单子叶植物无融合生殖的研究进展

植物的无融合生殖是指不经过雌雄配子融合而产生种子的一种特殊生殖方式。由于利用无融合生殖途径可以固定杂种优势,从而改良现有植物的育种策略,因此对无融合生殖的研究已成为生物学科的新生长点。本文主要从无融合生殖的概念和类型,无融合生殖在单子叶植物中的分布,无融合生殖的胚胎学,分子生物学和遗传学机制及创造新的无融合生殖种质资源的方法等6方面对单子叶植物的无融合生殖的研究进展进行了综述,并提出了今后开展无融合生殖研究的思路和设想。     

单子叶植物无融合生殖的研究进展

植物的无融合生殖是指不经过雌雄配子融合而产生种子的一种特殊生殖方式。由于利用无融合生殖途径可以固定杂种优势 ,从而改良现有植物的育种策略 ,因此对无融合生殖的研究已成为生物学科的新生长点。本文主要从无融合生殖的概念和类型 ,无融合生殖在单子叶植物中的分布 ,无融合生殖的胚胎学 ,分子生物学和遗传学机制及创造新的无融合生殖种质资源的方法等 6方面对单子叶植物的无融合生殖的研究进展进行了综述 ,并提出了今后开展无融合生殖研究的思路和设想     

植物无融合生殖相关基因研究进展

无融合生殖是指不经过精卵融合即可形成胚从而进行种子繁殖后代的一种特殊的无性生殖方式, 无融合生殖胚的形成没有父本的参与, 其后代是母本基因型的完整克隆, 因此是植物杂种优势固定与利用的一种最理想的途径, 具有巨大的潜在利用价值, 被誉为“无性革命”。按其胚体发生的途径, 无融合生殖可分为二倍体孢子生殖、无配子生殖和不定胚生殖三种类型。本文介绍了植物胚发育、胚乳发育、减数分裂等涉及无融合生殖过程的相关基因的研究进展, 同时介绍了可能与植物无融合生殖途径调控相关的几个基因片段的研究情况。     

植物无融合生殖的筛选和鉴定研究进展

植物无融合生殖具有复杂的发育过程,与细胞学、遗传学、生物化学和分子生物学等相关的各种技术均被应用于植物无融合生殖的筛选和鉴定.本文结合新近发表的研究文献,介绍了常规的植物无融合生殖筛选和鉴定技术的新应用,评介了流式细胞种子筛选技术、胚珠整体透明技术、外源标记基因转入法等植物无融合生殖筛选和鉴定的新技术,并对各种筛选和鉴定技术的优势和不足进行了评述.     

雀稗属无融合生殖研究进展

雀稗属(Paspalum)为禾本科黍亚科多年生或一年生植物,是黍亚科内最有经济价值的类群之一。雀稗属植物种群极其复杂,大多数为多倍体。由于多倍体的存在及有性生殖的自交不亲和等原因,雀稗属植物表现出复杂多样的生殖特性,是禾本科中具备无融合生殖特性种类最多的属。对雀稗属无融合生殖的分布、无融合生殖相关的细胞学和胚胎学基础、无融合生殖的特点及其遗传学和分子生物学研究进展进行了综述。     

无融合生殖与柑橘多胚现象的研究进展

植物无融合生殖是指植物的胚珠组织不经历正常的减数分裂和受精作用,而直接进行胚发育形成种子的无性生殖方式。无融合生殖植物完全继承了母体的全部基因型,因而具有独特研究与育种意义。芸香科柑橘属植物具有独特的多胚现象,其珠心组织能够发育成不定胚(称为珠心胚)进行无融合生殖。文中介绍了柑橘类植物的珠心胚生殖现象、细胞学和遗传学研究进展。珠心胚现象虽然对柑橘杂交后代获得有较大影响,但在生产上可产生性状整齐一致的后代,可以培育无病毒苗木。     

植物无融合生殖研究新进展

无融合生殖是指不经过雌雄配子融合而产生种子的一种特殊生殖方式,能使基因型的杂合性得以保持,从而可以固定杂种优势,对作物育种具有极其重要的意义。目前大量的研究都在设法将无融合生殖作为一种重要的植物育种手段。本文对近几年来无融合生殖新种质资源的发现、主要研究方法、遗传机制和相关基因等方面的最新进展作了介绍,并对无融合生殖研究中存在的问题和发展前景作了讨论。     

大黍无融合生殖研究概况

从胚胎学和遗传学角度论述了大黍（Panicum maximum Jacq)的无融合生殖研究进展和存在的问题,展望了大黍作为无融合生殖基因供体。在无融合生殖研究上的利用前景。     

