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The present investigation was conducted to know the impact of bio-inoculants in low input field conditions on the magnitude and direction of gene effects and mean performance of some morphological and productivity traits in three wheat cultivars WH 147 (medium mineral input), WH 533 (drought tolerant), Raj 3077 (drought tolerant) and six generations namely P 1 , P 2 , F 1 , F 2 , BC 1 and BC 2 of three crosses i.e. WH 147 × WH 533, WH 533 × Raj 3077 and WH 147 × Raj 3077. The experiment was conducted in randomised block design with three replications and three treatments i.e. control (C, without inoculation), inoculation with arbuscular mycorrhiza fungi (AMF, Glomus fasciculatum), and AMF + Azotobacter chroococcum (Azc). Mineral fertilizer (80 kg N/ha + 40 kg P/ha + 18 kg ZnSO 4 /ha) was applied in all the three treatments. The application of bio-inoculants, AMF and AMF + Azc had a positive effect on plant height, peduncle length, grain yield, biological yield and harvest index in various populations of all the crosses. However, in some of the generations the impact of bio-inoculants was insignificant. The joint scaling test revealed that additive-dominance gene effects were mainly operative in governing expression of peduncle length, tillers per plant, plant height, grains/spike, grain yield and all traits except days to flowering and harvest index in crosses WH 147 × WH 533 and WH 533 × Raj 3077. The application of bioinoculants influenced gene effects for days to flowe ring, days to maturity, flag leaf area, spike length, grains/spike, 1000 grain weight and harvest index where complex genetic interactions were changed to simple additive-dominance gene effects in the cross WH 147 × Raj 3077. Likewise, additive-dominance gene effects were altered and digenic interactions exhibited for days to maturity, flag leaf area in WH 147 × WH 533 and days to flowering, plant height, flag leaf area in WH 533 × Raj 3077. Flag leaf area and plant height were governed by additive gene effects while for days to maturity and 1000-grain weight both additive and dominance gene effect were important. Duplicate epistasis was important in all the three crosses for days to flowering and harvest index and in the cross WH 147 × Raj 3077 for grain weight grains per spike and flag leaf area.

Genetically modified (GM) strains now exist for many organisms, producing significant promise for agricultural production. However, if these organisms have some fitness advantage, they may also pose an environmental harm when released. High mating success of GM males relative to WT males provides such an important fitness advantage. Here, we provide documentation that GM male medaka fish modified with salmon growth hormone possess an overwhelming mating advantage. GM medaka offspring possess a survival disadvantage relative to WT, however. When both of these fitness components are included in our model, the transgene is predicted to spread if GM individuals enter wild populations (because of the mating advantage) and ultimately lead to population extinction (because of the viability disadvantage). Mating trials indicate that WT males use alternative mating tactics in an effort to counter the mating advantage of GM males, and we use genetic markers to ascertain the success of these alternative strategies. Finally, we model the impact of alternative mating tactics by WT males on transgene spread. Such tactics may reduce the rate of transgene spread, but not the outcome.

Using Hayman's model of genetic analysis of the F1 hybrids from crosses between early- and late-ripening forms of cotton Gossypium hirsutum L., we examined inheritance of the duration of vegetative period at various contents of nitrogen in soil. Two variants of hybrid plants were studied. With the natural content of soil nitrogen, incomplete directionally dominance of earliness over late ripening with prevalence of additive gene effect of nonallelic interactions was observed. The genetic formulas of this trait proved to change with varying nitrogen nutrition.

Despite tremendous efforts, few genes involved in the susceptibility for complex disorders have been identified. One explanation is that these disorders are a result of an interaction between genes and environment, and under such conditions, it may be difficult to measure the true genetic effect without accounting for the interaction. Umbach and Weinberg ([2000] Am. J. Hum. Genet. 66:251–261) proposed an association test which looks at the joint effects of genotype and environment, using case-parent trios. In this study, we explore under which conditions accounting for G×E interaction enhances one's ability to detect the role of genetic factors in complex diseases. Using asymptotic power calculations, we investigate the power to detect the gene effect over varying exposure frequencies and different scenarios of G×E interaction. We show that for a given sample size, interaction scenario, and allele frequency, the actual gain in power while accounting for the interaction depends on the magnitude of the exposure frequency: the largest gains are seen for relatively low exposure frequencies. Moreover, a loss of power can be observed when the exposure is frequent and/or the exposure effect is strong. If we consider a gene with a disease allele frequency of 0.2, with no effect in the absence of exposure, an exposure with a 10-fold increase risk and a G×E relative risk of 2, then when the exposure frequency is 0.1, accounting for G×E interaction increases the power to detect the gene effect in 200 trios by 10%; alternatively, when the exposure frequency is 0.9, it decreases the power by 15%. Genet Epidemiol 24:200–207, 2003. © 2003 Wiley-Liss, Inc.

The mode of inheritance and gene effect for plant height of 7x7 half diallel crosses of wheat varieties and lines was evaluated in F1 and F2 generation. The mode of inheritance, calculated for each combination separately, was different and depended on the cross combination. The absence of interallelic interaction between the genes determining the expression of plant height was concluded from the regression analysis. The regression line intercepts the Wr axis below the origin in F1 indicating overdominance over an average of all arrays. In F2 the regression line cuts the Wr axis above the origin indicating partial dominance.

