木通科基部类群花和叶的形态发育及系统发育研究

【作者】 张小卉；

【导师】 任毅；

【作者基本信息】 陕西师范大学 ， 植物学， 2009， 博士

【摘要】 木通科(Lardizabalaceae)是真双子叶类群中进化地位较低的一个科,隶属基部真双子叶植物的毛茛目(Ranunculales),共有9属(包括大血藤属Sargentodoxa),我国产7属。猫屎瓜属(Decaisnea)、串果藤属(Sinofranchetia)和大血藤属三属均为我国特有或准特有的单种属,因具有原始的广义形态学特征,均被置于木通科的基部。器官发育包括花的形态发生发育、胚珠的形态发生发育、叶的形态发生发育等等,这些器官是木通科植物系统发育研究的关键形态学性状,是成熟结构所不能提供的,同时能够为器官发育基因的研究提供基本资料。本文对木通科大血藤属、猫屎瓜属、串果藤属3个基部类群及木通属(Akebia)和八月瓜属(Holboellia)2个发展较高级的类群植物的花、胚珠、叶的发育特征进行了观察研究,结果表明:1)木通科花的形态发生发育该科功能上的单性花在早期器官形成时为两性花;花部器官呈螺旋状或轮状发生,成熟花中呈轮状排列。大血藤属:雄花、雌花和两性花同时存在;花瓣具有延迟发育现象:雌、雄花后期器官发生、发育特点不同:雌花中的中央花原基剩余部分明显增大,早期的6个心皮在雄蕊内方轮状发生,随后形成的多数心皮以不规则的方式发生,共形成约90个心皮,完全占据顶端;雄花中顶端的剩余原基不再增大,以不规则方式形成0～10个不育心皮;两性花中心皮的发生方式与雌花相似,只是心皮数目较少。心皮囊状,成熟心皮柱头外翻,具有子房柄:雌花中花被及退化雄蕊数目变异大;顶花的花部器官的发生方式不规则。猫屎瓜属:第一轮雄蕊延迟发育;对折心皮发育特征,心皮顶端外翻形成头状柱头;心皮发生后,花原基顶端具有空白区域;雌花中退化雄蕊呈花瓣状。串果藤属:花瓣和雄蕊未形成共同原基,花瓣原基和雄蕊原基的外形、发生时间、位置均不同;花瓣延迟发育;第一轮雄蕊延迟发育;对折心皮发育特征,成熟心皮在子房的顶部形成近头状的柱头区域;退化雄蕊体积略小。仍然开裂;心皮发生后,花原基顶端具有空白区域。木通属:萼片两轮,第二轮萼片原基形成后退化;心皮为螺旋式发生,对折发育特征,在子房的顶部形成一近头状的柱头区域;退化雄蕊体积小。八月瓜属:花瓣原基和雄蕊原基的外形、发生时间、位置不同,花瓣延迟发育;心皮不同时发生,对折心皮发育特征,成熟心皮在子房的顶部形成近头状的柱头区域。2)木通科胚珠发生发育特征成熟胚珠一般为倒生、弯生至横生,双珠被。早期胚珠原基半球形;内珠被在胚珠原基中部环状发生;外珠被的发生有两种:半环状发生,即近珠柄腹侧没有形成,如大血藤属、猫屎瓜属、串果藤属、木通属、八月瓜属的五月瓜藤(Holboellia fargesii);或明显的环状发生,如八月瓜属的大花牛姆瓜(Holboelliagrandiflora)和八月瓜(Holboellia latifolia);内珠被在成熟胚珠中为杯状;外珠被为兜状,仅大血藤属为杯状外珠被:珠孔形成较晚,由内珠被形成:珠柄附属物缺乏,仅串果藤属的胚珠发育后期在珠柄一侧形成脊状附属结构。3)木通科叶的发生发育特征具有羽状复叶、三出复叶、掌状复叶等复叶类型,也有个别单叶出现,如大血藤中有单叶到复叶的变化。各种类型的复叶在叶芽(或混合芽)中分化形成,叶原基之间形成的时间间隔基本相似。叶原基早期以三出式分化产生3部分,随后小叶的发生发育有三种方式:三出式,三出的-向顶式和三出的-向基式。ⅰ.羽状复叶为三出的-向顶式的分化方式,猫屎瓜属叶原基中央顶端部分伸长,并由下向上依次形成6～11对小叶原基,最后顶端剩余原基发育为顶生小叶;随后小叶的组织分化和成熟也是沿同样的方向进行;ⅱ.掌状复叶的分化方式为三出的-向基式,八月瓜属的叶原基上,中央的顶端部分先形成顶生小叶,然后在顶生小叶下方,向下依次分化出1～4对小叶原基:ⅲ.三出复叶的分化中,木通属的三叶木通、串果藤属及大血藤属的叶原基分为三部分后就不再进行分化,直接形成顶生小叶和一对侧生小叶。4)系统发育分析基于105个广义形态学性状的分支系统学分析显示,木通科为单系发生,支持率80%。在木通科内,大血藤属位于最基部,与其它属形成姐妹群,支持率为80%,次基部的猫屎瓜属支持率为66%,其次是串果藤属,支持率为88%。Boquila和Lardizabala未形成姐妹群,八月瓜属、木通属、长萼木通属、野木瓜属作为木通科的核心类群支持率为72%。长萼木通属作为木通属的姐妹群具有较高的支持率89%。木通属的三叶木通及其变种白木通Akebiatrifoliata subsp.australis形成姐妹群,支持率高达90%。这个结果与综合基因序列和形态数据的分类系统中的结论一致。5)性状演化花器官发生方式的分化中,轮状发生方式、或各轮内的器官不同时发生特征为共同的祖征,而大血藤属器官不规则的发生方式为自征;花器官定数为祖征,大血藤属花被、雄蕊、心皮等器官的异常增多和木通属花被数目减少、心皮数目增多为各自的自征:萼片两轮发生为祖征,单轮或2轮以上为各自的衍征:花瓣应该是多次进化的结果,有花瓣类群的大血藤属、串果藤属和八月瓜属花瓣的发生相似,花瓣延迟发育明显,无花瓣类群如猫屎瓜属和木通属早期没有花瓣原基的形成;6枚离生雄蕊为祖征,而猫屎瓜属的合生雄蕊(花丝合生)为衍征;3心皮对折发育为祖征,大血藤属的90多个囊状心皮为衍征。外珠被半环状发生为祖征,八月瓜属环状发生的外珠被为衍征;成熟胚珠中兜状外珠被为祖征,大血藤属的杯状外珠被为衍征;胚珠无附属结构为祖征,串果藤属的脊状附属物为衍征。复叶分化方式中,三出式为祖征,由三出式衍生的向顶或向基式为衍征;三出复叶为祖征,羽状复叶和掌状复叶为衍征。综合以上特征,猫屎瓜属和串果藤属存在不同于其它各属的发育特征,各自沿不同的方向演化,大血藤属具有不同于其他属的花、胚珠、叶形态发生发育特点,如心皮数目、单胚珠等,较它们的分化特征更为原始,三属具有各自孤立的演化位置,位于木通科基部。结合以前对于木通科形态、结构、孢粉、胚胎学以及系统学的结果,我们支持王伟(2007)的分类系统中给予大血藤属亚科的分类地位,木通科由大血藤亚科和木通亚科组成(包括串果藤族和猫屎瓜族)。更多还原

