植物耐盐基因工程研究进展

盐害是影响植物生长和作物产量的主要因素之一。用于提高植物耐盐性的基因工程方法很多,最常见的就是在植物中过量表达抗盐相关的功能基因,包括植物信号传导蛋白基因、植物离子通道蛋白基因和合成小分子渗透剂的酶基因等。归纳了近年来植物耐盐基因工程的研究进展,并展望了植物耐盐基因工程的研究前景。     

植物花香基因工程研究进展

花香是一系列低分子量、挥发性物质的复杂混合物,由花朵释放来吸引和引导授粉的昆虫.花香在植物繁殖上具有重要作用,还能提高观赏植物和切花的审美价值.在过去的数十年里,随着生物技术的发展,有数种花香相关基因已经相继被克隆,花香物质的生物合成和代谢工程也得到了研究.本文综述了植物花香物质生物合成途径及其相关酶和基因的研究进展;探讨了基因工程调控及改良植物花香的策略;同时简要评述了花香基因工程研究的影响因素并展望了其应用前景.     

花香的生物合成、调控及基因工程研究进展

花香能提高观赏植物的审美特性,并且在植物的繁衍中起着重要作用。近年来,随着分子生物学的发展,花香分子水平的研究呈现加速发展的趋势,已成为当前的一大研究热点。该文主要论述了花香的生物合成途径及关键酶基因、分子水平的调控和共调控探索、花香基因工程策略,以期为花香性状改良提供参考。     

植物耐热相关基因研究进展

植物受到高温胁迫时,会激活某些特定基因的表达,从而增强植物的耐热性。近年来,随着生物技术的不断发展,植物耐热相关基因被相继克隆并转化植物体。本文对植物耐热的分子机制、相关基因的克隆、耐热性基因工程研究进展进行了综述,并提出了植物耐热基因工程的研究方向。     

植物质体基因工程调控元件研究进展

随着植物合成生物学的发展,质体逐渐成为许多具有商业价值的次生代谢产物和治疗性蛋白异源生产的理想平台。与核基因工程相比,质体基因工程在外源基因高效表达和生物安全性等方面具有其独特优势。然而,外源基因在质体系统中的组成型表达或对植物生长不利,因此需进一步挖掘、设计调控元件实现对外源基因的精准调控。本文概述了质体基因工程调控元件的研究进展,内容包括操纵子设计与优化思路、多基因共表达调控策略及新型表达调控元件的挖掘等,为植物合成生物学的发展提供参考。     

ABA相关基因抗旱基因工程研究进展

干旱是影响植物生长发育的重要因素之一。ABA在植物生长发育及应对胁迫反应方面发挥着重要的作用。随着分子生物学等相关学科的快速发展,人们对ABA合成及信号通路相关基因的研究取得了长足进展,并进行了转基因抗旱基因工程研究。对ABA相关基因抗旱基因工程研究进展进行了综述。     

植物抗寒基因工程研究进展

温度是影响植物分布、产量及品质的重要环境因素,提高植物抗寒性对农业生产具有重要的意义.近年来,随着基因工程的发展,对植物的抗寒机理进行了深入的研究,并克隆了许多与抗寒相关的基因.本文从膜稳定性、抗氧化酶活性、抗冻蛋白、低温信号转录因子和渗透调节物质等方面对植物耐冷性基因工程研究进展进行了分析、归纳与总结,旨在为植物抗寒机理研究及植物抗寒育种提供参考.     