Sunflower is the main crop species for the production of edible oil in many countries of the world, including ours. Plant height and head size, form and position on the stem as well as the number of leaves, their size, duration and distribution on the plant all play an important role in defining optimal plant architecture in sunflower hybrids (Škorić, 1975, 1989, 2002). In order to monitor the mode of inheritance and gene effects for head diameter in the F1 and F2 generations, half diallel crosses were made in six genetically divergent sunflower inbreds. The mean values of the trait in question differed significantly. The mode of inheritance of head diameter in the F1 generation was superdominance in all but four crosses, which had dominance instead. In the F2 generation, on the other hand, the prevailing mode was dominance, while superdominance was recorded in four cases. The dominant component accounted for the bulk of genetic variance, and the mode of inheritance of head diameter taking into account both the F1 and F2 generations was superdominance. These findings may prove valuable for developing high-yielding sunflower genotypes. Suncokret je u mnogim zemljama u svetu i kod nas osnovna biljka za proizvodnju jestivog ulja. Visina biljke, veličina, forma i položaj glave na stablu, broj listova, njihova veličina, trajanje i raspored na biljci imaju važnu ulogu u definisanju optimalne arhitekture hibrida suncokreta (Škorić 1975; 1989; 2002). U cilju praćenja načina nasleđivanja i efekta gena prečnika glave suncokreta u F1 i F2 generaciji izvršena su dialelna ukrštanja isključujući recipročna sa šest genetski divergentnim inbred linijama suncokreta. Dobijene su značajne razlike u srednjim vrednostima za ispitivano svojstvo. Prečnik glave se u F1 generaciji nasleđivao superdominantno jedino se u četiri ukrštanja javila dominacija, dok se u F2 generaciji nasleđivao dominantno, a superdominacija se zadržala u četiri kombinacije. Glavni deo genetske varijanse čini dominantna komponenta, a način nasleđivanja prečnika glave je superdominacija uzevši u obzir sve kombinacije ukrštanja u obe generacije (F1 i F2). Ova istraživanja mogu biti od značaja u stvaranju visoko prinosnih genotipova suncokreta.

Field-based adult plant resistance assessment at multi-location rust hot spot sites is a crucial job for those plant pathologists screening several wheat lines at a time against the rusts. Rust resistant bread wheat genotypes that have been extracted from previous studies have sustained wheat production in Ethiopia. The objective of this study was to evaluate advanced bread wheat lines extracted from wheat breeding trials against stem rust at adult plat stage under stem rust hot spot sites and at seedling stages in the greenhouse. Eighty three lines were further re-evaluated in consecutive two years. Check varieties were included for comparison. High disease pressure was developed on adult plant in the trial as it has been revealed by high severity on susceptible check varieties. Over years average final rust severity, co-efficient of infection and field reaction have used for differentiating Adult plant resistances. Based on ACI, the 843 genotypes evaluated in initial trial in 2013 were categorized into 10 resistance levels, of which 188 genotypes were in high level resistance category, revealing that various level of adult plant resistance is operating in these test materials. Most of 83 genotypes r-evaluated in consecutive two years after initial stage have sustained low final stem rust severity and coefficient of infection as compared with check varieties. Genotypes were varied by adult plant reaction to stem rust, however, lines ETBW7818, ETBW7819, ETBW7258, ETBW 8008, ETBW 8009, ETBW 8017, ETBW 8027, ETBW 8052, ETBW 8054 and ETBW 8055 concisely showed a reaction of R to R-MR invariably with environments. Of the 83 lines tested at seedling stages against four races, 21 lines exhibited resistance to three races JRCQC, TKTTF, TTKSK and TRTTF whereas 24 lines showed susceptibility to the latter three races. Based on adult reaction, final disease severity and coefficient of infection data, Sixty six bread wheat lines and two cultivars Shorima and Huluka sustained final rust severity

Genetic variability studies provide basic information regarding the genetic properties of the population based on which breeding methods are formulated for further improvement of the crop. The estimates of herit- ability, coefficients of variability and genetic advance computed for 31 yield contributing traits. High GCV and PCV reported for the traits Unfilled spikelets panicle-1, filled spikelets panicle-1, seed yield plant-1, pollen viability, total spikelets panicle-1, effective tillers plant-1, panicle weight plant-1, tillers plant-1, spikelet density, spikelet fertility, biological yield plant-1, harvest index, flag leaf length and culm length. The traits viz., unfilled spikelets panicle-1, filled spikelets panicle-1, seed yield plant-1, panicle weight plant-1, total spikelets panicle-1, effective tillers plant-1, pollen viability, spikelet density, tillers plant-1, spikelet fertility, harvest index, biological yield plant-1, flag leaf width, panicle index, length breadth ratio, head rice recovery, 1000 seed weight, length breadth ratio of de- corticated seed, culm length, plant height, flag leaf length, panicle length, decorticated seed width, milling percent, hulling percent, decorticated seed length, seed width and seed length had high heritability accompanied with high genetic advance indicating lesser environmental influence and were under the control of additive gene effect.

Deletion of a genomic locus may affect the function of neighboring loci, creating genetic uncertainty. Researchers now present a computational algorithm for identifying such neighboring-gene effects and improving the quality of functional annotations.

Knowledge of major gene effects for quantitative traits (e.g. milk performance traits) and the consequent selection of animals with desirable genotypes can accelerate breeding progress and can therefore equal large gain in profits. It is generally accepted that in most cases, the total breeding value for quantitative traits of any animal can be divided in one or some major gene effects and a pure random polygenic component, in which the latter results from a finite number of remaining loci (FERNANDO et al. 1994). Thus, the aim of this study was to investigate, how the estimation of heritability is influenced by the application of two different models, one of them containing a major single gene effect. The myostatin gene (MSTN) was chosen because the knowledge of this gene effect is used for selection decisions in the Dual Purpose Belgian Blue Breed (DP-BBB) in the Walloon Region of Belgium.

U radu je analizirana varijabilnost, genski efekti, nasleđivanje komponenata prinosa u ukrštanju pet sorti heksaploidne pšenice (Triticum aestivum L.). Rezultati istraživanja iv ukazuju da između roditelja i generacija potomstava postoje značajne razlike u srednjim vrednostima ispitivanih svojstava. Metodom dialelnog ukrštanja utvrđena je kombinaciona sposobnost roditeljskih linija i dobijene su informacije o prirodi genskih efekata za važne agronomske osobine. U nasleđivanju komponenata prinosa (visina biljke, masa biljke, dužina klasa, broj zrna po klasu, masa zrna po klasu i masa zrna po biljci), primenom aditivno-dominantnog modela, uočeno je prisustvo nealelne interakcije – epistaze. Analizom međuzavisnih odnosa ustanovljene su značajne ili visoko značajne vrednosti koeficijenata korelacije između većine ispitivanih svojstava., A study has been conducted to assess variability, gene effect and inheritance of yield components in five crosses of hexaploid wheat genotypes (Triticum aestivum L.). The results of the study have shown that the mean values of parents and their progenies were significantly different. In diallel vii crossing information about combining ability of parental lines and the nature of genetic effects for some important agronomic traits had been obtained. Non-allelic interactions, epistatic gene effect, were observed in the inheritance of yield components (stem height, biomass, spike length, kernel number per spike, kernel weight per spike and kernel weight per plant) using the additive-dominance model. Significant and highly significant values of correlation coefficients were calculated for the most of studied traits.

