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题名: 被子植物基部类群细辛和三白草MADS-box基因研究
作者: 胡金勇
学位类别: 博士
答辩日期: 2003
授予单位: 中国科学院昆明植物研究所
授予地点: 中国科学院昆明植物研究所
导师: 李德铢
关键词: 被子植物基部类群 ; 细辛 ; 三白草 ; 花被 ; 发育
学位专业: 植物学
中文摘要: 进化发育遗传学认为,发育调控基因体系的进化和变异是引起生物形态多样性的一个重要因素,因而了解发育调控基因体系的进化和变化将有助于了解生命进化的历程。基于对拟南芥和金鱼草等模式植物同源基因体系的研究,人们提出了关于植物开花的ABC模型,并且随着研究的深入和研究对象的拓展,ABc模型己经发展成为ABCDE系统。在这一重要演变过程中,植物MADS-box基因家族研究起了非常重要的作用。植物MADs一box基因家族在几乎植物发育的每一个重要过程中都起重要调控作用。这一重要基因家族可以分成多个基因亚族,其中包括A-dass SQuA一亚族、B~class的AP3/DEF-和PI/GLO-亚族、C-和D-class的AG-亚族以及E-class的AGL2-/AGL6手亚族等。它们分别在花发育的不同过程具有重要调节功能。目前研究比较详细和系统主要是B-class的两个亚族,从裸子植物到基部真双子叶植物、从单子叶植物到真双子叶植物都已经分离到了B-class基因的同源基因;C/D-class的AG-亚族基因也已经从裸子植物中分离到。但是,对于SQUA-亚族基因的研究目前还主要集中在单子叶植物和真双子叶植物中,被子植物基部类群的SQuA一like基因还未见报道;而被子植物基部类群对于整个被子植物起源和进化研究、对于花和花被的起源研究是非常关键的。古草本三白草科和马兜铃科植物是被子植物系统研究过程中两个非常重要的类群。三白草( Saurrzls chinensis Baill.)的花形态非常简单,无花被(achialnydeolls),非常类似Sarcandra花的结构;细辛(A sarum caudigerum Hance.)的花则只具有一层融合的花被,没有明显分化成为粤片或花瓣,很类似ANITA中Amborella花的结构。因此,从无花被的三白草到单层融合花被的细辛再到结构典型分化的(马蹄香)拟南芥、金鱼草、水稻等,花被的进化经过了一个从无到有、从简单到复杂的过程。因为拟南芥、水稻等植物发育过程有很多重要调控基因参与,研究无被花和单被花的发育调控过程则具有了非常重要的意本论文以二白草和细辛为研究对象,利用3'-和5'-RACE技术分离到了9个花发育过程相关MADS-box基因,利用RT-PCR和原位杂交等技术对它们的时空表达模式进行了分析,重建了它们与已知基因的系统发生树。结果,三白草和细辛分别有一个基因ScM-I和AcA-1属于SQUA-亚族,为被子植物基部类群中同类型基因首报。它们具有SQUA-like基因的某些典型结构和转录表达模式,但也出现了明显差异。转录模式分析表明,这两个基因的转录分布很广,预示了功能的多样性;对他们进行系统发育分析的结果表明,它们处于整个SQUA-亚族基因的基部位置,这与三白草科和马兜铃科植物处于被子植物较基部的位置相适应。本论文分析还表明,被子植物SQUA-亚族基因可以主要分成Cladel和n两支;SQUA-亚族基因祖先的出现在被子植物分化成单子叶植物和双子叶植物两个主要类群之前;第一个SQUA一le基因功能很可能是多样化的;从第一个SQUA-like基因出现到真双子叶植物SQUA-like基因,SQUA-like基因很可能经历了一个从复杂到具体、从泛化到特异的一个进化历程。在本论文中分离到的9个MADS-box基因中,有5个属于B-class,AcM-6、AcM-15、ACM-5和ScM-3属于AP3/DEF-亚族,ScM-2基因属于PILGLO-亚族。除了Ac脉'基因以外,其它基因都具有各自亚族基因所具有的典型保守结构。Ac林万和Acl-4基因的转录产物分布非常广泛,除了在根中没有检测得到它们的转录产物之外,在花被、雄蕊和心皮中都有它们的分布;但除了具有几乎与Ac拯4基因完全相同的MADS-box和I-region之外,AcM-6基因没有K-domain,而且只在雄蕊和心皮中检测到该基因的转录发生。三白草ScM-3和ScM-2基因也只在花序中表达。从细辛中分离到的AcM-3基因属于C-class AG-亚族基因,具有AG-亚族基因所具有的典型结构特征。在所有检测用到的材料中,没有检钡纽到该基因在营养器官中的转录发生;它的转录主要发生在各种发育时期的胚珠、雄蕊中。值得注意的结果是,该基因还在花被中具有明显转录存在,而已报道的C-class基因主要在可育性器官中表达;A感'3基因有可能处于从D一功能AG-like向C-功能AG-like基因过渡的位置。另外一个细辛基因AcM-2属于TM3-亚族,具有TM3-亚族的明显结构特征。AcM-2主要在营养器官中表达,在花被、雄蕊和心皮中没有明显转录信号;因而该基因很可能主要参与了营养生长调控或者是在细辛花发育的早期起作用。总之,被子植物基部类群中已经具有了SQUA-llke基因,该基因的功能很可能是多样化的;无被花和单被花发育过程中很可能象拟南芥、水稻等植物那样也需要SQUA-like和B-class基因的参与;第一个SQUA-like基因可能出现早于单子叶植物和真双子叶植物的分化;虽然具有A、B、C-class基因的同源基因,ABC模型可能并不完全适用于基部类群被子植物的开花过程。
英文摘要: It is assumed in evolutionary developmental genetics (evodevotics) that evolution and variation in developmental control genes are a major aspect of evolutionary changes in morphology. The study of the phylogeny and evolution of developmental control genes will bridge the gaps of our understanding of the evolution of life on earth. Based on the studies of homeotic genes in model plants Arabidopsis and Antirrhinum, especially on the plant MADS-box genes, the ABC model of flowering was proposed. With the broadening of plant materials and lucubrating of MADS-box genes in these species, the ABC model has been developed into the ABCDE system. Plant MADS-box genes play very important roles in almost all key processes of plant growth and development. They can be divided into several important subfamilies according to their function and gene structure. These subfamilies include the A-class SQUA-subfamily, the B-class AP3/DEF- and PI/GLO- subfamilies, the C-and D-class G-subfamily and the E-class AGL2- and GZ6-subfamily. Among them, the B-class AP31DEF- and PI/GLO- subfamilies have been intensively studied, though more work is still needed. The B-class, and C- and D-class genes have been isolated from gymnosperms, basal eudicots, monocots and higher eudicots. However, there is still no report on SQUA-like genes in basal angiosperms, needless to say the gymnosperms or ferns. However, the basal angiosperms are one of the key plant groups in the origin and evolution of angiosperms. The Saururaceae and Aristolochiaceae are two important basal families of paleo-herbs of angiosperms. The flower of Saururus chinensis is achlamydeous, very like the flower of Sarcandra, which has been put the basal most position of the angiosperms. Flower of Asarum caudigerum, one member of the Aristolochiaceae, also is very simple with only single-whorl perianth that has not been differentiated. From Saururus to Asarum, (to Saruma) to Arabidopsis and rice, the perianth has experienced one