Triple Test Cross Families Research Articles

TRIPLE TEST CROSS ANALYSIS FOR DETERMINING GENE ACTION, GENETIC CORRELATIONS AND PREDICTION FOR YIELD AND YIELD COMPONENTS IN BREAD WHEAT

In two crosses of bread wheat (Gemmeiza11 x Misr1 and Gemmeiza12 x Misr2) to investigate gene action, genetic correlations and predicating new recombinant lines for days to heading, plant height, flag leaf area, number of spikes/plant, number of grains/spike, 1000-grain weight, spike grain weight and grain yield /plant, triple test cross was used. The starting materials for triple test cross was the F1 and their grand parents (P1 and P2) for the two studied wheat crosses. The first cross Gemmeiza 11 x Misr1 and the second cross was Gemmeiza 12x Misr2. The F1’s were selfed to produce F2’s grains. In order to create F1 and F2 plants, the obtained materials (F1 and F2 grain genotypes) and the parental genotypes were seeded together. Thirty individual F2 plants were randomly labeled from each cross and crossed back to their grand parents (P1 and P2) and F1 between then to produce three types of families L1 (F2i x P1i), L2 (F2i x P2i) and L3 (F2i x F1i) in each cross. On November 10, 2018, during the winter growing season, the triple test cross families (L1, L2 and L3), along with the parents, F1 and F2 in each cross, were seeded. Results showed that in the genetic system for the investigated features for two crosses, epistatic gene effects were significant. The types of epistasis (additive x additive, additive x dominance and dominance x dominance) were significant for all studied characters. For the majority of traits in both crossings, both additive and dominant genetic components were significant and involved in the genetic system. The average level of dominance for spikes/plant in cross 1 and spike grain weight in cross -2 was overdominance, while for the remaining characters, additive gene effects were more pronounced. The F value was positive and significant for 1000-grain weight in two crosses, suggesting that dominant genes controlling these characters were unidirectional. The highest proportion of inbreds excepted to outperform parental rang in cross 1 for days to heading and flag leaf area. In both crosses, grain yield per plant was positively and significantly correlated with number of spikes per plant, number of grains per spike, and 1000-grain weight, according to epistasis, additive, and dominance genetic correlations.

THE ROLE OF NON-ALLELIC INTERACTION IN INHERITANCE OF SOME ECONOMIC TRAITS IN G. BARBADENSE

The triple test cross analysis was used to study different components of genetic variation by using 75 triple test cross families and their parents, F1 and F2 in one cotton cross (Giza 95 x Australy) for yield, its components and fiber quality traits. The 75 TTC families (25L1, 25L2 and 25L3) were sown at Sakha Experimental Station; Agriculture Research Center, Kafr El-Sheikh government; Egypt. Mean squares between L1, L2 and L3 were highly significant for all traits studied, while between L1 and L2 Families found to be significant for boll weight, lint percentage, lint index, fiber length and micronaire reading. Overall epistatic gene effects were highly significant differences for all traits studied except for fiber length and fiber strength. The (i) fixable type (additive × additive) was the most important epistatic effect than j and 1 non-fixable type for all traits. Both additive and dominance components were highly significant for all the traits studied. The degree of dominance was less than unity and confirmed the presence of partial dominance for all traits studied except for lint yield/plant; lint index and seed index were over-dominance. The Additive gene action played an important role in controlling inheritance for all traits studied than dominance one except for lint yield/plant; lint index and seed index. Direction of dominance (r) was non-significant for most traits indicating absence of dominance directional. Due to influence of (i) type of epistatic effects for the majority of the studied traits selection in early generations may be recommended. Genotypic correlation was positive and significant between yield traits and its components. This could help cotton breeder to use indirect selection to increase yield traits. All the studied traits showed higher proportion of recombinants inbreds falling outside parental range nearly 40%. So, these higher values of prediction revealed that it would be feasible to predict as early as possible for transgressive segregation which can surpass parental range for most studied traits.

