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To improve brown planthopper (Nilaparvata lugens Stal; BPH) resistance of an elite indica cultivar of South China, Hemeizhan (HMZ), we applied marker-assisted backcross (MABC) to incorporate three BPH-resistance genes (Bph3, Bph14 and Bph15) into the genetic background of HMZ. In the third backcross (BC3) generation, we obtained near-isogenic lines (Bph3-NIL, Bph14-NIL, Bph15-NIL and Bph14 + Bph15-NIL) with more than 96% recovery of recurrent parent genome, and pyramided lines (Bph3 + Bph14-PYL, Bph3 + Bph15-PYL and Bph3 + Bph14 + Bph15-PYL) with more than 89% recovery of recurrent parent genome. These lines showed stronger resistance against BPH than HMZ at seedling and booting stages. The rank of resistance gene effect was Bph3 + Bph14 + Bph15 ≥ Bph3 + Bph15 ≥ Bph3 +Bph14 ≥ Bph14 + Bph15 ≥ Bph3 ≥ Bph15 ≥ Bph14 > none. Compared with HMZ, only Bph3 + Bph14 + Bph15-PYL had a significant difference in yield per plant, and the lines carrying Bph3 had higher amylose contents, indicating that Bph3 was tightly linked to Wxa allele. These improved lines are good intermediate sources of broad-spectrum and durable BPH resistance to improve other indica cultivars. Our results demonstrate that MABC is a very efficient approach to improve BPH resistance of elite rice cultivar.

We sought the novel concept, transcript capacity (TC) and analyzed TC. Our approach to estimate TC was through an in silico method. TC refers to the capacity that a transcript exerts in a cell as enzyme or protein function after translation. We used the genome-wide association study (GWAS) beta effect and transcription level in RNA-sequencing to estimate TC. The trait was body fat percent and the transcript reads were obtained from the human protein atlas. The assumption was that the GWAS beta effect is the gene's effect and TC was related to the corresponding gene effect and transcript reads. Further, we surveyed gene ontology (GO) in the highest TC and the lowest TC genes. The most frequent GOs with the highest TC were neuronal-related and cell projection organization related. The most frequent GOs with the lowest TC were wound-healing related and embryo development related. We expect that our analysis contributes to estimating TC in the diverse species and playing a benevolent role to the new bioinformatic analysis.

Rapeseed ( Brassica napus L.) with purple-red leaf is a valuable resource for plant breeder. It was utilized in breeding program as a morphological marker, and the source of resistance gene to biotic or abiotic stress due to its anthocyanin content (AC). However, the inheritance of AC and the correlation with chlorophyll content (CC) in rapeseed leaf are still unknown. This study aimed to investigate the gene action and heritability of AC and CC in a 10-Zi006 × 10-4438 rapeseed cross using generation mean analysis. The results indicated that AC and CC were controlled by main gene effect and non-allelic interactions. The AC was mainly controlled by genetic effect. However, the genetic effect and non-genetic effect were both important for CC. In addition, the total fixable gene effects was higher than unfixable gene effects for AC, but opposite results was found for CC. Both negative and positive correlations between AC and CC were obtained in different generations. RESUMO: Colza ( Brassica napus L.) de folhas vermelho-púrpura é um recurso valioso para os produtores. Foi utilizada em programas de melhoramento como um marcador morfológico ao gene de resistência a estresses abióticos, bióticos ou devido ao seu teor de antocianinas (AC). No entanto, a herança da AC e a correlação com o teor de clorofila (CC) na folha de colza ainda são desconhecidos. Este estudo teve como objetivo investigar a ação dos genes e hereditariedade da CA e CC em 10 Zi006 × 10-4438 colza, usando geração de análise. Os resultados indicaram que CA e CC foram controladas por efeito do gene principal e interacções não-alélicas. O AC foi controlado principalmente por efeito genético. No entanto, os efeitos genético e não genético foram ambos importantes para CC. Além disso, o total de efeitos gênicos solucionáveis foi maior do que os efeitos de genes para AC, mas os resultados opostos foram encontrados para CC. Correlações negativas e positivas entre CA e CC foram obtidas em diferentes gerações.

