Morning glory systemically accumulates scopoletin and scopolin after interaction with Fusarium oxysporum

An isolate of non-pathogenic Fusarium, Fusarium oxysporum 101-2 (NPF), induces resistance in the cuttings of morning glory against Fusarium wilt caused by F. oxysporum f. sp. batatas O-17 (PF). The effect of NPF on phenylpropanoid metabolism in morning glory cuttings was studied. It was found that morning glory tissues responded to treatment with NPF bud-cell suspension (108 bud-cells/ml) with the activation of phenylalanine ammonia-lyase (PAL). PAL activity was induced faster and greater in the NPF-treated cuttings compared to cuttings of a distilled water control. High performance liquid chromatography analysis of the extract from tissues of morning glory cuttings after NPF treatment showed a quicker induction of scopoletin and scopolin synthesis than that seen in the control cuttings. PF also the induced synthesis of these compounds at 10(5) bud-cells/ml, but inhibited it at 10(8) bud-cells/ml. Possibly PF produced constituent(s) that elicited the inhibitory effect on induction of the resistance reaction. These compounds could potentially be useful as markers to detect early beginning interactions between Fusarium and morning glory tissues cuttings.     

Structural characterization of the dihydroflavonol 4-reductase B (DFR-B) gene in the sweet potato.

A genomic fragment containing the dihydroflavonol 4-reductase B (DFR-B) gene was cloned from the sweet potato (Ipomoea batatas) and its nucleotide sequence was analyzed. The exons and flanking regions were highly homologous to those of previously reported DFR-B genes of the Japanese morning glory, whereas the introns and the intergenic region were less conserved. In addition to the sequences of three miniature inverted-repeat transposable elements (MITEs) and one direct repeat previously reported in the DFR-B gene of Japanese morning glory, two mobile element-like sequences were newly identified in the sweet potato DFR-B gene. At least four allelic sequences were found to exist by amplification of the DFR-B gene from various sweet potato cultivars. One of these allelic sequences had a 2-kb deletion in the intergenic region and was observed in the cultivars with high anthocyanin content in their storage roots.     

An examination of the monophyly of morning glory taxa using Bayesian phylogenetic inference

The objective of this study was to obtain a quantitative assessment of the monophyly of morning glory taxa, specifically the genus Ipomoea and the tribe Argyreieae. Previous systematic studies of morning glories intimated the paraphyly of Ipomoea by suggesting that the genera within the tribe Argyreieae are derived from within Ipomoea; however, no quantitative estimates of statistical support were developed to address these questions. We applied a Bayesian analysis to provide quantitative estimates of monophyly in an investigation of morning glory relationships using DNA sequence data. We also explored various approaches for examining convergence of the Markov chain Monte Carlo (MCMC) simulation of the Bayesian analysis by running 18 separate analyses varying in length. We found convergence of the important components of the phylogenetic model (the tree with the maximum posterior probability, branch lengths, the parameter values from the DNA substitution model, and the posterior probabilities for clade support) for these data after one million generations of the MCMC simulations. In the process, we identified a run where the parameter values obtained were often outside the range of values obtained from the other runs, suggesting an aberrant result. In addition, we compared the Bayesian method of phylogenetic analysis to maximum likelihood and maximum parsimony. The results from the Bayesian analysis and the maximum likelihood analysis were similar for topology, branch lengths, and parameters of the DNA substitution model. Topologies also were similar in the comparison between the Bayesian analysis and maximum parsimony, although the posterior probabilities and the bootstrap proportions exhibited some striking differences. In a Bayesian analysis of three data sets (ITS sequences, waxy sequences, and ITS + waxy sequences) no supoort for the monophyly of the genus Ipomoea, or for the tribe Argyreieae, was observed, with the estimate of the probability of the monophyly of these taxa being less than 3.4 x 10(-7).     

