植物矮化相关基因研究进展

矮化植株株型紧凑,冠幅小,抗倒伏,且生产管理方便,丰产性能好,矮化育种是植物育种的发展趋势。国内外学者对植物矮化的机理、矮化基因、矮化育种等进行了比较深入的研究。我们对植物矮化的遗传特点、分子标记在矮化基因研究上的应用、矮化基因的定位、矮化基因的分离与克隆、矮化转基因等方面的研究进展进行了概述。     

木质素降解酶及相关基因研究进展

生物质的高效综合利用已成为全球关注的热点问题。生物质的主要成分是木质素、纤维素和半纤维素,其利用的关键是如何去除木质素,从而提高纤维素和半纤维素的得率。其中利用真菌的生物预处理方法因条件温和、无二次污染等优点符合全球经济可持续发展需要,受到研究者的普遍关注。综述了近年国内外真菌分泌的主要木质素降解酶,包括木质素过氧化物酶(Li P)、锰过氧化物酶(Mn P)、漆酶(laccase)和多功能过氧化物酶(VP)的主要特点,总结了木质素降解相关酶的基因工程、基因组学的研究成果,并对其发展前景进行了展望。     

获得多价转基因作物的策略

本探讨了在利用植物基因工程技术的基础上,通过构建多基因或多个表达载体,进行一次,多次基因转化或共转化方法获得转多价基因作物的一些策略,并进行了展望。     

木聚糖降解酶系基因代谢调控研究进展

木聚糖是半纤维素的主要组成部分,是一类数量很大的再生生物资源,工业利用前景广阔。木聚糖降解需要多种酶的参与,主要有木聚糖酶、木糖苷酶、α-葡萄糖醛酸酶、乙酰木聚糖酯酶、阿拉伯糖酶、阿魏酸酯酶、p-香豆酸酯酶等。主要综述了木聚糖降解酶系基因代谢调控的研究进展,主要包括转录激活因子XlnR、抑制蛋白CreA、不同诱导物、pH值、HAP-CCAAT复合物等对木聚糖降解酶系基因表达的影响,最后探讨了木聚糖降解酶系基因代谢调控存在的问题,并对今后的研究进行了展望。     

获得多价转基因作物的策略

本文探讨了在利用植物基因工程技术的基础上,通过构建多基因或者多个表达载体,进行一次、多次基因转化或共转化方法获得转多价基因作物的一些策略,并进行了展望。 Abstract：Based on present plant gene engineering techniques, some strategies to develop transgenic crops expressing multiple genes by constructing a multigenes expression vector or a number of expression vectors and then making one or more transformations or co-transformation are discussed and the prospects are described as well in this paper.     

麦角碱生物合成途径中酶学及相关基因研究进展

简要介绍了麦角碱(ergot alkaloids)的化学、药理学及生物合成方面的相关知识．综述了近年来麦角碱生物合成途径中酶学和相关基因方面的研究进展以及它对麦角碱生产的影响,探讨了麦角碱生物合成途径方面的研究方向和发展前景。     

蚯蚓纤溶酶组分及其基因的多态性

生化制备证明,蚯蚓纤溶酶为一组含有10个以上同工酶组分的混合酶.为了研究这些组分的DNA和蛋白质序列的异同,本文通过对数据库中已报道的28条蚯蚓纤溶酶基因按相似性进行归类,将它们分为4组(基因型).同一组中的序列具有共同特征,即保守的N-末端、C-末端和相同的结构域,而且这些结构域在序列中分布的位置也相同;但它们之间在中间部分存在明显差异,这些差异说明了基因型中存在多态性.这种多态性可能是它们在体内溶栓的药理药效作用存在差异的结构基础.     

Cloning of Fish Enzymes and Other Fish Protein Genes

ABSTRACT:?

Fish metabolism needs special enzymes that have maximum activity at very different conditions than their mammalian counterparts. Due to the differences in activity, these enzymes, especially cold-adapted proteases, could be used advantageously for the production of some foods. In addition to the enzymes, this review describes some other unique fish polypeptides such as antifreeze proteins, fluorescent proteins, antitumor peptides, antibiotics, and hormones, that have already been cloned and used in food processing, genetic engineering, medicine, and aquaculture. Recombinant DNA technology, which allows these biological molecules to be cloned and overexpressed in microorganisms is also described, highlighting innovative applications. The expected impact of cloning fish proteins in different fields of technology is discussed.     

