小麦叶片水分利用效率及相关生理性状基因的染色体定位

利用中国春-埃及红代换系对控制小麦水分利用效率、光合速率、蒸腾速率、POD活性以及SOD活性等的基因进行了染色体定位。结果表明,控制高水分利用效率的基因可能位于5A和5D染色体上;控制高光效的基因可能位于3A和3D染色体上;控制高蒸腾速率的基因可能位于7B染色体上;诱导POD和SOD活性增强的有利培因可能分别位于7D和6D、2B染色体上。这些研究结果可以为小麦机抗旱节水的遗传育种研究提供一定参号信息。     

Characterization and quantification of low molecular weight glutenins in durum wheats

Durum wheat proteins have been considered as a model because of the very clear-cut relationship previously evidenced between the electrophoretic type '42' or '45' of the components that are coded by the Gli-B1 chromosome locus and the intrinsic quality (gluten viscoelasticity) of cultivars. The proteins from 4 cultivars were subjected to sequential extraction and separated into five groups, respectively, in: NaCl, EtOH (gliadins-I), EtOH + mercaptoethanol (ME) (gliadins-II), AcOH + ME (glutenins-I) and SDS + ME (glutenins-II) and characterized using polyacrylamide gel electrophoresis (PAGE), SDS-PAGE and 2-dimensional (NEPHGE X SDS - PAGE) electrophoretic systems. EtOH-soluble fractions were also separated by ion-exchange chromatography, each fraction being characterized in PAGE and SDS-PAGE and its composition in major bands determined by densitometry. From the ratio of each chromatographic fraction and of each solubility group, an estimation of the major bands or electrophoretic zones was also made in respect to the whole proteins. In 'type 45' cultivars, it was shown that only 67% of the EtOH-soluble fraction (although considered as classical gliadins) had a monomeric character, giving rise to discrete bands in PAGE systems. The remainder (33%) were aggregated fractions, essentially those referred to as low molecular weight glutenins (LMWG), that migrate, upon reduction only, in SDS-PAGE systems. LMWG make up 27% of total proteins and are revealed as a strong triplet in the 44,500-51,500 MW region, in gliadin-I and especially in gliadin-II groups. In type '42' cultivars, the LMWG ratio is reduced about by half (18% of EtOH soluble fraction, 14% of total proteins). This difference, coupled with their aggregative behavior, leads to their consideration as the major functional markers of gluten quality, gliadins 42/45 being genetic markers only. Without excluding possible physicochemical differences between different LMWG allelic types, it is hypothesized that quantitative differences could explain by themselves the quality differences between the two durum wheat genetic types. Concerning the other aggregative fractions, like high molecular weight glutenin (HMWG) subunits in glutenin-I and II groups, they do not show (unlike bread wheats) quantitative or qualitative differences large enough to play a major role in explaining genetic differences in durum wheat gluten characteristics. It is recommended, especially for physicochemical studies of wheat quality, to rely on a protein classification based on monomeric or aggregative characteristics, instead of Osborne's scheme based only on fractionation by solubility.(ABSTRACT TRUNCATED AT 400 WORDS)     

Molecular evolution of two consecutive carotenoid cleavage dioxygenase genes in strigolactone biosynthesis in plants

Strigolactones are newly discovered plant hormones that perform various functions, from signaling in symbiotic interactions with arbuscular mycorrhizal fungi to controlling outgrowth of axillary buds. We examined the phylogenetic relationships of two carotenoid cleavage dioxygenase genes (CCD7 and CCD8) that are involved in consecutive upstream steps of the proposed strigolactone biosynthesis pathway. The CCD7 and CCD8 sequences from 11 model species, divided into two clades, correspond to sequences from monocotyledons and dicotyledons. However, the sequences from the primitive moss, Physcomitrella patens, appeared to be evolutionarily distinct from those of the angiosperms. CCD7 and CCD8 are much conserved, since no significant positive selection was detected among these plants. Ks values indicated that CCD7 and CCD8 diverged about 290 to 430 million years ago. As essential genes in the strigolactone pathway, the divergence timing of the conserved CCD7 and CCD8 genes reflects the approximate time of generation of strigolactone as a regulatory substance. This timing calculation also coincides with initiation of symbiosis between plants and microorganisms, inferred from the fossil record. Molecular evolution analyses of genes in metabolic pathways can provide insight concerning gene evolution.     

