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We have successfully applied a hybridization selection method using biotinylated-viroid transcripts and streptavidin-coupled magnetic beads, followed by re-amplification, restriction enzyme digestion and concatemerization, to clon...
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We have successfully applied a hybridization selection method using biotinylated-viroid transcripts and streptavidin-coupled magnetic beads, followed by re-amplification, restriction enzyme digestion and concatemerization, to clone viroid small RNAs. The cloning efficiency with the PSTVd-specific small RNAs increased more than 100-fold over that with random cloning of unselected small RNAs. The method can be used to analyze small RNA biogenesis, especially to find hotspots, in various host–pathogen interactions.
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The purpose of this study was to assess the extent of genetic erosion of traditional upland germplasm in northern Thailand as a result of gene-flow from distinct strains carrying different genotypes. Even modern variety specific m...
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The purpose of this study was to assess the extent of genetic erosion of traditional upland germplasm in northern Thailand as a result of gene-flow from distinct strains carrying different genotypes. Even modern variety specific markers have not beendeveloped, there is a comparative population in Laos. Thus, both populations were compared with various characters to evaluate gene-flow from modern variety to landraces. Glutinous and glabrous strains are predominated in Laos. However, such strains weredrastically decreased in north-east Thailand. Gene diversity is higher in Thailand, compared to Laos at seven isozyme loci. This was a result of the higher frequencies of Indica strains and heterozygotes in Thailand. Plastid type was also determined byusing an INDEL marker. Nearly half of Indica strains carried the Japonica plastid. Heterozygotes also tended to carry Japonica cytoplasm. Such nuclear-cytoplasm substituted strains and heterozygotes were probably generated by natural hybridization. Japonica strains tended to be a maternal donor rather than Indica ones. Or Indica strains would easily release pollens, which grow outside of upland fields.
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Tomato plants infected with Potato spindle tuber viroid (PSTVd) had severe leaf curling and vein necrosis. The disease symptoms began to diminish during the late stages of infection, however, and almost healthy-looking leaves bega...
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Tomato plants infected with Potato spindle tuber viroid (PSTVd) had severe leaf curling and vein necrosis. The disease symptoms began to diminish during the late stages of infection, however, and almost healthy-looking leaves began to appear on the upper portion of the plants. PSTVd concentrations reached their highest levels in leaves with severe symptoms and decreased in upper leaves recovering from severe symptoms. PSTVd-specific short interfering RNAs (siRNAs), characteristic of RNA silencing, accumulated in all leaves in which PSTVd reached a detectable level, suggesting that recovery from severe disease was induced by RNA silencing via sequence-specific degradation of PSTVd.
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We have examined sequence variability among nine isolates of hop stunt viroid (HSVd) collected from hop gardens in Tohoku district in Japan, the only area in the world where hop stunt disease is endemic. Six different consensus an...
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We have examined sequence variability among nine isolates of hop stunt viroid (HSVd) collected from hop gardens in Tohoku district in Japan, the only area in the world where hop stunt disease is endemic. Six different consensus and one-consensus sequences as well as 12 sequence variants were detected in the nine HSVd-hop isolates, which suggested the sequence of HSVd-hop was remarkably variable. A neighbor-joining analysis was carried out on the new HSVd-hop sequences together with 44 previously described variants of HSVd isolated from hop and other species. All the HSVd-hop sequences recovered from hops cultivated in the Tohoku district of Japan as well as the type isolate and two Korean isolates form a cluster with the HSVd-g subtype 1 commonly recovered from grapevine. This close relationship between HSVd-hop and -grapevine isolates strongly supports the grapevine origin for hop stunt disease.
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To better understand the biogenesis of viroid-specific small RNAs and their possible role in disease induction, we have examined the accumulation of these small RNAs in potato spindle tuber viroid (PSTVd)-infected tomato plants. L...
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To better understand the biogenesis of viroid-specific small RNAs and their possible role in disease induction, we have examined the accumulation of these small RNAs in potato spindle tuber viroid (PSTVd)-infected tomato plants. Large-scale sequence analysis of viroid-specific small RNAs revealed active production from the upper portion of the pathogenicity and central domains, two regions previously thought to be underrepresented. Profiles of small RNA populations derived from PSTVd antigenomic RNA were more variable, with differences between infected Rutgers (severe symptoms) and Moneymaker (mild symptoms) plants pointing to possible cultivar-specific differences in small RNA synthesis and/or stability. Using microarray analysis, we monitored the effects of PSTVd infection on the expression levels of >100 tomato genes containing potential binding sites for PSTVd small RNAs. Of 18 such genes down-regulated early in infection, two genes involved in gibberellin or jasmonic acid biosynthesis contain binding sites for PSTVd small RNAs in their respective ORFs.
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The postharvest economic quality of mature apple (Malus x domestica Borkh.) is determined by the fruit shelf-life, which is associated with the fruit softening rate at room temperature. Ethylene is the factor that has been most st...
