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Background and Aims Dioscorea alata
is a polyploid species with a ploidy level ranging from diploid (2n = 2x = 40) to tetraploid (2n = 4x = 80). Ploidy increase is correlated with better agronomic performance. The lack of knowledge about the origin of D. alata spontaneous polyploids (triploids and tetraploids) limits the efficiency of polyploid breeding. The objective of the present study was to use flow cytometry and microsatellite markers to understand the origin of D. alata polyploids.Methods
Different progeny generated by intracytotype crosses (2x × 2x) and intercytotype crosses (2x × 4x and 3x × 2x) were analysed in order to understand endosperm incompatibility phenomena and gamete origins via the heterozygosity rate transmitted to progeny.Results
This work shows that in a 2x × 2x cross, triploids with viable seeds are obtained only via a phenomenon of diploid female non-gametic reduction. The study of the transmission of heterozygosity made it possible to exclude polyspermy and polyembryony as the mechanisms at the origin of triploids. The fact that no seedlings were obtained by a 3x × 2x cross made it possible to confirm the sterility of triploid females. Flow cytometry analyses carried out on the endosperm of seeds resulting from 2x × 4x crosses revealed endosperm incompatibility phenomena.Conclusions
The major conclusion is that the polyploids of D. alata would have appeared through the formation of unreduced gametes. The triploid pool would have been built and diversified through the formation of 2n gametes in diploid females as the result of the non-viability of seeds resulting from the formation of 2n sperm and of the non-viability of intercytotype crosses. The tetraploids would have appeared through bilateral sexual polyploidization via the union of two unreduced gametes due to the sterility of triploids. 相似文献3.
Dioscorin isolated from Dioscorea alata activates TLR4-signaling pathways and induces cytokine expression in macrophages 总被引:2,自引:0,他引:2
Fu SL Hsu YH Lee PY Hou WC Hung LC Lin CH Chen CM Huang YJ 《Biochemical and biophysical research communications》2006,339(1):137-144
The Toll-like receptor 4 (TLR4)-signaling pathway is crucial for activating both innate and adaptive immunity. TLR4 is a promising molecular target for immune-modulating drugs, and TLR4 agonists are of therapeutic potential for treating immune diseases and cancers. Several medicinal herb-derived components have recently been reported to act via TLR4-dependent pathways, suggesting that medicinal plants are potential resources for identifying TLR4 activators. We have applied a screening procedure to systematically identify herbal constituents that activate TLR4. To exclude possible LPS contamination in these plant-derived components, a LPS inhibitor, polymyxin B, was added during screening. One of the plant components we identified from the screening was dioscorin, the glycoprotein isolated from Dioscorea alata. It induced TLR4-downstream cytokine expression in bone marrow cells isolated from TLR4-functional C3H/HeN mice but not from TLR4-defective C3H/HeJ mice. Dioscorin also stimulated multiple signaling molecules (NF-kappaB, ERK, JNK, and p38) and induced the expression of cytokines (TNF-alpha, IL-1beta, and IL-6) in murine RAW 264.7 macrophages. Furthermore, the ERK, p38, JNK, and NF-kappaB-mediated pathways are all involved in dioscorin-mediated TNF-alpha production. In summary, our results demonstrate that dioscorin is a novel TLR4 activator and induces macrophage activation via typical TLR4-signaling pathways. 相似文献
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The abundance and inherent potential for variations in simple sequence repeats (SSRs) or microsatellites resulted in valuable source for genetic markers in
eukaryotes. We describe the organization and abundance of SSRs in fungus Fusarium graminearum (causative agent for Fusarium head blight or head
scab of wheat). We identified 1705 SSRs of various nucleotide repeat motifs in the sequence database of F. graminearum. It is observed that
mononucleotide repeats (62%) were most abundant followed by di- (20%) and trinucleotide repeats (14%). It is noted that tetra-, penta- and
hexanucleotide repeats accounted for only 4% of SSRs. The estimated frequency of Class I SSRs (perfect repeats ≥20 nucleotides) was one SSR per 124.5
kb, whereas the frequency of Class II (perfect repeats >10 nucleotides and ≫20 nucleotides) was one SSR per 25.6 kb. The dynamics of SSRs will be a
powerful tool for taxonomic, phylogenetic, genome mapping and population genetic studies as SSR based markers show high levels of allelic variation,
codominant inheritance and ease of analysis. 相似文献
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Summary Field trials were conducted in the forest zone of southern Nigeria on three soil series, gravelly loamy sand Ibadan soil (Oxic paleustalf), gravelly sandy loam Egbeda soil (Oxic paleustalf) and sandy loam Alagba soil (Oxic paleustalf). The trials were carried out to study the effects of planting on flatversus various mound sizes and NPK fertilizer on performance of white Guinea yam (Dioscorea rotundata) cultivar Laoko.Mound size appeared to have a more pronounced effect on tuber yield than fertilizer even on land which was in the second and third year of cropping after bush fallow. The average tuber yield for the three locations without fertilizers was 7.83 tons/ha on the flat compared with 9.44 tons/ha on large mound (about 30 cm height). With fertilizer application, tuber yields were 7.43 tons/ha on the flat and 11.30 tons/ha on large mound respectively. Total yield reduction on flat may in part be related to physical soil impedence. Planting on large mounds also resulted in longer tubers and shorter harvesting time. 相似文献
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X. Wang R. Trigiano M. Windham B. Scheffler T. Rinehart J. Spiers 《Tree Genetics & Genomes》2008,4(3):461-468
Abundant, codominant simple sequence repeats (SSRs) markers can be used for constructing genetic linkage maps and in marker-assisted
breeding programs. Enrichment methods for SSR motifs were optimized with the ultimate aim of developing numerous loci in flowering
dogwood (C. florida L.) genome. Small insert libraries using four motifs (GT, CT, TGG, and AAC) were constructed with C. florida ‘Cherokee Brave’ deoxyribonucleic acid (DNA). Colony polymerase chain reaction (PCR) of 2,208 selected clones with three
primers we reported previously indicated that 47% or 1,034 of the clones harbored one of the four targeted SSR motifs. Sequencing
the putative positive clones confirmed that nearly 99% (1,021 of 1,034) of them contained the desired motifs. Of the 871 unique
SSR loci, 617 were dinucleotide repeats (70.8%), and 254 were trinucleotide or longer repeats (29.2%). In total, 379 SSR loci
had perfect structure, 237 had interrupted, and 255 had compound structure. Primer pairs were designed from 351 unique sequences.