The emerging complexity of self-incompatibility (S-) loci

 A complex picture of S-loci is beginning to emerge from recent studies of the S-locus of RNase-based gametophytic self-incompatibility displayed by the Rosaceae, Solanaceae, and Scrophulariaceae, and of the S-locus of the type of sporophytic self-incompatibility displayed by the Brassicaceae. It now appears that not only do these S-loci contain two separate genes, one controlling pollen function and the other controlling pistil function in self-incompatibility interactions, but also many other genes whose functions are largely unknown. The implications of these recent findings for the study of the mechanisms of self-incompatibililty interactions and evolution of the self-incompatibility systems are discussed. Received: 7 January 1999 / Revision accepted: 13 January 1999     

Genetic control of meiosis in Drozophila

By the beginning of 2000, more than 80 genes specifically controlling meiosis and meiotic recombination in Drosophila melanogaster have been described. Meiosis in Drosophila is different from the classical model. In females, these differences concern cytological features of prophase I, which have no principal genetic significance. Drosophila males lack lateral synapsis of chromosomes, recombination and chiasmata, and their chromosomes segregate in meiosis I following the "touch-and-go" principle. Meiotic genes in Drosophila can be classified according to their functions as affecting prerequisites for recombination and crossing over, controlling chromosome segregation in meiosis I separately in males and females and controlling sister-chromatid segregation in meiosis II in both sexes. Some meiotic genes are pleiotropic. There are meiotic genes controlling mitosis, and vice versa. Some genes for DNA repair in somatic cells are also involved in meiosis. Meiotic genes in Drosophila are compared with their counterparts in other organisms.     

Genetics of tolerance to aluminium in wheat (Triticum aestivum L. Thell)

Preliminary studies indicated that aluminium-tolerance in wheat (Triticum aestivum L. Thell.) is a dominant character controlled by several genes. The present paper describes further work on localization and characterization of some of these genes in the genome of the medium Al tolerant wheat cultivar Chinese Spring (C.S.), using an aneuploid series (ditelosomics). Aluminium-tolerance of seedlings was assessed using the modified pulse method; the aluminium concentration in the nutrient solution causing irreversible damage to the root apical meristems on exposure for 24 h at 25°C was the measure of Al-tolerance. At least three different factors controlling Al-tolerance in the C.S. cultivar were located on chromosomes 5As, 2Dl and 4Dl. Significant differences were found in Al-uptake and accumulation in roots of the respective ditelosomic lines and euploid seedlings of C.S. Genes controlling Al-tolerance located in the D genome (2Dl and 4Dl) were not expressed in solution culture when genes located on 5As were missing, whereas some tolerance was observed in aneuploid lines in which genes from 5As were present while genes from 2Dl and 4Dl were missing. It is concluded that Al-tolerance genes located in A genome control the expression of other Al-tolerance genes located in the D genome. The implications of the obtained results for chromosome and gene manipulations in cereals are discussed.     

杨树CYCD基因的功能鉴定及其对糖和植物激素的响应

G1到S期的转换是植物细胞周期中一个关键的调控点,而D型细胞周期蛋白(CYCD)在这一转换过程中起着重要作用.CYCD通过感受外界信号的刺激,调控细胞周期进程,进而影响植物的生长发育.为研究木本植物中不同CYCD基因家族的功能,从黑杨中克隆出6个CYCD基因,并将其转化至酵母G1期细胞周期蛋白突变体进行功能鉴定.各家族...     

Lack of linkage between gene(s) controlling the synthesis of the seventh component of complement and the HLA region on chromosome No. 6 in man

Summary The family of an individual was studied who lacks the seventh component of complement in his serum (C7 homozygous deficiency). Both parents are C7 heterozygousdeficient. In this investigation, the following parameters were determined: complement components in functional and immunochemical tests; HLA-A,B antigens, HLA-D (MLC) determinants; the Bf system; glyoxalase I and B cell antigens. No evidence for linkage between the immunogenetic linkage group on chromosome 6 and gene(s) controlling the synthesis of the seventh component of complement was obtained. This is in accordance with the assumption that only genes controlling components of the initiating rather than the membrane attack unit of complement are linked to the HLA region.     

