Research Project: 水稻半糯性基因之定位選殖與功能鑑定
Loading...
Contributors
Funders
ID
Description
摘要：本計畫最終的目的是與嘉義農業試驗分所吳永培博士合作，一起以定位選策略選殖水稻半糯性基因Dull，並在分子、生化和生理層次進行基礎研究探討 Dull基因功能，除了可以闡述Dull基因在調控直鏈澱粉含量的角色外，並深入探討影響米質之因素，並可應用於水稻育種，改良米質和育成不同直鏈澱粉含量的新品種，提升水稻的附加價值。
台灣於2002年加入世界貿易組織（WTO），近年來政府積極推動稻米產業調整措施，推薦農友種植適合國人口味之良質米品種，因此對於影響米質最重要的因素之一的直鏈澱粉含量的研究，有助於育成新的良質米品種。低直鏈澱粉含量之黏性米較為較受到台灣的消費者喜歡，吳永培博士篩選純化之TNG67誘變的半糯品系，其直鏈性澱粉只含8~12％，此突變的半糯基因與已發表的Du1 為不同的基因，因此我們將以定位選殖策略將此突變的Dull選殖出。目前共收集4876顆的半糯品系雜交TCS17之F2種子，於96年第二期作種植136 F2 植株，開始以93個SSR和indel分子標幟進行粗定位，截至96年12月已完成46 F2植株之27個分子標幟之基因型鑑定，希望在本計畫正是執行之前能完成此初步的連鎖分析結果。我們將以循序漸進的方以更多的indel和SNP 分子標幟慢慢逼近此標的Dull基因，於97年第一期作完成以1000 F2之連鎖分析、於98年第二期作完成以超過 2000 F2之連鎖分析，最終達到高解析度基因圖譜分析，以touchdown此Dull基因。待此Dull基因選殖出來後，將進行基礎的研究，如RT-PCR瞭解此Dull基因在半糯品種與TNG67在不同組織轉錄表現、利用competitive RT-PCR看是否此基因也為控制mRNA splicing 的transcriptional factor、探討植物post-transcriptional對於基因的表現影響等等的相關研究。除此之外，在未來我們將以此定位選殖策略應用於其他的半糯突變基因、巨胚等等與米質相關的突變基因的選殖，這些研究結果將有助於增加米質、提升稻農的收益。
<br> Abstract: The aim of this project is to clone Dull, which can reduce amylose contents in rice endosperm, by using the positional cloning strategy, and to study the gene function on molecular, physical, biochemical and histological levels. This work will contribute not only to elucidate the role of Dull in starch biosynthesis in endosperm but also to explore factors affecting rice eating and cooking quality, which can be applied to rice breeding program to improve rice quality and to breed varieties containing various amylase contents for promoting rice product value. Dr. Yong-Pei Wu, Chiayi Agricultural Experiment Station, TARI, is one Co-PI of this project and participate the field planting and breeding.
Because Taiwan has been one of the members of WTO since 2002, the government has been promoting to adjust rice production policy by planting elite cultivars with good palatability in these years. Amylose content is one of key factors affecting grain quality, which high amylose contents lowers rice eating quality due to dry and fluffy after cooking and the grains with low amylose contents are more popular in Taiwan. Thus, the investigation of amylose contents in rice grain would assist the breeding of rice varieties with good palatability.
Dr. Wu screened and purified a dull mutant from the TNG67 mutant pool induced by sodium azide. The dull mutant has lower amylose contents, only 8~12% relative lower than TNG67 of 20%, and exhibits intermediate degree of translucence when its grains are dry. We found this mutated dull gene is different from the only one cloned dull gene, Du1, by sequence alignment analysis of Du1 and the Du1 allele of this dull mutant derived from TNG67. It indicates that this dull is a novel or one of the other 10 dull genes have not been cloned yet. We employ the positional cloning to clone this dull gene since it might be point mutation induced by sodium azide. Up to now, we have collected 4876 F2 seeds of the dull mutant TCS17 and planted 136 F2 individuals in the field during the 2nd crop season of 2007. A total of 93 polymorphic SSR and indel markers at average distance of 16.9 cM are subjected to coarse mapping. Twenty-seven markers have been applied to 46 F2 individuals for genotyping till Dec 2007. We expect that the coarse mapping can be done in prior to the 2nd crop season of 2008. We also expect to subject genotyping more indel and SNP markers against 1000 F2 and over 2000 F2 individuals during the 2nd crop season of 2008 and the 1st crop season of 2009, respectively, to approach the target gene, dull, step-by-step. Once the dull gene been cloned, we will study the gene function under molecular and biochemical levels for basic research such as the transcription levels in various tissues of mutants and TNG67 by RT-PCR, or mRNA splicing if the dull protein is a transcription factor by competitive RT-PCR, gene expression by post-transcriptional analysis, and so on. Furthermore, we will employ the positional cloning strategy to clone other dull genes, a giant embryo gene, and other genes related to grain quality. We wish all the information of basic research on grain quality can be integrated together and applied in breeding program to improve rice grain quality and promote rice economic value.
Keywords
水稻
半糯
米質
直鏈澱粉含量
連鎖分析
定位選殖
rice
dull
rice quality
Amylose content
linkage analysis
positional cloning
半糯
米質
直鏈澱粉含量
連鎖分析
定位選殖
rice
dull
rice quality
Amylose content
linkage analysis
positional cloning