evolutionary trend from achlamydeous to single-whorl, to differentiated two-whorl. As reported, the development of flower of Arabidopsis and rice has been regulated by one gene network, especially the MADS-box genes. Therefore, isolation and characterization of the MADS-box genes from the achlamydeous Saururus flowers and single-whorl perianth Asarum flowers seem to be very important for the understanding of evolutionary process of flowers, especially the perianths, as well as the evolution of the angiosperms as a whole. In this dissertation, 3'- and 5'- Rapid Amplification of cDNAEnds (3'-/5'-RACE) were used to isolated MADS-box genes from S. chinensis and A. caudigerum. Then RT-PCR and RNA in situ hybridization were applied to analysis the transcription patterns of these genes. Phylogeny analyses were also carried out to study the relationships among the new genes and previously reported MADS-box genes. In total, 9 genes were isolated and characterized. Among the 9 genes, the ScM-1 from S. chinensis and AcMADS669 from A. caudigerum are members of the SigC/d-subfamily. This is the first report of SQUA-Yks genes from species outside of monocots and eudicots. These two genes have the typical structures and conserved domains of SQUA-subfamily genes. They are widely transcribed not only in vegetative tissues but also in reproductive organs, suggesting their multiple roles in the development of plants. Sequences alignments and phylogeny analyses have revealed the SQUA -subfamily can be divided into two main clades, I and II. Clade I genes were mainly isolated from the higher eudicots, while clade II members coming from the monocots. Jnterestingly, the ScM-1 and AcM-1 are basal to other members of the Sg^-subfamily. Based on these results, it can be proposed that function of the first SQUA-Yiks, gene would be multiple; the first SQUA-like gene should have emerged before the divergence of the two main lineages, the monocots and the eudicots, of angiosperms, at least 200 million years ago. From the emergence of the first SQUA-like gene to present API, SQUA and SQUA-\ike genes in Arabidopsis and Antirrhinum, function of SQUA-Mkz genes would have experienced one evolutionary process from complex to simple, from complicated to specified. Five genes are B-class genes. The AcM-6, AcM-5, AcM-4 from A. caudigerum and ScM-3 from S. chinensis are clustered into AP3IDEF- subfamily; while the ScM-2 from S. chinensis is grouped in P//GZ0-subfamily with strong bootstrap support. Except for AcM-6, the other four B-class genes own typical structures and conserved domains as in other B-class genes. With one identical MADS-box and I-region to AcM-4, the AcM-6 gene has no typical K-domain. RT-PCR has shown that transcription signals of AcM-5 and AcM-4 can be found in almost all organs except roots. However, AcM-6 can only be transcribed in stamens and carpels. Expression of ScM-3 and ScM-2 is only transcribed in inflorescences. These results show that these B-class genes should play different roles in floral patterning of S. chinensis and A. caudigerum. Another gene, AcM-3 from A. caudigerum, is a member of the AG-subfamily. Not in vegetative tissues, but in floral organs is the AcM-3 transcribed, implying its roles in flower development. Besides very strong signals in stamens and ovules, it should be noted that, AcM-3 gene could also be transcribed in perianths. Considering the phylogenetic results, AcM-3 might be at the transitional position from D-class AG- to C-class AG-subfamily. In this dissertation, one TAO-like MADS-box gene, AcM-2, is also isolated and characterized from A. caudigerum. This gene has the typical TM3-like structure. Transcription signals of AcM-2 gene can only be detected in vegetative tissues, such as. leaves and stems. No signal has been"detected in floral organs. It can be deduced that AcM-2 gene should' play some roles in vegetative growth of A. caudigerum. In conclusion, though A-, B-, C- classes genes can be found in basal angiosperms, the ABC model would not be applicable to the basal angiosperms.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.kib.ac.cn/handle/151853/678
Appears in Collections:昆明植物所硕博研究生毕业学位论文_学位论文

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被子植物基部类群细辛和三白草MADS-box基因研究.胡金勇[d].中国科学院昆明植物研究所,2003.20-25
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