花、基因、禾本科

进化发育生物学的一个重要任务就是揭示形态多样性的分子基础,该领域的研究包含形态、形态发育相关基因和形态所属类群等三个要素。花/花序是进化发育生物学研究的首要对象,系统发育重建和个体发育剖析的结合将促进认知花的形态进化。发育相关基因的进化表现为等位基因遗传或表观遗传的突变,基因家族生与死的进化,不同基因组拥有独特的基因。运用形态学或序列分析方法很大程度揭示了禾本科植物花进化过程中的基因进化。试从学科问题、思路方法以及具体例子介绍植物进化发育生物学。     

植物MADS盒基因与花器官的进化发育

已在维管植物中发现百余种MADS盒基因,此种基因家族由表达模式和功能关系密切的基因构成多种特定的亚族和DEF／GLO类（B功能）,AG类（C和D功能）等,植物花器官发生和花形态多样性的遗传机理和进化规律都可能与MADS盒基因的结构,表达以及功能进行相关。     

进化发育生物学--发育、进化和遗传的再联合

发育生物学和进化生物学,以及遗传学历史上曾一度是彼此不分的统一体,后来由于各自研究重点的不同和相应研究手段的独立发展彼此分道扬镳了。如今,由于分子遗传学研究手段的革新使得基因序列测定成为分析发育机理、区分物种和评估种间亲缘关系的常规手段,三者又在基因水平上再度统一起来了,并形成一门被称为进化发育生物学（ｅｖｏｌｕｔｉｏｎａｒｙ ｄｅｖｅｌｏｐｍｅｎｔａｌ ｂｉｏｌｏｇｙ）的新学科。     

烟草花蜜腺花育的解剖学研究

烟草的花蜜腺位于子房基部,围绕子房,属于子房蜜腺,蜜腺由分泌表皮和泌蜜组织组成,分泌表皮角质膜厚薄不均,表皮上分布少量气孔器,气孔凹陷,孔下室不明显,泌蜜组织细胞多层。蜜腺邻接子房壁维管束,本身没有维管组织,蜜腺由子房基部的外壁表皮及其相邻的的内侧细胞经分裂,生长、分化而来,在发育过程中,细胞中的液泡和淀粉粒都呈现一定的水长规律,原蜜汁由子房壁维管束提供,经过泌蜜组织细胞加工后,蜜汁通过气孔和薄的角膜处泌出。     

花对称性的研究进展

花对称性(floral symmetry)是被子植物花部结构的典型特性之一,主要有辐射对称和两侧对称两种形式。被子植物初始起源的花为辐射对称,而两侧对称的花则是由辐射对称的花演变而来。两侧对称的花部结构是被子植物进化过程中的一个关键的革新,被认为是物种形成和分化的关键推动力之一。近年来有关花对称性的形成和进化机制的研究在植物学科的不同领域均取得了长足的进展。本文综述了花对称性在发育生物学、传粉生物学、生殖生态学及分子生物学等方面的研究进展。两侧对称形成于被子植物花器官发育的起始阶段,随后贯穿整个花器官发育过程或者出现在花器官发育后期的不同阶段。花器官发育过程中一种或多种类型器官的败育以及特异性花器官结构的形成是两侧对称形成的主要原因。研究表明,在传粉过程的不同阶段,花对称性均会受到传粉昆虫介导的选择作用。相比辐射对称的花,两侧对称的花提高了特异性传粉者的选择作用,增加了花粉落置的精确性,进而确保了其生殖成功。花对称性的分子机理已经在多种双子叶植物中进行了深入的研究。现有的证据表明,CYC同源基因在花对称性的分子调控方面起着非常重要的作用。花对称性在被子植物进化过程中是如何起源,与其他花部构成之间是否协同作用,一些不符合一般模式的科属其花对称性的形成机制等都是今后要进一步研究的命题。     

兰花蕉花的形态解剖学

兰花蕉（Orchidantha chinensis)的子房室顶部闭合后向上延长成延长部,实心,但有花柱沟和隔膜蜜腺管通过,隔膜蜜腺管,可分为中央蜜腺管和三条侧蜜腺管;中央蜜腺管位于三个心皮连接处,自子房室区下部产生,向上于延长部的部顶端终止;三条侧管分别位于两个心皮连接处,于子房室区近中部产生,开口于花柱基部。兰花蕉子房室区与延长部均具6枚雄蕊的维管束系统,即3枚心皮背束的伴束与3枚隔膜束,近轴面1枚事膜向上进入唇瓣的维管束系统,位于唇瓣的中央,致使兰花蕉仅具5枚功能雄蕊,唇瓣具双重结构,本文还讨论了兰花蕉科的系统发育位置。     

禾本科系统学与演化研究的进展

：综合近年来禾本科不同分支学科的研究进展,对当前禾本科研究的4个热点进行讨论：1．禾本科内不同阶元系统的种系发育研究方法,有传统的、实验的、历史的、分支的4种分析方法;2．性系统的演化,涉及自交亲和繁育方式的优势、偏离正常性比的发育模式、性别决定的分子生物学基础3个方面;3．花序演化的形态学、遗传学、发育形态学研究;4．禾本科的起源时间。总的看来,不同性状的数据比较和不同研究方法的综合已构成现代禾本科系统学研究的必然趋势,建立一个反映植物系统发育历史的分类是禾本科系统学研究的最终目标。     

花发育的基因调控与花性状的改造

花发育的基因调控与花性状的改造华志明（厦门大学生物学系,厦门３６１００５）植物种子萌发后,经过一段时间的营养生长,在内外界环境因子共同作用下,植物开始由营养生长向生殖生长转变。花的发育（成花过程）就是这种转变的重要标志。成花过程不仅是植物生长发育中的...     