植物无融合生殖研究的新进展

植物无融合生殖是指不经过雌雄配子融合而产生种子的一种特殊生殖方式,能使基因型的杂合性得以保持,从而可固定杂种优势。对近几年来植物无融合生殖的研究进展及发展动态作一综述,列举了新发现的具有无融合生殖特性的植物种类：总结了控制无融合生殖的遗传机理：指出该研究领域中存在的问题：展望了该领域的发展前景。     

植物无融合生殖的遗传机理和分子机理的研究进展

利用植物无融合生殖固定杂种优势,已被认为是一条生产杂交种子的高效途径。近年来,由于RAPD、RFLP和差异显示等技术的应用,已使植物无融合生殖的研究面貌一新。特别是一系列与无融合生殖有关的特异DNA片段的发现,为深入了解其遗传机理和分子机理增加了大量新的知识,这些知识无疑为定位和克隆植物无融合生殖基因,进而利用遗传操作的手段来改变植物的生殖方式积累了必要的理论基础。本文对植物无融合生殖遗传机理和分子机理的研究进展作了综述。 Abstract:Apomixis allows the establishment of genetically stable seed propagating clones of crops,which can perpetuate themselves across countless sporophytic generations.This asexual mode of reproduction,which naturally occurs in some angiosperms,may prove to be an unrivalled tool to improve crop yields.The current state of knowledge on the molecular and genetic basis of apomixis is reviewed.     

MIME--有丝分裂替代减数分裂及其在作物无融合生殖中的应用

无融合生殖因其在杂种优势固定中的巨大潜力而受到广泛关注,人工创制无融合生殖是当前无融合生殖研究的重要方向,有丝分裂替代减数分裂(Mitosis instead of Meiosis,MIME)能产生与母本遗传组成完全一致的二倍体配子,是人工创制无融合生殖的关键步骤。文中对MIME的发生及其在作物无融合生殖中的应用以及MIME应用中的问题进行综述,以期为扩大MIME在作物无融合生殖中的应用提供参考。     

Apomixis technology and the paradox of sex

Most plant species produce genetically variable seeds by the fusion of meiotically reduced egg cells and pollen grains. However, a small proportion of seed plants produces clonal, asexual seeds by the process of apomixis. The fixation of heterosis by apomixis is of great interest for plant breeding. The prospect of changing sexual crop species into apomictic crop species by genetic engineering--apomixis technology--has recently caused a boom in apomixis research. According to evolutionary biological theories, a dominant apomixis gene will rapidly become fixed in an outcrossing sexual population. Therefore, in theory, apomixis transgenes could have unconditional advantages that could result in the uncontrollable spread of the transgenes. By contrast, 'classic' transgenes might only have conditional advantages. Paradoxically, sexual reproduction and not apomixis is common in nature. However, this is no guarantee that apomixis transgenes will be ecologically safe because there could be essential differences between natural and transgenic apomicts.     

Developmental genetics of gametophytic apomixis

Some higher plants reproduce asexually by apomixis, a natural way of cloning through seeds. Apomictic plants produce progeny that are an exact genetic replica of the mother plant. The replication is achieved through changes in the female reproductive pathway such that female gametes develop without meiosis and embryos develop without fertilization. Although apomixis is a complex developmental process, genetic evidence suggests that it might be inherited as a simple mendelian trait - a paradox that could be explained by recent data derived from apomictic species and model sexual organisms. The data suggest that apomixis might rely more on a global deregulation of sexual reproductive development than on truly new functions, and molecular mechanisms for such a global deregulation can be proposed. This new understanding has direct consequences for the engineering of apomixis in sexual crop species, an application that could have an immense impact on agriculture.     

禾本科植物无融合生殖(综述)

禾本科植物包含了世界上最重要的农作物,也包含了最多的无融合生殖的种类,通过无融合生殖可将农作物的F1代杂种优势固定下来,这在固定农作物杂种优势的利用上具有巨大的潜力,然而禾本科植物无融合生殖作为其繁殖多样性的一种形式,在系统进化过程中的作用是非常复杂的,本文统计了禾本科无融合生殖的分布,概述了其无融合生殖的细胞学,遗传学和分子生物学研究进展。     

Molecular and genetic regulation of apomixis

Apomixis is defined as the asexual plant reproduction through seeds that results in the production of genetically uniform progeny. In fact, apomixis could be considered as a natural way of cloning. Currently there are more than 400 plant species known to use apomixis as a strategy for their propagation. The primary fundamental aspects of apomixis are the bypassing of meiosis and parthenogenetic development of the embryo without fertilization Apomixis attracts special attention because of its potential value for agriculture, as it could be harnessed for plant breeding programs enabling the permanent fixation of heterosis in crop plants. A better understanding of the molecular and genetic regulation of apomixis is important for developmental and evolutionary perspectives but also for implementation of engineering of apomixis traits into agricultural crop plants. Despite apomixis is considered as one of the key technologies for the improving agriculture, it is currently not fully known how the genetic and molecular regulation of this important trait occurs. In this review, an up to date information on the biology of apomixis and the known genes and genetic loci associated with regulation of different components of apomixis is provided.     

