The inheritance of restriction fragment length polymorphisms in the flax rust Melampsora lini

Summary Random cDNA sequences synthesized from poly A⁺ RNA extracted from germinated urediospores of the flax rust fungus, Melampsora lini, were used as probes to detect restriction fragment length polymorphisms (RFLPs) in three races of M. lini originating from cultivated flax, Linum usitatissimum, and one race originating from Australian native flax, L. marginale. Fourteen out of 22 probes tested detected RFLPs in the three races from cultivated flax while 19 of the probes detected polymorphisms between these three races and the race from L. marginale. The segregation of seven RFLPs was determined in a family of 19 F₂ progeny derived from a cross between two of the rust races. With six of these the inheritance was consistent, in each case, with the segregation of alleles at a single locus. Inheritance of the seventh was unusual and an explanation involving two loci with null alleles at each was proposed. No linkage was detected between any of the RFLP loci and nine unlinked loci specifying avirulence.     

Immunolocalization of β-(1→4) and β-(1→6)-D-galactan epitopes in the cell wall and Golgi stacks of developing flax root tissues

Summary Most cell wall components are carbohydrate including the major matrix polysaccharides, pectins and hemicelluloses, and the arabinogalactan-protein proteoglycans. Both types of molecules are assembled in the Golgi apparatus and transported in secretory vesicles to the cell surface. We have employed antibodies specific to -(16) and -(14)-D-galactans, present in plant cell wall polysaccharides, in conjunction with immunofluorescence and electron microscopy to determine the location of the galactan-containing components in the cell wall and Golgi stacks of flax root tip tissues. Immunofluorescence data show that -(14)-D-galactan epitopes are restricted to peripheral cells of the root cap. These epitopes are not expressed in meristematic and columella cells. In contrast, -(16)-D-galactan epitopes are found in all cell types of flax roots. Immunogold labeling experiments show that both epitopes are specifically located within the wall immediately adjacent to the plasma membrane. They are also detected in Golgi cisternae and secretory vesicles, which indicates the involvement of the Golgi apparatus in their synthesis and transport. These findings demonstrate that the synthesis and localization of -(14)-D-galactan epitopes are highly regulated in developing flax roots and that different -linked D-galactans associated with cell wall polysaccharides are expressed in a cell type-specific manner.     

亚麻籽木酚素预防乳腺癌的作用及机制研究

目的:探讨亚麻籽木酚素预防乳腺癌的作用及机制。方法:分别采用基础饲料(BD组)和添加亚麻籽木酚素的饲料(FS组)喂养大鼠两周后,通过二甲基苯蒽灌胃复制乳腺癌模型大鼠,连续观察并测定两组大鼠瘤体的体积和重量,采用免疫组织化学技术分别检测和比较两组大鼠乳腺癌组织中PCNA、Her-2、Ki-67的表达。结果:BD组大鼠乳腺癌的发生率及瘤体重量和体积均较FS组更高(P0.05)。FS组乳腺癌组织中Ki-67、Her-2、PCNA阳性表达率均较BD组显著降低(P0.010)。结论:亚麻籽木酚素可发挥预防乳腺癌的效应,该效用可能与其降低Ki-67、Her-2、PCNA的表达有关。     

国外引进亚麻种质资源的聚类分析及评价

通过对国外引进的150份亚麻种质资源的农艺性状鉴定与聚类分析研究,将其分为4个类群。各个类群具有不同的特点,其中类群Ⅰ表现为株高较高、抗倒伏能力差、出麻率高、产量较高;类群Ⅱ株高较矮、较抗倒伏、出麻率较低、产量较低;类群Ⅲ表现为高抗倒伏、抗白粉病、产量较低;类群Ⅳ株高和产量最高。不同类群在育种中有不同的利用价值,尤其类群Ⅲ和Ⅳ中有高抗及高产材料,具有十分重要的利用价值。     

Haploid formation in maize, barley, flax, and potato

Summary. The article is reviewing some significant features and issues in the process of haploid formation in two important monocotyledonous crop plants – maize and barley – and in two dicotyledonous plants – flax and potato. Exotic maize lines with higher androgenic response turned up as a good source for this heritable trait and this valuable trait can be incorporated into elite maize lines via crossing. Lots of attempts were devoted to identifying some cytological and/or morphological markers for androgenic response in maize microspore cultures. The “starlike” organization of the cytoplasm inside the induced maize microspores together with the enlarged size of induced microspores can be considered as morphological markers for androgenic response. In barley, microspores with rich cytoplasm that was of granular appearance with the nucleus located near the cell wall and with no visible vacuole had the largest survival rate and many of these cells continued in development and produced embryos. In flax, a dramatic increase of induction rate in anther cultures (up to 25%) was achieved when flax anthers were pretreated for 3 days at 4 °C and afterwards kept for 1 day at 35 °C. Also gynogenesis in flax has been reported already and complete plants were obtained. In potato microspore cultures, formation of two dissimilar cells indicated a strong polarization in the system and as a result of this polarization a prominent suspensor developed that persisted until the torpedo stage of the androgenic embryo. This was the first time the formation of a well developed suspensor was described in connection with androgenesis. Correspondence and reprints: Institute of Plant Genetics and Biotechnology, Slovak Academy of Sciences, P.O. Box 39A, 950 07 Nitra, Slovak Republic.     