The possible roles of nutrient deprivation and auxin repression in apical control

Apical control is the suppression of growth in lower branches by a higher dominant branch or leader shoot. We investigated possible mechanisms involved in this developmental response in three widely diverse species (Japanese morning glory, Ipomoea nil, hybrid poplar, Populus trichocarpa, × P. deltoides, and Douglas-fir, Pseudotsuga menziesii). The following two hypotheses were tested: (1) the mineral nutrient-deprivation hypothesis, which is that the continued growth of the lower branches is repressed by the diversion of nutrients to the upper dominating branch or shoot, and (2) the auxin-repression hypothesis, which is that auxin produced in the upper dominating branch or shoot moves down to the lower branches where continued growth is repressed. The results of experiments involving the manipulation of available nutrients by dominant branch removal and fertilization were consistent with the first hypothesis for morning glory, poplar, and for second- or third flushing of lateral branches in Douglas-fir. The results of the experiments involving auxin (NAA, 1-naphthalene acetic acid) replacement treatments on decapitated shoots bearing growing lateral branches were inconsistent with the second hypothesis in morning glory, poplar and in first-flushing Douglas-fir. However, despite concerns about possible NAA toxic effects, there was evidence of auxin repression of second flushing in Douglas-fir. Overall, the data supported a significant role for nutrient availability but not for auxin repression in apical control of morning glory and poplar. In Douglas-fir, apical control in first-flushing lateral branches from over-wintered buds was largely insensitive to both nutrient availability and auxin repression; however, second flushing was sensitive to both.     

Volatile metabolites controlling germination in buried weed seeds

Velvetleaf (Abutilon theophrasti Medic), morning glory (Ipomoea purpurea [L.] Roth), and wild mustard (Brassica kaber [D.C.] L. C. Wheeler) seeds exhibited decreased germination with increased planting depth in soil. Flushing the soil for 2 minutes each day with air overcame the inhibition. A sealed in vitro system was used to sample the volatile components produced by weed seeds. Inhibition of seed germination was accompanied by decreased O₂ levels and production of volatile metabolites identified as acetaldehyde, ethanol, and acetone. The effectiveness of these compounds in reducing germination was dependent on O₂ levels.     

Isolation and identification of two potential phytotoxic substances from the aquatic fern <Emphasis Type="Italic">Marsilea crenata</Emphasis>

Organic agriculture emphasized using of biologically originated herbicides and phytotoxic substances are being considered as a replacement to chemical herbicides. Marsilea crenata is an aquatic perennial fern distributed in the South-East Asian countries and is well known for various biological properties. However, to date, there has been no report that addresses the phytotoxicity of Marsilea crenata. Therefore, we explored phytotoxic properties and phytotoxic substances from Marsilea crenata. An aqueous methanol extracts of Marsilea crenata showed inhibition on the seedling growth of cress, lettuce, alfalfa, barnyard grass, Italian ryegrass, and foxtail fescue. Inhibition increased with increasing extract concentration. The extract was purified by several chromatographic steps and two phytotoxic substances were isolated and identified by spectroscopic analysis as loliolide and isololiolide. At the concentration of 30 μM, loliolide and isololiolide inhibited seedling growth of cress and barnyard grass by 41.3 to 51.1%, and 58.15 to 87.5% of control seedlings, respectively. The concentrations required for 50% inhibition of cress and barnyard grass seedlings ranged from 32.1 to 128.5 μM for loliolide, 37.0 to 176.2 μM for isololiolide. These results suggest these compounds may be responsible for phytotoxic effects of Marsilea crenata extract and could be an important part of organic agriculture.     

Herbivory on aquatic vascular plants by the introduced golden apple snail (<Emphasis Type="Italic">Pomacea canaliculata</Emphasis>) in Lao PDR

The effect of naturally found densities of the exotic and herbivorous golden apple snail (Pomacea canaliculata) on three dominant aquatic plants – duckweed (Lemna minor), water hyacinth (Eichhornia crassipes) and morning glory (Ipomoea aquatica) – was assessed in a wetland survey and quantified in a field experiment in Laos in southeast Asia. Snail grazing reduced plant biomass, but plant species were differently affected by grazing. Duckweed had almost disappeared after 6 and water hyacinth after 21 days, whereas morning glory remained at 80% of initial biomass after 32 days. Snail growth was lowest on morning glory and, when all plant species were simultaneously presented to snails, this plant was not preferred. We suggest that the negative effect the golden apple snail had on the growth of these plant species in field enclosures is present in the natural environment as well. This new and intense herbivory could have serious negative effects on invaded freshwater ecosystems in this region.     

甘薯基因组 TCP转录因子鉴定与逆境胁迫表达分析

基于甘薯( Ipomoea batatas ( L.) Lam.)全基因组序列, 利用生物信息学方法鉴定筛选了全基因组中的TCP( teosinte branched1/cincinnata/proliferating cell factor)转录因子, 并分析了甘薯苗期在蔓割病菌胁迫及块根储藏期低温胁迫下TCP基因的...     