The ability of the 351 SSR primer pairs to amplify specific loci was evaluated with genomic DNA of ‘Appalachian Spring’ and
‘Cherokee Brave’. Of these primers, 311 successfully amplified product(s) with ‘Cherokee Brave’ DNA, 21 produced weak or faint
products, and 19 did not amplify any products. Additionally, 218 of the 311 primers pairs revealed polymorphisms between the
two cultivars, and 20 out of 218 primers detected an average of 13.7 alleles from 38 selected Cornus species and hybrids. These SSR loci constitute a valuable resource of ideal markers for both genetic linkage mapping and
gene tagging of flowering dogwood.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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Phytochrome-induced increases in enzyme activities for phenylalanine ammonia-lyase (EC 4.3.1.5) and chalcone isomerase (EC 5.5.1.6), and in amounts of the related end products, anthocyanin and the flavonol, quercetin, were measured in cotyledons of mustard (Sinapis alba L.). There was no correlation between the activities of these enzymes and the rate of anthocyanin accumulation; however, some correlation was found with the quercetin accumulation rate. Since anthocyanin and flavonol accumulation is spatially separated in mustard (flavonols in the upper epidermis, anthocyanin in the lower epidermis), it was possible to measure anthocyanin-associated phenylalanine ammonia-lyase independently. This activity correlated well with the accumulation rate for anthocyanin during the first few hours after induction. The phytochrome effect on anthocyanin formation differed from that on quercetin formation: anthocyanin was strongly induced by continuous far-red light and by both continuous red light and red light pulses, whereas quercetin was only effectively induced by continuous far-red light.Abbreviations CHI
chalcone isomerase
- PAL
phenylalanine ammonia-lyase 相似文献
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Stefan Martens Author Vitae Anja Preuß Author Vitae Author Vitae 《Phytochemistry》2010,71(10):1040-1049
Flavonols and conditionally also anthocyanins, aside from flavonols, are the predominant polyphenols accumulated in various tissues of the model plant Arabidopsis thaliana L. In vitro experiments suggested that the dioxygenases involved in their biosynthesis, flavonol synthase and anthocyanidin synthase, are “multifunctional” enzymes showing distinct side activities. The in vivo relevance of the additional activities attributed to these enzymes, however, has remained obscure. In this review we summarize the most recent results and present final proof of the complementing activities of these synthases for flavonol and anthocyanidin formation in the model plant A. thaliana. The impact of their modification on the biosynthetic pathway and the pattern of flavonoids in different plant tissues are discussed. 相似文献
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Tissue slices from developing potato tubers (Solanum tuberosum L.) and developing cotyledons of faba bean (Vicia faba L.) were incubated with specifically labelled [13C]glucose and [13C]ribose. Enriched[13C]glucose released from starch granules was analysed by nuclear magnetic resonance (NMR). Spectral analyses were also performed on sucrose purified by high-performance liquid chromatography. In both tissues a low degree of randomisation (< 11 % in potato and < 14% in Vicia) was observed between carbon positions 1 and 6 in glucose released from starch when material was incubated with [13C]glucose labelled in positions 6 and 1, respectively. Similarly, with [2-13C]glucose a low degree of randomisation was observed in position 5. These findings indicate that extensive transport of three-carbon compounds across the amyloplast membrane does not occur in storage organs of either species. This is in agreement with previously published data which indicates that sixcarbon compounds are transported into the plastids during active starch synthesis. When [1-13C]ribose was used as a substrate, 13C-NMR spectra of starch indicated the operation of a classical pentose-phosphate pathway. However, with [2-13C]glucose there was no preferential enrichment in either carbon positions 1 or 3 relative to 4 or 6 of sucrose and starch (glucose). This provides evidence that entry of glucose in this pathway may be restricted in vivo. In both faba bean and potato the distribution of isotope between glucosyl and fructosyl moieties of sucrose approximated 50%. The degree of randomisation within glucosyl and fructosyl moieties ranged between 11 and 19.5%, indicating extensive recycling of triose phosphates.Abbreviation NMR
nuclear magnetic resonance
We are grateful to Dr. George Ratcliffe for his critical reading of the text and Dr. Bernard Goodman for helpful suggestions on the NMR measurements. The research was funded by a European Economic Community research grant, which the authors duly acknowledge. 相似文献
