Metabolic Engineering to Modify Flower Color

Thanks to the rapid progress in molecular biology of flavonoidbiosynthesis and plant transformation, it has become feasibleto modify the pathway and flower color through genetic engineering.One of the advantages of molecular breeding is that flower colorcan be specifically modified without changing the other characteristicsof the targeted variety. Novel flower color varieties such asbrick-red petunias and violet carnations have been successfullymade by expression of heterologous flavonoid genes. Flavonoidmetabolic engineering has and will give new perspectives inplant molecular biology besides its industrial application. (Received August 26, 1998; Accepted October 9, 1998)     

Genetic Modification in Floriculture

An important driving force for the floriculture industry is the development of novel plants and flowers. New varieties provide marketing opportunities for retailers and judicious selection can increase productivity for growers, as well as improving the quality of the final product in the consumer's hands. While plant exploration and conventional breeding programs have been very successful in achieving these goals, genetic modification offers additional routes for the generation of new varieties of important floricultural plants. This can be achieved by the incorporation of genes from outside of the normally available gene pool. This paper provides a summary of the potential applications of gene technology in floriculture and reviews progress to date, with a particular emphasis on the manipulation of flower color. The manipulation of the anthocyanin biosynthesis pathway in carnation to produce novel-colored flowers is so far the only commercial application of genetic modification in floriculture. This progress is in stark contrast to the widespread cultivation of genetically modified broad-acre crops. The commercial use of gene technology requires adherence to regulatory regimes specific to genetically modified plants, and compliance with intellectual property laws. These added complexities are a significant cost, which may be hampering the use of gene technology by breeders of floricultural crops. Another factor may be a perception that the public and retail trade may not accept genetically modified floricultural products. Experience in the real marketplace with the Florigene Moon-series? of genetically modified carnation suggests that these concerns are unwarranted.     

Genetically modified probiotics in foods

Probiotics have many potential therapeutic uses, but have not been universally accepted because of a lack of understanding of their action. Lactic acid bacteria (LAB) have been modified by traditional and genetic engineering methods to produce new varieties. Modern techniques of molecular biology have facilitated the identification of probiotic LAB strains, but only a few LAB have been modified by recombinant-DNA technology because of consumer resistance to their introduction to markets, especially in Europe.     

Novel coloured flowers

The floricultural industry has focused its attention primarily on the development of novel coloured and longer living cut flowers. The basis for this was laid down some years ago through the isolation of 'blue' genes and ethylene biosynthesis genes. Recently, a novel 'blue' gene has been discovered and yellow pigments were produced in petunias by addition of a new branch to the phenylpropanoid pathway. More insight was obtained into the sequestration of anthocyanin pigments into storage vacuoles. Significant progress has been achieved in the commercialisation of genetically modified flower varieties.     

花卉基因工程研究进展Ⅰ：花色

1987年人们首次通过转基因技术获得了改变花色的矮牵牛,使得花卉选育迈入分子时代。其优点在于可有目的的地改变花卉的某一性状而不影响其它性状,并缩短育种周期。目前,与花色基因工程有关调控机理已日益清楚,分离到大量的相关酶和基因,获得了一批转基因花卉。本文重点介绍了国内外花色基因工程的研究进展,同时简单评述了花卉基因工程研究中存在的问题并展望其应用前景。     

Markers for ornamental traits in Phalaenopsis orchids: population structure, linkage disequilibrium and association mapping

Although Phalaenopsis orchids are among the most economically important potted plants, little is known about either the genetic diversity among varieties or the genetic complexity of key ornamental traits. Therefore, we analysed the genetic diversity of a broad collection of Phalaenopsis varieties and selected wild species by means of molecular markers. The marker data were used to obtain genetic distances, estimates of the degree of linkage disequilibrium and population structure for the genotypes under study. With a total of 492 markers, the genotypes clustered according to their horticultural classification (for example, old hybrids vs. more recent hybrids) but not according to their origin, indicating extensive exchange of germplasm among breeders. Linkage disequilibrium was found to decrease relatively slowly, most likely due to the small number of generations that have occurred since the first hybrids were generated. Based on the most likely estimates for the population structure (ranging from 10 to 12 subpopulations), associations between ornamental traits like flower size, flower colour, flower type, flower texture, stem length and leaf shape were calculated. These results can now serve as starting points for detailed analyses of the genetic architecture of these traits.     

Current status of genetic engineering in cotton (Gossypium hirsutum L): an assessment

Abstract

Cotton is considered as the foremost commercially important fiber crop and is deemed as the backbone of the textile industry. The productivity of cotton crop, worldwide, is severely hampered by the occurrence of pests, weeds, pathogens apart from various environmental factors. Several beneficial agronomic traits, viz., early maturity, improved fiber quality, heat tolerance, etc. have been successfully incorporated into cotton varieties employing conventional hybridization and mutation breeding. Crop losses, due to biotic factors, are substantial and may be reduced through certain crop protection strategies. In recent years, pioneering success has been achieved through the adoption of modern biotechnological approaches. Genetically engineered cotton varieties, expressing Bacillus thuringiensis cry genes, proved to be highly successful in controlling the bollworm complex. Various other candidate genes responsible for resistance to insect pests and pathogens, tolerance to major abiotic stress factors such as temperature, drought and salinity, have been introduced into cotton via genetic engineering methods to enhance the agronomic performance of cotton cultivars. Furthermore, genes for improving the seed oil quality and fiber characteristics have been identified and introduced into cotton cultivars. This review provides a brief overview of the various advancements made in cotton through genetic engineering approaches.     

