滇南桫椤的系统位置:来自叶绿体trnL内含子和DNA trnL-F间隔区序列的证据

为了探讨滇南桫椤Alsophilaaustroyunnanensis的系统位置 ,我们对该植物与中华桫椤Alsophilacostularis的叶绿体DNAtrnL内含子和trnL F间隔区序列进行PCR扩增和序列测定。滇南桫椤的trnL内含子、trnL F间隔区序列的长度分别为 5 70bp ,36 2bp ;中华桫椤的trnL内含子、trnL F间隔区序列的长度分别为 5 72bp ,36 1bp。结合已经发表的其他桫椤科植物的相应序列进行系统发育分析 ,用简约法和邻接法构建的系统发育树基本一致。结果表明 :1)所分析的桫椤科植物构成一个单系群 ;2 )滇南桫椤与Gymnosphaerapodophylla、Gymnosphaerapectinata、Gymnosphaerapseudogigantea、Gymnosphaeratinganensis、Gymnosphaeragigantea关系较近 ,聚成一支系 ;3)中华桫椤与Cyatheatsangii、Alsophilaspinulosa关系较近 ,聚成一支系。本文系统发育分析的结果支持将滇南桫椤归入黑桫椤属Gymnosphaera。     

trnK基因5′端内含子区序列在榆科(广义)系统发育研究中的应用

本文测定了广义榆科 Ulmaceae s．l．及其近缘类群的trn K基因5′端内含子区序列。在尝试利用该内含子区进行榆科系统发育研究的同时,探讨了其在植物系统学研究中的应用前景。利用PAUP软件进行的系统发育分析仅得到1棵最简约树。该简约树的树长为665步,其一致性指数(CI)和保持性指数(RI)分别为0.7714和0.7965。分析结果表明：广义榆科为多系群;狭义榆科Ulmaceae s．str．为荨麻目rticales其他类群的姊妹群;大麻科Cannabacea嵌在朴科Celtidacea中,即朴科为一并系群;系统位置有争议的2个属——白颜树属Gironniera和糙叶树属 Aphananthe与朴科类群聚为一支。本研究还表明trnK基因5′端内含子区序列分析在植物较低分类等级(如近缘属间,属下种间)的系统发育研究中具有很好的应用前景。     

基于叶绿体基因组数据的芸香科属间系统发育初步分析

为探究花椒属种水平系统进化关系以及为新品种培育研究奠定理论基础，该研究以芸香科物种的叶片为材料，采用改良CTAB法提取叶绿体DNA,利用BGISEQ-500平台进行叶绿体基因组测序，并对叶绿体基因组进行组装、注释，联合NCBI数据库数据，共获得芸香科19属49个物种的全叶绿体基因组序列。构建了芸香科属间系统进化关系。结果表明，(1)基于叶绿体基因组序列矩阵(总长196 641 bp),ML和BI 2种方法得到的系统发育树的拓扑结够基本一致，系统发育树各分支具有较强的支持率，叶绿体基因组数据可以解决芸香科属间的系统发育关系。(2)芸香科为单系类群，并进一步形成两大分支，其中柑橘亚科为单系，与芸香亚科内的芸香属聚为分支I,分支Ⅱ由芸香亚科和飞龙掌血亚科组成，两亚科均不是单系，其中飞龙掌血亚科的香肉果属，茵芋属与芸香亚科的白鲜属，臭常山属是最早分化出来的类群，其次是蜜茱萸属和山油柑属；黄檗属和吴茱萸属与花椒属类群形成姊妹群，飞龙掌血属的物种飞龙掌血嵌套于花椒属分支中，支持飞龙掌血物种并入花椒属的处理。     

白豆杉的叶绿体基因组结构与系统进化分析

以红豆杉科单种属植物白豆杉(Pseudotaxus chienii(W.C.Cheng)W.C.Cheng)为材料,进行叶绿体全基因组测序,并对其基因含量、结构及重复序列进行分析。结果显示:白豆杉叶绿体基因组不包含典型的反向重复区,基因组全长为130427 bp,共编码116个基因,包含83个蛋白编码基因、4个rRNA基因和29个tRNA基因;其叶绿体基因组包含44个简单重复序列和11个串联重复序列。系统发育关系分析结果表明,红豆杉科和三尖杉科互为姐妹群;在红豆杉科内部,白豆杉属(Pseudotaxus)与红豆杉属(Taxus)亲缘关系较近,榧树属(Torreya)与穗花杉属(Amentotaxus)聚为一支。红豆杉科8种植物的叶绿体基因组结构比较结果显示,红豆杉属与白豆杉属的叶绿体基因组结构基本一致,红豆杉科其他属之间存在不同程度的重排。研究结果表明采用叶绿体基因组数据可以较好地解决红豆杉科植物的系统发育关系。     

