Presence Of Non-allelic Interactions Research Articles

Gene effects for pod yield and horticultural traits of garden pea (Pisum sativum var. hortense L.) using Trigenic model of generation mean analysis

The inheritance of pod yield and related horticultural traits of garden pea using 12 generations was followed in three inter-varietal crosses. The non-fixable gene effects are higher than the fixable as a consequence of higher magnitude of epistatic interactions. Duplicate type of epistasis for different traits in three crosses in one or the other environment suggested to proceed with mild selection intensity in the early generations followed by intense in the later. The failure of the trigenic model for shelling (%), pods/plant, pod yield/ plant, pod length and seeds/ pod in all or in one of the crosses and environments revealed the complexity in the inheritance of these characters suggesting either presence of minor or modifier genes, and linkage rather than higher order interactions is responsible. The non-additive gene effects along with presence of non-allelic interactions for majority of the traits in respective crosses directed to adopt population improvement methods to break undesirable linkages through recombination or to defer selection in later generations following bulk pedigree or SSD methods with one or two inter-matings like recurrent selection.

Genetic analysis for yield and its attributes in bitter gourd (Momordica charantia)

Genetic interaction and inheritance study in bitter gourd was carried out using six-generation mean analysis to determinate the types and magnitude of gene effects for yield and its attributes. The knowledge portioning to gene action and interaction, is tool for designing appropriate breeding strategy for developing varieties in bitter gourd. Four crosses, viz. DBGS-54 × DBGS-34, DBGS-2 × DBGS-34, PVGy-201 × Pusa Do Mousami and DBGS-2 × DBGS-3 were used for studying six generation (P1, P2, F1, F2, B1 and B2) model. The presence of non-allelic interaction were detected by both scaling test and joint scaling test and observed inadequacy of the additive-dominance model for all traits except vine length in cross PVGy-201 × Pusa Do Mousami.The results revealed the contribution of additive (d), dominance (h) and epistasis interaction (i, j, l) towards expression of all traits studied. In most of the characters magnitude of dominance gene effect was greater than additive gene effect suggested that recurrent selection or heterosis breeding would prove useful. Duplicate epistasis was prevalent in most of the traits like vine length, days to first female flower and fruit weight. Fruit epicarp colour and seed coat colour inheritance suggested these traits were controlled by monogenic.

Genetics of Quality Attributes and Powdery Mildew Severity in Garden Pea (Pisum sativum Var. Hortense L.) under Sub Temperate Conditions of North-Western Himalayas

Background: The choice of appropriate breeding method for improvement of traits depends largely on gene action. Hence, an understanding of the inheritance of quantitative traits is essential to develop an efficient breeding strategy.Methods: Twelve generations of three inter-varietal crosses involving four diverse parents of garden pea were studied for biochemical traits and powdery mildew disease severity to analyze the nature of gene effects by using generation mean anaylsis.Result: Duplicate type of epistasis was observed for protein content in all or one or other crosses. In most cases, the presences of linkage among interacting genes or higher order interactions at several loci were involved. Non-fixable gene effects were many times higher than fixable one in all the crosses indicating a major role non-additive gene effects in the inheritance of these traits. The type of gene effects along with presence of non-allelic interactions suggested the adoption of population improvement methods to break undesirable linkages through recombination. The other alternative can be to defer selection in the later generations by advancing segregating populations through bulk pedigree or SSD methods with one or two inter-matings like recurrent selection. Based on pod characteristics and powdery mildew disease severity203 single plant progenies were isolated over the generations of three crosses along with bulk seed following SSD and bulk method to isolate transgressive segregants.

Genetic Analysis of Earliness and Lint Yield under Normal and Late Sowing Dates in Egyptian Cotton

THE PRESENT work was conducted to study the effects of late planting on the performance of Egyptian cottons, sensitivity to environments and gene action controlled earliness, lint yield/plant, lint % and lint index. A half diallel crosses of eight Egyptian cottons varieties were evaluated under normal and late plantings. The reduction % in lint yield/plant was 23.21 and 23.87% for the parents and F1 hybrids; respectively. The results of stress susceptibility index of LY/P indicated that six parents were tolerant for LY/P to late planting. Sixteen out of the 28 hybrids showed tolerance in LY/P to late planting. The diallel analysis revealed significant (p ≤ 0.01) items; ‘’a’’ and ‘’b’’, indicating that both additive and dominance effects of genes were involved in the inheritance of the five studied traits. The genetic parameter indicating that ‘’H1’’ tended to be more than the additive parameter ‘’D’’ under late planting. The regression analysis of Wr/Vr indicated the presence of non-allelic interaction in the inheritance of lint yield/plant under late planting. However, the additive–dominance model was adequate in the inheritance of days to first flower under normal and late plantings. The ‘’b2’’’ item and KD/KR indicated unequal distribution of dominance and recessive genes in the parents for all traits. The non-additive effects of genes were reflected in the departure of narrow form broad sense heritability. Therefore, pedigree and recurrent selection breeding methods could be effective to isolate lines adapted to late planting.

