The use of mixture models to detect effects of major genes on quantitative characters in a plant breeding experiment.

Abstract

An analysis based on Elston's model of mixed major locus and polygenic inheritance is extended to include populations of progeny testing such as F3, B1s and B2s families derived from F2 and backcrosses in a cross between two inbred lines. Genetic hypotheses that can be validly tested by the likelihood ratio method in the analysis of a breeding experiment include homogeneity of variances due to environment and/or polygenes with transformable scale effect by Box-Cox power function, random and independent segregation of major genes, invariance of the effects of major genes with population types and additive and dominant models for polygenes. Testing hypotheses in the order suggested here can lead to a gradual simplification of the models and increases the feasibility of the subsequent analysis, but caution must be paid to the possible bias in parameter estimation and hypotheses tests. The procedure is applied to a set of data on plant height of rice with the effects of dwarf genes in crosses among three varieties. Two recessive dwarf genes are shown to be nonallelic and unlinked. One dwarf gene is shown to reduce plant height about 36-56 cm, and another 52-61 cm. The effect of polygenes, estimated as the standard deviation among possible inbred lines derived from these crosses, is about 11.7 cm. Interactions between the dwarf genes and the polygenic background are found, especially for one of the two genes. Both the polygenic effects and the interactions are much smaller than the effects of the major dwarf genes.

Analysis of Early Maturity Gene Sources in Upland Cotton Using Molecular Markers

“…杂 的 数量 性状。迄今为止, 利用棉花数据库(http:// www.cottonmarker.org/) 公 布 的 微 卫 星 (simple sequence repeat, SSR)标记已经构建了多张高密度的棉 花种间 [17][18][19][20][21] 及种内 [22][23][24][25][26][27][28] 遗传图谱, 为研究棉花复杂 数量性状的遗传机制和基因资源的发掘利用奠定了 基础。目前, 国内外学者对棉花产量、品质、抗性 等许多重要性状进行了 QTL 定位研究 [29][30][31][32][33] , 有关早 熟性及其相关性状的基因定位研究报道较少 [34][35][36][37][38] 。 范术丽等 [35] 利用中棉所 36×TM-1 组合, 定位了果枝 始节、现蕾期、开花期、全生育期、霜前花率等控 制熟性相关性状的 12 个 QTL; 张先亮等 [34] 定位了控 制生育期性状的 5 个主效 QTL。Guo 等 [36] 定位了位 于染色体 16、21、25 上的控制第一果枝节位的 3 个 QTL。努斯来提等 [37] 分别定位了位于染色体 5 和…”