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Kalaiselvi Senthil Murukarthick Jayakodi Pankajavalli Thirugnanasambantham Sang Choon Lee Pradeepa Duraisamy Preethi M Purushotham Kalaiselvi Rajasekaran Shobana Nancy Charles Irene Mariam Roy Arul Kumar Nagappan Gon Sup Kim Yun Sun Lee Senthil Natesan Tae-Sun Min Tae Jin Yang 《BMC genomics》2015,16(1)
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Tarazi R Moreno MA Gandara FB Ferraz EM Moraes ML Vinson CC Ciampi AY Vencovsky R Kageyama PY 《Genetics and molecular biology》2010,33(1):78-85
Dipteryx alata is a native fruit tree species of the cerrado (Brazilian savanna) that has great economic potential because of its multiple uses. Knowledge of how the genetic variability of this species is organized within and among populations would be useful for genetic conservation and breeding programs. We used nine simple sequence repeat (SSR) primers developed for Dipteryx odorata to evaluate the genetic structure of three populations of D. alata located in central Brazil based on a leaf sample analysis from 101 adults. The outcrossing rate was evaluated using 300 open-pollinated offspring from 25 seed-trees. Pollen dispersal was measured by parentage analysis. We used spatial genetic structure (SGS) to test the minimal distance for harvesting seeds in conservation and breeding programs. Our data indicate that the populations studied had a high degree of genetic diversity and population structure, as suggested by the high level of divergence among populations . The estimated outcrossing rate suggested a mixed mating system, and the intrapopulation fixation index was influenced by SGS. We conclude that seed harvesting for genetic conservation and breeding programs requires a minimum distance between trees of 196 m to avoid collecting seeds from related seed-trees. 相似文献
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Simple sequence repeats (SSRs) can be derived from the complete genome sequence. These markers are important for gene
mapping as well as marker-assisted selection (MAS). To develop SSRs for cotton gene mapping, we selected the complete genome
sequence of Gossypium raimondii, which consisted of 4447 non-redundant scaffolds. Out of 775.2 Mb sequence examined, a total of
136,345 microsatellites were identified with a density of 5.69 kb per SSR in the G. raimondii genome leading to development of
112,177 primer pairs. The distributions of SSRs in the genome were non-random. Among the different motifs ranging from 1 to 6
bp, penta-nucleotide repeats were most abundant (30.5%), followed by tetra-nucleotide repeats (18.2%) and di-nucleotide repeats
(16.9%). Among all identified 457 motif types, the most frequently occurring repeat motifs were poly-AT/TA, which accounted for
79.8% of the total di-nt SSRs, followed by AAAT/TTTA with 51.5% of the total tetra-nucleotede. Further, 18,834 microsatellites
were detected from the protein-coding genes, and the frequency of gene containing SSRs was 46.0% in 40,976 genes of G. raimondii.
These genome-based SSRs developed in the present study will lay the groundwork for developing large numbers of SSR markers
for genetic mapping, gene discovery, genetic diversity analysis, and MAS breeding in cotton. 相似文献
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The effects of photoperiod (8, 12 or 16 h), mineral medium strength (dilutions of a tuberization medium, the T medium), sucrose
(0, 2, 4, 8% w/v) and kinetin (0, 2.5μM) on the development of roots, shoots and microtubers in shoot cultures of Dioscorea alata L. and D. bulbifera L. yams were evaluated. All of the factors were found to have substantial effects on microtuber induction in these two species.
The effects of high and low inorganic ammonium containing media on microtuberization of yam shoot cultures indicated that
ammonium ions inhibited microtuber induction in D. alata but not in D. bulbifera. Microtubers of D. alata were only formed on shoot cultures if these were held under 8-h days. D. bulbifera cultures on the other hand produced microtubers under this photoperiod treatment as well as under 16-h photoperiods provided
that kinetin was present in media at 2.5μM. Most microtuberization in D. alata shoot cultures occurred on full-strength T medium supplemented with 2% sucrose, 2.5μM kinetin held under 8-h photoperiod
at 25°C, whereas most microtuberization in D. bulbifera shoot cultures occurred on full-strength MS medium supplemented with 4% sucrose, 2.5μM kinetin held under 8-h photoperiods
at 25°C. Under these two sets of conditions, yam shoot cultures consistently produced microtubers with individual weights
in excess of 100 mg which were large enough to be capable of direct planting and subsequent growth in unsterilized soils. 相似文献