The development of sunflower hybrids with high genetic potential for seed and oil yields requires information on the general combining ability (GCA) and specific combining ability (SCA) for plant height and head diameter in the F1 generation. Used in this study were thirteen new divergent cms inbred lines (A), three Rf restorers utilized as testers, and their F1 hybrids. The inbred A-lines, Rf-testers and F1 hybrids differed significantly in the mean values for plant height and head diameter. The mode of inheritance for plant height was superdominance of the better parent and for head diameter it was dominance and superdominance of the better parent. Highly significant positive values of GCA for both traits were found in cms inbred line NS-G-7 and restorer line RHA-N-49. Based on the GCA values chosen were lines with the best GCA for plant height (NS-G-9, NS-G-7) originating from PRA-RUN and head diameter (NS-G-13, NS-G-12) originating from DES. The greatest highly significant positive SCA value was found in NS-G-1xRHA-N-49 for plant height and in NS-G-8xRUS-RF-OL-168 for head diameter. Non-additive genetic variance played the main role in the inheritance of both traits as confirmed by the GCA/SCA ratios in the F1 generation, which were invariably smaller than unit. The female A lines had the highest contribution to the expression of head diameter and plant height. [Projekat Ministarstva nauke Republike Srbije, br. TR 31025]

In Ethiopia, there are several maize production constraints, among which shortage of improved varieties is the major one. The objective of this study was to observe the mean performance of crosses and estimate combining abilities for grain yield and other agronomic traits in thirty six maize inbred lines using Line x Tester mating design. Seventy-two lines x test crosses (L1xT1, L1xT2, L2xT1, L2xT2… L36xT1 and L36xT2) and three standard checks were evaluated for 11 traits in alpha lattice design at Melkassa, Ethiopia. Analyses of variances showed significant mean squares due to crosses for all traits. Among the crosses, L34xT2, L36xT2, L30xT1, L19xT1 and L33xT2 crosses were the top five highest grain yield mean performance. While L35xT1, L23xT1, L13xT1, L24xT2 and L15xT1 crosses were lowest mean grain yield performance. GCA Mean squares were significant, but SCA mean squares were non-significant for all traits. The ratio of GCA/SCA mean square was high which exhibited the preponderance of additive gene effects in the inheritance of all traits. Furthermore, the GCA sum of square component was greater than the SCA sum of square for all traits, supported that variation among crosses was mainly due to additive rather than non-additive gene effect. Inbred lines L15, L25, L27, L33, L34 and L35 were the best general combiners for grain yield, and hence were promising parents for hybrids as well as for inclusion in breeding programmes for yield improvements. Inbred lines L2, L3, L4, L6, L10, L27, L30, L31 and L32 had negative and significant GCA effects for the days to anthesis, indicating that the lines had gene combinations that can enhance early maturity.

Genetic improvement of acid soil tolerance of wheat (Triticum aestivam L.) adaptable to the Great Plains involves the transfer of Al tolerance from other gene pools. One hindrance may be the interaction of gene effect with genetic background. Aluminum-tolerant near-isolines of hard red winter (HRW) wheat were selected on the basis of the hematoxylin assay using 'Atlas 66' as the source of tolerance. The objectives were to enumerate the genes for Al tolerance in these lines and to quantify their expression in artificial solution and natural soil media containing Al. Laboratory and growth chamber experiments were conducted with Al-tolerant and Al-susceptible near-isolines of 'Chisholm' and 'Century'. Segregation for hematoxylin staining score in populations derived from crossing the tolerant isoline with its recurrent parent indicated a single dominant gene was transferred from Atlas 66. This gene does not appear to be unique relative to '2180'. Dose-response curves for relative root length (RRL) measured in solution culture confirmed differences in Al tolerance predicted by the hematoxylin assay. Each tolerant isoline showed a linear decline in RRL to increasing Al concentration (0.09-0.72 mM Al), while the susceptible isolines and recurrent parents showed a more acute curvilinear response. The tolerant isolines exceeded their recurrent parent by 19% (Chisholm) and 38% (Century) in RRL, measured in five acidic Appalachian soils. While the hematoxylin assay enabled selection of a dominant gene conferring increased root growth in response to Al, complete expression of tolerance from Atlas 66 was not achieved or was modified in these HRW backgrounds.

This study was conducted to evaluate the types of gene action governing the inheritance of resistance to peanut bud necrosis disease (PBND) in populations derived from three crosses involving two resistant (ICGV 86388 and IC 10) and one susceptible (KK 60–1) peanut lines. Populations were composed of P1 P2, F1 F2, BC11, BC12, BC11S and BC12S. These populations were evaluated for PBND incidence in a farmer's field in Kalasin province in north-east Thailand, where PBND is a recurring problem. Results showed variations between crosses in the relative contributions of different types of gene effect. The results indicate that multiple genes control the PBND resistance trait, and that the two resistant lines differ in some of these genes. As non-additive gene effects are important in all three crosses, selection for low PBND incidence in these crosses would be more effective in later generations.

Combining ability estimates of roselle cultivars were studied in a 6 x 6 half diallel analysis. The results showed significant entries, parents and crosses for all the traits studied in the individual and also in the poolled analysis, suggesting that roselle populations were highly variable for all the traits and therefore would most likely respond to selection. Significant GCA and SCA variances were also obtained in all the traits,implying that both the additive and non-additive gene effects were operating in the genetic expression of the traits. The non-additive gene effect was however greater in magnitude as shown by the δ2GCA/δ2SCA ratios, which were all less than unity. The combining ability analysis of parents also revealed that Gerio-AB3, Bazza-AB2 and Bazza-AB1 yielded consistently higher general combining ability effect for most of the traits, indicating that their crosses should produce desirable segregates for the improvement of calyx yield of roselle. SCA effects identified Bazza-AB2 x Gerio-AB2, Bazza-AB1 x Gerio-AB3 and Bazza-AB1 x Michika-AB1 as the best crosses.