甘薯与牵牛EST资源的SSR信息分析

为挖掘番薯（Ipomoea）属EST-SSR资源,从NCBI数据库下载23406条甘薯（Ipomoea batatas (L.) Lam.）EST和62282条牵牛（Ipomoea nil (L.) Roth）EST,利用生物信息学软件预处理、去冗余、拼接处理后得到12812条无冗余的甘薯EST（6.70 Mb）和28422条牵牛唯一序列（17.19 Mb）。对这些序列进行SSR搜索,在甘薯上获得328个SSR位点,发生频率为2.56%;牵牛上筛选到962个SSR位点,出现频率为3.38%。甘薯和牵牛EST-SSR具有多个共同特征：在SSR位点中,主要是二核苷酸重复类型,其次是三核苷酸重复;在二核苷酸重复中,出现最多的重复基序为AG/CT,其次是AT/AT;在三核苷酸重复中,主要基序是AAG/CCT;SSR位点的长度主要集中在20~22 bp。结果表明,这些搜索出的EST-SSR重复基序类型丰富、多态性潜能高,具有较高的开发和利用价值。     

Morning glory as a powerful model in ecological genomics: tracing adaptation through both natural and artificial selection

Many diverse questions in ecology and evolution have been addressed using species belonging to the genus Ipomoea, commonly referred to as the morning glory genus. Ipomoea exhibits a wide range of diversity in floral color, growth form, mating system and tolerance to environmental factors, both within and among species, and as such has been a focal group of many investigations in the last 80 years. In this review, we highlight recent work to which Ipomoea species have contributed-from studies of the mating system, molecular evolution, plant-herbivore and plant-parasite interactions to their impact on and importance to agriculture. Genomic resources for this group are currently under development, and given the breadth of studies and history of this group, combined with an expanding genetics toolkit, we argue that Ipomoea should provide the next model organism for ecological genomics.     

Evaluation of phytotoxic potential and identification of phytotoxic compounds in Rumex maritimus

Rumex maritimus (Polygonaceae) is an annual herb and is well known for its use in medicinal treatments. Although the pharmacological properties of R. maritimus are well documented, no phytotoxic activity of R. maritimus has yet been found. Therefore, we investigated the phytotoxic potential of R. maritimus to identify phytotoxic compounds. Inhibitory activity was found in aqueous methanol extracts of R. maritimus on the seedling growth of cress, rapeseed, barnyard grass, and foxtail fescue, in which inhibition increased with increasing extract concentration. Two compounds were isolated using chromatography, and using spectroscopy their structure was determined as 5,7-dihydroxyphthalide and altechromone A. 5,7-Dihydroxyphthalide significantly inhibited cress seedling growth by 27.2–43.0% of control seedlings at 3 mM, whereas altechromone A inhibited seedling growth by 65.4–66.3% at 0.01 mM. The concentrations required for 50% inhibition of cress seedling growth were 1.73–2.48 mM for 5,7-dihydroxyphthalide and 0.66–1.41 mM for altechromone A. These results indicate that the compounds 5,7-dihydroxyphthalide and altechromone A may contribute, to a certain extent, to the phytotoxic activity of R. maritimus.     

Synthesis of new phytogrowth-inhibitory substituted aryl-p-benzoquinones

Reaction of [(2-alkyloxy)methyl]-1,4-dimethoxybenzene 10 (alkyl=butyl, hexyl, decyl, tridecyl, tetradecyl, hexadecyl, and octadecyl) with ceric ammonium nitrate in order to produce p-benzoquinones (=cyclohexa-2,5-diene-1,4-diones) afforded 5-[(alkyloxy)methyl]-2-(4-formyl-2,5-dimethoxyphenyl)benzo-1,4-quinones 12a-12g in yields that varied from 46 to 97%, accompanied by 2-[(alkyloxy)methyl]benzo-1,4-quinones 11a-11g in only small quantities (< or =5%). These quinones resemble the natural phytotoxic compound sorgoleone, found in Sorghum bicolor. This reaction exemplifies a general procedure for the synthesis of novel aryl-substituted p-benzoquinones. The selective effects of compounds 12a-12g, at the concentration of 5.5 ppm, on the growth of Cucumis sativus, Sorghum bicolor, Euphorbia heterophylla, and Ipomoea grandifolia were evaluated. All compounds caused some inhibition upon the aerial parts and root growth of the tested plants. The most active compound, 2-(4-formyl-2,5-dimethoxyphenyl)-5-[(tridecyloxy)methyl]-benzo-1,4-quinone (12d), caused between 3 and 18%, and 12 and 29% inhibition on the roots and aerial parts development of Cucumis sativus and Sorghum bicolor, respectively, and between 77 and 85%, and 34 and 52% inhibition on the roots and aerial parts growth of Euphorbia heterophylla and Ipomoea grandifolia, respectively.     

