水稻幼苗期根系耐冷的遺傳定位

Genetic Mapping of Cold Tolerance Roots of Rice (Oryza sativa L.) Seedling

游岳儒(Yueh-Ru You)

指導教授 ： 胡凱康

國立臺灣大學/生物資源暨農學院/農藝學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201602273

摘要

台灣的水稻 (Oryza sativa L.) 栽培屬移植苗系統，因機械化操作，常對幼根造成系統性的損傷。一期作多在一至三月間進行移植，若有寒流侵襲，幼苗根系生長受限，吸收養分能力不足，將使水稻產生葉黃化。但栽培者以為是缺乏養分而增加施肥，待寒流離開，幼苗根系恢復生長，過多的養分反對植株造成不良影響。為了有效選擇具耐冷特性的材料，用於未來育成耐冷品種，我們以 44K panel 內的種原為對象，利用全基因組關聯性分析 (genome-wide association study, GWAS) 尋找與耐冷特性有關之數量性狀基因座 (QTL, quantitative trait locus)。統計模式則採取P模式以控制族群結構，減低可能發生第一型錯誤 (false positive) 的機會。我們於第2條染色體上找到一介於18.10 ~ 18.44 Mb的顯著區域，區域內的SNP經簡化後，可歸類出7種haplotype。其中Hap 2 表現優於它者，且屬Hap 2的種原大多為來自中緯度地區的溫帶型稉稻 (temperate japonica, TEJ)。以Hap 2配合外表型資料，挑選具耐冷潛力的種原，擴大重複數進行外表型驗證，其耐冷表現也大致穩定。再以選出的種原 (Kon Suito) 與台中秈10號 (TCS10) 進行雙親本雜交，並以其F2族群的QTL定位對GWAS進行驗證，但兩者的結果無法相互印證。雖然我們已經以PCA校正族群結構，但本次GWAS的結果顯示我們無法完全消除族群結構帶來的影響，未來可能需要其它方法來校正族群結構；而GWAS與雙親本雜交的QTL定位也需同時進行以彌補互相的缺陷。

關鍵字

幼苗根系 ； 耐冷特性 ； 全基因組關聯性分析 ； P模式 ； 數量性狀基因座

並列摘要

Mechanical transplanting commonly used in rice (Oryza sativa L.) cultivation usually caused systematic damages to the root system of rice seedlings. The retarded regrowth of adventitious roots may occur as the result of cold current between January and March in Taiwan, and limit nutrient uptake of the seedlings to a point that the seedling leaves become discolored. In this study, a genome-wide association study (GWAS) was conducted on the 44K panel to identify QTLs associated with seedling root regrowth under low temperature treatment. P model was used to reduce the possibility of false positive caused by population structure. We have found a significant region of 18.10 to 18.44 Mb on Chromosome 2, and simplified the significant SNPs in this region into 7 haplotypes. Accessions possessing haplotype 2 performed better than others, and most of them are temperate japonica. A set of 10 cold tolerant and 5 cold sensitive accessions were selected based on both phenotypic and genotypic data, and their root growth difference were verified by subject them to the same cold treatment with extended repeats. However, bi-parental mapping on the F2 population derived from the cross between cold tolerant “Kon Suito” and cold sensitive “Taichung Sen 10” did not reveal any QTL related to the root growth characteristic under cold treatment. It is speculated that while P model was used in the GWAS, the population structure was still not fully corrected. In light of the result of this study, we recommend to conduct bi-parental mapping as a verification measure after GWAS.

並列關鍵字

seedling roots ； cold tolerance ； GWAS ； P model ； QTL

參考文獻

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