be analyzed.

Five new taraxerene-type triterpenes from the branch barks of Davidia involucrata.

Five new taraxerene-type triterpenes, 2-nor-D-friedoolean-14-en-28-ol (1), 2-nor-d-friedoolean-14-en-3α,28-diol (2), 6α-hydroxy-2-nor-D-friedoolean-14-en-3,21-dione (3), 6α,11α,29-trihydroxy-D-friedoolean-14-en-3,16,21-trione (4), and 6α,23,29-trihydroxy-D-friedoolean-14-en-3,16,21-trione (5), were isolated from the MeOH extract of the branch barks of Davidia involucrata, together with five known compounds. Their structures were elucidated by means of various spectroscopic analyses. Five of the identified compounds showed moderate cytotoxicities against the cell proliferation of SGC-7901, MCF-7, and BEL-7404.

Complete genome sequence of narcissus late season yellows virus infecting Chinese narcissus in China.

The complete genome sequence of a Chinese narcissus isolate of narcissus late season yellows virus from Zhangzhou, China (NLSYV-ZZ), was determined to be 9,651 nucleotides in length, excluding the 3'-terminal poly (A) tail, by amplification and sequencing of virus RNA. The viral genome contains a single long open reading frame of 9,315 nucleotides encoding a polyprotein of 3,105 amino acids. The polyprotein was predicted to be cleaved into ten mature proteins by three viral proteases. Complete genome sequence comparison and phylogenetic analysis indicated that NLSYV-ZZ was most closely related to narcissus yellow stripe virus (NYSV), which was also isolated from narcissus. These viruses shared 69.9 % identity in their complete nucleotide sequences and 77.0 % identity in their polyprotein amino acid sequences.

Identification and expression of caspase-1 gene under heat stress in insecticide-susceptible and -resistant Plutella xylostella (Lepidoptera: Plutellidae).

A caspase gene in Plutella xylostella (DBM) was identified firstly and named Px-caspase-1. It had a full-length of 1172 bp and contained 900 bp open reading frame that encoded 300 amino acids with 33.6 kDa. The deduced amino acid of Px-caspase-1 had two domain profile including caspase_p20 (position 61-184) and caspase_p10 (position 203-298) (i.e. the big and small catalytic domains), and the highly conserved pentapeptide QACQG in caspase_p20 domain (the recognized catalytic site of caspases). Being highly homologous to effector caspase genes in other insect and mammalian species, Px-caspase-1 was thought to be an effector caspase gene. Heat stress could result in significant mortality increase on adult DBM. Px-caspase-1 mRNA expression and caspase-3 enzyme activity (a effector caspase) were elevated with age and heat treatment. And, heat stress facilitated the procession of Px-caspase-1 expression. Significantly higher mRNA transcription levels were found in a chlorpyrifos-resistant DBM strain, as compared to those in insecticide-susceptible DBM. The results indicated that high temperature could significantly promote apoptosis process resulting in an the increased DBM mortality rate, and that insecticide-susceptible DBM had a significantly higher physiological fitness at high temperatures than insecticide-resistant DBM.

A new phenolic glycoside and cytotoxic constituents from Celosia argentea.

A new phenolic glycoside, 4-O-ß-D-apifuranosyl-(1→2)-ß-D-glucopyranosyl-2-hydroxy-6-methoxyacetophenone (2) and 11 known compounds were isolated from the MeOH extract of the plant Celosia argentea. The structures of the compounds were elucidated on the basis of spectroscopic analysis and chemical methods. Among the isolated compounds, stigmasterol (10) showed moderate inhibitory activities against SGC-7901 and BEL-7404 cells.

Coleus blumei viroid 6: a new tentative member of the genus Coleviroid derived from natural genome shuffling.

Coleus blumei can be infected by several viroids of the genus Coleviroid. One year after detecting a mixed infection of coleus blumei viroid 1 (CbVd-1) and 5 (CbVd-5) in coleus seedlings inoculated with these two viroids, we found an additional viroid-like RNA. Sequence analysis revealed a viroid of 342 nucleotides that contains the central conserved region of coleviroids and is a chimera of the left half of CbVd-3 and the right half of CbVd-5. This new viroid, tentatively referred to as coleus blumei viroid 6 (CbVd-6), appears to have arisen from a natural recombination event or genome shuffling.

Identification and characterization of a new coleviroid (CbVd-5).