【Abstract】 It is widely accepted that Lardizabalaceae is the basal family in Ranunculales which is the basal eudicots.Lardizabalaceae consists of nine genera including Sargentodoxa and seven of them occurr in China.Sargentodoxa,Decaisnea and Sinofranchetia show many primary characters in anatomy, structure,and other aspects,the three genera occupy the primary systematic position in Lardizabalaceae,and they are monotypic genus endemic to China.The ontogeny character of organs includes floral,ovule and leaf morphogenesis and development,the data of ontogeny is the key morphological character to the phylogeny of Lardizabalaceae,and it can supply some fundamental information to organ identity genes.Organ morphogenesis and development of Sargentodoxa,Decaisnea,Sinofranchetia,Akebia and Holboellia in Lardizabalaceae are observed in this paper,the results are as follows:1)Floral morphogenesis in LardizabalaceaeThe functionally unisexual flowers have a bisexual morphogenesis in the early developmental stages;the floral organs arise spirally(or whorled) and whorled arranged later in mature flower.In Sargentodoxa,ⅰ.the male,female and bisexual flower exist together;ⅱ.petal retarded;ⅲ. carpels and androecia morphogenesis and development exhibit different pattern in female,bisexual and male flowers in later developmental stages,in the female flower,the floral primordia apex enlarged obviously and more than 90 carpels initiated,the floral apex is occupied totally,the first six carpel appeared as whorled and the numerous carpels occurred irregular later;on the other hand,in the male flower,the floral primordia apex does not enlarged and about 10 or none sterile carpels appeared unordered;the carpel initiation in the bisexual flower is as the same as it in the female flower,the number of the carpels is fewer than it in the female one;ⅳ.ascidiate carpel with short stalks,the mature carpels have decurrent and oblique stigmas;ⅴ.the perianth and staminodes number is variable in the female flowers;ⅵ.the floral morphgenesis in uppermost flower is different from others.In Decaisnea,ⅰ.three stamens in the first whorl retarded;ⅱ.conduplicate carpels with headed stigma;ⅲ.the remained floral apex exist after carpels formed;the staminodes in the female flowers are petaloid.In Sinofranchetia,ⅰ.petals and androecia are not come from the "common primordium",the petal primordium and the androecium primordium are different in shape,postion and time when they initiate;ⅱ.petals retarded;ⅲ.three stamens of the first whorl retarded;ⅳ.conduplicate carpels without style,stigma formed in the upper parts of the carpel and approximately headed;ⅴ.the staminodes are smaller than the stamen in the male flower;ⅵ.the remained floral apex exists after carpels formed.In Akebia,two whorls of sepals occured,and the inner whorl degenerated later;ⅱ.conduplicate carpels is initiated spirally,stigma formed in the upper parts of the carpel and approximately headed;ⅲ.the staminodes are smaller than the stamen in the male flower.In Holboellia,the petal are differ from the androecium in primordium shape,initiation postion and time;ⅱ.petals retarded;ⅲ.conduplicate carpels occurred successively with short style,stigma headed.2)Ovules morphogenesis of LardizabalaceaeMature ovules are anatropous,campylotropous to hemianatropous,bitegmic integument.The young ovule is hemisphere;the inner integument is arised annularly in the middle part of the ovule and developed into cup-shaped;the outer integuments formed with