稉型稻雜交F2族群分子標誌偏差分離現象之探討
Other Title
Studies on Segregation Distortions of Molecular Markers in the F2 Population from the Cross within Japonica Rice
Journal
中華農藝
Journal Volume
13
Journal Issue
4
Pages
241-251
Date Issued
2003-12
Author(s)
Abstract
本研究以稉型稻臺農69號與越光雜交所得到的160個衍生品系所建立之基因定位族群為材料，藉以探討基因之偏差離。此一稉型稻分子圖譜係由135個分子標誌所建立，連鎖圖譜總長度為1,350cM，平均間距為14.67cM。族群分子標誌的偏差分離分析結果，發現135個分子標誌中有50個不符合孟德爾分離率(P<0.01)，佔所有已定位標誌的37.0%，共分佈在八個連鎖群上，並在連鎖群A及H上有偏分離標誌群聚的現象；50個偏分離標誌中有35個是來自父本地越光的DNA片段，佔所有偏分離標誌的70.0%，其中30個標誌是偏歪分離向越光，僅5個是偏分離向臺農69號，顯見在雜交後，越光的配偶子相較於臺農69號有較強勢的作用。偏差分離一般存在於親緣係數較遠的雜交組合中，但本試驗為亞種內的?型稻雜交亦存在無此高比例的標誌異常分離，有可能為母本臺農69號是種間雜交的後代，帶有野生稻的對偶基因，故在兩基因型之間可能存在著雜種不孕基因的作用，加上野生稻基因常會在後代中不平衡的消失，而導致在雜交後越光的配偶子有較強勢的作用，形成後代高度偏離的現像。就作物育種而言，若目標基因位於易發生分離偏差之染色體上，且所欲選拔之基因型出現頻度偏低，則需增加族群數目來克服，以提高選拔的效率。
The study segregation distortion, a molecular linkage map constructed by 160 -derived lines of TNG69×Koshinhikari population was applied. This map consisted of 135 DNA markers, totally spanning 1,350cM with an average interval of 14.67cM. According to the genotypic frequencies of molecular markers, segregation distortion was detected in the population. About 37.0% of investigated markers, or 50 out of 135, segregated distortedly from Mendelian (3:1) ratio at P < 0.01 level. The markers with distorted segregation were clustered on linkage groups A and H. Seventy percent of these markers, or 35 out of 50, originated from the male parent Koshihikari, and 30 markers skewed toward Koshihikari alleles and 5 skewed toward TNG69 alleles. It implied that selective fertilization was occurred in the hybrid and the competition was in favor of the gametophyte from Koshihikari. Segregation distortion has often been found in the population so outbreeding or interspecific cross. In this study, we detected high percentage of distorted segregation of markers in the population derived from intrasubspecific cross between two japonica rice varieties. The cause for thigh frequency of segregation distortion might be due to TNG69, which is a progeny of interspecific cross. TNG69 possesses the alleles of wild rice, which tends to lose disproportionately. Therefore, we hypothesized that the interaction of hybrid sterility genes between two genotypes were the result of the preferential fertilization of the gametophytes from Koshihikari. If a t target gene located in the segregation distortion region, fewer individuals of expected genotypes would be observed. As a consequence, larger population for advanced selection effort would be required.
Subjects
水稻
分子標誌
偏差分離
rice
oryza sativa
molecular marker
Segregation distortion
Publisher
中華農藝學會
Type
journal article