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The postharvest economic quality of mature apple (Malus x domestica Borkh.) is determined by the fruit shelf-life, which is associated with the fruit softening rate at room temperature. Ethylene is the factor that has been most studied in relation to the regulation of fruit softening. Softening rate and ethylene production differ widely among apple cultivars. 1-aminocyclopropane-1-carboxylic acid synthase (ACS) is one of the key regulatory enzymes involved in the synthesis of ethylene. In apple, at least four members of the ACS gene family have been identified, two of which, MdACS1 and MdACS3, have been studied extensively due to their specific expression in fruit tissue. Recent characterization of these genes has provided insight into the molecular basis of ACS gene involvement in fruit ripening, and a role of ACS genes in the regulation of system-1 and system-2 ethylene biosynthesis has been proposed. This paper reviews advances in our understanding of the relationship between ACS gene expression and the fruit shelf-life of apple, and also discusses other factors that influence fruit ripening. In addition, we prospectively overview promising research avenues that could lead to further clarification of the regulatory events involved in ripening.
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Eight species in Pleomassariaceae are described and illustrated. They are Pleomassaria maxima, Pl. swidae, Pl. siparia “type A,” Prosthemium canba, Asteromassaria macroconidica, A. pulchra, Splanchnonema mori, and S. argus. Of t...
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Eight species in Pleomassariaceae are described and illustrated. They are Pleomassaria maxima, Pl. swidae, Pl. siparia “type A,” Prosthemium canba, Asteromassaria macroconidica, A. pulchra, Splanchnonema mori, and S. argus. Of these, Pl. swidae on twigs of Swida controversa, Pr. canba on Betula ermanii, and A. macroconidica on twigs of Prunus ×yedoensis and an unknown woody plant are new. Three species, Pl. siparia “type A,” A. pulchra, and S. argus, are reported from Japan for the first time. A new combination, S. mori (≡ Massaria mori), is proposed.
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摘要 :
Eight species in Pleomassariaceae are described and illustrated. They are Pleomassaria maxima, Pl. swidae, Pl. siparia “type A,” Prosthemium canba, Asteromassaria macroconidica, A. pulchra, Splanchnonema mori, and S. argus. Of t...
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Eight species in Pleomassariaceae are described and illustrated. They are Pleomassaria maxima, Pl. swidae, Pl. siparia “type A,” Prosthemium canba, Asteromassaria macroconidica, A. pulchra, Splanchnonema mori, and S. argus. Of these, Pl. swidae on twigs of Swida controversa, Pr. canba on Betula ermanii, and A. macroconidica on twigs of Prunus ×yedoensis and an unknown woody plant are new. Three species, Pl. siparia “type A,” A. pulchra, and S. argus, are reported from Japan for the first time. A new combination, S. mori (≡ Massaria mori), is proposed.
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Apple fruit crinkle viroid (AFCVd) infects apples and hops. To analyze the genetic diversity of AFCVd, nine apple and six hop isolates were collected from several locations in Japan. In total, 76 independent cDNA clones were used ...
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Apple fruit crinkle viroid (AFCVd) infects apples and hops. To analyze the genetic diversity of AFCVd, nine apple and six hop isolates were collected from several locations in Japan. In total, 76 independent cDNA clones were used for sequencing and phylogenetic analyses. Two major population clusters were identified. The first consisted of all four hop isolates from Akita and some from Yamagata. The second cluster consisted of some Yamagata hop and all apple isolates. On the basis of the polymorphism found in the nucleotide insertion between positions 142/143 of the AFCVd genome and the history of hop cultivation in the region, it appears likely that one of the AFCVd populations that pre-existed in the Yamagata hops served as a “founder” for the Akita hop cluster. In this scenario, a genetic bottleneck caused by vegetative propagation played an important role in the shaping of viroid populations in a cultivated crop.
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A new viroid was detected in hops cultivated in Akita Prefecture, Japan where it is prevalent in many hops fields. In a survey of hop samples collected during the 1986-2002 growing seasons, the new viroid was present in the major ...
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A new viroid was detected in hops cultivated in Akita Prefecture, Japan where it is prevalent in many hops fields. In a survey of hop samples collected during the 1986-2002 growing seasons, the new viroid was present in the major Japanese hop-cultivating areas as early as the 1980s. A single-stranded circular RNA of 368-372 nucleotides that assume a highly basepaired, stable, rod-like secondary structure, shares 93%–98% sequence homology with Apple fruit crinkle viroid (AFCVd) isolated from apple and 85%-87% with Australian grapevine viroid (AGVd) isolated from grapevine. Taking into account the present concept of viroid species, we conclude that the viroid is AFCVd. Circumstantial evidence suggests that AFCVd from apples and hops were endemic in Japan only where cultivation of the two host plants overlapped, thereby strongly supporting the possibility that AFCVd (or an ancestral viroid) was transmitted across the species barrier from apples to hops or hops to apples somewhere in the region. Phylogenetic analysis of AFCVd from hops, AFCVd from apples, and AGVd together with the other members of the genus Apscaviroid revealed that the Akita isolates of AFCVd from hops (AFCVd-hop) formed a cluster that is distinct from AFCVd-apple and AGVd. Accumulation of host-specific sequence variation following their isolation in different host species may be leading to the formation of two viroid species from a common ancestor.
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