Eucalypt MADS-Box Genes Expressed in Developing Flowers

Three MADS-box genes were identified from a cDNA library derived from young flowers of Eucalyptus grandis W. Hill ex Maiden. The three egm genes are single-copy genes and are expressed almost exclusively in flowers. The egm1 and egm3 genes shared strongest homology with other plant MADS-box genes, which mediate between the floral meristem and the organ-identity genes. The egm3 gene was also expressed strongly in the receptacle or floral tube, which surrounds the carpels in the eucalypt flower and bears the sepals, petals, and numerous stamens. There appeared to be a group of genes in eucalypts with strong homology with the 3′ region of the egm1 gene. The egm2 gene was expressed in eucalypt petals and stamens and was most homologous to MADS-box genes, which belong to the globosa group of genes, which regulate organogenesis of the second and third floral whorls. The possible role of these three genes in eucalypt floral development is discussed.     

The MADS and the Beauty: Genes Involved in the Development of Orchid Flowers

Since the time of Darwin, biologists have studied the origin and evolution of the Orchidaceae, one of the largest families of flowering plants. In the last two decades, the extreme diversity and specialization of floral morphology and the uncoupled rate of morphological and molecular evolution that have been observed in some orchid species have spurred interest in the study of the genes involved in flower development in this plant family. As part of the complex network of regulatory genes driving the formation of flower organs, the MADS-box represents the most studied gene family, both from functional and evolutionary perspectives. Despite the absence of a published genome for orchids, comparative genetic analyses are clarifying the functional role and the evolutionary pattern of the MADS-box genes in orchids. Various evolutionary forces act on the MADS-box genes in orchids, such as diffuse purifying selection and the relaxation of selective constraints, which sometimes reveals a heterogeneous selective pattern of the coding and non-coding regions. The emerging theory regarding the evolution of floral diversity in orchids proposes that the diversification of the orchid perianth was a consequence of duplication events and changes in the regulatory regions of the MADS-box genes, followed by sub- and neo-functionalization. This specific developmental-genetic code is termed the "orchid code."     

Pollination-Induced Expression of Ethylene Biosynthetic Genes at Transcription Level in Orchid Flowers

The authors investigated pollination-induced ethylene production and expression patterns of genes encoding 1-aminocyclopropane-l-carboxylate (ACC) synthase and ACC oxidase in orchid flowers (Doritaenopsis hybrida Hort. ). Following pollination both ACC synthase and ACC oxidase mRNAs were detected in the different organs of flowers, and the patterns of both ACC synthase and ACC oxidase mRNA accumulation were similar, mRNA accumulation of ACC synthase mRNA was more organ-specific than that of ACC oxidase mRNA. However, ACC oxidase mRNAs were much more abundant than ACC synthase mRNAs in the flower organs.     

Pistil-Specific and Ethylene-Regulated Expression of 1-Aminocyclopropane-1-Carboxylate Oxidase Genes in Petunia Flowers

The differential expression of the petunia 1-aminocyclopropane-1-carboxylate (ACC) oxidase gene family during flower development and senescence was investigated. ACC oxidase catalyzes the conversion of ACC to ethylene. The increase in ethylene production by petunia corollas during senescence was preceded by increased ACC oxidase mRNA and enzyme activity. Treatment of flowers with ethylene led to an increase in ethylene production, ACC oxidase mRNA, and ACC oxidase activity in corollas. In contrast, leaves did not exhibit increased ethylene production or ACC oxidase expression in response to ethylene. Gene-specific probes revealed that the ACO1 gene was expressed specifically in senescing corollas and in other floral organs following exposure to ethylene. The ACO3 and ACO4 genes were specifically expressed in developing pistil tissue. In situ hybridization experiments revealed that ACC oxidase mRNAs were specifically localized to the secretory cells of the stigma and the connective tissue of the receptacle, including the nectaries. Treatment of flower buds with ethylene led to patterns of ACC oxidase gene expression spatially distinct from the patterns observed during development. The timing and tissue specificity of ACC oxidase expression during pistil development were paralleled by physiological processes associated with reproduction, including nectar secretion, accumulation of stigmatic exudate, and development of the self-incompatible response.     

