胁迫诱导植物体细胞胚发生中相关基因及蛋白的研究进展

植物体细胞胚发生是一个复杂的发育过程,体细胞胚发生已成为研究植物胚胎发育过程中生理、生化、分子生物学等方面分子机理的模式系统。胁迫被认为是对体细胞胚的诱导有重要作用的因素。植物生长调节物质如2,4-D、ABA等目前认为是与胚性能力获得有关的胁迫物质。在蛋白和转录水平上对基因表达的分析中已鉴定出一些与体细胞胚发生相关的基因和蛋白。该文主要对近年来国内外有关胁迫诱导体细胞胚发生的相关基因及蛋白的研究进展进行综述。     

植物抗盐分子机制及作物遗传改良耐盐性的研究进展

盐胁迫是全球农业生产上的一个主要逆境因子。解析耐盐分子机制有助于培育耐盐能力提高的作物新品种。我们综述了植物对盐胁迫的感应及信号传导、主要Na^＋运输体、盐胁迫下的解毒途径以及耐盐途径中涉及到的表观遗传研究。此外,我们还讨论了利用遗传改良手段提高作物耐盐性的研究进展。     

耐糖β-葡萄糖苷酶基因的挖掘、突变及应用研究进展

降低木质纤维素生物炼制的用酶成本,对推动木质纤维素的绿色利用至关重要。作为纤维素水解过程中的限速酶,β-葡萄糖苷酶酶解活性受高浓度葡萄糖的胁迫抑制。目前,挖掘和突变耐糖β-葡萄糖苷酶的基因是解决这一问题的重要策略。本综述总结了近年来在耐糖β-葡萄糖苷酶基因的挖掘、酶耐糖分子机制的分析、旨在提高酶耐糖性能的酶基因突变以及基于β-葡萄糖苷酶基因的微生物菌株基因工程改造等方面所取得的进展,并进行了展望。本综述为构建高产耐糖β-葡萄糖苷酶的基因工程菌株提供参考,这对推动木质纤维素生物炼制工业化进程具有重要意义。     

麻疯树根边缘细胞生物学特性及镉对其活性的影响

以麻疯树为试材,采用悬空气法,探讨麻疯树离体根边缘细胞的生物学特性及重金属镉(Cd2+)对根边缘细胞活性的影响.结果表明,麻疯树根边缘细胞大多数呈椭圆型,少数成弯曲的长条型;根长为15 mm时,边缘细胞的生物学活性(存活率)最大;根冠果胶甲基脂酶(PME)酶活性随着根的伸长有所降低.镉对麻疯树根边缘细胞产生明显毒害,随着镉浓度和处理时间的增加,边缘细胞的活性都呈现下降的趋势.     

体外选择与体细胞无性系变异在抗病育种中的应用

本文综述了体外选择与体细胞无性系变异进行抗病育种的方法、影响因素、优缺点及研究进展等。 Application of in vitro Selection and Somaclonal Variation in Improvement of Disease Resistance LIU Jin-ping,ZHENG Cheng-mu South China University of Tropical Agriculture,Agronomy College Zhanzhou,Hainan 571737,China Abstract:Techniques,influencing factors,advantages,disadvantages and advances in improvement of disease resistance using in vitro selection and somaclonal variation were summarized. Key words：in vitro selection;somaclonal variation;improvement of disease resistance     

植物凝集素类受体蛋白激酶研究进展

自然界中植物的生长发育受到各种环境变化的影响。为了响应外界各种环境条件,植物演化出一系列识别和传递环境信号的蛋白分子,其中比较典型的是植物细胞质膜上的类受体蛋白激酶(RLKs)。凝集素类受体蛋白激酶(LecRLKs)是类受体蛋白激酶家族中的一个亚族,它主要包含3个结构域:细胞外凝集素结构域、跨膜结构域和细胞内激酶结构域。根据细胞外凝集素结构域的不同,LecRLKs可分为3种不同类型:L、G和C型。近年来,研究表明LecRLKs在植物生物/非生物胁迫和发育调控中发挥非常重要的作用。该文综述了植物凝集素类受体蛋白激酶的研究历史、结构特点、分类以及生物学功能,并重点阐述凝集素类受体蛋白激酶在植物生物/非生物胁迫响应和调控发育方面的功能。对不同类型和不同功能的植物凝集素类受体蛋白激酶进行阐述将有利于对该类蛋白开展功能研究,并为作物改良提供有益借鉴。     

木葡聚糖及其在植物抗逆过程中的功能研究进展

木葡聚糖(XyG)是一种存在于所有陆生植物细胞壁中的基质多糖, 是双子叶植物初生细胞壁中含量(20%-25%, w/w)最丰富的半纤维素成分。作为细胞壁的组分, XyG不仅与植物的生长发育密切相关, 还在植物抵抗各种生物和非生物逆境过程中发挥重要作用。XyG代谢相关基因主要通过改变植物细胞壁的组成以及对细胞壁进行重排进而改变细胞壁的弹性/硬度等特性, 影响植物的抗逆性。XyG及其寡糖也可能作为信号分子, 或与其它信号分子协同作用应对逆境胁迫。该文概述了XyG的结构与类型及参与XyG生物合成与降解的相关基因, 重点阐述XyG相关基因应答生物和非生物胁迫的作用机制。     