THE ROLE OF NON-ALLELIC INTERACTION IN INHERITANCE OF SOME ECONOMIC TRAITS IN G. BARBADENSE

The triple test cross analysis was used to study different components of genetic variation by using 75 triple test cross families and their parents, F1 and F2 in one cotton cross (Giza 95 x Australy) for yield, its components and fiber quality traits. The 75 TTC families (25L1, 25L2 and 25L3) were sown at Sakha Experimental Station; Agriculture Research Center, Kafr El-Sheikh government; Egypt. Mean squares between L1, L2 and L3 were highly significant for all traits studied, while between L1 and L2 Families found to be significant for boll weight, lint percentage, lint index, fiber length and micronaire reading. Overall epistatic gene effects were highly significant differences for all traits studied except for fiber length and fiber strength. The (i) fixable type (additive × additive) was the most important epistatic effect than j and 1 non-fixable type for all traits. Both additive and dominance components were highly significant for all the traits studied. The degree of dominance was less than unity and confirmed the presence of partial dominance for all traits studied except for lint yield/plant; lint index and seed index were over-dominance. The Additive gene action played an important role in controlling inheritance for all traits studied than dominance one except for lint yield/plant; lint index and seed index. Direction of dominance (r) was non-significant for most traits indicating absence of dominance directional. Due to influence of (i) type of epistatic effects for the majority of the studied traits selection in early generations may be recommended. Genotypic correlation was positive and significant between yield traits and its components. This could help cotton breeder to use indirect selection to increase yield traits. All the studied traits showed higher proportion of recombinants inbreds falling outside parental range nearly 40%. So, these higher values of prediction revealed that it would be feasible to predict as early as possible for transgressive segregation which can surpass parental range for most studied traits.

Triple test cross and six-population techniques for partitioning the components of genetic variance in faba bean (Vicia faba)

The efficiency of the triple test cross (TTC) and the six-population biometrical analyses was compared in terms of assessing and quantifying the components of genetic variance for two faba bean crosses: Triple White×Giza 843 and NA112×Giza 429. Several traits were studied including days to first flower, plant height, branches/plant, pods/plant, seeds/pod, 100-seed weight and seed yield/plant. The results supported the triple test cross biometrical approach as it uses first degree statistics and can be applied to any population irrespective of its genetic architecture. Absence of a scalar relationship between triple test cross families (orthogonality) ensures independence between means and variance with no restrictive assumptions. Both methods provided evidence for epistasis, and both additive and dominance genetic components in the genetic control of the studied traits.

Triple test cross analysis in four sesame crosses (Sesamum indicum L.)

The present study was carried out during 1996, 1997 and 1998 to estimate the additive, dominance and epistatic components of genetic variation for yield, yield components and wilt infection by using 90 triple test cross families and their parents, F1 and F2 in each of four sesame crosses, i.e. Bengalian×Giza 32 (TTC1), Intro 259×Giza 25 (TTC2), Intro 413×Intro 777 (TTC3) and Shandaweel 5×Line 107 (TTC4). Mean squares from the genetic analysis of variance and the overall epistatic gene effects were highly significant differences for all studied characters. The [i] type (additive×additive) was the most important epistatic effect for height of the first capsule (TTC4), number of branches/plant (TTC1 and TTC3), length of the fruiting zone (TTC1, TTC2 and TTC3), days to the first flower and number of capsules/plant (TTC1, TTC2 and TTC4), 1000-seed (TTC3), wilt infection percentage (TTC3 and TTC4) and plant height, capsule length and seed yield/plant in all crosses. The ratio of (H/D)1/2 confirmed the presence of partial dominance for all studied traits. The highest proportion of recombinant lines was obtained for days to the first flower, number of branches/plant, height of the first capsule and seed yield/plant in TTC3 and plant height, capsule length, length of the fruiting zone number of capsules/plant, 1000-seed weight and oil percentage in TTC2.

TRIPLE TEST CROSS ANALYSIS IN FOUR SESAME CROSSES (SESAMUM INDICUM L.) 2. YIELD, YIELD COMPONENTS AND WILT INFECTION

The present study was carried out during the three successive growing seasons of 1996, 1997 and 1998 to estimate the additive, dominance and epistatic components of genetic variation for the yield, yield components and wilt infection by using ninety triple test cross families and their parents, F1 and F2 in four sesame crosses. A randomized complete block design with three replications was used. The results indicated that mean squares of the genetic analysis of variance and the overall epistatic gene effects for the crosses showed highly significant differences for all studied characters. The [i] type (additive × additive) was considered as a major component of the overall epistatic effects for 1000-seed weight in the TTC3 cross, wilt infection percentage in TTC3 and TTC4, number of capsules/plant in TTC1, TTC2 and TTC4 and seed yield/plant in all crosses. The ratio of (H/D)1 for all crosses confirms the presence of partial dominance for all studied traits. The direction of dominance was positive and significant for wilt infection in TTC4, oil percentage in TTC1 and TTC4, number of capsules/plant and 1000-seed weight in TTC2 and seed yield/plant in all four crosses. The results also revealed that the highest proportion of recombinant lines was obtained for number of capsules/plant, 1000-seed weight and oil percentage in the TTC2 cross and for seed yield/plant in TTC3.