瑞香狼毒根中活性物质的分离鉴定及作用机理

以瑞香狼毒根为研究材料,模式植物拟南芥为受体,采用实验室活体生物实验方法研究了瑞香狼毒根提取物及不同极性溶剂萃取物对7 d龄拟南芥幼苗的生长抑制作用;采用活性跟踪的化合物分离方法,分析了其中的活性化合物成分,并通过拟南芥DR5-GUS转基因株系,研究了单体化合物对拟南芥生长发育及根系生长素分布的影响.结果显示,瑞香狼毒根乙醇提取物对拟南芥有很强的生长抑制作用,其乙酸乙酯和氯仿萃取物的抑制活性最为显著,从氯仿萃取物中分离得到两种香豆素类化合物伞形花内酯(1)和西瑞香素(2),其中化合物1能够显著抑制拟南芥幼苗生长及根系发育,且明显降低了根部内源生长素的分布水平;化合物2也有较为明显的抑制活性.研究表明,氯仿和乙酸乙酯萃取物是瑞香狼毒植物毒活性的主要有效部位;伞形花内酯(1)和西瑞香素(2)是瑞香狼毒植物毒活性的有效成分,化合物1对拟南芥生长发育的抑制作用与生长素途径密切相关.     

The gravity-regulated growth of axillary buds is mediated by a mechanism different from decapitation-induced release

When the upper part of the main shoot of the Japanese morning glory (Pharbitis nil or Ipomoea nil) is bent down, the axillary bud situated on the uppermost node of the bending region is released from apical dominance and elongates. Here, we demonstrate that this release of axillary buds from apical dominance is gravity regulated. We utilized two agravitropic mutants of morning glory defective in gravisensing cell differentiation, weeping (we) and weeping2 (we2). Bending the main shoots of either we or we2 plants resulted in minimal elongation of their axillary buds. This aberration was genetically linked to the agravitropism phenotype of the mutants, which implied that shoot bending-induced release from apical dominance required gravisensing cells. Previous studies have shown that basipetal translocation of auxin from the apical bud inhibits axillary bud growth, whereas cytokinin promotes axillary bud outgrowth. We therefore compared the roles of auxin and cytokinin in bending- or decapitation-induced axillary bud growth. In the wild-type and we plants, decapitation increased cytokinin levels and reduced auxin response. In contrast, shoot bending did not cause significant changes in either cytokinin level or auxin response, suggesting that the mechanisms underlying gravity- and decapitation-regulated release from apical dominance are distinct and unique.     

Identification and characterization of an Ipomoea nil glucosyltransferase which metabolizes some phytohormones

A glucosyltransferase gene InGTase1 was identified from the immature seeds of morning glory (Ipomoea nil), whose product shows a broad substrate-preference, including that of some phytohormones. When 2-trans-abscisic acid, indole-3-acetic acid, salicylic acid (SA) or (+/-)-jasmonic acid was reacted with InGTase1 and UDP-[(14)C]-glucose, each (14)C-labeled compound with high polarity was detected after thin layer chromatography. SA metabolites were identified as SA glucosyl ester by using (1)H NMR and GC/MS. Detailed substrate-preferences of InGTase1 were examined with some analogous compounds, which elucidated that the arm length and/or orientation of a carboxyl group of the compounds or its surrounding electron density severely affected the enzymatic activity. The broad substrate-preference will greatly contribute to the synthesis of various glucoconjugates.     

Evolutionary history of the Tip100 transposon in the genus Ipomoea

Tip100 is an Ac-like transposable element that belongs to the hAT superfamily. First discovered in Ipomoea purpurea (common morning glory), it was classified as an autonomous element capable of movement within the genome. As Tip100 data were already available in databases, the sequences of related elements in ten additional species of Ipomoea and five commercial varieties were isolated and analyzed. Evolutionary analysis based on sequence diversity in nuclear ribosomal Internal Transcribed Spacers (ITS), was also applied to compare the evolution of these elements with that of Tip100 in the Ipomoea genus. Tip100 sequences were found in I. purpurea, I. nil, I. indica and I. alba, all of which showed high levels of similarity. The results of phylogenetic analysis of transposon sequences were congruent with the phylogenetic topology obtained for ITS sequences, thereby demonstrating that Tip100 is restricted to a particular group of species within Ipomoea. We hypothesize that Tip100 was probably acquired from a common ancestor and has been transmitted vertically within this genus.     