Genetic analysis of various quantitative traits ininter-varietal crosses of Vigna mungo

Gene effects for 13 characters in four crosses of Vigna mungo were studied by six parameter generation mean model to determine the potential for the improvement of yield components. Scaling tests revealed inadequacy of the additive-dominance model for all the traits indicating the presence of non-allelic interactions. Duplicate gene action was observed for six characters in KUG-216 x HPBU-111, five in KUG-216 x Palampur-93, two in IPU-05-13 x Palampur-93 and one in IPU-05-13 x HPBU-111 and complementary gene action for one character each in KUG-216 x Palampur-93 and IPU-05-13 x HPBU-111 cross. Selection in later generations for duplicate gene action and early generation selection involving intermatings in F2 f or complementary gene action should be adopted for harnessing desirable recombinants.

Scaling and joint scaling test for quantitative traits of generation mean analysis insesame (Sesamum indicum L.)

Gene effects for important quantitative traits of five crosses of sesame (Sesamum indicum L.) were estimated by partitioning the means and variances of means of six basic generations from each cross into their genetic components to assess the gene action governing the inheritance of traits. The additive, dominance and digenic non-allelic gene interactions were observed to govern most of the yield traits. The non-additive gene effects were more pronounced than additive onesfor most ofthe traits. The A,B,C and D scalesshowed highly significant values for all the traits and crosses studied and departure from zero indicated the presence of epistasis. But, these tests verify only the presence of epistasis but do not provide the kind of gene action. This indicates the inadequacy of scaling and joint scaling test and presence of non allelic interactions. The next possibility is to include the effect ofepistasis which can be estimated as additive x additive, additive x dominance and dominance x dominance gene effects in the inheritance of the characters.

GENETIC SYSTEM CONTROLLING THE YIELD AND ITS COMPONENTS IN THREE BREAD WHEAT (TRITICUM AESTIVUM, L.) CROSSES

This investigation was carried out at El. Gemmeiza Agric. Res. Station , A.R.C, Egypt, during the three successive seasons, 2009/2010, 2010/2011 and 2011/2012 to study genetic variance, gene action, heterosis, inbreeding depression, heritability and genetic advance for grain yield and its components and some agronomic characters. Six populations (P1, P2, F1, F2, Bc1 and Bc2) for three crosses were used in this study coming from (P1x P3), (P2 x P4) and (P3 x P4). Analysis of variance showed significant differences among the studied generations' means for all studied traits. Scaling test showed that most studied characters were significant indicating the presence of non-allelic interaction.. Additive type of gene effect was significant either positive or negative for no .of spikes / plant, 100-kernel weight and grain yield /plant in the first and second crosses. Meantime, dominance gene effects was significantly positive for all studied traits except plant height, no. of spikes /plant and grain yield /plant in the second cross .Additive x additive and additive x dominance type of gene actions were significantly positive or negative for all studied traits in the three crosses except for no .of spikes / plant in the first and second crosses and 100- kernel weight in the second and third crosses. On the other hand dominance x dominance type gene effect was found to be significant for all studied traits except plant height and 100-kernel weight in the first and third crosses, respectively. Heritability for days to heading in narrow sense was high and nearly equal to its corresponding in broad sense. High estimates for hertibility in broad sense were accompanied bymoderate value of narrow sense for no. of kernels /spike, 100 –kernel weight and grain yield plant in the three crosses.The third cross gave the highest heterotic effect towards earliness for number of days to heading and number of days to maturity with moderate heritability in narrow sense and with genetic advance being 1.59 and 1.98 days for both characters , respectively .Significant positive heterotic effects relative to better parent was obtained for no . of kernels / spike , 100 kernel weight and grain yield in the second and third crosses .

Inheritance of quantitative traits in opium poppy (Papaver somniferum L.)