The genetical basis of hybrid vigour in a highly heterotic cross of Nicotiana tabacum

The genetical control of F1 heterosis, observed in a cross of desirable Nicotiana tabacum varieties, was investigated by analysing the data of the basic generations, triple test cross-families and random samples of doubled haploids (DH) and single-seed descent (SSD) lines. Analyses of the first-degree statistics revealed a complex control underlying the genetic variation, including the presence of epistasis, linkage, maternal effects and their interactions, in addition to the additive and dominance effects of the genes segregating in the cross. These analyses identified gene dispersion, directional dominance, and duplicate epistasis, as the main causes of heterosis. The triple test-cross analysis also confirmed the presence of non-allelic interactions and indicated that the dominance ratio, although inflated by epistasis, is consistently partial for all the traits. The extent of transgression in the recombinant inbred lines finally established unequivocally that, as in numerous other crosses, gene dispersion and unidirectional, but partial, dominance are the true causes of heterosis in this cross too.

A further modification in the triple testcross analysis when testers share common loci

For investigating the genetical structure of a population of homozygous lines, modifications in the triple testcross analysis that allow for the effect of common loci shared by the pure-breeding testers, L1 and L2, have been previously proposed. The unbiased estimates of the additive genetic and dominance components are, however, correlated as they are obtained from statistics that are nonorthogonal. Further modifications are suggested where full triple testcross families L1i (= Pi × L1), L2i (= Pi × L2) and L3i (= Pi × L3; L3 = L1 × L2) along with selfed progenies of L1i (= L1si) and L2i (= L2si) and pure-breeding lines (Pi) themselves are raised. Alternatively, full triple testcross progenies (L1i, L2i, and L3i) can be raised along with the selfs of L3i (= L3si) families and parental (Pi) lines. These combinations of normal and selfed progenies allow one to test and estimate unbiased additive and dominance components, free from the effect of common loci in the testers and from statistics that are statistically orthogonal. The components of variation are, therefore, estimated independently.Key words: triple testcross, inadequate testers, components of variation.

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

Distributive properties of the second cycle hybrids that are produced by inter-crossing 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 1 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.

Triple test cross analysis in three barley populations under saline-alkali soil conditions

SUMMARYOne hundred and eighty triple test cross families arising from three barley crosses (C 164 x EB 1556, BG 25 x NP 21 and BH 15 x RD 103) were grown in two blocks of a randomized-block design in saline-alkali soil prepared in micro-plots. The families were evaluated for number of days from sowing to heading, plant height, number of tillers per plant, ear length, number of grains per ear, 100-grain weight and grain yield per plant. The cross BG 25 x NP 21 showed epistasis only for number of days toheading and number of grains per ear; in contrast, epistasis was present in all traits in BH 15 x RD 103. In cross C 164 x EB 1556, epistasis was detected for plant height, ear length and number of grains per ear. Thus, epistasis appears to be related to specific cross combination. The ‘j and l’ type epistasis was more pronounced than the ‘i’ type. Early generation selection may be used for number of days to heading which Exhibited epistasis marginally with preponderance of additive gene effects, while for the remaining traits selection should be deferred till an advanced generation.

Erratum: Comparing predictions of mean performance and environmental sensitivity of recombinant inbred lines based upon F3 and triple test cross families

Erratum: Comparing predictions of mean performance and environmental sensitivity of recombinant inbred lines based upon F3 and triple test cross families

Comparing predictions of mean performance and environmental sensitivity of recombinant inbred lines based upon F3 and triple test cross families

Comparing predictions of mean performance and environmental sensitivity of recombinant inbred lines based upon F 3 and triple test cross families

An investigation of gene action and genotype × environment interaction in two crosses of Nicotiana rustica by triple test cross and inbred line analysis

Data from two random samples of inbred lines and from the two sets of the triple test cross in which these inbreds are crossed to the pure-breeding parents and F1 of the cross from which they were derived, one involving material derived from the cross between varieties 1 and 5 of Nicotiana rustica and the other material from the cross between varieties 2 and 12, are analysed and the results compared to those reported earlier. Detection of epistasis and the estimation of the additive and dominance components of variation among the triple test cross families is based on the orthogonal analysis of Jinks and Perkins (1970) while the additive component is also estimated directly from the inbred families. Tests are carried out to detect genotype × micro-environment interaction in the L1 and L2 families of the triple test cross and in the inbred families and the interaction partitioned into that involving additive and dominance gene action. Their relationship with the corresponding additive and dominance components of mean performance is investigated by linear regression analysis. As expected the material from the V1 × V5 cross segregates at loci the alleles of which display large additive effects but little or no dominance and epistasis while dominance and epistasis are larger components of the genetic variation in V2 × V12 cross. In both crosses, the micro-environmental interaction involves mainly the additive genetic component. For some characters there is evidence of independent segregation of genes controlling environmental sensitivity. Estimates of the additive genetic component D from the triple test cross and the inbred families, are consistent for all the characters in both crosses. The triple test cross analysis, therefore, provides satisfactory estimates of the genetic variation among a random set of inbred lines, even for those characters which display non-allelic interactions.