Not accounting for interaction in association analyses may reduce the power to detect the variants involved. We investigate the powers of different designs to detect under two-locus models the effect of disease-causing variants among several hundreds of markers using family-based association tests by simulation. This setting reflects realistic situations of exploration of linkage regions or of biological pathways. We define four strategies: (S1) single-marker analysis of all Single Nucleotide Polymorphisms (SNPs), (S2) two-marker analysis of all possible SNPs pairs, (S3) lax preliminary selection of SNPs followed by a two-marker analysis of all selected SNP pairs, (S4) stringent preliminary selection of SNPs, each being later paired with all the SNPs for two-marker analysis. Strategy S2 is never the best design, except when there is an inversion of the gene effect (flip-flop model). Testing individual SNPs (S1) is the most efficient when the two genes act multiplicatively. Designs S3 and S4 are the most powerful for nonmultiplicative models. Their respective powers depend on the level of symmetry of the model. Because the true genetic model is unknown, we cannot conclude that one design outperforms another. The optimal approach would be the two-step strategy (S3 or S4) as it is often the most powerful, or the second best. Genet.

The inheritance of capsaicinoid content was studied in five Capsicum pubescens Ruiz & Pav. genotypes using diallel analysis. General combining ability and specific combining ability effects were significant for all capsaicinoids studied, indicating additive and nonadditive gene actions are present. The association of high capsaicinoid contents with high positive general combining ability of the parents also indicates the predominance of additive gene action in capsaicinoid inheritance. Because of the predominant additive gene effect, recurrent selection would be a good breeding method to increase capsaicinoid level in the population studied. Heterosis was observed in hybrids for some of the capsaicinoids, suggesting that F 1 hybrids could also be used to increase capsaicinoid content. useful to study the inheritance of capsaicinoids. Therefore, this research was undertaken to determine the inheritance of the individual capsaicinoids based on general combining ability and specific combining ability.

This study evaluated the types of gene action governing the inheritance of resistance to Phytophthora nicotianae necrosis in populations derived from two crosses involving two susceptible (Beldi and Nabeul II) and one resistant (CM334) cultivars of pepper (Capsicum annuum L.). Populations, composed of Pr, Ps, F(1) , F (2) , BC (1) Pr, and BC (1) Ps generations, were inoculated with six P. nicotianae isolates. Generation means analysis indicated that an additive-dominance model was appropriate for P. nicotianae isolates Pn (Ko1) , Pn (Ko2) and Pn (Kr1) , which showed low aggressiveness in the two crosses. For the more aggressive isolates Pn (Bz1) , Pn (Bz2) and Pn (Kr2) , epistasis was an integral component of resistance in the two crosses. The presence of epistasis in the resistance of pepper to P. nicotianae was dependent on the level of aggressiveness of the isolates. Selection in pepper with less aggressive isolates was efficient, but not with more aggressive isolates; on the other hand, selection with more aggressive isolates was more stable. The minimum number of genes controlling resistance was estimated at up to 2.71. In the majority of cases, the additive variance was significant and greater than the environmental and dominance variance.

Diallel mating design experiment with reciprocal crosses was used to determine combining abilities of five maize inbred lines and their hybrid combinations for grain yield, ear length, ear diameter, number of kernel rows per ear, number of kernels per row in 2005. and 2006. year. GCA and SCA significant values were observed for all traits under study in both years. GCA/SCA relation showed that dominant gene effect had prevalent influence in the inheritance of grain yield, ear length and ear diameter. Additive gene effect had larger importance in the inheritance of number of kernel rows per ear. NS-1445 inbred line showed best GCA effect for grain yield, ear length and number of kernels per row, but worst GCA effect for number of kernel rows per ear. Best GCA effect for ear diameter achieved inbred line F-7R. Line BL-47 showed best GCA effect for number of kernel rows per ear in both years, but also the worst GCA effect for grain yield and number of kernels per row. Hybrid combination NS-1445 x BL-47 showed largest SCA effect for grain yield in both years and also showed, like hybrid combination F-7R x NS-1445, significant SCA effects for all other traits, except ear diameter. This cross also proved that hybrid combinations that include one parent with good GCA effect and the other parent with bad GCA effect can have very successful performance. It will be useful during selection material testing, to keep also genotypes which show bad GCA effect, but have phenotypic favorable trait values. Reciprocity effect was significant for SCA effects of all traits but ear diameter. It is the conformation of involvement of plasmagenes in maize quantitative traits inheritance. The largest reciprocity effect for grain yield achieved F-7R x BL-47 in both years. Significantly higher grain yield in this hybrid combination was achieved when line F-7R was used as a female parent and significantly higher number of kernel rows per ear was achieved when line BL-47 was used as a female parent. Metodom dialelnog recipročnog ukrštanja utvrđene su kombinacione sposobnosti pet inbred linija kukuruza i njihovih hibridnih kombinacija za prinos zrna, dužinu klipa, prečnik klipa, broj redova zrna i broj zrna u redu u 2005. i 2006. godini. Ustanovljene su značajne vrednosti OKS i PKS za sve ispitivane osobine u obe proučavane godine. Odnos između OKS i PKS, pokazuje da dominantno delovanje gena ima preovlađujuću ulogu u nasleđivanju prinosa zrna, dužine klipa i prečnika klipa, dok aditivno delovanje gena ima veći značaj u nasleđivanju broja redova zrna. Najbolju OKS za prinos zrna, dužinu klipa i broj zrna u redu pokazala je linija NS-1445, koja je ujedno imala i najslabiju OKS za broj redova zrna. Najbolju OKS za prečnik klipa pokazala je linija F-7R. Najbolju OKS za broj redova zrna pokazala je linija BL-47 u obe proučavane godine, a ujedno je imala i najslabiju OKS za prinos zrna i za broj zrna u redu. Najveću vrednost PKS za prinos zrna pokazao je hibrid NS-1445 x BL-47 u obe proučavane godine, koji je osim toga, kao i hibrid F-7R x NS-1445, pokazao značajne vrednosti PKS i za sve ostale osobine, osim prečnika klipa. To je dokaz da pojedine hibridne kombinacije koje uključuju jednog roditelja sa dobrim OKS i drugog roditelja sa lošim OKS, mogu imati izuzetno dobre performanse. Zbog toga bi prilikom testiranja selekcionog materijala, korisno bilo zadržati i one genotipove koji pokazuju loše OKS, a ujedno imaju fenotipski poželjne osobine. Ustanovljeno je da recipročno ukrštanje utiče na efekat PKS za sve ispitivane osobine, osim prečnika klipa. To ukazuje, da osim nuklearnih gena i plazma geni imaju važnu ulogu u nasleđivanju kvantitativnih osobina kukuruza. Najveću razliku u vrednosti PKS za prinos zrna između direktnog i recipročnog ukrštanja ostvario je hibrid F-7R x BL-47 u obe proučavane godine. Pri tome su značajno veći prinosi zrna ostvareni korišćenjem linije F-7R kao ženskog roditelja. Suprotno prinosu, ovaj hibrid je imao značajno veći broj redova zrna sa linijom BL-47 na poziciji ženskog roditelja.