A viroid-like RNA was detected from coleus (Coleus blumei) in China. It consisted of 274 nucleotides and had 66% sequence identity with a member of the closest known viroid species. The predicted secondary structure is rod-shaped with extensive base pairing, and it has the conserved region characteristic of the genus Coleviroid. Two terminal sequences that are highly conserved among some members of the genus were also identified. The viroid-like RNA was successfully transmitted to coleus by slash-inoculation. This viroid was identified as a new member of the genus Coleviroid, and we tentatively propose the name Coleus blumei viroid 5 (CbVd-5).

New asperxanthone and asperbiphenyl from the marine fungus Aspergillus sp.

BACKGROUND: Marine fungi are of great importance as potential sources of agricultural pesticide leads. To continue work on new and biologically active metabolites from marine fungi, culture extracts of selected isolates were screened for inhibitory activity against tobacco mosaic virus (TMV), a typical member of the tobamovirus group of plant viruses. RESULTS: A new difuranxanthone, asperxanthone (1), and a new biphenyl, asperbiphenyl (2), as well as seven known unsaturated fatty acid glycerol esters, were isolated from a selected marine fungus, identified as Aspergillus sp. (MF-93), collected in the Quan-Zhou Gulf. Two-dimensional NMR methods and FAB-MS established the structures of the new compounds. Among the compounds, 1 and 2 showed moderate activity (inhibitory rates 62.9 and 35.5% respectively) in inhibiting multiplication of TMV, higher than that of the other seven known lipids but much lower than that of the extract at the identical concentration of 0.2 mg mL(-1). CONCLUSION: Two new compounds, asperxanthone and asperbiphenyl, were identified as active components from Aspergillus sp. (MF-93).

Constituents from the seeds of Brucea javanica with inhibitory activity of Tobacco mosaic virus.

Three new constituents were obtained along with 10 known compounds from the seeds of Brucea javanica. The structures of these compounds were determined based on spectral and chemical evidence. These new compounds included a monoterpenoid glycoside and two sesquiterpenes. Bioactivity screening of these constituents showed that compounds 1, 3, 8, 9, and 13 with obvious activities in inhibiting multiplication of the Tobacco mosaic virus.

Antiphytoviral activity of bruceine-D from Brucea javanica seeds.

BACKGROUND: Brucea javanica (L.) Merr. is widely distributed throughout the southern parts of China and has been used in traditional medicine to treat a variety of diseases. The objective of the present study was to identify the active antiphytoviral compound in the seeds of B. javanica and evaluate the inhibitory activity of the compound against plant virus. RESULTS: Bioassay-guided fractionation of the most active extract from the seeds led to the isolation of an antiphytoviral compound which was identified as bruceine-D by conventional spectroscopy methods. The compound exhibited significant inhibitory activity against the infection and replication of tobacco mosaic virus (TMV), with IC(50) values of 13.98 and 7.13 mg L(-1) respectively. The compound also showed a strong inhibitory effect on the infectivity of potato virus Y (PVY) and cucumber mosaic virus (CMV). Furthermore, the compound could effectively inhibit systemic TMV infection in the host tobacco plant under glasshouse conditions. CONCLUSION: The results suggested that bruceine-D from Brucea javanica may have the potential to be used as a natural viricide, or a lead compound for new viricides.

Two new phenolic water-soluble constituents from branch bark of Davidia involucrata.

Two new phenolic water-soluble constituents, involcranoside A (1) and involcranoside B (2) have been isolated along with five known phenolic compounds: 3,4-dimethoxyphenyl-O-beta-D-gluco-pyranoside (3), picein (4), and 1,4-dihydroxy-3-methoxy-phenyl-4-O-beta-D-glucopyranoside (5), leonuriside A (6) and 4-hydroxy-3-methoxybenzoic acid (7) from the branch bark of Davidia involucrata. Identification of their structures was achieved by 1D and 2D NMR experiments, including (1)H-(1)H COSY, NOESY, HMQC and HMBC methods and FAB mass spectral data.

Anti-tobacco mosaic virus (TMV) triterpenoid saponins from the leaves of Ilex oblonga.

Ten triterpene saponins have been isolated from a MeOH extract of the leaves of Ilex oblonga. In their structures, six new triterpenoid saponins were named as oblonganosides H-M (2, 4, 5, and 8-10). All structures were elucidated on the basis of spectroscopic analysis. Among the triterpenoid saponins, three compounds (7, 8, and 10) showed obvious activities in inhibiting multiplication of the tobacco mosaic virus (TMV).

rRNA Pseudogenes in Filamentous Ascomycetes as Revealed by Genome Data.

