Mapping Genes with Recombinant Inbreds

1994 ◽  
pp. 249-254 ◽  
Author(s):  
Benjamin Burr ◽  
Frances A. Burr ◽  
Eileen C. Matz
Keyword(s):  
Genetics ◽  
1993 ◽  
Vol 135 (1) ◽  
pp. 223-231
Author(s):  
J Moreno-Gonzalez

Abstract Knowledge about the efficiency of generations for estimating marker-associated QTLs is needed for selection. The objective of this paper is to develop a theory to compare the efficiency of segregating generations and testcrosses from the cross of two inbred lines differing in value for a quantitative trait (P1 x P2) for estimating additive, dominance and heterotic effects of QTLs by stepwise regression. An equation that predicts the smallest gene effect in genetic standard deviation units that can be detected with 50% chance at a significance level as a function of the heritability (h2) and the recombination frequency (r) of markers was developed for the segregating generations and testcrosses. For estimating additive effects, the most efficient generation was the doubled-haploid (DH) lines; the most inefficient was the North Carolina Design III (NCD III), followed by selfed backcrosses (SB); the selfed families from F2 individual plants (F2:3 lines) are inferior to the recombinant inbreds (RI) for low r, but are better than RI for high h2 and r. Dominance effects are less efficiently estimated than additive effects. The NCD III is better than the SB and the F2:3 lines for detecting dominance effects. The RI and DH do not estimate dominance effects. The differential heterotic QTL effects of lines P1 and P2 when crossed with tester T can be estimated by evaluating testcrosses of individual F2 plants (F2T), recombinant inbreds (RIT) and double-haploid lines (DHT). The DHT is superior to the other generations. The F2T is better than the RIT for r > or = 0.20, but inferior for r < or = 0.1 or low heritability.


Author(s):  
Viveka Katoch ◽  
Prem Singh ◽  
Mayanglambam Bilashini Devi ◽  
Akhilesh Sharma ◽  
G. D. Sharma ◽  
...  

The present investigations involving forty five diverse pea recombinant inbreds and three standard checks were carried out for two successive years during 2011-2012 and 2012-13. The objective of the study was to ascertain genetic variability, heritability, genetic advance, correlation and path coefficient among yield and other horticultural and quality traits and identification of superior recombinants for their utilization in crop improvement programme. Wide range of variability was observed for most of the characters under study. The magnitude of phenotypic coefficient of variation (PCV) was higher than the genotypic coefficient of variability (GCV) for all the traits. High phenotypic and genotypic coefficient of variations were recorded for protein content, ascorbic acid, plant height and pod yield per plant for both the years. Pod yield per plant and plant height exhibited high heritability associated with high genetic advance in the respective years indicating the additive gene action for their expression and are likely to respond better to selection. Pod yield showed a positive and significant correlation with number of pods per plant, pod length and number of seeds per pod both the years. Path analysis revealed that number of pods per plant and pod length have highest positive direct effect both the years and thus it may be treated as selection criteria for isolating higher yielding genotypes in garden peas. In heterosis study, some of the recombinant inbreds were found superior over standard checks which include L-14 and L-13 for pod yield/plant, number of pod/plant and earliness. These findings can be further utilized to develop and enhance the yield potential of garden pea.


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