Expression profiling in HcrVf2-transformed apple plants in response to Venturia inaequalis

Apple scab resistance is one of the most well-characterized plant–pathogen interactions in a woody plant species. While the HcrVf2 gene from the wild apple Malus floribunda 821 has proved capable of conferring scab resistance to the susceptible cv. Gala after genetic transformation, its identification represents only the first step in understanding the molecular mechanisms and, hence, the network of genes underlying the defence response. We used a PCR-based suppression subtractive hybridization to identify apple genes that are differentially expressed after Venturia inaequalis inoculation. Subtractive hybridization was performed between cDNA from challenged leaves of HcrVf2-resistant transgenic Gala and susceptible cv. Gala plants. A library of 523 unigenes was constructed and characterized by assigning a putative function via comparison with public databases. This set of pathogen-modulated apple genes includes many defence-related genes and is therefore an important source of information for understanding the molecular basis of the Malus–V. inaequalis interaction. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Genomic regions involved in productivity of two interspecific poplar families in Europe. 1. Stem height, circumference and volume

Interspecific hybrids of Populus species are known for their superior growth. In this study, we examined the effect of the genetic background and contrasting environmental conditions on growth and searched for quantitative trait loci (QTL) affecting growth traits. To this end, two hybrid poplar families resulting from controlled crosses, Populus deltoides ‘S9-2’ × P. nigra ‘Ghoy’ (D × N, 180 F₁) and P. deltoides ‘S9-2’ × P. trichocarpa ‘V24’ (D × T, 182 F₁), were grown at two contrasting sites, Northern Italy and Central France. At the end of the second growing season, tree dimensions (stem height, circumference, and volume) were assessed. The performances of both families significantly differed within and between sites. Tree volume was significantly larger at the Italian site as compared to the French site. Genotype by environment interactions were significant but low for both families and for all growth traits. Tight correlations among the individual growth traits indicated that there may be a common genetic mechanism with pleiotropic effects on these growth traits. In line with previous studies, linkage groups I, VII, IX, X, XVI, XVII, and XIX appeared to have genomic regions with the largest effects on growth traits. This study revealed that (1) both families have high potential for selection of superior poplar hybrids due to the pronounced heterosis (hybrid vigor) and the large genetic variability in terms of growth and (2) the choice of site is crucial for poplar cultivation. Dillen and Storme contributed equally to the work. An erratum to this article can be found at     

Prediction of crop response by linearisation about control approximation

A new method for modelling genotype x environment interaction: APLAT. The yield predicted by a crop-simulation model is developed as a Taylor series in the neighbourhood of a parameter vector of a control genotype. With this local linearisation, these genotype parameters can be estimated by a linear regression of the observed yield on the derivatives of the crop-simulation model predictions with respect to its parameters.     

Molecular-marker analysis of quantitative traits for growth and development in juvenile apple trees

Random amplified polymorphic DNAs (RAPDs) were used in combination with a double pseudo-testcross mapping strategy to estimate the position and effects of quantitative trait loci (QTLs) for traits influencing juvenile tree growth and development in two apple cultivars. The mapping population consisted of 172 F₁ trees from a cross between the columnar mutant ‘Wijcik McIntosh’ and a standard form disease-resistant selection NY 75441-58. Significant associations were found between markers and height increment, internode number, internode length, base diameter increment, base diameter after 9 years of growth, branch number, and leaf break. The number of genomic regions associated with each trait varied from one to eight. The amount of variation explained by linear regression on individual marker loci (R²) ranged from 3.9 to 24.3%, with an average of 7%. Multiple regression using markers for each putative QTL explained from 6.6 to 41.6% of the phenotypic variation, with an average value of 24.3%. A large number of traits had significant variation associated with the map position of the dominant columnar gene, Co. QTL stability over years was estimated by comparing the locations of putative QTLs for traits measured in multiple years. The majority of genomic regions were associated with a trait in only a single year, although regions associated with a trait in more than 1 year were also detected. The limitations of dominant markers and an outbred mapping pedigree for QTL analysis are discussed. Received: 27 August 1997 / Accepted: 10 February 1998     