Considering the potential threat of grey leaf spot (GLS) to maize production, the national maize research program of Ethiopia has been screening local and exotic maize genotypes against the disease as the commercially available and advanced inbred lines susceptible to GLS. This experiment was, therefore, conducted to investigate the general (GCA) and specific (SCA) combining ability of selected maize inbred lines for grain yield and GLS disease resistance. Eight maize inbred lines with contrasting reactions to GLS were crossed in diallel mating to generate 28 hybrids. The parents and hybrids were evaluated in randomised complete block design with three replications at Bako, Ethiopia in 2001 and 2002. Significant differences were observed among entries for disease parameters, plant height, days to maturity and grain yield. GCA and SCA effects were significant for all traits. Mean squares due to GCA were higher than that of SCA for all traits, except for grain yield, indicating the predominance of non-additive gene effect for grain yield and additive gene effect for other traits. Some inbred lines with resistance reaction have been identified. Parental lines 143-5-i and CML-387 showed a better per se performance and GCA effects while A-7016 was the worst parent for GLS disease reaction. Inbred parent 143-5-i was the best general combiner for grain yield; but a poor general combiner for plant height and days to maturity. The information from this study will be useful for the development of high-yielding and GLS disease-resistant maize varieties., East African Journal of Sciences, Vol. 2 No. 2 (2008): East African Journal of Sciences

Gossypium hirsutum L. türüne ait 5 ana ve 3 baba genotipin line x tester uyarınca melezlenmesi sonucu oluşan 15 melez populasyon verim, verim komponentleri, lif kalite özellikleri, koza içi verim kompenentleri ve Verticillium dahliae Kleb.'e dayanıklılığın genetik yapısı yönünden değerlendirilmiştir. İncelenen özellikler yönünden uygun anaçlar, ümitvar melezler ve heterotik etkiler incelenmiştir. Çalışma Nazilli Pamuk Araştırma Enstitüsünde hastalıkla bulaşık tarlada ve iklim odası koşullarında yürütülmüştür.Genel uyuşma yeteneği varyansının, özel uyuşma yeteneği varyansına oranına göre; hasta bitki oranı, tarla denemesi hastalık enfeksiyon şiddeti, çırçır randımanı, bitki boyu, tek koza kütlü ağırlığı, kozada tohum verimi, kozada lif verimi, kozada tohum sayısı, tohumda lif verimi, lif esnekliği, lif yeknesaklığı, lif iplik olabilirlik özellikleri yönünden eklemeli gen etkileri; iklim odası hastalık enfeksiyon şiddeti, pamuk kütlü verimi, lif verimi, erkencilik, bitkide koza sayısı, metrekarede tohum verimi, metrekarede lif verimi, metrekarede koza sayısı, yüz tohum ağırlığı, kozada çenet sayısı, çenette tohum sayısı, tohumda lif sayısı, tek lif ağırlığı, lif uzunluğu, lif inceliği, lif mukavemeti özellikleri yönünden eklemeli olmayan gen etkileri saptanmıştır.İncelenen özelliklerin tümü yönünden Nazilli 84, Carmen, Şahin 2000, DPL 5690 ve Acala Maxa uygun anaçlar olduğu bulunmuştur. Öte yandan incelenen özelliklerin çoğu yönünden Şahin 2000 x Carmen, Nazilli 84 x Carmen, Sg 125 x Acala Maxa, Şahin 2000 x Acala Maxa, Nazilli 84 x Fibermax 819 ve Şahin 2000 x Fibermax 819 kombinasyonlarının ümitvar melezler olduğu belirlenmiştir. Fifteen cotton (Gossypium hirsutum L.) F1 hybrids obtained by crossing 5 lines and 3 testers in line × tester mating system were evaluated in terms of yield, yield components, fiber quality parameters, within-boll yield components, and genetic structure of resistance to Verticillium dahliae Kleb.. The suitable parents, promising hybrids and heterotic effects for investigated traits were detected. Experiments were conducted at disease infected field and climate chamber at Nazilli Cotton Research Institute.The additive gene effects for infected plants ratio, disease infection severity, lint percentage, plant height, boll weight, seed yield per boll, boll lint yield, seed number per boll, seed lint yield, elongation, uniformity, and spinning consistency index; non-additive effects for yield, lint yield, earliness, number of boll per plant, seed yield per unit area, lint yield per unit area, number of boll per unit area, 100 seed weight, number of locule per boll, number of seeds per locule, fibers per seed, single fiber weight, fiber length, micronaire, fiber strength were estimated according to the ratio of general combining ability to specific combining ability variance.Nazilli 84, Carmen, Şahin 2000, DPL 5690 and Acala Maxa were found to be suitable parents for all traits. Şahin 2000 x Carmen, Nazilli 84 x Carmen, Sg 125 x Acala Maxa, Şahin 2000 x Acala Maxa, Nazilli 84 x Fibermax 819 and Şahin 2000 x Fibermax 819 combinations were determinate promising hybrids for majority of its component traits. 125