The nuclear ribosomal DNA (rDNA) is considered as a paradigm of concerted evolution. Components of the rDNA tandem repeats (45S) are widely used in phylogenetic studies of different organisms and the internal transcribed spacer (ITS) region was recently selected as a fungal DNA bar code. However, rRNA pseudogenes, as one kind of escape from concerted evolution, were reported in a wide range of organisms, especially in plants and animals. Moreover, large numbers of 5S rRNA pseudogenes were identified in several filamentous ascomycetes. To study whether rDNA evolves in a strict concerted manner and test whether rRNA pseudogenes exist in more species of ascomycetes, intragenomic rDNA polymorphisms were analyzed using whole genome sequences. Divergent rDNA paralogs were found to coexist within a single genome in seven filamentous ascomycetes examined. A great number of paralogs were identified as pseudogenes according to the mutation and secondary structure analyses. Phylogenetic analyses of the three rRNA coding regions of the 45S rDNA repeats, i.e., 18S, 5.8S, and 28S, revealed an interspecies clustering pattern of those different rDNA paralogs. The identified rRNA pseudogenic sequences were validated using specific primers designed. Mutation analyses revealed that the repeat-induced point (RIP) mutation was probably responsible for the formation of those rRNA pseudogenes.

The complete chloroplast genome sequence of Anoectochilus roxburghii.

The complete chloroplast sequence of the Anoectochilus roxburghii, a popular traditional Chinese medicine for the treatment of cancer, was determined in this study. The chloroplast genome (cpDNA)^ was 152,802 bp in length, containing a pair of inverted repeats of 52,728 bp separated by a large single-copy region and a small single-copy region of 82,641 bp and 17,433 bp, respectively. The chloroplast genome encodes 116 predicted functional genes, including 81 protein-coding genes, four ribosomal RNA genes, and 31 transfer RNA genes, 25 of which are duplicated in the inverted repeat regions. The cpDNA is GC-rich (36.9%).

Purification and Characterization of AAVP, a Protein Inhibitor of TMV Infection, from the Edible Fungus, Agrocybe aegerita.

A protein with activity of inhibiting TMV infection on Nicotiana glutinosa, named AAVP, was isolated and purified from the fruiting bodies of edible fungus Agrocybe aegerita by precipitation of 40%--80% saturation of (NH(4))(2)SO(4) followed by DEAE-Fast Flow and S-200 column chromatography. The protein was proved to be homogeneous by SDS-PAGE and IEF. Analysis of the composition of amino acids showed that this protein contained no cysteine, poor in methionine and phenylalanine and rich in acidic and hydroxyl amino acids. The inhibition of TMV was 84.32% when the concentration of AAVP was 200 mg/L. N-terminus of this protein was blocked by pyroglutamyl, and the N-terminal sequence was QGVNIYNIVAGA. On potato-sucrose-agar medium, the purified protein did not inhibit the growth of three plant pathogen fungi, Trichoderma viride, Colletotrichum musae and Fusarium oxysporum.

[Sequence analysis of RNA3 of Rice stripe virus isolates found in China: evidence for reassortment in Tenuivirus].

The RNA3 segments of four isolates of Rice stripe virus (RSV), isolated from endemic sites at Panjin (PJ), Liaoning Province, Kunming (KM) and Yiliang (YL), Yunnan Province, as well as from outbreak sites at Hongze (HZ), Jiangsu Province, were determined. RNA3 of these four isolates were 2480 bp, 2509 bp, 2489 bp and 2497 bp in length, respectively. Compared with RNA3 of T and M isolates from Japan and Y isolate from Yunnan Province of China, that had been previously reported, these seven isolates could be divided into two groups. KM and YL isolates formed group one, and PJ, HZ, Y, T and M isolates belonged to another group. The two groups shared 97%-98% and 93%-94% sequence homology in viral RNA3 (vRNA3) and viral complementary RNA3 (vcRNA3) at the nucleotide levels, respectively, and there was no significant difference between the two groups at the amino acid levels. In the first group, Y isolate was significantly different from HZ,PJ and two Japan isolates in their RNA4 segment. These results show that there were two subgroups in RSV natural population related with geographical location, and reassorment may be the main factor leading to different segments of Y isolate belonging to different subgroups. The results may provide another evidence for reassortment variation in Tenuivirus.