水稻親緣係數變異性之探討

An Investigation on Variability of Coefficient of Coancestry of Rice (Oryza sativa L.)

劉馨雅(Hsin-Ya Liu)

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(2004年)

https://doi.org/10.6342/NTU.2004.01899

摘要

作物在育種程序裡自交純化的過程中，選拔和遺傳漂變的雙重影響，使得用以計算親緣係數的親本貢獻量，常會有不同程度的偏移。本研究以簡單重複序列的分子標記，估算三個不同的水稻雜交族群F4單株的親本貢獻量，由實驗結果的分布情形，將親本貢獻量的偏移分離為選拔以及漂變的部分。以此偏移的親本貢獻量隨機置入637個台稉育品系水稻譜系中，進行200次的模擬，最後觀察637個台稉育品系兩親的親緣係數。模擬試驗的結果顯示，637個台稉育品系200次模擬結果的親緣係數平均值，和以親本貢獻量期望值為基礎所計算出的親緣係數並無太大的差別（R2 = 0.997），而這200次模擬所得到的親緣係數的標準偏差主要和親緣係數本身的大小有關，而和譜系中參與品系總數、原始親本數、雜交數、譜系中的最大世代數之間無明顯的關聯。將200次模擬結果所得到的親緣係數的平均值與標準偏差以對數轉換後，可得到一解釋力較高的直線回歸模式（R2 = 0.939）。利用此直線模式和Beta分布，以親緣係數的期望值和標準偏差的估計值為參數，求得親緣係數95％信賴區間。此信賴區間和200次模擬的結果95％的位置相較，上限最大的差距為0.16，下限最大的差距為0.06。同時我們也觀察到，改變原始親本間的親緣係數，會使親緣係數的大小有著顯著的改變，但對受試品系間親緣係數的相對大小並沒有很大的影響。

關鍵字

親本貢獻量 ； 信賴區間 ； 簡單重複序列 ； 親緣係數

並列摘要

Selection and genetic drift during inbreeding may cause parental genomic contribution to progenies deviate from the expected values; therefore, it affects the value of coefficient of coancestry (f). This study used Simple Sequence Repeat markers to estimate the distribution of parental contribution in three F4 rice populations. Each expected parental contribution was substituted by random variables from these distributions in 637 joponica rice pedigrees of Taiwan. After 200 times simulations, we observed that the means of 200 simulative f are fairly close to that of the expected f (R2＝0.997). The standard deviations (SD) and means of 200 simulative f were not correlated with number of lines in the pedigree, number of common ancestors, number of crosses involved and maximum generations of the pedigrees. However, there was a relationship between the logarithmic mean and the logarithmic SD (R2=0.939). Confidence intervals (CIs) of f were fitted by the log-liner model and Beta distribution. The largest difference between CIs and simulative f was 0.16. Moreover, assigning common ancestors with a larger f may raise the value of final f, but has small effect on relationships among tested lines.

並列關鍵字

parental contribution ； Simple Sequence Repeat ； coefficient of coancestry ； confidence intervals ； coefficient of parentage

參考文獻

Ahnert, D., M. Lee, D.F. Austin, C. Livini, W.L. Woodman, S.J. Openshaw, J.S.C. Smith, K. Porter, and G. Dalton. 1996. Genetic diversity among elite sorghum inbred lines assessed with DNA markers and pedigree information. Crop Sci. 36:1385-1392.

Akagi, H., Y. Yokozeki, A. Inagaki, T. Fujimura. 1996. Microsatellite DNA markers for rice chromosomes. Theor Appl Genet 93:1071

Beal, W.J. 1880. Report of the Michigan Board of Agriculture.

Bernardo, R. 1996. Best linear unbiased prediction of maize single cross performance. Crop Sci. 36:50-56.

Bernardo, R., A. Maurigneux, J.P. Maisonneuve, C. Johnsson, and Z. Karaman. 1997. RFLP-based estimates of parental contribution to F2- and BC1-derived maize inbreds. Theor Appl Genet 1997:652-656.