Genetic architecture of two commercial open-pollinated varieties of pearl millet (ICTP 8203 and ICMV 221) for grain iron and zinc densities was studied using 160 full-sib progenies each that were developed following North Carolina Design-1 and evaluated for two seasons. Results showed predominantly additive genetic variance and nonsignificant additive gene effect × environment interaction variance compared to large and significant dominance × environment interaction variance for both micronutrients in both populations. This translated into high narrow-sense heritability for Fe (65%) and Zn (86%) in ICTP 8203, and moderate heritability of 45% for both micronutrients in ICMV 221. In comparison, 1000-seed weight, generally assumed to be highly heritable, was predominantly under dominance gene control and had large dominance × environment interaction, giving the narrow-sense heritability estimates of 31% in ICTP 8203 and 13% in ICMV 221. These results, and highly significant and positive correlation observed between Fe and Zn densities, and non-significant correlations of these micronutrients with grain weight suggest that simultaneous selection for Fe and Zn densities in these populations can be effectively made without compromising the grain size.

In diallel crosses (without reciprocals) of four genetically divergent wheat cultivars (Jugoslavija, Osijecanka, Zitnica, and NS Rana 2) the variability and inheritance of physiological nitrogen efficiency (PEN) in wheat plant were investigated. The mode of inheritance, gene effect, combining ability of parent cultivars and F1 and F2 hybrids for physiological nitrogen efficiency (PEN) were studied. The different mode of inheritance: partial dominance, dominance and overdominance for analyzed traits were established. On the base of genetic components of variance was estimated that non-aditive gene action have gene higher impact than additive in the inheritance of PEN. The best general combiner for PEN in both F1 and F2 generation was Zitnica cultivar. The combination Zitnica x NS Rana 2 in both F1 and F2 generation was the best for PEN.

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The mean identity-by-descent (IBD) specification used in the Generalized Estimating Equations (GEE) methodology for linkage is only valid, strictly speaking, under the assumption of fully polymorphic markers. In practice, markers often provide only partial IBD information, which can potentially result in inconsistency of the locus location and gene effect estimates obtained by the GEE method. Using both simulations and theory, we identify some realistic conditions about marker information under which the validity of the GEE linkage methods may be arguable. Namely, researchers should not trust the GEE parameters' estimates and their associated confidence intervals in areas of the genome where IBD information is sparse or when this information changes abruptly. We show that properly standardized statistics based on IBD sharing provide a valid alternative.

Quantitative trait locus (QTL) analysis on pooled data from multiple populations (pooled analysis) provides a means for evaluating, as a whole, evidence for existence of a QTL from different studies and examining differences in gene effect of a QTL among different populations. Objectives of this study were to: (1) develop a method for pooled analysis and (2) conduct pooled analysis on data from two soybean mapping populations. Least square interval mapping was extended for pooled analysis by inclusion of populations and cofactor markers as indicator variables and covariate variables separately in the multiple linear models. The general linear test approach was applied for detecting a QTL. Single population-based and pooled analyses were conducted on data from two F(2:3) mapping populations, Hamilton (susceptible) x PI 90763 (resistant) and Magellan (susceptible) x PI 404198A (resistant), for resistance to soybean cyst nematode (SCN) in soybean. It was demonstrated that where a QTL was shared among populations, pooled analysis showed increased LOD values on the QTL candidate region over single population analyses. Where a QTL was not shared among populations, however, the pooled analysis showed decreased LOD values on the QTL candidate region over single population analyses. Pooled analysis on data from genetically similar populations may have higher power of QTL detection than single population-based analyses. QTLs were identified by pooled analysis on linkage groups (LGs) G, B1 and J for resistance to SCN race 2 whereas QTLs on LGs G, B1 and E for resistance to SCN race 5 in soybean PI 90763 and PI 404198A. QTLs on LG G and B1 were identified in both PI 90763 and PI 404198A whereas QTLs on LG E and J were identified in PI 90763 only. QTLs on LGs G and B1 for resistance to race 2 may be the same or closely linked with QTLs on LG G and B1 for resistance to race 5, respectively. It was further demonstrated that QTLs on G and B1 carried by PI 90763 were not significantly different in gene effect from QTLs on LGs G and B1 in PI 404198A, respectively.

Two dwarf brown-egg layer lines, differing in their genotype for the naked neck gene (NA), line L2 (NA*NA/*NA) and line L1 (NA*N/*N), have been selected for 16 generations for increased average clutch length. A control line from the same base population, dwarf and segregating for the NA gene, was maintained by random mating. Genetic parameters were estimated by a multivariate derivative-free restricted maximum likelihood procedure, and the NA gene effect was estimated within the unselected control line. The studied traits included clutch traits, egg production traits, abnormal eggs, egg weight at 36 wk, and BW at 42 wk. The average clutch length, egg number, and maximum clutch length were normalized using the Box-Cox transformation. In response to 16 generations of direct selection for increased average clutch length, other egg production traits, such as laying rate and total egg number, have been indirectly improved in a dwarf layer genetic background. The estimated heritabilities were 0.406 to 0.424 for transformed average clutch length (TCL), 0.373 to 0.411 for transformed egg number (TEN), 0.529 to 0.559 for age at first egg (AFE), 0.275 to 0.282 for laying rate (LR), 0.455 for dutch number (CN), and 0.319 for the number of double-yolked eggs (DYEN). The TCL had high genetic correlations with TEN (0.777), LR (0.863), maximum clutch length (0.902), and CN (-0.845). Selection for increased average clutch length was an effective method for increasing egg production. Line L2 showed a higher egg weight than L1, which indicates that the combined effect of NA and DW genes was favorable to maintain egg weight when egg number could be improved. Line L1 showed a higher number of DYEN, suggesting that the regulation of follicular maturation was changed in this line.