基于叶绿体基因组探讨桃金娘目及其近缘类群的系统发育关系

该研究基于叶绿体基因组数据,对桃金娘目(6科44属97种)及其近缘类群(牻牛儿苗目2科5属25种)的系统发育关系进行了分析。结果表明:(1)桃金娘目基因组大小为152~171 kb,包括的蛋白质编码基因数目为74~90个;牻牛儿苗目基因组大小为116~242 kb,包括的蛋白质编码基因数目为75~132个。(2)对比叶绿体基因组序列和蛋白质编码基因所构建的系统发育树结果,在目间及牻牛儿苗目内差异显著,但在桃金娘目内基本一致。(3)基于蛋白质编码基因所构建的系统发育树表明,桃金娘目和牻牛儿苗目均为单系,为姐妹类群;桃金娘目内形成两个大支,桃金娘科、Vochysiaceae、野牡丹科形成一支,其中桃金娘科和Vochysiaceae关系较近是姐妹群,柳叶菜科、千屈菜科和使君子科形成另一支,其中柳叶菜科和千屈菜科关系较近为姐妹群;科级水平,桃金娘科、Vochysiaceae、野牡丹科、柳叶菜科、千屈菜科、使君子科和牻牛儿苗科均为单系(仅包括一个物种的科除外)。(4)支持将石榴属及菱属置于千屈菜科。(5)对蛋白质编码基因序列变异分析的结果表明,野牡丹科19个属的共享变异基因数目为53个,变异范围为5.84%~29.53%,桃金娘科9个属的共享变异基因数目为57个,其变异范围为1.31%~15.78%。该研究结果为进一步研究桃金娘目及相关科属的系统发育提供了理论依据。     

基于线粒体COⅡ基因的中国蝽科分子系统学研究(半翅目,异翅亚目)

扩增并测定了我国蝽科4亚科8属11种昆虫线粒体COⅡ基因585 bp的序列,对序列的碱基组成、转换颠换、遗传距离等进行分析,探讨了COⅡ基因在该科的分子进化机制.并基于COⅡ基因序列数据,分别采用邻接法(NI)、最大简约法(MP)和贝叶斯推论法(BI)建立蝽科分子系统发育关系.研究结果表明,蝽科昆虫COⅡ基因A T含量平均为71.7%,存在较强的A T含量偏向性,氨基酸的变异率为27.2%;亚科间的遗传距离介于0.168～0.242之间,大于亚科内属种间的遗传距离,蝽科与盾蝽科2外群之间遗传距离最大,两科之间存在明显的间断.分子系统发育树表明,短喙蝽亚科为蝽科中较为原始的类群,分化较早,益蝽亚科与舌盾蝽亚科关系较近,形成一对姐妹群,蝽科中捕食性种类--益蝽亚科是较为特化的类群,它是由植食性种类分化而来.蝽科4亚科间的分子系统发育关系为Phyllocephalinae (Pentatominae (Asopinae Podopinae).     

毛茛科和芍药科叶绿体基因组密码子特征和系统发育比较

为研究和比较毛茛科和芍药科叶绿体基因组密码子使用模式和系统进化关系,以完成测序的毛茛科33种植物、芍药科7种植物叶绿体基因组为材料,采用分析软件CodonW在线软件CUSP和R软件对叶绿体基因进行密码子特征分析。用MAFFT 软件,MEGA软件进行系统发育分析。研究结果表明芍药科植物叶绿体基因组和毛茛科植物（耧斗菜属除外）叶绿体基因组高频密码子一致性高,具有29个高频密码子,基本偏向与于A/U结尾,但最优密码子存在差异。毛茛科和芍药科叶绿体基因组密码子偏好性的形成因素主要受自然选择的影响,且芍药科叶绿体基因组密码子偏好性受自然选择的影响大于毛茛科。基于叶绿体基因组全序列和基于叶绿体基因组CDS序列的系统进化关系表明,芍药科基于叶绿体基因组全序列和基于叶绿体基因组CDS序列的系统进化关系虽然部分不同,但都可以被划分为芍药组和牡丹组。毛茛科基于叶绿体基因组的系统进化关系不符合中国植物志分类关系,但支持把毛茛科划分为4亚科14族。系统进化分析结果也支持芍药科独立于毛茛科和毛茛目,被划分到虎耳草目,同时证明了叶绿体基因组作为超级DNA条形码的可行性。     