A new semi-dwarfing gene identified by molecular mapping of quantitative trait loci in barley

Semi-dwarfing genes have been widely used in spring barley (Hordeum vulgare L.) breeding programs in many parts of the world, but the success in developing barley cultivars with semi-dwarfing genes has been limited in North America. Exploiting new semi-dwarfing genes may help in solving this dilemma. A recombinant inbred line population was developed by crossing ZAU 7, a semi-dwarf cultivar from China, to ND16092, a tall breeding line from North Dakota. To identify quantitative trait loci (QTL) controlling plant height, a linkage map comprised of 111 molecular markers was constructed. Simple interval mapping was performed for each of the eight environments. A consistent QTL for plant height was found on chromosome 7HL. This QTL is not associated with maturity and rachis internode length. We suggest the provisional name Qph-7H for this QTL. Qph-7H from ZAU 7 reduced plant height to about 3/4 of normal; thus, Qph-7H is considered a semi-dwarfing gene. Other QTLs for plant height were found, but their expression was variable across the eight environments tested.     

几个水稻品种抽穗期主效基因与微效基因的定位研究

在构建２张ＲＦＬＰ图谱的基础上,定位分析了控制水稻抽穗期的主效基因和微效基因。在特三矮２号／Ｃ．Ｂ．群体中定位到２个主效基因和２个微效基因。该２个主基因分别位于第３、８染色体上,累加贡献率约达５０％,加性效应值分别为７天和６天,而分别位于第１、１２染色体的２个微效基因的贡献率仅分别为８．３％和９．６％,加性效应值仅为３天和４天。在外引２号／Ｃ．Ｂ．群体中定位了２个连锁于第６染色体的主效基因和１个位于第８染色体的微效基因,该２个主效基因的贡献率分别为３５．５％和２７．４％,来自外引２号的该２个基因其效应均为明显推迟抽穗,因而可推测它们为感光性基因,微效基因的贡献率仅为８．９％,基因效应值较小。     

cDNA microarray analysis of the differential gene expression in the neuropathic pain and electroacupuncture treatment models

Partial nerve injury is the main cause of neuropathic pain disorders in humans. Acupuncture has long been used to relieve pain. It is known to relieve pain by controlling the activities of the autonomic nervous system. Although the mechanism of neuropathic pain and analgesic effects of electroacupuncture (EA) have been studied in a rat model system, its detailed mechanism at the molecular level remains unclear. To identify genes that might serve as either markers or explain these distinct biological functions, a cDNA microarray analysis was used to compare the expression of 8,400 genes among three sample groups. Messenger RNAs that were pooled from the spinal nerves of 7 normal, 7 neuropathic pain, and 7 EA treatment rat models were compared. Sixty-eight genes were differentially expressed more than 2-fold in the neuropathic rat model when compared to the normal, and restored to the normal expression level after the EA treatment. These genes are involved in a number of biological processes, including the signal transduction, gene expression, and nociceptive pathways. Confirmation of the differential gene expression was performed by a dotblot analysis. Dot-blotting results showed that the opioid receptor sigma was among those genes. This indicates that opioid-signaling events are involved in neuropathic pain and the analgesic effects of EA. The potential application of these data include the identification and characterization of signaling pathways that are involved in the EA treatment, studies on the role of the opioid receptor in neuropathic pain, and further exploration on the role of selected identified genes in animal models.     

Towards unravelling the Igf2/H19 imprinted domain

Genomic imprinting is an epigenetic marking process that confers parent-of-origin-dependent expression on certain genes. These imprinted genes are sometimes found in clusters, suggesting a possible involvement of higher order regulatory elements controlling expression and imprinting of genes organised in such clusters. In the distal chromosome 7 there are at least four imprinted genes: Mash2, Ins2, Igf2 and H19. Recent evidence⁽¹⁾ suggests that imprinting and expression of at least Igf2 and H19 may be mechanistically linked.     

小麦幼苗磷利用率及相关基因的染色体定位

利用小麦'中国春-埃及红'代换系对调控不同水分和磷素胁迫处理下磷素利用效率及相关性状进行了染色体定位和遗传分析,为作物磷素高效利用的遗传改良研究奠定基础.结果表明,染色体7A和7D代换系在Hoagland营养液(WP)、10% PEG-6000 Hoagland营养液(-WP)、1/2P Hoagland营养液(W-P) 处理下,可能携带有对磷素利用有促进作用的基因.遗传分析表明,磷素利用率的遗传力、遗传进度、相对遗传进度都较高,说明该性状的变异由遗传作用引起的比重较大,环境因素对它的遗传影响不大,适合在遗传育种中进行早代选择.