我国观赏花卉品质形成的功能基因研究进展

花色、花香、花形和花期等品质性状与花卉商品价值体现有着直接的关系, 花卉品质形成相关的功能基因研究十分重要。该文综述了近10年来我国观赏花卉品质形成相关的功能基因研究成果, 以期为花卉分子育种研究提供理论参考。     

禾本科三倍体: 形成、鉴定与利用

禾本科三倍体的形成途径包括2n配子融合、倍性间杂交、多精受精和胚乳培养。其中, 2n配子融合和倍性间杂交分别为自然界和人工合成三倍体的主要途径。该文介绍了形态学观测、染色体分析、流式细胞术和分子标记等倍性鉴定方法在禾本科三倍体中的应用及其优缺点。目前, 三倍体在禾谷类作物中无直接应用价值, 但可作为通往多倍体、非整倍体和转移异源基因的遗传桥梁。多年生禾本科三倍体(特别是异源三倍体)在饲草或能源作物中已得到广泛应用, 在该类型禾本科作物中均可直接尝试三倍体育种。多倍体的三倍体育种和无融合生殖三倍体育种可作为未来禾本科三倍体的研究方向。三倍性胚乳培养可以一步合成三倍体, 多精受精可以实现遗传上3个不同基因组的一步融合, 在三倍体研究中应予以重视。鉴于2n配子融合、多精受精的稀有特性和倍性间杂交、胚乳培养频繁的染色体变异, 高通量三倍体鉴定技术的发展将是三倍体研究实现突破的关键。     

Expression of Ethylene Biosynthetic Genes Regulated by Pollination associated Factors in Doritaenopsis hybrida Flowers

Pollination of flowers initiates postpollination development in orchid ( Doritaenopsis hybrida Hort. ) flowers, including perianth senescence, stigma closure, and ovary development. Because ethylene is thought to play a key role in coordinating these developmental changes, the authors studied the temporal and spatial patterns of expression of genes encoding 1-aminocyclopropane-l-carboxylic acid (ACC) synthase and ACC oxidase following pollination-associated factor treatments in orchid flowers. Both ACC synthase and ACC oxidase mRNA accumulation in the various parts of the flowers is induced by auxin, and ethylene, but not by emasculation. The patterns of both ACC synthase and ACC oxidase mRNA accumulation are similar in all floral organs following auxin and ethylene treatments. Further, in situ hybridization analysis indicates that the ACC oxidase mRNA is localized in epidermal and parenchyma cells of the stigma after auxin and ethylene treatments. The putative roles of auxin, ethylene and emasculation are discussed in terms of the regulation of ACC synthase and ACC oxidase gene expression in flowers.     

与授粉有关的因子调节的乙烯生物合成基因在兰花花器官中的表达

分析了与授粉有关的因子调节的ＡＣＣ合酶和ＡＣＣ氧化酶基因在朵丽蝶兰（ＤｏｒｉｔａｅｎｏｐｓｉｓｈｙｂｒｉｄａＨｏｒｔ．）花中的表达。生长素和乙烯均可诱导ＡＣＣ合酶和ＡＣＣ氧化酶的ｍＲＮＡ在花器官中积累。然而,去雄却不能诱导这两个基因在花器官中表达。生长素和乙烯所诱导的ＡＣＣ合酶和ＡＣＣ氧化酶的ｍＲＮＡ在花器官中的积累模式相似。原位杂交结果表明,生长素和乙烯处理后ＡＣＣ氧化酶的ｍＲＮＡ在柱头的表皮和薄壁细胞中积累。根据ＡＣＣ合酶和ＡＣＣ氧化酶基因表达的结果,对生长素、乙烯和去雄在兰花授粉后乙烯生物合成过程中的作用进行了分析。     

Three 1-Aminocyclopropane-1-Carboxylate Synthase Genes Regulated by Primary and Secondary Pollination Signals in Orchid Flowers

The temporal and spatial expression patterns of three 1-aminocyclopropane-1-carboxylate (ACC) synthase genes were investigated in pollinated orchid (Phalaenopsis spp.) flowers. Pollination signals initiate a cascade of development events in multiple floral organs, including the induction of ethylene biosynthesis, which coordinates several postpollination developmental responses. The initiation and propagation of ethylene biosynthesis is regulated by the coordinated expression of three distinct ACC synthase genes in orchid flowers. One ACC synthase gene (Phal-ACS1) is regulated by ethylene and participates in amplification and interorgan transmission of the pollination signal, as we have previously described in a related orchid genus. Two additional ACC synthase genes (Phal-ACS2 and Phal-ACS3) are expressed primarily in the stigma and ovary of pollinated orchid flowers. Phal-ACS2 mRNA accumulated in the stigma within 1 h after pollination, whereas Phal-ACS1 mRNA was not detected until 6 h after pollination. Similar to the expression of Phal-ACS2, the Phal-ACS3 gene was expressed within 2 h after pollination in the ovary. Exogenous application of auxin, but not ACC, mimicked pollination by stimulating a rapid increase in ACC synthase activity in the stigma and ovary and inducing Phal-ACS2 and Phal-ACS3 mRNA accumulation in the stigma and ovary, respectively. These results provide the basis for an expanded model of interorgan regulation of three ACC synthase genes that respond to both primary (Phal-ACS2 and Phal-ACS3) and secondary (Phal-ACS1) pollination signals.