最大似然法和贝叶斯推论与似然比检验探讨泽泻目系统发育关系

应用最大似然法(ML)、贝叶斯推论(BI)、邻接法(NJ)和似然比检验(hLRTs)进行泽泻目分子系统学研究。所用的rbcL基因序列代表了泽泻目14科46属以及作为外类群的6相关属。研究结果表明,*等级制似然比检验表明泽泻目rbcL序列最适合的DNA进化模型为GTR+I+G,最大似然法、贝叶斯法和邻接法构建的系统发育树拓扑结构相似,没有显著的差异,但贝叶斯树支持率较高;泽泻目为一单系类群,由两个主要谱系分支构成,深层分布格局由5个主要分支构成。基于分子系统发育树,文中对泽泻目科间、水鳖科+茨藻科、泽泻科+花蔺科+黄花蔺科、和"Cymodoeaceae complex"的系统发育关系进行了讨论。研究结果还表明,泽泻目系统发育关系可能还需要更多的证据进一步的澄清。     

双壳纲贝类18S rRNA基因序列变异及系统发生

双壳纲贝类栖息于环境多变的海域,是一个形态学和生态学都具有多样性的类群,清晰而可靠的进化关系对于养殖与相关种类的管理具重要意义。然而,目前对双壳类宏观分子系统学研究的报道较少。研究用18S rRNA基因(18S)分析了双壳类3个亚纲贝类的系统发育关系。从GenBank下载帘蛤目、海螂目、贻贝目、胡桃蛤目、蚶目、珍珠贝目6个目94个种类的18S全/部分序列107个,通过ClustalX软件进行序列比对, 用MEGA4.1软件和PHyML软件计算遗传距离, 构建系统发育树, 研究了双壳类18S变异规律及其在系统发生研究中的应用。结果显示18S有插入/缺失序列, 存在长度多态性。序列比对显示有5段约30 70bp的保守区, 4段约130 550bp的高变区。碱基组成平均为T:24.4%, C:23.6%, A:24.5%, G:27.5%。G+C含量为51.1%。在1796个比对位点中, 变异位点占31.7%, 简约信息位点占24.0%。目内科间遗传距离为0.003 0.043, 目间遗传距离为0.026 0.093。NJ树和ML树显示贻贝目、珍珠贝目、胡桃蛤目、蚶目和海螂目的缝栖蛤科先分别聚为支持率很高(BPN=94 100)的单系支, 后聚为一大支(BPN=100)。蛤蜊科与帘蛤目的其他科分离形成一置信度很高的单系支(BPN=93)。帘蛤科种类聚为置信度较低(BPN=60)的一支。海螂目、帘蛤目的种类没能完全聚到所属支系, 彼此嵌套,缝栖蛤科的种类从海螂目中分离出来。18S资料揭示帘蛤目的蛤蜊科、海螂目的缝栖蛤科已经进化为独立的支系。     

基于ITS与 trn L-F序列探讨槭树科的系统发育

报道了槭树科41种(其中槭属39种)植物的 trn L-F和ITS序列(其中部分种的ITS序列为重新测定),以期通过分子手段对槭树科内部尤其是复杂的槭属的系统发育关系进行重建.以无患子科和七叶树科为外类群,基于对57个种单独的ITS序列(包括从GenBank下载的16种的序列)、41种 trn L-F序列及41种两者序列的联合数据,分别采用最大简约法(Maximum Parsimony Method)和邻接法(Neighbor-Joining Method)对槭树科的系统发育进行了分析.结果显示,整个槭树科为一单系类群;金钱槭位于槭树科的基部;但由于云南金钱槭( Dipteronia dyerana )聚在了槭属内部,认为金钱槭属和槭属均可能是非单系类群;槭属内组间关系的支持率普遍较低,但多数组的组内关系得到了较好的支持.将两个片段结合比单独的ITS或 trn L-F分析能更好地解决槭属内部的系统关系,其中sect.Palmata 和sect.Microcarpa ,sect.Platanoidea 、sect.Lithocarpa 和sect.Macrophylla ,sect.Integrifolia 、sect.Trifoliata 和sect.Pentaphylla ,以及sect.Acer 、sect.Goniocarpa 和sect.Saccharina (sensu Ogata)的组间亲缘关系得到了一定的支持,但对其中部分组的划分可能应做进一步调整.重新评价了徐廷志系统中对sect.Rubra 和sect.Saccharodendron 的处理.     