植物花色呈现的生物化学、分子生物学机制及其基因工程改良

文章综述了植物花色基因工程改良的前提、策略和特殊性。植物主要花色色素类黄酮、类胡萝卜素的合成途径和相关酶的基因表达已基本研究清楚,关键酶的基因已被克隆。花色的基因工程改良遵循一般植物基因工程规律,而且是系统工程,要求花器官特异性启动子,基本策略为抑制关键酶的基因表达、导入调节基因或新的外源基因。花色基因工程可能成为获得雄性不育的方式之一,应与传统育种技术有机结合,当然也存在安全性问题。     

参与植物次生代谢调控的转录因子及其在植物次生代谢遗传改良中的应用

转录因子与结构基因的结合,激活合成基因的表达是次生代谢物合成途径启动前的重要分子事件,对植物次生代谢起着十分重要的调节作用。转录因了可激活次牛代谢物合成途径中多个基因协同表达,从而有效启动次生代谢途径。因此,转录因子为揭示植物次生代谢调控机制提供重要工具,转录因子的基因工程可为植物次生代谢的遗传改良提供有效的手段。     

植物抗真菌病害基因工程研究进展

从表达水解酶、植物病程相关蛋白、抗真菌蛋白、病原毒性因子失活蛋白、抗病基因、植保素合成限速酶、植物细胞壁结构修饰分子、植物抗生反应调节基因等角度综述了植物抗真菌病害基因工程的策略,并就各种策略的研究进展,存在问题和发展趋势进行了探讨。     

Genetic aspects of floral fragrance in plants

It is generally assumed that compounds are emitted from flowers in order to attract and guide pollinators. Due to the invisibility and the highly variable nature of floral scent, no efficient and reliable methods to screen for genetic variation have been developed. Moreover, no convenient plant model systems are available for flower scent studies. In the past decade, several floral fragrance-related genes have been cloned; the biosynthesis and metabolic engineering of floral volatiles have been studied with the development of biotechnology. This review summarizes the reported floral fragrance-related genes and the biosynthesis of floral scent compounds, introduces the origin of new modification enzymes for flower scent, compares different methods for floral fragrance-related gene cloning, and discusses the metabolic engineering of floral scent. Finally, the perspectives and prospects of research on floral fragrance are presented. Published in Russian in Biokhimiya, 2007, Vol. 72, No. 4, pp. 437–446.     

Scent engineering: toward the goal of controlling how flowers smell

Floral scent has an important role in the reproductive processes of many plants and a considerable economic value in guaranteeing yield and quality of many crops. It also enhances the aesthetic properties of ornamental plants and cut flowers. Many floral scent volatiles fall into the terpenoid or phenylpropanoid/benzenoid classes of compounds. Although the biochemistry of floral scent is still a relatively new field of investigation, in the past decade investigators have begun to identify 'scent genes'. Several of these genes, most of which, but not all, encode enzymes that directly catalyze the formation of volatile terpenoid or phenylpropanoid/benzenoid compounds, have now been used to manipulate, through genetic engineering techniques, the mix of volatiles emitted from the flowers of several plant species. The outcomes of these experiments, which are discussed here, have indicated that the genetic engineering approach to altering floral scents has potential; however, they have also revealed the limitations that result from our inadequate knowledge of the metabolic pathways responsible for scents and their regulation.     

Emission mechanism of floral scent in Petunia axillaris

The mechanism of floral scent emission was studied in Petunia axillaris, a plant with a diurnal rhythm of scent output. The emission rate of each volatile compound oscillated in synchrony with its endogenous concentration, so that the intensity of the floral scent appeared to be determined by the endogenous concentrations. The composition of major volatiles in the flower tissue and the flower headspace showed characteristic differences. A negative correlation was found between the boiling points of the volatile compounds and the ratio of their emitted and endogenous concentrations, indicating that the composition of the floral scent depends directly on the endogenous composition of the volatile compounds. We conclude that in P. axillaris, the physiological regulation of floral scent emission operates not in the vaporization process but in the control of the endogenous concentrations of volatiles through biosynthesis and metabolic conversion.     