Cowpea [Vigna unguiculata (L.) Walp.] is one of the most widely adapted grain legumes in hot regions of Africa, Asia and the Americas. In the semiarid Northeast of Brazil, it is the main subsistence crop, an excellent protein source of low cost, for the poor population. The objective of this work was to estimate genetic parameters to understand the inheritance of seed sizes in cowpea. The parents P1 and P2 and the generations, F1, F2, BC1 and BC2 of the cross TVx5058-09C X Manteiguinha formed the genetic material for this study. These six generates (P1, P2, F1, F2, BC1 and BC) were evaluated in a completely randomized block-design with six replications, in Teresina - PI, Brazil, in 1998. The genetic parameters estimated were: phenotypic and total genetic variance, additive and dominance genetic components of variance and the variance attributed to the environment, heritability in the broad and narrow senses, average degree of dominance and the number of genes controlling the character. The additive - dominance model fitted the data for 100-seeds weight in as much as the midparental value and the additive effect were the more important genetic parameters for the determination of this character. The number of genes that control its expression is five. The occurrence of high values for narrow sense heritability indicates that the selection for seed size can be made in early generations. Caupi [Vigna unguiculata (L.) Walp.] é uma das leguminosas mais adaptadas às regiões quentes da África, Ásia e das Américas. No semi-árido do nordeste do Brasil é a principal cultura de subsistência, por ser uma excelente fonte de proteína de baixo custo para a população mais carente. O objetivo deste trabalho foi estimar parâmetros genéticos que podem explicar a herança do tamanho das sementes de caupi. Os genótipos parentais P1 e P2 e as gerações F1, F2, RC1 e RC2 do cruzamento TVx5058-09C X Manteiguinha, constituíram o material genético utilizado no estudo. As seis populações (P1, P2, F1, F2, RC1 e RC2) foram avaliadas num experimento em blocos casualizados com seis repetições, em Teresina - PI; o plantio foi realizado em março de 1998. Os parâmetros genéticos estimados foram variâncias fenotípica, genética total, genética aditiva e dos desvios de dominância e devido aos efeitos do ambiente, herdabilidades no sentido amplo e restrito, grau médio de dominância e número dos genes que controlam o caráter. O modelo aditivo - dominante ajustou-se aos dados do peso de 100 sementes, visto que a média e o efeito gênico aditivo foram os parâmetros genéticos mais importantes na determinação desse caráter. O número dos genes que controlam sua expressão é cinco. A ocorrência de alto valor para a herdabilidade no sentido restrito indicou que a seleção para o tamanho da semente pode ser realizada em gerações segregantes iniciais.

Exploitation of genetic variability of Populus deltoides Bartr. through control crossing involving Line x Tester mating design was attempted with the objective of selection of suitable clones as well as parents for hybridization in future and identification of best families and best individuals with in family for releasing first stage clones. Lines ST-72, D-121, G-48, exhibited the highest positive GCA effects for plant height, collar diameter, plant height at first branch and root length. In general G-48 also proved to be the best combiner for survival percentage, inter nodal length and leaf area. Among the testers ST-63 and ST-70 expressed highest GCA effects and excelled for a number of desirable characters. Full sib families (F1s) of D-121 x ST-70 and G-48 x ST-63 showed desirable SCA for plant height and collar diameter and therefore F1 hybrids of these crosses are recommended at first stage of selections. The percent contribution of line x tester interactions was higher than that of lines and testers except number of leaves per plant. 13 traits expressed higher SCA variance than GCA variance and dominant gene effect (σ2D) were found higher than additive gene effect (σ2A) except in root length. For recurrent selection based on GCA effects, parents G-48, ST-70, D-121 and ST-63 appeared more appropriate in crossing programme directed towards clonal improvement of Poplar in India.

Editor—Neurofibromatosis 2 (NF2) is a rare autosomal dominant disease that is characterised by benign nervous system tumours, skin lesions, and ocular abnormalities.1-3 Two studies have found that NF2 patients with a family history of the disease and with maternal inheritance have more severe disease than inherited cases with paternal inheritance. Kanter et al 4noted that patients with maternal inheritance had an earlier age at onset and Evans et al 5 found that patients with maternal inheritance had both an earlier age at onset and an earlier age at death. In both studies, the mean age at onset was 18 years with maternal inheritance and 24 years with paternal inheritance. These results require confirmation for several reasons. First, Parry et al 6 found identical mean ages at onset (22.8 years) in symptomatic NF2 patients with paternal or maternal inheritance. Second, these studies were based on relatively small numbers of patients. Kanter et al 4 studied 38 inherited cases, Evans et al 5 studied 56 inherited cases, and Parry et al 6 studied 36 inherited cases; 66% …

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

In order to enable progress in sunflower breeding, an increasing amount of attention has to be paid to the morpho-physiological traits (petiole angle and length) of this crop that have a significant effect on its seed yield and oil concentration. In the inheritance of petiole angle and petiole length the additive component of genetic variance had the predominant role in the F1 and F2 generation. The mean degree of dominance (H1/D)1/2 and the intersection of the expected regression line with the Wr axis indicated partial dominance in the inheritance of petiole angle and petiole length. Broad sense heritability for petiole angle was 88% and for petiole length 85%. Da bi se obezbedio napredak u selekciji suncokreta potrebno je obratiti veću pažnju na morfo-fiziološke osobine (ugao lisne drške i dužinu lisne drške) koje značajno utiču na prinos semena i sadržaj ulja. Radi proučavanja nasleđivanja, efekta gena, komponenti genetske varijanse i heritabilnosti ugla i dužine lisne drške šest genetski divergentnih inbred linija suncokreta u F1 i F2 generaciji primenjena analiza dialelenih ukrštanja za kombinacione sposobnosti, Griffing, 1956 metod 2, model I. Za ocenu komponenti genetske varijanse i regresionu analizu korišćen je metod MATHER and Jinks (1982). Ocena heritabilnosti u užem smislu je rađena po formuli MATHER and Jinks (1971). U nasleđivanju ugla i dužine lisne drške aditivna komponenta genetske varijanse je bila predominantna u F1 i F2 generaciji. Prosečan stepen dominacije (H1/D)1/2 i presek očekivane linije regresije sa Wr osom ukazuje na parcijalnu dominaciju u nasleđivanju ugla i dužine lisne drške. Heritabilnost u užem smislu za ugao lisne drške iznosi 88%, a za dužinu lisne drške 85%.

