利用回交世代鉴定数量性状主基因-多基因混合遗传模型

主多基因性状在分离世代中表现出多峰或偏态现象，具有混合分布的特征。本文利用混合分布理论提出从回交世代鉴定主基因的存在并估计其遗传效应的统计分析方法。利用所提出的方法可鉴别主基因的存在并估计其遗传效应和方差等遗传参数。

Study on Inheritance Mechanism of Tomato Fruit Firmness

[Objective] This study aimed to investigate the inheritance mechanism of tomato fruit firmness.[Method] Two tomato cultivars significantly different in fruit firmness were selected for investigation of the inheritance mechanism of tomato fruit firmness using combination analysis of six generations （P1,P2,F1,F2,B1 and B2）.[Result] The results indicated that the heredity of tomato fruit firmness was consistent with the additive-dominant model controlled by one pair of major genes; the additive effect （d）,dominant effect （h） and degree of dominance （h/d） of major genes were 17.37,-7.96 and-0.46,respectively,showing positive additive effect and incompletely dominant-negative effect; the hereditability of major gene effect in B1,B2 and F2 generation was 88.59％,45.81％ and 85.62％,respectively.[Conclusion] The heredity of fruit firmness was controlled by one pair of major gene,showing significant additive effect and dominant effect.

Genetic Analysis on Plant Height in Rice in Different Growing Seasons

[Objective] The aim was to carry out the genetic analysis on plant height of rice（Oryza sativa L.）cultivated in different seasons.[Method] Three rice parents with great difference in plant height including CB1（83.1 cm）,CB4（105.5 cm）and CB7（115.6 cm）were chosen to construct two parental combinations：CB1×CB4 and CB7×CB4,and the corresponding filial generations P1,F1,P2,B1,B2 and F2 were obtained.The 6 populations were planted in middle and late seasons respectively to measure their height traits.The Akaike＇s information criterion（AIC）of the mixed major gene and polygene model was used to indentify the existence of major genes affecting quantitative traits in B1,B2,F2 populations.When the major genes existed,the genetic effects of the major genes and polygenes and their genetic variance were estimated through segregation analysis.[Result] One additive major gene plus additive-dominance polygenes was the most fitted genetic model for the trait in all B1,B2,F2 populations in two planting seasons.The heritability values of the major genes varied from 38.63% to 78.53% and those of polygenes varied from 1.72% to 36.04%,and the total heritability values were 45.52-92.93%.The additive effect d value of the two genetic populations under two planting seasons was-4.56,-9.16,-7.19,and-9.38,respectively,as suggested that additive effect of the major genes would decrease the express of the plant height trait.[Conclusion] The heritability of plant height trait was affected by planting seasons and the combinations clearly as a whole.

Genetic Analysis of Embryo Production Frequency in Wheat × Maize Cross

A DH population derived from C49S-87/01Y1-1069 was used to study the inheritance of wheat haploid embryo production frequency（EPF） in wheat × maize cross with the mixed major gene and polygene inheritance model of quantitative traits. The results showed that the EPF of wheat × maize cross was controlled by two dominant epistatic genes and polygene with gene effects of 1.95 for the first major gene, 6.69 for the second one and 2.80 for the polygene. The inheritability of major genes was as high as 72.09%, suggesting that the differences in EPF among wheat materials were mainly influenced by genotype. However, non-genetic factors were still important, especially for wheat materials with low EPF.

Analysis of Fruit Length Using Mixed Major Gene and Polygene Inheritance Model in Summer Squash

[Objective]The aim was to provide scientific basis for breeding on the fruit length of summer squash.[Method]Inheritance of the fruit length of summer squash in P1,P2,F1,B1,B2 and F2 from two crosses q-1 ×23-4G（cross 1） and q-1 ×A-7（cross 2） was investigated by the mixed major gene and polygene inheritance model of quantitative traits.[Result]The results showed that the fruit length was controlled by D2 model;Genetic effect of fruit length of cross 1 was mainly additive effect,but genetic effect of fruit length of cross 2 was mainly dominant effect.Heritability values of the genes of F2 were relatively high and the environmental effect was relatively low.[Conclusion]The fruit length breeding of summer squash should be selected in early generation selection.

Analysis of Fruit Width Using Mixed Major Gene and Polygene Inheritance Model in Summer Squash

[Objective] The aim was to provide scientific basis for breeding on the fruit width of summer squash.[Method] Inheritance of the fruit width traits of summer squash in P1,P2,F1,BC1,BC2 and F2 from two crosses q-1×23-4G（cross 1）and q-1×A-7（cross 2）was investigated by the mixed major gene and polygene inheritance model of quantitative traits.[Result] The fruit width was controlled by B-1 model.Heritability values of the major genes of F2 were relatively high and the environmental effect was relatively low.[Conclusion] The fruit width breeding of summer squash should be selected in early generation selection.

Analysis of Flesh Thickness of Summer Squash by Using Mixed Major Genes and Polygene Inheritance Model

[Objective]The aim was to study the inheritance of flesh thickness,so as to provide a theoretical basis for breeding of thicker-flesh summer squash variety.[Method]Using mixed major genes and polygene inheritance model,a joint analysis of six generations from two crosses q-1×23-4G（Cross 1）and q-1×A-7（Cross 2）was conducted to investigate the inheritance of the flesh thickness of summer squash.[Result]The results showed that the flesh thickness was controlled by D-2 model（a pair of additive major genes plus additive-dominant polygene）;genetic effect of flesh thickness in the two crosses was mainly the dominant effect of polygene.Heritability values of the genes of F2 generation were relatively low,while the environmental effect was great.[Conclusion]To flesh thickness,the method of individual selection on high separated generations was effective in the breeding of summer squash with thick flesh.