Development of a novel roving-treatment process employing sequential chelating agent and enzymatic stages, utilising thermal analysis for assessment of fibre and yarn quality

Despite the potential benefits of utilising enzyme-based treatments to remove specific non-cellulosic polysaccharide components from flax fibre prior to spinning, attempts to date have not proved successful. At present, techniques employing conventional chemical reagents are solely employed within this industry. To establish the feasibility of incorporating an enzyme treatment stage within a novel process sequence, small-scale laboratory test protocols have been developed and employed to screen the performance of a range of commercial enzyme formulations on commercial dew-retted flax rovings. Thermal analysis and physical testing permitted rapid assessment and the best-performing treatment sequences, based on Pectinex AR and Pentopan 500 BG, respectively (Novozymes A/S, Bagsvaerd, Denmark) were then successfully scaled-up for industrial spinning trials. The results of these trials have shown that treatment with a chelating agent followed by pectinase and peroxide bleaching processes is capable of producing good quality yarn. The compositional and structural changes occurring in the fibre at each stage of treatment were detected using derivative thermogravimetry, and revealed quantitative changes in weight loss, decomposition temperature and peak widths in response to process steps. Assessment of chemical and physical performance data for the yarns obtained indicates that such a process may have commercial applications, supplementing the repertoire of traditional techniques and reagents available to the industry.     

Ontogenic variations in n-alkanes during somatic embryogenesis of flax (Linum usitatissimum L.)

Hypocotyl segments (HS) of flax seedlings germinated in vitro, were used to induce indirect somatic embryogenesis on solid medium. The composition and distribution of n-alkanes in flax tissues collected at different developmental stages were studied by capillary gas chromatography (GC) and capillary gas chromatography-mass spectrometry (GC-MS). During induction and development of callus from hypocotyl tissues a decrease in the percentage of total lipids was observed. In all types of tissue sampled – HS used as primary explants, HS with differentiating calli at the cut ends (HSC), embryogenic (EC) and non-embryogenic calli (NEC) and somatic embryos (SE) – a skewed-normal distribution of n-alkanes with a low mass range (C₁₃–C₂₁) were found. The highest content of n-alkanes occurred in the primary hypocotyl explants and in the early stages of callus development. Longer carbon chain n-alkanes were observed only in the mature or differentiated tissues of hypocotyls and SE. Although the n-alkane contents decreased with time, in SE and calli, a significantly lower n-alkane content was observed in EC when compared to NEC independent of the time in culture. These results suggest the utilisation of n-alkanes for heterotrophic cellular growth as well as its mobilisation from EC to developing SE.     

A possible role of prolyl oligopeptidase during Linum usitatissimum (flax) seed development

Involvement of prolyl oligopeptidases (POPs) in the control of several mammalian peptide hormone signalling pathways has been studied extensively in recent years. POPs are ubiquitous enzymes, but little attention has been paid to understanding their function in plants. Using a cDNA-AFLP approach, two flax (Linum usitatissimum) POP ESTs were identified as being specifically expressed in the early stages of flax seed development. This specific expression was confirmed using real time RT-PCR and in situ hybridisation approaches. Seed expression of Arabidopsis POP genes was measured and showed no specificity. Comparison between results obtained with flax and Arabidopsis is discussed in order to address a hypothetic function for POPs during seed formation. These results provide the first insights into POP gene expression and hypothetical function in plants.     

Cloning of a Novel Omega-6 Desaturase from Flax (<Emphasis Type="Italic">Linum usitatissimum</Emphasis> L.) and Its Functional Analysis in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

The Δ12 desaturase represents a diverse gene family in plants and is responsible for conversion of oleic acid (18:1) to linoleic acid (18:2). Several members of this family are known from plants like Arabidopsis and Soybean. Using primers from conserved C- and N-terminal regions, we have cloned a novel Δ12 desaturase gene amplified from flax genomic DNA, denoted as LuFAD2-2. This intron-less gene is 1,149-base pair long encoding 382 amino acids—putative membrane-bound Δ12 desaturase protein. Sequence comparisons show that the novel sequence has 85% similarity with previously reported flax Δ12 desaturase at amino acid level and shows typical features of membrane-bound desaturase such as three conserved histidine boxes along with four membrane-spanning regions that are universally present among plant desaturases. The signature amino acid sequence ‘YNNKL’ was also found to be present at the N terminus of the protein, which is necessary and sufficient for ER localization of enzyme. Neighbor-Joining tree generated from the sequence alignment grouped LuFAD2-2 among the other FAD2 sequences from Ricinus, Hevea, Jatropha, and Vernicia. When LuFAD2-2 and LuFAD2 were expressed in Saccharomyces cerevisiae, they could convert the oleic acid to linoleic acid, with an average conversion rate of 5.25 and 8.85%, respectively. However, exogenously supplied linoleic acid was feebly converted to linolenic acid suggesting that LuFAD2-2 encodes a functional FAD2 enzyme and has substrate specificity similar to LuFAD2.