Generation mean analysis was carried out using five parameter model on five cross combinations with five generations i.e. parents, F1s, F2s, and F3s randomly selected from partial diallel breeding experiment. The aim of study was to investigate the mode of gene actions involved in the inheritance of quantitative traits viz. days to 50% flowering, plant height, leaves/plant, capsules/plant, capsule size, capsule weight/plant, seed yield/plant and opium yield/plant. C and D scaling test showed the presence of non allelic interaction in the inheritance for all the traits except for plant height, seed yield/plant (ND1001xIS13) and capsule size (NBR5xND1002) which showed non interacting mode of inheritance. In general, the interaction effect together i.e. additive x additive [i] and dominance x dominance [l] found in higher magnitude than the combined main effects of additive [d] and dominance [h] effects for all the traits in all the five crosses. Dominance effect [h] was found pronounced for most of the traits except days to 50% flowering where additive effect [d] was found prevalent. Among the interaction effects dominance x dominance [l] was predominant over additive x additive [i] for all traits in all the five crosses except capsules/plant and capsule size in cross ND1001xNBRI11 and leaves/plant and opium yield/plant in cross NBRI5xND1002. As per sign of dominance (h) and dominance x dominance (l) duplicate epistasis were noticed for all the traits except plant height and leaves/plant in cross ND1001xUO1285. Potence ratio indicated presence of over dominance for almost all the traits. Substantial amount of realized heterosis, residual heterosis in F2 and F3 progenies and high heritability with moderate to high genetic advance in F2 progeny and significant correlation among important traits in desirable direction were observed. A breeding strategy of diallel selective mating or biparental mating in early segregating generation followed by recurrent selection may be used for genetic improvement.

Components of genetic variability and heritability of the number of rows per ear in silage maize

The aim of this study was to estimate the following components for the number of rows per ear in silage maize: variability of inbred lines and their diallel hybrids, superior-parent heterosis and components of genetic variability and heritability on the basis of diallel hybrids. It was determined that the variability of this trait was significantly affected by a genotype, year and their interaction. Inbred lines ZPLB 402, ZPLB 403 and ZPLB 405 had a higher number of rows per ears than majority of hybrids in both years of investigation, which resulted in negative values of heterosis. The analysis of components of genetic variance indicates that the additive component (D) was higher that the dominant (Hi and H2) genetic variance while a positive value of the component F and frequency of dominant (u) and recessive (v) genes for the observed trait point out that dominant genes prevailed over recessive ones. Furthermore, this is confirmed by a dominant to recessive genes ratio in parental genotypes for the number of rows per ear (Kd/Kr>l) in both years. The evaluated average degree of dominance a/h^7d was below 1, indicating to a partial dominance in heritability of this trait in both years. Results of the Vr/Wr regression analysis point out to a partial dominance in heritability of the number of rows per ear. Moreover, a presence of non-allelic interaction was detected, which indicates to a need to study effects of epistasis as it can be more important in certain hybrids. The greater value of additive variance resulted in greater narrow-sense heritability for the number of rows per ear in both years of investigation (86.83% and 69.44%, respectively).

Genetic components of pod shattering in soybean

Half diallel crosses among ten pure breeding lines of soybean were made in 1997 and 1998 to study the inheritance of pod shattering in soybean. Evaluation for pod shattering among F2 segregating populations was carried out in an oven set at 80 °C for 12 hours. Diallel analysis was carried out to estimate genetic parameters and detect presence of non allelic interaction of genes affecting pod shattering. Hayman's diallel analysis indicated significant variation of Wr + Vr and Wr – Vr over arrays, suggesting epistatic gene action. Similarly results from a joint regression coefficient over replications were significantly (p < 0.05) different from unity and zero, suggesting presence of non allelic interaction of genes. The intercept was positive, suggesting partial dominance for the shattering trait. Both general combining ability (GCA) and specific combining ability (SCA) effects were significant (p < 0.05).

Test of the Additive-Dominance Model of grain weight and grain uniformity of oat, Avena sativa L, genotypes.

An investigation of the genetic mechanisms controlling grain weights for the primary and secondary grains uniformity expressed in primary: secondary individual grain weight (P: S IGW) ratio and % tertiary grains produced was conducted using a backcross experiment'. Two oat, parental genotypes, I.L82-1657 (pistillate) and 10589 Cn (staminate) with different grain weight characteristics were hybridized to obtain 6 backcross generations viz. P1, P2, F1, B1, B2 and F2. The scaling test indicated that overall average, primary and secondary individual grain weights and % tertiary grain weight produced failed to satisfy the additive - dominance model and digenic interactions were detected except for the secondary individual grain weight. Grain weight uniformity expressed as P:S IGW ratio satisfied the additive - dominance model and was highly heritable (h2 narrow sense >98%). However, additive gene effect was important in the control of all the grain weight variables except the primary: secondary grain yield ratio. Dominance effect was important only for the overall average grain weight and the proportion of tertiary grains produced. Attainment of uniformity of oat grains looks promising through genetically improving the P:S IGW ratio but is challenged by the presence of non-allelic interactions in the control of % tertiary grain weight. Tanzania Journal of Science Volume 27 (2001), pp. 121-134

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.

