Faculty Opinions recommendation of Overdominant epistatic loci are the primary genetic basis of inbreeding depression and heterosis in rice. I. Biomass and grain yield.

2001 ◽  
Author(s):  
Thomas Mitchell-Olds
Keyword(s):  
Grain Yield ◽  
Inbreeding Depression ◽  
Genetic Basis

scholarly journals Overdominant Epistatic Loci Are the Primary Genetic Basis of Inbreeding Depression and Heterosis in Rice. II. Grain Yield Components

Genetics ◽  
2001 ◽  
Vol 158 (4) ◽  
pp. 1755-1771 ◽  
Author(s):  
L J Luo ◽  
Z-K Li ◽  
H W Mei ◽  
Q Y Shu ◽  
R Tabien ◽  
...  
Keyword(s):  
Grain Yield ◽  
Inbreeding Depression ◽  
Yield Components ◽  
Genetic Basis ◽  
Mixed Model ◽  
Gene Action ◽  
Recombinant Inbred Lines ◽  
Hybrid Breakdown ◽  
Multilocus Genotypes ◽  
Grain Yield Components

Abstract The genetic basis underlying inbreeding depression and heterosis for three grain yield components of rice was investigated in five interrelated mapping populations using a complete RFLP linkage map, replicated phenotyping, and the mixed model approach. The populations included 254 F10 recombinant inbred lines (RILs) derived from a cross between Lemont (japonica) and Teqing (indica), two backcross (BC) and two testcross populations derived from crosses between the RILs and the parents plus two testers (Zhong413 and IR64). For the yield components, the RILs showed significant inbreeding depression and hybrid breakdown, and the BC and testcross populations showed high levels of heterosis. The average performance of the BC or testcross hybrids was largely determined by heterosis. The inbreeding depression values of individual RILs were negatively associated with the heterosis measurements of the BC or testcross hybrids. We identified many epistatic QTL pairs and a few main-effect QTL responsible for >65% of the phenotypic variation of the yield components in each of the populations. Most epistasis occurred between complementary loci, suggesting that grain yield components were associated more with multilocus genotypes than with specific alleles at individual loci. Overdominance was also an important property of most loci associated with heterosis, particularly for panicles per plant and grains per panicle. Two independent groups of genes appeared to affect grain weight: one showing primarily nonadditive gene action explained 62.1% of the heterotic variation of the trait, and the other exhibiting only additive gene action accounted for 28.1% of the total trait variation of the F1 mean values. We found no evidence suggesting that pseudooverdominance from the repulsive linkage of completely or partially dominant QTL for yield components resulted in the overdominant QTL for grain yield. Pronounced overdominance resulting from epistasis expressed by multilocus genotypes appeared to explain the long-standing dilemma of how inbreeding depression could arise from overdominant genes.

Overdominant Epistatic Loci Are the Primary Genetic Basis of Inbreeding Depression and Heterosis in Rice. I. Biomass and Grain Yield

Genetics ◽  
2001 ◽  
Vol 158 (4) ◽  
pp. 1737-1753 ◽  
Author(s):  
Zhi-Kang Li ◽  
L J Luo ◽  
H W Mei ◽  
D L Wang ◽  
Q Y Shu ◽  
...  
Keyword(s):  
Grain Yield ◽  
Inbreeding Depression ◽  
Genetic Basis ◽  
Mixed Model ◽  
Recombinant Inbred Lines ◽  
Hybrid Breakdown ◽  
Mixed Model Approach ◽  
Epistatic Qtl ◽  
Main Effect ◽  
Mapping Populations

