The consequences of using inadequate testers in the simplified triple test-cross

Virk, D. S.; Jinks, J L

doi:10.1038/hdy.1977.29

Cited by 29 publications

(12 citation statements)

References 5 publications

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“…The diallel crosses and selfs were produced during 1954 and the experiment conducted during 1955 by Dr E. L. Breese. Experimental details and results from this diallel have already been published in one form or another by Jinks, Perkins and Breese (1969), Virk and Jinks (1977) and Pooni, Jinks and Singh (1984).…”

Section: Experiments and Results (I) Predicted Propertiesmentioning

confidence: 94%

Predicting the properties of second cycle hybrids produced by intercrossing random samples of recombinant inbred lines

1984

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SUMMARYDistributive properties of the second cycle hybrids that are produced by intercrossing the recombinant inbreds extractable from the F2 of a cross between two pure breeding lines can be predicted from the early generations of the original cross. Hence the frequency of such hybrids that will outperform the extreme recombinant inbreds or the original F1 can be predicted. Basic generations and triple test cross families provide the most reliable estimates of the predictors and therefore should be used whenever possible although, in the presence of linkage, randomly mated F2's may give improved predictions. Simpler experiments consisting of the parental varieties and their F1 and F2 generations, however, provide all the information that is likely to be necessary for most practical purposes.The predictive power of the new approach is demonstrated on material extracted from the cross of varieties I and 5 of Nicotiana rustica. The predictors were estimated from the means and variances of V1, V5, F1 and F2 raised in six environments between 1973 and 1983. The predicted frequencies of second cycle F1's which outperform the extreme recombinant inbred lines derived from this cross are compared with those observed among 190 second cycle hybrids in a diallel between 20 recombinant inbreds derived from the same cross.

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Section: Experiments and Results (I) Predicted Propertiesmentioning

confidence: 94%

Predicting the properties of second cycle hybrids produced by intercrossing random samples of recombinant inbred lines

1984

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“…The non-significant trait, pods per cluster in the kharif season, was not analyzed further because the L 1 and L 2 testers were inadequate, probably due to the presence of common loci for this trait. The genetical consequences of common alleles in the L 1 and L 2 testers provide an ambiguous test for epistasis and can spuriously detect non-allelic interactions when they may not be present (Virk and Jinks 1977).…”

Section: Analysis Of Variancementioning

confidence: 99%

Genetic Architecture of Secondary Yield Components in Mungbean (Vigna radiata (L.) Wilczek).

Khattak¹,

Haq

Ashraf³

et al. 2002

Breed. Sci.

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Triple Test Cross (TTC) analyses were carried out to detect epistasis, and to estimate additive and dominance components of genetic variation in two seasons (kharif and spring/summer) for branches per plant, pod clusters per plant, pods per cluster, pod length, biomass, and harvest index in mungbean. The results revealed the absence of epistasis for all the traits in the kharif season but in contrast the presence of epistasis for pod clusters per plant and biomass in the spring/summer season. The partitioning of total epistasis revealed that both i type (additive × additive), and j and l type (additive × dominance, and dominance × dominance) interactions were significant with predominance effect of i type for pod clusters per plant and biomass. The additive and dominance gene effects were highly significant for branches per plant, pod length, and harvest index in both seasons; for pod clusters per plant and biomass in the kharif season; and for pods per cluster in spring/ summer season. The magnitude of additive variance was higher for all these traits in both seasons except for pods per cluster and pod length in the spring/summer season, which exhibited a higher value of dominance than additive variance. The direction of dominance was observed towards fewer pod clusters per plant, small pod size, and high harvest index. The predominance of i type interaction and additive gene action for most of the traits in the present investigation suggests the occurrence of selection in the late generations in the segregating population for the improvement of seed yield through yield components in mungbean.

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“…The arrays that we chose from the diallel are those of varieties 1R8 and 1R29 which had the highest (27.26 per cent) and the lowest (0 per cent) amylose contents among the seven lines. These varieties were chosen to maximize genetic diversity in the testers and to avoid gene fixation which can affect the efficiency of the analysis adversely (Virk & Jinks, 1977).…”

Section: Materials and Analysesmentioning

confidence: 99%

A general method of detecting additive, dominance and epistatic variation for metrical traits. V. Triple test cross analysis of disomically inherited traits expressed in triploid tissues

Pooni

Kumar

Khush³

1994

Heredity

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The applicability of the triple test cross design to the genetic analysis of metrical traits that subscribe to disomic inheritance but are expressed in a trisomic state has been investigated both theoretically and experimentally. Theory has shown that the standard sets of triple test cross families (L1 etc.) do not provide unambiguous tests of the additive, dominance and epistatic effects when reciprocal crosses are analysed separately. Analysis of the backcross families also suffers from similar problems but only in respect of the additive component and the tests of dominance and epistasis are not biased by the parentage of the families. Selfs of the standard families, on the other hand, do not display reciprocal differences (of heritable kind) and therefore provide umambiguous tests of the additive, dominance and epistatic effects, but the dominance component is now detected with reduced reliability as the level of heterozygosity is halved due to selfing. Theory further shows that biases of the various tests are eliminated rather easily by including the reciprocal families in the analysis. This is confirmed to a large extent by the analysis of amylose content in rice which also reveals that it is controlled by genes that display both interallelic (additive and dominance) and nonallelic interactions. Furthermore, dominance is shown to be partial but the dominance ratio seems to be high for both the hai and ha2 types of non-additive effects.

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The consequences of using inadequate testers in the simplified triple test-cross

Cited by 29 publications

References 5 publications

Predicting the properties of second cycle hybrids produced by intercrossing random samples of recombinant inbred lines

Predicting the properties of second cycle hybrids produced by intercrossing random samples of recombinant inbred lines

Genetic Architecture of Secondary Yield Components in Mungbean (Vigna radiata (L.) Wilczek).

A general method of detecting additive, dominance and epistatic variation for metrical traits. V. Triple test cross analysis of disomically inherited traits expressed in triploid tissues

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