semi-annularly shape in Sargentodoxa,Decaisnea,Sinofranchetia,Akebia and Holboellia fargesii Reaub.,in which the outer integument is not formed in the ventral side of the funicle,or the outer integuments arised annularly in Holboellia grandiflora Reaub.and Holboellia latifolia Wall.;the outer integument developed into hood-shaped in the most genera,while Sargentodoxa has a copular-shaped outer integument;the micropyles is endostomic and formed late(the nucellus is not wrapped with integuments obviously in blooming);the raphe-shaped appendages arise in Sinofranchetia.3)Leaf ontogeny of LardizabalaceaeLardizabalaceae have compound leaf,pinnate in Decaisnea,ternate in Sinofranchetia and Sargentodoxa,palmate or trifoliolate in Akebia and Holboellia,rarely simple leaf(in Sargentodoxa, the leaf can be observed varies from ternate leaves to the simple leaf).The compound leaves formed in the leaf bud(or mix bud) with a equal interval gap between two leaf primordia,such as in Decaisnea,Sinofranchetia,Akebia,Holboellia and Stauntonia.The first fractionation of leaf primordium is ternate,and three equal parts formed in the early stage.Three developmental types formed as a result of ternation in compound leaves,ternate, ternate-acropetal and ternate-basipetal,ⅰ.ternate-acropetal growth in the pinnately compound leaf differentiation in Decaisnea,if the middle part of ternation,which develops further,a pinnate leaf would result,6 to 11 pairs of leaflets initiated from the basal to the upper in middle part,and the tip leaflet formed by the remain part of leaf primordia,the leaflet tissue differentiation is in the same direction in the following development;ⅱ.ternate-basipetal growth accompany with the palmate compound leaf in Holboellia,the tip leaflet formed by the middle part of ternation,and with short basipetal growth,1 to 4 pairs of leaflets initiated successively from upper to the basal below the middle part;ⅲ.if the ternation does not develop further,three part formed the tip leaflet and two lateral leaflets,and results into ternate or trifoliolate compound leaf in Sinofranchetia,Akebia (Akebia trifoliata(Thunb.) Koidz.)and Sargentodoxa.4)Phylogeny analysisThe results based on 105 morphological characters show that Lardizabalaceae is monophyletic with a bootstrap support of 80%.Within Lardizabalaceae,Sargentodoxa is the most archaic genus which is sister to other genera of Lardizabalaceae with a bootstrap support of 80%,Decaisnea is another diverged at the base of the family with a support of 66%,and Sinofranchetia is the next basal genera with a support of 88%.Boquila Decne.and Lardizabala Ruiz & Pav.are not supported as sister group.Core Lardizabalaceae consists of Holboellia,Akebia,Stauntonia DC.and Archakebia Wu,Chen & Qin with a bootstrap support of 72%.Archakebia is sister to Akebia with a high bootstrap support of 89%.The two species of Akebia,Akebia trifoliata(Thunb.)Koidz.and Akebia trifoliata(Thunb.) Koidz.subsp,australis(Diels) T.Shimizu are well supported by a bootstrap support value of 90%.The results is consistent with