抗虫基因研究及在芸薹属作物上的应用

芸薹属作物属十字花科,包括多种重要的蔬菜和油料作物。该类作物易受病虫害侵袭,造成品质和产量严重受损。化学方法防治害虫不仅破坏环境而且费用昂贵,所以培育抗虫品种成为既经济又环保的措施之一。但由于目前抗虫资源匮乏,难以通过常规育种培育出抗虫的品种,植物基因工程技术的应用,能加快育种进程,提高育种效率。简要介绍近年来抗虫基因的发掘及其在芸薹属中的应用进展。     

蔬菜作物重要农艺性状相关基因分离的研究进展

本文简要综述了蔬菜作物基因分离的主要方法和近年来蔬菜作物重要农艺性状相关基因分离的研究进展,指出在分离蔬菜作物目的基因的研究中,必须加强基因分离的原创性;充分利用现有的研究条件,做到基因分离与功能基因组研究相互协调,均衡发展,从而为我国蔬菜作物开展分子育种研究奠定基础。     

六种作物内标准基因开发与检测研究进展

内标准基因（internal reference gene）是指能够区分物种的特异性、具有单一或恒定的低拷贝数、低变异的保守DNA序列。指定作物种类的内标准基因在转基因成分检测、物种及其产品判别等众多领域内作为鉴别其他物种的主要遗传标志,尤其是在转基因产品定量定性检测中,可用于检测样品中的物种来源以及转基因含量,对转基因产品定量定性检测具有重要意义。目前,已有多种作物的内标准基因被开发,其中玉米、油菜和水稻开发的内标准基因数量较多,但仍缺乏更为透彻的比较研究,导致选择与应用较为困难。基于此,根据国内外已有的研究成果,综述了6种检测或鉴定需求较大的作物（包括玉米、大豆、油菜、棉花、水稻和小麦）的内标准基因的研究进展,并对常见作物的内标准基因进行了系统的比较和研究,以期为植物源性、转基因成分及相关检测鉴定提供技术支撑。     

Genome-Wide Identification and Analysis of Genes Encoding Proteolytic Enzymes in Pineapple

Pineapple, Ananas comosus, is an economically important fruit crop. Recently its genome was completely sequenced and a total of 27,024 protein coding genes were predicted. Using a set of well evaluated bioinformatics tools we have predicted the protein subcellular locations and comparatively analyzed the protein conserved domains of the predicted proteomes in pineapple, Oryza sativa (rice), Sorghum bicolor (sorghum), and Brachypodium distachyson. Our analysis revealed that ~24–26 % of proteins were located in nucleus, 17–21 % in cytosol, 9–11 % in chloroplast, and 8–11 % proteins were secreted in these monocot plants. The secretomes in the four species were analyzed comparatively and a large number of secreted glycosyl hydrolases were identified. As pineapple proteolytic enzymes, knowns as bromelains, have been used for medical treatments, we focused on genome-wide identification and analysis of pineapple genes encoding proteases. A total of 512 pineapple genes encoding putative proteolytic enzymes were identified, with 152 secreted, 74 localized in cytosol, 67 in nucleus, 60 in chloroplast, 18 in mitochondria, and the remaining in other subcellular locations. The top large protease families in pineapple were papain family cysteine protease (62 genes), peptidase S8 family (56 genes), aspartyl protease family (38 genes), and serine carboxypeptidase (33 genes). Gene expression analysis revealed that among 512 protease genes 432 were expressed in various tissues and 72 genes were differentially expressed. The highly expressed protease genes were identified including 7 papain family cysteine proteases. The protease genes with the predicted protein subcellular locations will facilitate the efforts for examining their biological roles in pineapple growth and development and for expressing the recombinant proteases for medical use. The information of protein subcellular location of all plant species can be accessed at the PlantSecKB website (http://proteomics.ysu.edu/secretomes/plant.php).     

高等植物中蔗糖降解酶及其基因表达与调控

大多数植物的库器官都是以蔗糖的形式接受碳源和能源,蔗糖进入库代谢需要转化酶和蔗糖合成酶降解成为葡萄糖和果糖,而糖又调节植物代谢过程中许多酶的基因表达,因此蔗糖降解酶是植物生长发育中起关键作用的酶．综述了近年来蔗糖合成酶和转化酶的作用及它们基因表达和调节的研究进展．     

Purine Utilization by Klebsiella oxytoca M5al: Genes for Ring-Oxidizing and -Opening Enzymes