Apomixis in agriculture: the quest for clonal seeds

Apomixis, or asexual reproduction through seeds, is a natural trait that could have an immense positive impact on crop production. Apomictic breeding strategies could allow the fixation and indefinite propagation of any desired genotype, however complex. Apomicts display a wide variety of developmental mechanisms, which can be viewed as a short-circuiting of sexual development. Gametophytic and sporophytic apomixis are distinguished by the developmental origin of apomictically derived embryos. Genetic studies suggest that individual elements of gametophytic apomixis, such as apomeiosis and parthenogenesis, are either controlled by one or two dominant Mendelian factors. As recombination around apomeiosis loci is suppressed, it is currently not known how complex these loci are. Much less is known regarding the genetic control of sporophytic apomixis but initial studies suggest a complex genetic control. Genetic analyses of sexual reproduction in plant model systems have identified genes that, when mutated, display elements of apomixis. Such studies help in the identification of candidate genes and promoters that can be used for the de novo engineering of apomixis through biotechnology. Molecular genetic studies in apomictic and sexual systems will generate the knowledge necessary for the engineering of conditional apomixis technology. Approaches encouraging collaboration and widespread dissemination of the acquired knowledge will constitute the most innovative route to the development, deployment and acceptance of apomixis technology in agriculture.     

AFLP指纹图谱试验体系在甜菜无融合生殖系中的应用

目的：比较甜菜无融合生殖品系M14子代之间的同一性及亲缘关系,从而验证AFLP试验体系在甜菜无融合生殖系中的适用性。方法：利用已建立的AFLP试验体系,通过琼脂糖凝胶电泳和聚丙烯酰胺凝胶电泳检测以及遗传距离的比较来验证这一试验体系。结果：M14子代之间及二倍体甜菜之间的同一性较好,其亲缘关系也较近。结论：验证了所建立的AFLP试验体系的适用性,同时也确证了AFLP技术在构建DNA指纹图谱中的优越性,为无融合生殖的进一步研究奠定了基础。     

Is supernumerary chromatin involved in gametophytic apomixis of polyploid plants?

Gametophytic apomixis, or unreduced embryo sac development that results in asexual reproduction through seeds, occurs in several families of angiosperms and must be polyphyletic in origin. The molecular mechanisms underlying gametophytic apomixis have not been discovered and are the subject of intense investigation. A common feature of almost all apomicts is their polyploid nature. From genetic mapping studies in both monocots and dicots, there is low genetic recombination associated with a single (rarely two), dominant locus for either aposporous or diplosporous embryo sac formation. In Pennisetum squamulatum and Cenchrus ciliaris, some DNA sequences mapping to the apospory locus are unique to apomictic genotypes and apparently hemizygous. This sequence divergence at the apomixis locus could be a consequence of genome rearrangements and isolation from genetic recombination, both of which may have contributed to the definition of a chromosomal region as supernumerary. The possible involvement of supernumerary chromatin, formed as a result of interspecific hybridization, in the origin of apomixis, is explored here. Received: 26 October 2000 / Revision accepted: 5 April 2001     

On the origin and evolution of apomixis in Boechera

The genetic mechanisms causing seed development by gametophytic apomixis in plants are predominantly unknown. As apomixis is consistently associated with hybridity and polyploidy, these confounding factors may either (a) be the underlying mechanism for the expression of apomixis, or (b) obscure the genetic factors which cause apomixis. To distinguish between these hypotheses, we analyzed the population genetic patterns of diploid and triploid apomictic lineages and their sexual progenitors in the genus Boechera (Brassicaceae). We find that while triploid apomixis is associated with hybridization, the majority of diploid apomictic lineages are likely the product of intra-specific crosses. We then show that these diploid apomicts are more likely to sire triploid apomictic lineages than conspecific sexuals. Combined with flow cytometric seed screen phenotyping for male and female components of apomixis, our analyses demonstrate that hybridization is an indirect correlate of apomixis in Boechera.