Hairy roots of Datura candida×D. aurea: effect of culture medium composition on growth and alkaloid biosynthesis

A transformed root clone of Datura candida×D. aurea was established following infection with Agrobacterium rhizogenes strain A4. This clone was examined for its growth and hyoscyamine and scopolamine content under various culture conditions. Among the three basal culture media tested, half-strength Gamborg's B5 medium supplemented with 5% sucrose was the best for root growth (288 mg dry weight/flask) and full-strength B5 medium for hyoscyamine and scopolamine content (0.36 and 0.17% dry weight, respectively). Experiments with exogenous nitrate added to the medium revealed that the biomass increased (353 mg dry weight/flask) and the hyoscyamine content improved remarkably (0.54% dry weight), but that the scopolamine content was significantly reduced. The addition of various precursors at two different concentrations did not significantly modify root growth. Feeding (R,S)-phenyllactic acid stimulated the biosynthesis of both alkaloids, whereas the addition of ornithine specifically reduced the scopolamine content. Received: 12 March 1997 / Revision received: 22 April 1997 / Accepted: 5 May 1997     

基于SSR分子标记的地被菊遗传多样性分析和指纹图谱构建

为了从分子水平上研究地被菊(Chrysanthemum×morifolium)种质资源的遗传多样性并建立地被菊品种的指纹图谱库,筛选出多态性高的引物用于地被菊品种间鉴定、亲缘关系分析和分子标记辅助选种体系的建立,本研究利用多态性好、条带清晰、重复性好的12对引物对91份地被菊材料和14份菊属近缘种材料进行简单重复序列(simple sequence repeat,SSR)分子标记和遗传多样性分析,从12对引物中筛选出9对核心引物对受试材料进行指纹图谱构建。结果显示,在105个样品中,12对引物检测出104个等位位点,范围为2−26,平均每个点位检测出9.25个等位基因数,平均每个点位检测得到的有效等位基因数(number of effective alleles,Ne)为2.7456,范围为1.2760−4.7425;Shannon信息指数(Shannon genetic diversity index,I)变化范围是0.5133−2.2399,均值是1.2090;Nei’s基因多样性指数(Nei’s gene diversity index,H)范围是0.2163−0.7891,均值是0.5780;观测杂合度(observed heterozygosity,Ho)的范围是0.2233−0.8952,均值是0.5575;期望杂合度(expected heterozygosity,He)的范围是0.2174−0.7933,均值是0.5808;多态信息含量(polymorphism information content,PIC)值变化范围是0.2115−0.7740,均值是0.5329;遗传相似性系数(genetic similarity,GS)范围为0.2285−1.0000,均值是0.6083。聚类分析表明,在遗传距离(genetic distance,GD)=0.30时,受试材料可以分为两个类群。Structure群体结构分析将受试材料分为3个种群和1个混合种群。从12对引物中筛选出可完全区分105份受试材料的9对核心引物,构建了91份地被菊材料和14份菊属近缘种材料的指纹图谱。地被菊材料之间具有显著的遗传差异和丰富的遗传多样性,对于地被菊的园林应用和品种选育具有重要意义。地被菊品种和菊属近缘种的指纹图谱库的构建,一定程度上揭示了105份实验材料的亲缘关系,为今后地被菊品种鉴定与筛选体系的研究提供了技术支撑。     

Species difference in the metabolic activation of phenacetin by rat and hamster liver microsomes

Phenacetin is mutagenic in Salmonella typhimurium TA 100 when liver 9,000 X g supernatant fractions from PCB-treated hamsters instead of rats are used. A mechanism of the species difference in phenacetin mutagenicity was investigated. By high-performance liquid chromatography analysis, it was found that phenacetin is activated to direct-acting mutagens through N-hydroxylation and deacetylation by hamster liver microsomes. Although no significant species difference was observed in N-hydroxylation, rates of deacetylation were 9 to 150 times higher in hamsters than in rats. The results indicate that the marked species difference in phenacetin mutagenicity is due to the difference in deacetylation activity between rat and hamster liver microsomes.     