AbstractTo understand the genetic basis of inbreeding depression and heterosis in rice, main-effect and epistatic QTL associated with inbreeding depression and heterosis for grain yield and biomass in five related rice mapping populations were investigated using a complete RFLP linkage map of 182 markers, replicated phenotyping experiments, and the mixed model approach. The mapping populations included 254 F10 recombinant inbred lines derived from a cross between Lemont (japonica) and Teqing (indica) and two BC and two testcross hybrid populations derived from crosses between the RILs and their parents plus two testers (Zhong 413 and IR64). For both BY and GY, there was significant inbreeding depression detected in the RI population and a high level of heterosis in each of the BC and testcross hybrid populations. The mean performance of the BC or testcross hybrids was largely determined by their heterosis measurements. The hybrid breakdown (part of inbreeding depression) values of individual RILs were negatively associated with the heterosis measurements of their BC or testcross hybrids, indicating the partial genetic overlap of genes causing hybrid breakdown and heterosis in rice. A large number of epistatic QTL pairs and a few main-effect QTL were identified, which were responsible for >65% of the phenotypic variation of BY and GY in each of the populations with the former explaining a much greater portion of the variation. Two conclusions concerning the loci associated with inbreeding depression and heterosis in rice were reached from our results. First, most QTL associated with inbreeding depression and heterosis in rice appeared to be involved in epistasis. Second, most (~90%) QTL contributing to heterosis appeared to be overdominant. These observations tend to implicate epistasis and overdominance, rather than dominance, as the major genetic basis of heterosis in rice. The implications of our results in rice evolution and improvement are discussed.

scholarly journals Epistasis for Three Grain Yield Components in Rice (Oryxa sativa L.)

Genetics ◽  
1997 ◽  
Vol 145 (2) ◽  
pp. 453-465 ◽  
Author(s):  
Zhikang Li ◽  
Shannon R M Pinson ◽  
William D Park ◽  
Andrew H Paterson ◽  
James W Stansel
Keyword(s):  
Grain Yield ◽  
Complex Traits ◽  
Yield Components ◽  
Genetic Basis ◽  
Kernel Weight ◽  
Progeny Testing ◽  
Grain Yield Components ◽  
Main Effects ◽  
Grain Number Per Panicle

The genetic basis for three grain yield components of rice, 1000 kernel weight (KW), grain number per panicle (GN), and grain weight per panicle (GWP), was investigated using restriction fragment length polymorphism markers and F4 progeny testing from a cross between rice subspecies japonica (cultivar Lemont from USA) and indica (cv. Teqing from China). Following identification of 19 QTL affecting these traits, we investigated the role of epistasis in genetic control of these phenotypes. Among 63 markers distributed throughout the genome that appeared to be involved in 79 highly significant (P < 0.001) interactions, most (46 or 73%) did not appear to have “main” effects on the relevant traits, but influenced the trait(s) predominantly through interactions. These results indicate that epistasis is an important genetic basis for complex traits such as yield components, especially traits of low heritability such as GN and GWP. The identification of epistatic loci is an important step toward resolution of discrepancies between quantitative trait loci mapping and classical genetic dogma, contributes to better understanding of the persistence of quantitative genetic variation in populations, and impels reconsideration of optimal mapping methodology and marker-assisted breeding strategies for improvement of complex traits.

scholarly journals GENETIC BASIS OF INBREEDING DEPRESSION INARABIS PETRAEA

Evolution ◽  
1999 ◽  
Vol 53 (5) ◽  
pp. 1354-1365 ◽  
Author(s):  
Katri Kärkkäinen ◽  
Helmi Kuittinen ◽  
Rob van Treuren ◽  
Claus Vogl ◽  
Sami Oikarinen ◽  
...  
Keyword(s):  
Inbreeding Depression ◽  
Genetic Basis

Epistatic interaction is an important genetic basis of grain yield and its components in maize

2007 ◽  
Vol 20 (1) ◽  
pp. 41-51 ◽  
Author(s):  
X. Q. Ma ◽  
J. H. Tang ◽  
W. T. Teng ◽  
J. B. Yan ◽  
Y. J. Meng ◽  
...  
Keyword(s):  
Grain Yield ◽  
Epistatic Interaction ◽  
Genetic Basis

Genetic Basis of Inbreeding Depression in Arabis petraea

Evolution ◽  
1999 ◽  
Vol 53 (5) ◽  
pp. 1354 ◽  
Author(s):  
Katri Karkkainen ◽  
Helmi Kuittinen ◽  
Rob van Treuren ◽  
Claus Vogl ◽  
Sami Oikarinen ◽  
...  
Keyword(s):  
Inbreeding Depression ◽  
Genetic Basis
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