Mutual affinities of Santalalean families

The paper represents a reassessment of familial relationships within the Order Santalales. Rafflesiaceae, Hydnoraceae, and Balanophoraceae are excluded from the order, and their reproductive similarities with some Santalales regarded as evolutionary convergence. The exclusion of Grubbiaceae from Santalales sponsored by other workers is accepted, as is the reassignment to other families of the two only genera of Octoknemaceae. The remaining members of the order are placed into six families, viz. Olacaceae (possibly representing several smaller families); Santalaceae; Loranthaceae (sensu stricto); Viscaceae (sensu stricto); Myzodendraceae ; and Eremolepidaceae (containingEremolepis, Eubrachion, andAntidaphne). It is suggested thatLepidoceras, formerly placed near the above three genera, is more properly placed in Loranthaceae (sensu stricto) nearTupeia. The proposed scheme of affinities of the families of Santalales, as reconstituted, is based to a large extent on inflorescence structure, but is supported by floral morphology and other features. The thesis is defended that Loranthaceae (sensu stricto), Santalaceae, Myzodendraceae, and Eremolepidaceae represent four inde pendent lines of development from portions of the Olacacean complex. Viscaceae (sensu stricto) may be derived directly from Santalaceae.     

The first mistletoes: origins of aerial parasitism in Santalales

Past molecular phylogenetic work has shown that aerial parasites have evolved five times independently in the sandalwood order (Santalales), but the absolute timing of these diversifications was not addressed. DNA sequences from nuclear SSU and LSU rDNA, and chloroplast rbcL, matK and trnL-F from 39 santalalean taxa were obtained. Separate and combined data partitions were analyzed with maximum parsimony and Bayesian inference. Time estimates were performed with Bayesian relaxed molecular clock and penalized likelihood methods using published fossil data. Both methods gave comparable divergence dates for the major clades. These data confirm five origins of aerial parasitism, first in Misodendraceae ca. 80 Mya and subsequently in Viscaceae (72 Mya), "Eremolepidaceae" (53 Mya), tribe Amphorogyneae in Santalaceae (46 Mya), and Loranthaceae (28 Mya). The rapid adaptive radiation and speciation in Loranthaceae coincides with the appearance of savanna biomes during the Oligocene. In all clades except Misodendraceae, it appears that aerial parasites evolved from ancestors that were polymorphic for either root or stem parasitism-a condition here termed amphiphagous. Convergences in morphological features associated with the mistletoe habit have occurred such as the squamate habit, seed attachment structures, unisexual flowers, and loss of chlorophyll.     

Perianth evolution in the sandalwood order Santalales

Flowers of Santalales remain largely unexplored with several questions of homology unanswered despite the large size of the order. Morphological and ontogenetic floral studies have the potential to identify new informative characters. We studied floral development in species of Loranthaceae, Santalaceae, Opiliaceae, and "Olacaceae" with scanning electron microscopy to clarify the origin and evolution of the perianth in Santalales. The perianth is either dichlamydeous or when monochlamydeous interpreted as sepals, petals, or tepals. A girdling calyculus of debatable origin is found in some clades. We show that species of Diogoa and Heisteria in "Olacaceae" have a dichlamydeous perianth, unlike Olax in which the calyx is replaced by a calyculus. The calyculus arises by development of two lateral primordia, supporting the hypothesis of bracteole origin. A calyculus with similar development is present in species of Loranthaceae and possibly of Opiliaceae, suggesting a position of Olax closer to these families than to traditional genera of "Olacaceae". The monochlamydeous perianth in Santalaceae is shown to correspond to petals of other members of Santalales. Flower ontogenetic evidence suggests a repeated loss of the calyx, replacement by a calyculus, and further loss, leading to monochlamydeous perianths in Santalaceae.     