Genetics of the guppy as a model for experiment in aquaculture

The guppy, Poecilia reticulata, is one of the most famous tropical ornamental fish in the world. There are many varieties and breeds which have been bred by aqua lists for many years. The guppy has frequently been used as model organism for experiments in fish genetics because of its short life cycle, ease of breeding and reproductive capacity. The laboratory strains which were created from local (Japanese) strains and varieties were used as an experimental genetic model for aquaculture. These laboratory strains were maintained as closed colonies for five to 20 years in our laboratory. One of the roles of model experiments in fish genetics to perform experiments which take a long time in which are commercially important, such as genetic drift, as the effect of inbreeding during the growth and maintenance of population. In this review, we mainly considered the results obtained in our laboratory relating to genetic drift, and the effects of inbreeding, heterosis and inheritance of quantitative traits.     

The quantitative genetics of floral trait variation in Lobelia: potential constraints on adaptive evolution

Abstract Although pollinator-mediated natural selection has been measured on many floral traits and in many species, the extent to which selection is constrained from producing optimal floral phenotypes is less frequently studied. In particular, negative correlations between flower size and flower number are hypothesized to be a major constraint on the evolution of floral displays, yet few empirical studies have documented such a trade-off. To determine the potential for genetic constraints on the adaptive evolution of floral displays, I estimated the quantitative genetic basis of floral trait variation in two populations of Lobelia siphilitica . Restricted maximum likelihood (REML) analyses of greenhouse-grown half-sib families were used to estimate genetic variances and covariances for flower number and six measures of flower size. There was significant genetic variation for all seven floral traits in both populations. Flower number was negatively genetically correlated with four measures of flower size in one population and three measures in the other. When the genetic variance-covariance matrices were combined with field estimates of phenotypic selection gradients, the predicted multivariate evolutionary response was less than or opposite in sign to the selection gradient for flower number and five of six measures of flower size, suggesting genetic constraints on the evolution of these traits. More generally, my results indicate that the adaptive evolution of floral displays can be constrained by tradeoffs between flower size and number, as has been assumed by many theoretical models of floral evolution.     

应用RAPD技术对甘肃栽培牡丹品种的分类鉴定研究

应用RAPD技术对甘肃栽培紫斑牡丹品种的分类进行了初步研究,筛选出10个随机引物在16个品种中共扩增出120个位点,其中114个位点呈多态性,4个位点具品种专一性。根据RAPD结果计算各品种间的遗传距离为0．212 8～0．744 4,所研究的16个品种中,除‘北国风光’外‘理想’与其它品种的遗传距离均很大,而皇冠型的‘春红争艳’与蔷薇型的‘怀念’两品种间的遗传距离最小。同一品种不同个体间与不同品种间在遗传距离上无明显差异,暗示在甘肃栽培牡丹品种中可能存在同物异名和同名异物。聚类分析表明,‘理想’和‘北国风光’与其它品种分别构成了遗传差异很大的两类,楼子类与千层类的品种在聚类时虽未完全分开,但楼子类大部分品种间表现出了更高的遗传相似性,且遗传距离与各种色系间没有明显的相关性。结果表明,RAPD技术能够克服传统上根据形态学性状对品种进行分类的缺点,可用于牡丹栽培品种的鉴定。     

Arguments for the use of physiological criteria for improving the salt tolerance in crops

Efforts to develop new crop varieties with improved salt tolerance have been intensified over the past 15–20 years. Despite the existence of genetic variation for salt tolerance within species, and many methods available for expanding the source of genetic variation, there is only a limited number of varieties that have been developed with improved tolerance. These new varieties have all been based upon selection for agronomic characters such as yield or survival in saline conditions. That is, based upon characters that integrate the various physiological mechanisms responsible for tolerance. Yet over the same time period, knowledge of physiological salt responses has increased substantially.Selection and breeding to increase salt tolerance might be more successful if selection is based directly on the physiological mechanisms or characters conferring tolerance. Basic questions associated with using physiological selection criteria are discussed in the paper. These are centred around the need for genetic variation, the importance of the targeted mechanism, the ease of detection of the physiological mechanism (including the analytical requirements) and the breeding strategy. Many mechanisms, including ion exclusion, ion accumulation, compatible solute production and osmotic adjustment have been associated with genetic variation in salt tolerance. Yet their successful use in improving salt tolerance, via physiological selection criteria, is largely non-existent. Consideration is given to the role of physiological criteria in the short and long term in improving salt tolerance. In several glycophytic species, particularly legumes, physiological selection based on ion exclusion from the shoots shows promise. Recent results for white clover indicate the potential for using a broad physiological selection criterion of restricted Cl accumulation in the shoots, with scope for future refinement based upon the specific physiological characters that combined result in ion exclusion.     