Changes of activity of daunorubicin,adriamycin and stereoisomers following the introduction or removal of hydroxyl groups in the amino sugar moiety

The results of a study of the effects of hydroxyl groups at positions, 2, 4 and 6 of the amino sugar on the activity of daunorubicin, adriamycin, and stereoisomers are presented. While the 4′-deoxy derivatives showed a slightly increased biological activity as compared with the parent compounds, the derivatives containing an additional hydroxyl group were less active. It is suggested that the changes in the polarity and in the DNA binding ability of these derivatives are the main factors accounting for the difference in the in vivo activity. The possible relations among the pK_a values, the DNA binding properties, and the cellular uptake of the compounds are discussed with particular reference to their therapeutic effectiveness.     

Covalent binding of benzo[a]pyrene to dna in fish liver

Benzo[a]pyrene became bound to the hepatic DNA in juvenile English sole ($\text{Parophrys vetulus}$) force fed tritiated benzo[a]pyrene. No statistically signïficant change was observed in the level of the binding from 16 h to 2 wk after the single exposure. Specific activities of binding were similar for both DNA and protein. Moreover, a binding index was calculated to represent the number of benzo[a]pyrene molecules bound per 10⁶ nucleotides after administration of a theoretical dose of 1 mmole of hydrocarbon per kg body weight. The value for English sole liver DNA was of the same order of magnitude as the values reported for mouse skin and mammary gland in which benzo[a]pyrene is carcinogenic.     

Studies on DNA repair in early spermatid stages of male mice after in vivo treatment with methyl-, ethyl-, propyl-, and isopropyl methanesulfonate.

In vivo DNA repair occurring in early spermatid stages of the mouse has been studied with four mutagens that are chemical homologs: MMS, EMS, PMS and IMS. Using the well-studied sequence of events that occurs during spermatogenesis and spermiogenesis in the mouse, aatids was measured by the unscheduled incorporation of [3H]dT into these germ cells which were recovered from the caudal epididymides 16 days after chemical treatment. Purification of the caudal sperm DNA at this time verified that the [3H]dT was incorporated into the DNA. For each chemical mutagen a study was made on the level of DNA repair occurring in early spermatids as a function of the administered, in vivo dose. Within experimental errors, all four chemicals produced a linear increase in DNA repair in early spermatids with increasing dose. Only the highest dose of MMS (100 mg/kg) produced a greater repair response than expected for a linear curve. At equimolar doses the most effective chemical in inducing DNA repair was MMS, followed by EMS, IMS and PMS. When testicular injections of [3H]dT were given at the same time as the intraperitoneal injections of the mutagens, the amount of unscheduled incorporation of [3H]dT into the DNA of early spermatids was maximized. Since [3H]dT has been shown to be available for incorporation into germ-cell DNA for only approximately 1 h after injection, all four mutagens must reach the DNA of early spermatids and begin producing "repairable" lesions within 1 h after treatment. The amount of DNA repair occurring at later times after chemical treatment of early spermatids was studied by testicular injections of [3H]dT 1/2, 1, 2 and 3 days after chemical treatment. Repair was still occurring in the early spermatids at 3 days post-treatment; this repair is most likely a manifestation of the finite rate of the repair process rather than resulting from newly alkylated DNA. For MMS and EMS there was a rapid decrease in the level of DNA repair in the first 1/2 day following treatment. This was followed by a much slower, exponential decrease in the level of repair out to 3 days post-treatment. The curves suggest that the amount of repair is proportional to the number of repairable lesions still present in the DNA. For PMS and IMS the level of repair decreases rapidly in the first 1/2 day after treatment and thereafter remains relatively constant through 3 days post-treatment. With all four mutagens, DNA repair in early spermatids was detectable at doses 5 to 10 times lower than those required to observe other genetic end points such as dominant lethals, translocations and specific-locus mutations in any germ-cell stage. The sensitivity of detection of in vivo DNA repair in the germ cells of male mice makes such a system a useful adjunct to other genetic tests for studying chemical mutagenesis in mammals.