Evolution of larval food plant associations in Delias Hübner butterflies (Lepidoptera: Pieridae)

A review of larval food plants of the genus Delias is presented. Larvae specialize primarily on aerial‐stem and root hemiparasites (“mistletoes”) in the order Santalales. Although butterfly food plant associations have been recorded for only a small proportion of the genus (28 species or ～11%, representing 12/24 species‐groups), available data suggest that the family Loranthaceae is used most frequently (77%), followed by the Santalaceae sensu stricto (14%) and Viscaceae (8%). With the possible exception of Euphorbiaceae (1%), almost all non‐mistletoe records are considered to be erroneous and, in most cases, probably represent the mistletoe host tree on which the larvae sometimes pupate. Of the eight major clades recognized in Delias, food plants have been recorded for six of these, although the majority of records (89%) are for three clades (hyparete, belladonna, nigrina). Optimization of the larval food plant data in the context of recent phylogenetic hypotheses for both butterflies and plants revealed little evidence of cospeciation at the higher systematic levels. The most parsimonious reconstruction was an origin of larval feeding on Loranthaceae, followed by at least six independent colonizations to Santalaceae + Viscaceae. In contrast to related pierids in the Aporiina associated with mistletoes in which further shifts from aerial‐stem mistletoes to distantly related plants (e.g. host trees parasitized by mistletoes) have facilitated differentiation at the generic level, there is no firm evidence to indicate that such secondary, monomorphic shifts have evolved in Delias. However, larvae of D. henningia (pasithoe group of belladonna clade) from Palawan and Luzon, the Philippines, appear to be polymorphic, feeding on both Loranthaceae and Euphorbiaceae.     

Potential phylogenetic utility of the low-copy nuclear gene pistillata in dicotyledonous plants: comparison to nrDNA ITS and trnL intron in Sphaerocardamum and other Brassicaceae.

We report the potential phylogenetic utility of DNA sequence data from the last 700 bp of a ca. 1-kb intron of the MADS-box gene pistillata from a sampling of Sphaerocardamum species and other Brassicaceae. These results are compared with nrDNA ITS and the chloroplast trnL intron for the same taxa to demonstrate the potential phylogenetic utility of this pistillata intron and to identify potential historically independent sequences for an ongoing study of relationships within Sphaerocardamum. Analyses of the DNA sequence data for Brassicaceae indicated that pairwise divergences and potentially informative characters were higher in the pistillata intron (0.6-30.8%, 284 characters) and ITS (0-24%, 94 characters) than in the chloroplast trnL intron (0-4.2%, 17 characters). A comparison of Sphaerocardamum sequences identified low divergences and numbers of informative characters for trnL intron (0-2.4%, 1 character) and nrDNA ITS (0-2.5%, 2 characters) and substantially more variation among the pistillata sequences (0.15-3.7%, 19 characters). Phylogenetic analyses of these pistillata sequences fully resolve ingroup relationships without character conflict. Results of pistillata PCR amplifications from a broader dicot sample showed that some primers may be useful in amplifying orthologous pistillata sequences. Ultimately this pistillata intron may be a valuable source of phylogenetic characters at lower taxonomic levels.     

Phylogenetic relationships of the Santalales and relatives

Summary Determining relationships among parasitic angiosperms has often been difficult owing to frequent morphological reductions in floral and vegetative features. We report 18S (small-subunit) rRNA sequences for representative genera of three families within the Santalales (Olacaceae, Santalaceae, and Viscaceae) and six outgroup dicot families (Celastraceae, Cornaceae, Nyssaceae, Buxaceae, Apiaceae, and Araliaceae). Using Wagner parsimony analysis, one most parsimonius tree resulted that shows the Santalales to be a holophyletic taxon most closely related toEuronymus (Celastraceae). The santalalean taxa showed approximately 13% more transitional mutations than the group of seven other dicot species. This suggests a higher fixation rate for mutations in these organisms, possibly owing to a relaxation of selection pressures at the molecular level in parasitic vs nonparasitic plants. Outgroup relationships are generally in accord with current taxonomic classifications, such as the grouping of Nyssaceae and Cornaceae together (Cornales) and the grouping of Araliaceae with Apiaceae (Apiales). These data provide the first nucleotide sequences for any parasitic flowering plant and support the contention that rRNA sequence analysis can result in robust phylogenetic comparisons at the family level and above.     