The enterobacterium Klebsiella oxytoca uses a variety of inorganic and organic nitrogen sources, including purines, nitrogen-rich compounds that are widespread in the biosphere. We have identified a 23-gene cluster that encodes the enzymes for utilizing purines as the sole nitrogen source. Growth and complementation tests with insertion mutants, combined with sequence comparisons, reveal functions for the products of these genes. Here, we report our characterization of 12 genes, one encoding guanine deaminase and the others encoding enzymes for converting (hypo)xanthine to allantoate. Conventionally, xanthine dehydrogenase, a broadly distributed molybdoflavoenzyme, catalyzes sequential hydroxylation reactions to convert hypoxanthine via xanthine to urate. Our results show that these reactions in K. oxytoca are catalyzed by a two-component oxygenase (HpxE-HpxD enzyme) homologous to Rieske nonheme iron aromatic-ring-hydroxylating systems, such as phthalate dioxygenase. Our results also reveal previously undescribed enzymes involved in urate oxidation to allantoin, catalyzed by a flavoprotein monooxygenase (HpxO enzyme), and in allantoin conversion to allantoate, which involves allantoin racemase (HpxA enzyme). The pathway also includes the recently described PuuE allantoinase (HpxB enzyme). The HpxE-HpxD and HpxO enzymes were discovered independently by de la Riva et al. (L. de la Riva, J. Badia, J. Aguilar, R. A. Bender, and L. Baldoma, J. Bacteriol. 190:7892-7903, 2008). Thus, several enzymes in this K. oxytoca purine utilization pathway differ from those in other microorganisms. Isofunctional homologs of these enzymes apparently are encoded by other species, including Acinetobacter, Burkholderia, Pseudomonas, Saccharomyces, and Xanthomonas.Purines and purine derivatives comprise a large portion of biomass and are involved in almost every step of life. Not only a major constituent of nucleic acids, they also are central to energy transfer and storage (ATP) as well as protein synthesis and signaling (GTP). Plants, animals, and many microorganisms use purines and purine derivatives to store and translocate nitrogen for assimilation or excretion (96).Salvage pathways operate to recycle purines, including hypoxanthine and xanthine, back into nucleoside pools (107). Additionally, some organisms can utilize purines as the sole source of nitrogen and carbon. Adenine and guanine are deaminated to form hypoxanthine and xanthine, respectively, which then are oxidized to form uric acid (urate at physiological pH) (Fig. ​(Fig.1).1). These oxidation steps are catalyzed by xanthine dehydrogenase, a well-studied molybdoflavoenzyme that is conserved from bacteria to humans (51). Two sequential ring-opening steps convert urate via allantoin to allantoate (Fig. ​(Fig.1).1). Subsequent steps, which comprise different pathways in different microorganisms (96), convert allantoate to ammonium, which is assimilated.Open in a separate windowFIG. 1.Purine ring oxidation and opening steps. The enzyme proposed to catalyze each step is shown. The K. oxytoca gene for adenine deaminase was not identified in this study. Dashed lines show reactions that can occur spontaneously.Some organisms express only the latter portion of the purine utilization pathway and cannot use purines or urate as sole sources of nitrogen. For example, Escherichia coli K-12 can use allantoin and its catabolites as the sole nitrogen source, albeit only under anaerobic conditions (21). Saccharomyces cerevisiae uses allantoin as a nitrogen storage compound (17). However, the complete pathway is present in other bacterial and fungal species, including Bacillus subtilis (84) and Aspergillus nidulans (83).Molybdoenzymes (excepting dinitrogenase) contain the molybdenum cofactor Mo-molybdopterin (42). Thus, mutations in genes for molybdenum cofactor biosynthetic enzymes (mol genes in bacteria and cnx in A. nidulans) confer pleiotropic phenotypes: these mutants can utilize neither nitrate nor purines, due to lack of the molybdoenzymes nitrate reductase and xanthine dehydrogenase (74). We previously reported that Klebsiella oxytoca mol mutants cannot assimilate nitrate but can utilize xanthine as the sole nitrogen source (32). This suggested, as one possibility, that K. oxytoca uses a molybdenum-independent enzyme in place of conventional xanthine dehydrogenase. Results reported here demonstrate that this is correct, as insertion mutants blocked specifically in xanthine and hypoxanthine utilization define the structural genes for an apparent two-component Reiske nonheme iron oxygenase.Here, we report analysis of 12 genes whose products catalyze conversion of purines to allantoate. Our investigation of the remaining genes, whose products catalyze allantoate utilization, is ongoing. Results show that several steps in the overall pathway are catalyzed by previously undescribed enzymes.While this paper was in review, the paper by de la Riva et al. (24), describing the hpxDE, hpxR, hpxO, and hpxPQT genes from Klebsiella pneumoniae W70, was posted in the “JB Accepts” section of the Journal of Bacteriology online edition. Results and conclusions concerning these seven genes are congruent between the two studies.(Some of the work presented here was submitted by Danielle Carl in 1994 as part of an undergraduate thesis to the Cornell University Division of Biological Sciences Honors Program.)     

转基因植物中外源基因及其表达产物转移的途径

随着转基因植物商品化应用的增多,全面了解转基因植物潜在的生态风险性尤为重要。国内外对“转基因植物中外源基因向野生亲缘物种漂移的可能性”、“昆虫对抗虫转基因植物的耐受性”以及“转基因植物对生物多样性的潜在影响”等问题已进行了广泛研究。对转基因植物中外源基因及其表达产物的几种可能转移途径作了概述。着重介绍了“经花粉散布或与野生亲缘物种杂交等途径引起的外源基因转移”以及“转基因植物对土壤生态系统的影响”等方面的研究情况。此外,还对“鉴定外源基因及其表达产物存在的方法”进行了简要探讨。     

植物芪类合成途径相关酶、基因和调控机制研究进展

植物芪类化合物,是一类具有抗菌植保作用的次生代谢产物,因具有抑菌、抗氧化、抗肿瘤等多种生物活性而越来越受到重视。本文对植物芪类生物合成途径中涉及到的相关酶、基因和代谢调控机制的研究现状和应用系统生物学研究芪类生物合成途径的相关酶、基因的方法进行综述,并讨论了芪类生物合成相关酶、基因研究的重要意义和应用,以期为调节芪类产量、满足药用保健需求及植物防御、作物品质改良提供帮助。