甘薯同一不亲和群内品种间体细胞杂种

利用PEG融合方法,融合甘薯(Ipomoea batatas ) B不亲和群内品种‘koganesengan’和‘bitambi’的原生质体。将融合处理的原生质体进行培养,共获得45株再生植株。4株再生植株形态上表现出融合双亲的中间特性,其中2株染色体数为融合两亲之和（2n = 12x (2n + 2n) = 180）,另外2株分别为41～103和35～100,因细胞不同而不同。经RAPD分析,这4株再生植株分别具有双亲特异的DNA扩增带或双亲都不具有的新扩增带。鉴定这4株再生植株为杂交不亲和的B群内品种间体细胞杂种。     

Flowering response of Ipomoea batatas scions grafted onto Pharbitis nil stocks

Young seedlings of Ipomoea batatas (L.) Lam. cv. Big One did not form floral buds, but were induced to flower when grafted onto Pharbitis nil Chois. cv. Violet with its cotyledons exposed to a 16 h dark period (SD). Four SD were required to induce flowering in I. batatas scions when the grafted plants were first grown under an 8 h dark period (LD) for 18 days and then exposed to SD. Transmission of the flowering stimulus across the graft union required 4 days. It was also slow in the graft combination of P. nil and P. nil , but increased greatly when the graft union was established more completely. These results suggest that the flowering stimulus of P. nil may move symplastically and its life may be between 4 and 6 days. Although the leaves of I. batatas inhibited flowering, the flowering response of P. nil grafted onto I. batatas suggested that the involvement of a transmissible flowering-inhibitor was unlikely.     

Phytotoxic lignans of Leucophyllum frutescens.

Bioassay-guided fractionation of the hexane:ethyl acetate (1:1) extract of the leaves of Leucophyllum frutescens (Berl.) I.M.Johnst (Scrophulariaceae) led to the isolation of its phytotoxic constituents diayangambin (1), epiyangambin (2), diasesartemin (3) and epiashantin (4). Phytotoxicity was demonstrated as inhibition of seed germination of Agrostis stolonifera cv. penncross (Poaceae) and inhibition of development of Lactuca sativa L. (Asteraceae) seedlings in a microassay using 24-well plates. Compound 1 was the most phytotoxic to L. sativa, showing strong inhibitory activity at 110 microM. Compound 1 was more active than 2 and 3 in inhibiting the growth of A. stolonifera with I(50) values of 160, 670 and 930 microM, respectively. At a concentration of 500 microM, these compounds inhibited all phases of onion root cell division. This is the first demonstration of antimitotic activity of these furofuran lignans, and the first report of their isolation from this species.     

Genes that determine flower color: the role of regulatory changes in the evolution of phenotypic adaptations

A central goal of evolutionary genetics is to trace the causal pathway between mutations at particular genes and adaptation at the phenotypic level. The proximate objective is to identify adaptations through the analysis of molecular sequence data from specific candidate genes or their regulatory elements. In this paper, we consider the molecular evolution of floral color in the morning glory genus (Ipomoea) as a model for relating molecular and phenotypic evolution. To begin, flower color variation usually conforms to simple Mendelian transmission, thus facilitating genetic and molecular analyses. Population genetic studies of flower color polymorphisms in the common morning glory (Ipomoea purpurea) have shown that some morphs are subject to complex patterns of selection. Striking differences in floral color and morphology are also associated with speciation in the genus Ipomoea. The molecular bases for these adaptive shifts can be dissected because the biosynthetic pathways that determine floral pigmentation are well understood and many of the genes of flavonoid biosynthesis have been isolated and extensively studied. We present a comparative analysis of the level of gene expression in Ipomoea for several key genes in flavonoid biosynthesis. Specifically we ask: how frequently are adaptive shifts in flower color phenotypes associated with changes in regulation of gene expression versus mutations in structural genes? The results of this study show that most species differences in this crucial phenotype are associated with changes in the regulation of gene expression.