Phylogenetic relationships among species of Hypochaeris (Asteraceae, Cichorieae) based on ITS, plastid trnL intron, trnL-F spacer, and matK sequences

Nuclear internal transcribed spacer (ITS) regions and chloroplast trnL intron and trnL/trnF spacer and matK sequences were used from 86 accessions to assess relationships among 31 European and South American species of Hypochaeris plus 18 representatives of related genera of tribe Cichorieae. The ITS tree shows high resolution compared to that of the maternally inherited trnL intron, trnL/F spacer, and matK sequences. The ITS and the combined tree reveal clades that agree well with sections of the genus established previously on morphological and cytological grounds, except for H. robertia, which groups with Leontodon helveticus and L. autumnalis. Monophyly of species of Hypochaeris from South America is strongly supported by both ITS and the joint matrix of ITS, trnL, and matK data. European species lie basal to South American taxa, which suggests that species in South America evolved from a single introduction from European progenitors and not from H. robertia as suggested previously. Low levels of sequence divergence among South American taxa suggest a pattern of rapid speciation, in contrast to much greater divergence among European representatives. Different species of Leontodon form two different clades that are also supported by chromosome numbers and morphology. Both nuclear and chloroplast markers suggest that Helminthotheca, Leontodon, and Picris are closely related to each other as well as to Hypochaeris.     

Discordance of chloroplast and nuclear ribosomal DNA data in Osmorhiza (Apiaceae)

Phylogenetic studies were conducted to evaluate interspecific relationships in Osmorhiza (Apiaceae: Apioideae) using sequences of the ITS regions of nuclear ribosomal DNA, the chloroplast ndhF gene, and two noncoding regions (trnL intron, and trnL [UAA] 3' exon-trnF [GAA] intergenic spacer). All data sets suggest the monophyly of the New World taxa and showed that Osmorhiza aristata from Asia is relatively divergent from other members of the genus, even though it is morphologically similar to the eastern North American O. claytonii and O. longistylis. The ITS and chloroplast DNA trees differ in the relationships among the New World taxa, especially the phylogenetic position of O. occidentalis, O. glabrata, and O. depauperata. The lack of congruence between the two data sets may be a result of hybridization or introgression. Although there is high discordance between nrITS and two chloroplast DNA data sets, the latter two show similar topologies.     

The use of chloroplast DNA to resolve plant phylogenies: noncoding versus rbcL sequences

Direct sequencing of polymerase chain reaction products is now an expanding area of plant systematics and evolution. Within angiosperms the rbcL gene has been widely sequenced and used for inferring plant phylogenies at higher taxonomic levels. Unfortunately rbcL does not usually contain enough information to resolve relationships between closely related genera, such as Hordeum, Triticum, and Aegilops. One solution to this problem could be to analyze noncoding regions of chloroplast DNA, which are supposed to evolve more rapidly than coding regions. Here we present pairwise comparisons among dicots and monocots for rbcL and two noncoding sequences of cpDNA (the trnL (UAA) intron and the intergenic spacer between the trnL (UAA) 3' exon and the trnF (GAA) gene). It appears that these regions evolve faster (more than three times faster, on average) than rbcL, as previously reported, and that the trnL intron evolves at a rate that is the same as that of the intergenic spacer. By the analysis of these regions, the genera Hordeum, Triticum, and Aegilops clearly could be distinguished. A phylogeny using trnL (UAA) intron sequences is also inferred for some species of the genus Gentiana L., clearly illustrating the phylogenetic utility of these zones at the generic level. The advantages and the disadvantages of the use of these regions to resolve plant phylogenies are discussed, as well as the desirability of a preliminary study before every large-scale analysis.      

Tissue culture of parasitic flowering plants: Methods and applications in agriculture and forestry

Summary Parasitic flowering plants from 23 genera in 7 families (Convolvulaceae, Lauraceae, Loranthaceae, Orobanchaceae, Santalaceae, Scrophulariaceae and Viscaceae) have been cultured in vitro. These plants include both hemiparasites and holoparasites that parasitize stems and roots of angiosperms and gymnosperms. This review highlights relevant information on each genus with regard to its biology, distribution, host range, and tissue culture procedures. Tissue culture has been used to study aspects of the development, metabolism, reproduction, physiology and nutritional requirements of these plants under controlled conditions. Studies of host-parasite relationships, including potential roles of signals/receptors that influence host development and physiology, and factors influencing seed germination and haustorium formation, have been conducted. The effects of chemicals and herbicides on the physiology and biochemistry of parasite embryo and seedling development have been studied, as well as the influence of inhibitors or stimulants on seed germination. Tissue culture has provided a method for propagation and genetic improvement of plants with commercial value.