Conversion of leaves into petals in Arabidopsis

More than 200 years ago, Goethe proposed that each of the distinct flower organs represents a modified leaf [1]. Support for this hypothesis has come from genetic studies, which have identified genes required for flower organ identity. These genes have been incorporated into the widely accepted ABC model of flower organ identity, a model that appears generally applicable to distantly related eudicots as well as monocot plants. Strikingly, triple mutants lacking the ABC activities produce leaves in place of flower organs, and this finding demonstrates that these genes are required for floral organ identity [2]. However, the ABC genes are not sufficient for floral organ identity since ectopic expression of these genes failed to convert vegetative leaves into flower organs. This finding suggests that one or more additional factors are required [3, 4]. We have recently shown that SEPALLATA (SEP) represents a new class of floral organ identity genes since the loss of SEP activity results in all flower organs developing as sepals [5]. Here we show that the combined action of the SEP genes, together with the A and B genes, is sufficient to convert leaves into petals.     

Genetic modification; the development of transgenic ornamental plant varieties

Plant transformation technology (hereafter abbreviated to GM, or genetic modification) has been used to develop many varieties of crop plants, but only a few varieties of ornamental plants. This disparity in the rate and extent of commercialisation, which has been noted for more than a decade, is not because there are no useful traits that can be engineered into ornamentals, is not due to market potential and is not due to a lack of research and development activity. The GM ornamental varieties which have been released commercially have been accepted in the marketplace. In this article, progress in the development of transgenic ornamentals is reviewed and traits useful to both consumers and producers are identified. In considering possible factors limiting the release of genetically modified ornamental products it is concluded that the most significant barrier to market is the difficulty of managing, and the high cost of obtaining, regulatory approval.     

The tolerance of black currant flowers to induced frosts

Flower buds on potted plants of 17 varieties of black currant were frosted to -3.3, -4.5 and -5.2 °C between the grape stage and full flower in 1979 and 1980. In all varieties more flower buds died after the -5.2 °C frosts and at full flower, and less after the -3.3 °C frosts and at the grape stage. Varieties related to Ben More and Ojebyn tolerated the -4.5 °C frosts until after first flower while Baldwin and Magnus became susceptible at the grape stage. Seabrooks Black, Greens Black and Ben Lomond and its relatives were intermediate. In both years flower buds tolerated frosts to similar growth stages but in 1980 the varieties flowered about 2 wk earlier than in 1979 and suffered more frost damage at full flower. The frosted plants had slightly larger fruits than the unfrosted ones in 1979. The immature fruit drop was similar in frosted and unfrosted plants in both years except when it was increased after -5.2 °C in 1980. It is pointed out that for reliable cropping, varieties should flower late as well as tolerate spring frosts and that tests of frost tolerance should be done for at least three growth stages.     

Floral patterning.

In recent years, flower development has emerged as a model system for studying pattern formation in plants. Homeotic mutants with an altered pattern of floral organs have been found in many species. Recently, several of the floral homeotic genes have been isolated; and the mechanisms underlying pattern formation during flower development are beginning to be elucidated.     

食用菌表型组技术研究进展

食用菌己成为我国农业的第五大种植业,在"精准扶贫"战役中发挥了重要作用.然而,经过40年的快速发展,食用菌行业依然面临着众多问题亟待解决,尤其是在工厂化栽培生产中我们还严重依赖国外选育的菌种.随着基因测序和表型组等新技术的蓬勃发展,"数据驱动"的生物学研究取得了一系列突破性进展.这些新技术也为解决食用菌行业面临的问题带...     

重要花卉植物高密度遗传连锁图谱构建研究进展

遗传连锁图谱是以遗传标记间重组频率为基础的染色体或基因组内位点相对位置的线性排列图,高密度遗传图谱构建可实现物理图谱和遗传图谱的整合,对促进基因图位克隆具有重要作用。利用遗传图谱可有效地提高育种效率和改良品种。重要花卉植物高遗传图谱精密度尚无法满足精细定位研究的要求,百合、紫薇、郁金香、向日葵等重要花卉高密度遗传图谱构建研究较少,制约了花卉植物分子育种研究进程。概述了高密度遗传图谱构建流程及作图方法,综述了牡丹、梅花、月季、菊花、兰花、荷花、桂花等重要花卉植物遗传图谱构建研究进展,讨论了重要花卉植物高密度遗传图谱构建存在的主要问题,对今后重要花卉植物遗传图谱构建研究的发展方向及其在育种中的应用前景进行了展望,以期为花卉植物基因定位、辅助基因组组装、比较基因组学、基因克隆、分子标记辅助育种等提供参考。     

Flower development

Several homeotic genes controlling flower development have been characterized in Antirrhinum and Arabidopsis. Comparisons of their mutant phenotypes, expression patterns and genetic interactions have revealed that many of the basic mechanisms controlling flower development have been conserved in evolution, although important differences in the balance and interactions of genes also exist.