非光合作用被子植物質體基因研究

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Project title/計畫英文名

非光合作用被子植物質體基因研究

Project Number/計畫編號

92-2311-B-002-026-

Translated Name/計畫中文名

非光合作用被子植物質體基因研究

Project Principal Investigator/計畫主持人

JER-MING HU

Funding Organization

Ministry of Science and Technology

Start date/計畫起

01-08-2003

Expected Completion/計畫迄

31-07-2004

摘要：所有的綠色植物體內都存在著葉綠體，並利用它來進行光合作用。然而有許多的被子植物失去了光合作用的能力，而成為全寄生或腐生的植物。有趣的是，大部份這些非光合作用的植物都仍然保有一個縮小的質體基因組(20-88kb)。在這些植物的質體中，大部份與光合作用相關的基因都已失去或成為偽基因(pseudogene)，比方說rbcL等。目前已經有一些相關的研究針對非光合作用植物的rbcL來進行分析，但是並沒有人研究在rbcL變成偽基因後，其核內相對的rbcS是否也會因不再需要它的功能，而也因此消失。為了要研究這些光合作用相關基因在非光合作用植物中的演化，我們選取了四個在台灣的非綠色被子植物: Cuscuta japonica (菟絲子，旋花科)，Mitrastemon kawasasakii (台灣奴草，大花草科)，Balanophora laxiflora (穗花蛇菰，蛇菰科)，和Cheilotheca humilis (水晶蘭，鹿蹄草科)。我們首先利用所有質體都共有的16S rDNA來進行PCR的分析，以鑑定它們是否存在質體基因組。接著我們會利用PCR鑑定其他質體基因rbcL和matK以及核內的r
Abstract: Green plants have photosynthetic ability by harboring a complex light harvesting apparatus in their chloroplasts. There are some flowering plants, however, lost this ability and became heterotrophic, either being parasitic or saprophytic. Non-photosynthetic plants usually retain their plastid genome, although many of the plastid genes are lost or become pseudogenes, especially the photosynthesis-related genes such as rbcL. rbcL has been characterized in several non-photosynthetic parasitic or saprophytic plants. However, no study has been done to examine if the nuclear counterpart, RUBISCO small subunit gene (rbcS), is sustained or deleted, when rbcL becomes a pseudogene. In order to examine the rbcL and rbcS genes in non-photosynthetic plants, we will use four non-photosynthetic plants native to Taiwan to study if they contain plastids: Cuscuta japonica (Convolvulaceae), Mitrastemon kawasasakii (Rafflesiaceae), Balanophora laxiflora (Balanophoraceae), and Cheilotheca humilis (Pyrolaceae). 16S rDNA, a conserved plastid gene, will be chosen to examine the presence of plastid genome by PCR. In addition, we will use PCR to identify rbcL and matK sequences in the plastid genome, and examine the nuclear rbcS genes in these plants. We proposed to utilize additional Southern-based screening on separated plastid and nuclear genomic DNAs, to determine the presence of plastid encoded 16S rDNA, rbcL, matK, and nuclear encoded rbcS. This is to clarify the possibility that the absence of PCR amplification is due to gene divergence, and there is no gene transfer event between nucleus and plastid genomes. RT-PCR and northern blot will be carried out for further expression analysis. The result will provide evidences of nuclear and plastid gene evolution once the genes have lost the functional constraints, in this case, the photosynthetic ability.

Keyword(s)

非光合作用植物
質體基因組
rbcL
rbcS
matK
16S rDNA
non-photosynthetic plants
plastid genome
rbcL
rbcS
matK
16S rDNA

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非光合作用被子植物質體基因研究

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