Correlations, epistasis, and heterosis of plant height and internode length in barley

The correlation between total height and its components, and between these and yield components, and the presence of nonallelic interactions and heterosis were studied in barley by means of a 6 × 6 diallel cross. The estimation of interaction and heterosis parameters were made in P1, P2, F1, F2, B1, and B2 generations according to the Jinks and Jones model. Total height had a positive correlation with each internode length. The values of such correlations seemed to indicate that peduncle length could be a good index of total height. The plants with short basal internodes had less total height and longer intermediate internodes. The positive correlation of total height with yield and its components suggests that the selection for short culm and short basal internodes would be to the detriment of yield. The predominant interaction was of the duplicate type, the total height being the character with greater epistasis. In the crosses with heterosis, this was always positive. 'Albacete' × M-168 and A.1.-2 × M-168 were the crosses where the selection for short culm and lodging resistance would be most effective. Key words: diallel cross, correlations, epistasis, heterosis, barley.

Comparison of the inbred lines derived from a hybrid of tobacco (burley × flue cured) by dihaploidy and single seed descent

Inbred lines extracted by single seed descent (129 SSD families) and by dihaploidy (60 DH families) from a cross of a flue cured (SCR) and an air cured burley (S3) variety of tobacco have been compared in a completely randomised experiment at two planting densities (normal and double) for 11 characters including yield. The basic generations (parental varieties, F1, F2 and first backcrosses, B1 and B2) were also included to provide contemporary genetical controls.Half the characters show no difference in mean between the SSD and DH samples of inbred lines and the majority (nine out of 11) show no difference in genetical variance. For most characters there is no suggestion that the DH sample is showing the widely reported reduction in vigour relative to the SSD sample and the original parental varieties. Indeed the DH mean is the larger, implying greater vigour in more than half the cases where the DH and SSD sample means differ significantly. It is quite clear, therefore, that the relationship between the properties of the SSD and DH samples of inbred lines differs widely between characters.Leaving aside non-genetical explanations, the means of the inbred lines and the mean of the original parental varieties (mp) are expected to differ only in the presence of non-allelic interaction whereas the means of the SSD and DH samples of lines are expected to differ only if there is a linkage disequilibrium involving these interacting genes. Within the limitations of the genetical analyses of the basic generations these expectations are borne out.

Comparison of associated and dispersed testers in the triple test cross

The theoretical consequences of using inbred testers for an F2 and F∞ triple test cross in which the allelic differences are associated as opposed to dispersed are described for four situations of increasing complexity that arise from the presence of non-allelic interaction and a linkage disequilibrium either singly or jointly. The theoretical expectations are confirmed by analyses of two F∞ triple test crosses on a random sample of 60 inbred families from the cross of varieties 2 and 12 of Nicotiana rustica for which the inbred testers are the two varieties and the two extremes of the 60 inbred families in respect of final height and flowering time. In the presence of non-allelic interaction and a linkage disequilibrium between interacting or non-interacting genes, the expectations of the mean squares in the analysis of variance of a triple test cross and of the estimates of the additive genetic, dominance and epistatic components obtained from them, differ characteristically according to whether a dispersed or an associated pair of inbred testers have been used. The pattern of the differences can, therefore, be used to detect these complex effects. Comparison of the corresponding mean squares and estimates from the two F∞ triple test crosses shows that non-allelic interactions and a linkage disequilibrium are present but there is no significant evidence that the disequilibrium involves interacting genes.

Diallel analysis in groundnut (Arachis hypogaea L.)

An 8 × 8 full diallel experiment based on 4 bunch plus 4 spreading types of groundnut (Arachis hypogaea L.) was conducted over three environments. For both number of pods and pod yield, additive, nonadditive and reciprocal cross effects were detected and these were also influenced by changes in environments. For number of pods additive genetic variance was predominant whereas it was approximately equal to non-additive genetic variance for pod yield. Graphical analysis revealed the presence of strong non-allelic interaction for number of pods whereas for pod yield absence of dominance and/or presence of non-allelic interaction was evident.