the new classifications which combined molecular and morphological data,Sargentodoxa is different from other Lardizabalaceae and should be treated as a subfamilial rank within Lardizabalaceae.5)Character evolutionThe floral organ arised in whorl pattern,or initiated in whorl(three organs formed successively in each whorl) are plesiomorphy,the irregular pattern in Sargentodoxa is automorphic.The floral organs show destiny number is plesiomorphy,variety number in perianth,androecium,and abnormal increase carpels in Sargentodoxa is automorphic,as well as the reduce number in perianth and the increase number in carpels in Akebia.Bicyclic initiation of the sepal is plesiomorphy,whereas monocyclic or more than bicyclic are apomorphic.The petal is the results of many times evolution, the petal morphogenesis and development is the same in Sargentodoxa,Sinofranchetia and Holboellia,retarded development.Contrast to it,there is no petal primordium appeared in Decaisnea and Akebia.Six free androecia is plesiomorphy,and the filament connect into a tube is in Decaisnea apomorphic.Three conduplicate carpels is plesiomorphy,whereas more than 90 ascidium carpels in Sargentodoxa is automorphic.Outer integuments initiate semi-annularly is plesiomorphy,whereas the outer integuments initiate annularly in Holboellia is automorphic.The outer integument becomes hood-shaped in maturity is plesiomorphy,and the copular-shaped outer integument in Sargentodoxa is automorphic or apomorphic.The ovule without appendage is plesiomorphy,and the raphe-shaped appendage in Sinofranchetia is automorphic.The ternate fractionation of leaf primordium in the Lardizabalaceae is plesiomorphy,thus, ternate-acropetal and ternate-basipetal are apomorphic which are derived from the ternate.The ternate compound leaf in Sinofranchetia and Sargentodoxa is plesiomorphy,the pinnate compound leaf in Decaisnea and the palmate or trifoliolate compound leaf in Akebia and Holboellia are apomorphic.According to the results above,comparing the floral morphogenesis in Decaisnea and Sinofranchetia to other genera in Lardizabalaceae,there are many different developmental features between them,Decaisnea and Sinofranchetia are isolated basal group in Lardizabalaceae for their primary characters which imply their different evolutional and diverged route,Sargentodoxa showed more primary characters than Decaisnea and Sinofranchetia,and it is differ from other Lardizabalaceae in floral morphogenesis,ovule morphogenesis,leaf ontogeny and other aspects, such as numerous carpel,uniovulate etc.The three genera have isolated systematic position and are the basal group in Lardizabalaceae.Our observation,together with evidence from anatomy, morphology,palynology,embryology,and molecular data,we agree with the classification of Lardizabalaceae by Wang(2007),suggested give Sargentodoxa a subfamilial rank;Lardizabalaceae consist of Sargentodoxoideae(Hutch.) Thorne & Reveal and Lardizabaloideae Kostel, Lardizabaloideae includes Decaisneeae Reaub.,Sinofranchetieae H.N.Qin & Y.C.Tang,and Lardizabaleae.更多还原