魔芋属植物组织培养与遗传转化研究进展

本文对近20年来魔芋生物技术研究取得的进展进行了系统的回顾分析。组织培养是当前魔芋生物技术研究的主要内容,魔芋离体植株再生以器官发生途径为主,包括不定芽和拟球茎两种途径,后者是当前研究的热点。利用组织培养进行有用突变体的筛选和种质资源的保存也取得了一些有价值的结果。以抗病和品质改良为目的的转基因技术取得了较快发展,如抗病基因和抗除草剂基因等已实现成功转化。此外,本文还分析了魔芋生物技术研究中存在的主要问题并提出了相应的对策。     

Heritable variability induced by the in vitro culture and genetic improvement of cultivated plants

Abstract

Genetic variability is found among plants derived from in vitro cultures of somatic cells. A number of different factors, such as the pre-existing genetic variation developed in vivo during tissue differentiation, the variation induced during the in vitro culture and also the selection for specific genotypes during plant regeneration, are considered as possible causes of the phenomenon.

The nature of the genetic changes induced in somaclones (variation in chromosome number, gross and cryptic chromosomal rearrangements, transposition of genetic elements, gene amplification and somatic gene rearrangements) is also discussed.     

Genetic changes in grapevine genomes after stress induced by in vitro cultivation, thermotherapy and virus infection, as revealed by AFLP

The Amplification Fragment Length Polymorphism (AFLP) technique was employed to study genetic variations which can be induced in vines by the stress occurring during different aspects of viticulture (in vitro cultivation, in vitro thermotherapy and virus infection). Analysis of AFLP banding patterns, generated by using 15 primer combinations, pointed to negligible genetic variation among plants exposed to individual stress. The average of similarity coefficients between differently stressed plants of the cultivars Müller Thurgau and Riesling were 0.984 and 0.991, respectively, as revealed by AFLP analysis. The low incidence of observed polymorphism demonstrates the high level of genome uniformity in plants reproduced by in vitro micropropagation via nodes, those subjected to in vitro thermotherapy and virus-infected plants.     

Effects of biotic and abiotic stress on the growth of three genotypes of Lolium perenne with and without infection by the fungal endophyte Neotyphodium lolii

The combinations of three genotypes of Lolium perenne with and without (i) infection by the fungal endophyte Neotyphodium lolii, (ii) infection by ryegrass mosaic virus and (iii) one of five different forms of abiotic stress were studied in pot experiments in a glasshouse. The five abiotic stress treatments were (i) low pH (compared with ‘optimal’ pH), (ii) cutting plants to a height of 1 cm (compared with 5 cm), (iii) shading (compared with no shading), (iv) cutting plants at 2‐weekly intervals (compared with 6 wk) and (v) low nitrogen applied (compared with ‘high’ nitrogen applied). On average, over the five experiments, the accumulated herbage dry weight was 10% more for N. lolii‐infected plants than uninfected, 22% more for virus‐free plants than infected, and 265% more for ‘unstressed’ plants than for plants with abiotic stress. The effects of N. lolii infection on plant growth when the plants were under abiotic or biotic stress were not consistent.     

生物质炭生物与非生物氧化特性研究进展

生物质炭是由植物生物质热解炭化产生的一类高度芳香化难熔性固态物质。生物质热解炭化还田能否成为人类应对全球气候变化的重要途径直接取决于其在土壤生态系统中的稳定性。生物质炭稳定性的研究对科学计算和评估土壤生态系统生物质炭输入的碳固持与减排作用具有重要现实意义。重点概述了土壤生态系统生物质炭生物与非生物氧化特性、影响因素及其机理研究进展,并对生物质炭在土壤环境中的稳定性预测模型研究进行了分析。在此基础上,今后需针对不同类型旱地土壤生态系统和不同类型稻田土壤生态系统生物质炭稳定性及其机理开展研究,并进一步开展土壤生态系统生物质炭稳定性预测模型研究。     

Characterization of human cells transformed by chemical and physical carcinogens in vitro

Summary Several different classes of chemical carcinogens induced the transformation of human fibroblasts grown in vitro. Characteristics of the events that occur from time of treatment through the expression of neoplastic transformation are presented. The S-phase appeared to be the portion of the cell cycle most vulnerable to insult. Staging of the cells by blocking them in G₁ before releasing them to proceed through scheduled DNA synthesis (S) was required to induce reproducible transformation. Compounds such as insulin were added to the cells upon release from the block to sensitize the cells to the carcinogen that was added during S. Growth of the transformed cells as distinct from nontransformed cells was promoted by growth in medium supplemented with 8X nonessential amino acids. Carcinogen-treated cells in the early stage of transformation exhibited abnormal colony morphology and were able to grow at 41°C, in air atmosphere, and in medium supplemented with only 1% serum. In addition, the transformed cells were insensitive to KB cell lysate and exhibited density independent, as well as anchorage independent, growth (i.e., growth in 0.33% agar). Cells that grew in soft agar also produced undifferentiated mesenchymal tumors in preirradiated nude mice. This work was supported in part by National Cancer Institute Grant ROI-CA-25907 and Air Force Office of Scientific Research Grant F49620-77-C0110 and EPA-R806638. The hydrazine compounds were furnished by Ms. Marilyn George and Dr. Kenneth Back, AFSOR Toxicology Division, Wright Patterson Air Force Base, Dayton, OH. The hydroxylate and phenyl napthylamines were furnished by Dr. Fred Kadlubar, Division of Chemical Carcinogenesis at the National Center for Toxicological Research, Jefferson, AR.