The transcriptome of flower development provides insight into floral scent formation in <Emphasis Type="Italic">Freesia hybrida</Emphasis>

Freesia hybrida is a popular cut flower that is globally cultivated. Despite fragrance being an important floral trait, little is known of its associated molecular mechanisms in F. hybrida. In this study, cDNA libraries were constructed for three floral developmental stages in F. hybrida. A total of 74,660 unigenes were obtained from RNA sequencing and de novo assembly, of which 72.20% were annotated by seven public protein databases. Approximately 12,420 differentially expressed genes were identified during flower development. Gas chromatography–mass spectrometry analysis detected a total of 34 floral volatile compounds, primarily volatile monoterpenes, which accounted for approximately 90% of the volatiles. Using a system analysis-based approach, 36 candidate genes related to volatile terpenes were identified, in which the majority of up-regulated genes associated with the biosynthesis of monoterpenes and the majority of down-regulated genes associated with the biosynthesis of sesquiterpenes. Of these, FhDXS2A, FhGPPs and FhTPSs were considered to be important in floral scent formation. This study provides an in-depth assessment of floral scent and a reference for the future molecular breeding of floral scent in ornamental plants.     

A multivariate approach to post-pollination changes in the floral scent of Platanthera bifolia (Orchidaceae)

The effect of pollination on floral scent composition and production in the moth-pollinated orchid Platanthera bifolia was studied. A significant decrease in scent production was detected both two and five days after pollination. The proportion of wilted flowers was higher in pollinated compared to control plants after seven days. A principal component analysis (PCA) showed how pollination reduced scent production. All scent compounds were affected by pollination, even though some compounds had larger impact on the overall scent reduction. A classification of samples offered a quantitative test of the changes found in individual plants after pollination. The induced decrease in floral scent production following pollination is suggested to be of adaptive value for both plants and pollinators.     

Integrating floral scent, pollination ecology and population genetics

1 . Floral scent is a key factor in the attraction of pollinators. Despite this, the role of floral scent in angiosperm speciation and evolution remains poorly understood. Modern population genetic approaches when combined with pollination ecology can open new opportunities for studying the evolutionary role of floral scent.
2 . A framework of six hypotheses for the application of population genetic tools to questions about the evolutionary role of floral scent is presented. When floral volatile chemistry is linked to pollinator attraction we can analyse questions such as: Does floral volatile composition reflect plant species boundaries? Can floral scent facilitate or suppress hybridization between taxa? Can the attraction of different pollinators influence plant mating systems and pollen-mediated gene flow? How is population genetic structure indirectly influenced by floral scent variation?
3 . The application of molecular tools in sexually deceptive orchids has confirmed that volatile composition reflects species boundaries, revealed the role of shared floral odour in enabling hybridization, confirmed that the sexual attraction mediated by floral odour has implications for pollen flow and population genetic structure and provided examples of pollinator-mediated selection on floral scent variation. Interdisciplinary studies to explore links between floral volatile variation, ecology and population genetics are rare in other plant groups.
4 . Ideal study systems for future floral scent research that incorporate population genetics will include closely related taxa that are morphologically similar, sympatric and co-flowering as well as groups that display wide variation in pollination mechanisms and floral volatiles.     

Metabolic regulation of floral scent in Petunia axillaris lines: biosynthetic relationship between dihydroconiferyl acetate and iso-eugenol

Aromatic scent-related compounds in flowers were comprehensively analyzed by high-performance liquid chromatography (HPLC) based on their absorption spectra to understand regulation of metabolism leading to floral scent diversity in Petunia axillaris lines. An unknown compound occurring at similar levels to scent compounds in some plant lines was identified to be dihydroconiferyl acetate. Based on the structure, dihydroconiferyl acetate is likely to be a biosynthetically closely related compound to aromatic scent compounds, especially iso-eugenol. Similar time-course changes of the concentrations suggest that the metabolism of dihydroconiferyl acetate is underlaid by the similar regulation to aromatic scent compounds. Dihydroconiferyl acetate and iso-eugenol occurred almost exclusively, implying that metabolism of the common precursors to each compound is selectively regulated in these plants. The branching of the biosynthetic pathway into dihydroconiferyl acetate and iso-eugenol is probably one of regulatory steps leading to scent diversity in P. axillaris lines.