The present work aimed to compare the efficiencies of the Oligogenic Trait Mapping Method (OTMM) and Interval Method (IM) for detecting oligogenic trait loci (OTL) in Recombinant Inbred Line (RIL) populations of different sizes. Populations consisting of 200, 500 and 1,000 individuals were employed and 100 repetitions performed for each population size. Four characteristics were evaluated: C1, determined by two genes with 50 and 30% effects on expression of the characteristic; C2, governed by three genes with 50, 20 and 10% effects; C3, regulated by two genes, each with 40% effect; and C4, controlled by two genes, each with 50% effect. The IM was efficient at detecting OTL in all evaluated characteristics; however, for characteristics determined by two genes with effects between 40 and 50%, the OTMM was more efficient at detecting and localizing OTL in simulated marks. In contrast, the IM method was more efficient at detecting and localizing OTL in simulated marks when the gene effect ranged from 10 to 30%. As a result, because oligogenic characteristics are governed by genes with greater effects, the OTMM was considered the most efficient method to be used for this type of characteristic.

El objetivo de este trabajo fue determinar la herencia de la precocidad presente en cruzamientos entre una variedad precoz de maíz (Zea mays sp. mays) llamada Gaspé y líneas coloradas, de grano tipo flint, argentinas. La información obtenida será utilizada en programas de mejoramiento para seleccionar materiales precoces. Se emplearon líneas endocriadas, de ciclo largo y buena aptitud combinatoria general, como progenitores femeninos, y a Gaspé como polinizador. La prueba de escala permitió analizar las medias generacionales de los progenitores, F1' s, F2' s y las dos retrocruzas para cada una de las cinco posibles combinaciones. Se utilizaron las unidades de calor acumuladas desde la siembra hasta el panojamiento como índice de precocidad. Sólo dos cruzamientos se ajustaron al modelo de aditividad-dominancia. Para las otras tres cruzas los efectos génicos simples y de interacción fueron mejor explicados por el modelo de 6 parámetros. Se estimó un número de 4 a 10 factores efectivos controlando el carácter. Dado que los efectos aditivos superaron ampliamente a los dominantes, se puede predecir un progreso consistente empleando métodos convencionales de selección. The objetive of this investigation was to determine the inheritance of earliness in crosses between an early variety of maize called Gaspé and orange flint inbred lines from Argentina. The information obtained will be applied in breeding programs to select early materials. Inbreeds, with a long cycle and a good general combining ability, were used as female parents and Gaspé as the pollinator. The joint scaling test allowed to analyze the means of the parents, F1?s, F2?s and the two backcross generations for each one of the five possible combinations. Cumulative heat units from planting to tasseling were used as an earliness index. Only two crosses fitted to the additive-dominance model. For the other three crosses, the single gene effects and interactions were better explained by the six parameter model. The number of effective factors controlling the trait was estimated between 4 to 10. As the additive effects widely overcome the dominance effects, a consistent progress can be predicted using conventional selection methods. Facultad de Ciencias Agrarias y Forestales

Researchers and policy makers need to get beyond the one chemical or one gene effect when considering the impact of environmental factors on health. The field must become more sophisticated, taking into account interactions between environmental factors, episodic exposure, and the timing of exposures. Those were central themes in the first focus issue on environmental challenges for health in the journal Health Affairs , which was released at a forum on 4 May in Washington, DC. Children and young adults undergo “windows of development,” from their time in the womb until they are in their early 20s, …

The present investigation was conducted to analyze gene effects for grain yield and its components under two different environments. Nine wheat genotypes were selected to generate the experimental material comprised six parental and segregating generations (P1, P2, F1, F2, BC1 and BS1 of BC1 of each of the following six crosses – PBW 343 x WH 283, PBW 343 x WH 542, PBW 343 x PBW 435, UP 2565 x UP 2425, EIGN 1 x Raj 3765 and EIGN 8 x UP 2425. Joint scaling tests revealed the presence of epitasis. Six parameter model revealed the significance of additive gene effects (d) for biological and grain yield and their components in most of the crosses. The relative magnitude of (h) was higher than (d) in all the crosses for most of the characters while additive x additive (i) effects appeared to be significant for grain yield per plant (E1) and number of grain per spike (E2) in PBW 343 x WH 283. Significant (i) type of interaction was recorded in PBW 343 x WH 542 for number of grain per spike (E1), number of tillers per plant (E2) in PBW 343 x PBW 435 and for 1000-grain weight in UP 2565 x UP 2425. Pedigree method and simple selection in crosses like PBW 343 x PBW 435, UP 2565 x UP 2425, PBW 343 x WH 283 and PBW 343 x WH 542 should be used for improvement of traits governed by additive and additive x additive gene effect.

Two hybrid combinations were made with a resynthesized specially-long pod line in H218 Brassica napus L., namely H218 x Zhongyou 821, H218 x MSP334 and their six generations F(1), F(2), backcrosses B(1) and B(2) and their parents P(1) and P(2) were used to study the inheritance of 3 pod related traits, namely the full pod length, the pod body length and the pod beak length. The results were the followings: the three traits in the F(2) population of the two combinations had a continuous normal distribution, indicating that these traits were quantitative in nature and controlled by polygenes. The broad-sense heritabilities of the full pod length, pod body length and pod beak length of the two combinations were 65.89%-70.77%, 60.14%-63.38% and 26.36%-46.44%, respectively. The narrow-sense heritabilities were 44.01%-46.78%, 46.89%-47.38% and 18.08%-37.87%, respectively. The results from the two combinations consistently showed that full pod length, pod body length and pod beak length were controlled by 5, 6 and 2 genes respectively. The preliminary study on the gene effect demonstrated that the three traits in the two combinations all fit the additive-dominant model and the epistatic effect was significant. The additive effects and the dominant effects of the three traits in the two combinations were both significant. Of the full pod length and the pod body length, the dominant effect was more significant than the additive effect; and it is the same case for the pod beak length.