Small gene effects influence complex phenotypes in a context dependent manner. Here we evaluated whether increasing dosage of the angiotensin I converting enzyme ( Ace) gene influence exercise-induced cardiac hypertrophy. Mice harboring one, two, three, and four copies of the Ace gene were assigned to sedentary (S1–4) and swimming exercise-trained (T1–4) groups (1.5 h twice daily, 5 days/wk, 4 wk). Exercising resulted in comparable bradycardia and elevated skeletal muscle citrate synthase activity, while blood pressure remained unchanged. Left ventricle mass index and cardiomyocyte diameter were similar among sedentary mice and the magnitude of their increase associated to exercising was not influenced by the Ace genotype (T1: 12.6 and 17.9%, T2: 15.2 and 13.8%, T3: 16.9 and 20%, T4: 17 and 19%, respectively). Plasma renin activity (PRA) levels were higher in one vs. three or four copies mice (4.89 ± 0.5 vs. 2.43 ± 0.6 and 2.12 ± 01.1 ng/ml Ang I, P < 0.05), while cardiac ACE activity was higher in three vs. two or one copy mice (5,946 ± 590.8 vs. 2,951.5 ± 328.3 and 3,504.1 ± 258.9 μF·min−1·ml−1, P < 0.05). With exercise, PRA remained unchanged in each group, while cardiac immunostaining for Ang II reached comparable levels. In summary: 1) exercise training led to similar aerobic adaptation regardless of the Ace genotype, and 2) higher number of Ace gene copies per se, which alters cardiac ACE activity, did not influence basal cardiac mass or, most importantly, the magnitude of swimming-induced cardiac hypertrophy. Collectively, these data indicate that small isolated genetic disturbances in ACE cardiac levels can be well compensated under physiological perturbations.

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.

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.

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.

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.

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.

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.

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.

SUMMARYG6PD measurements (expressed per g haemoglobin) in both males and females of the parental lines C57BL/6J and C57L/J and four recombinant inbred (RI) lines between them showed segregation of G6PD levels as parental classes (one line showed the higher C57BL/6J activity, three lines were indistinguishable from C57L/J). Haemoglobin also varied significantly among the parental and RI lines but this variation did not explain the variation in G6PD. NADP levels (expressed per g wet wt of erythrocytes) correlated with G6PD levels but one RI line was intermediate in males while two RI lines were lower than either parental line in females. Thus, the major autosomal locus affecting G6PD levels which segregates between these two inbred lines probably does not act directly on NADP levels. The variation in the G6PD levels in the four RI lines co-segregated with the brown coat color locus but the association is not significant because of the small number of RI lines available.

The results herein presented show that this anemia may be counteracted by the injection of normal blood which replaces the vital principle or principles necessary to life not found in the presence of this gene. It is thus shown that the gene effect may be replaced by the substitutions of materials taken from without the animal.

Estimation of the gene number and the effects for the inheritance of primary leaf size of soybean were studied using six populations, P1, P2, F1, F2, and two backcrosses (P1B1 and P2B2). The two parents were found to be differentiated in this character by two effective factor pairs which seemed to be controlled by the intra- and inter-allelic interaction of genes. The dominance genetic effect was about twice as large as additive effect. Epistasis due to dominance × dominance effects was found. It was also found that the dominance effect of the two genes interacted to reduce the primary leaf area.

Spatial visualization scores were obtained on the members of two hundred families. Large sex differences favoring males were found in both parents and offspring. Familial correlations, however, did not order themselves as predicted from the theory that human spatial visualization is under the control of an X‐linked recessive gene. The results are compatible with a sex limitation and/or socialization theory of ability acquisition.

The within-pair difference in lipid levels was examined in 142 monozygotic (MZ) twin pairs drawn from the population-based Norwegian Twin Panel. Mean within-pair difference in serum total cholesterol was lower in MZ pairs who were heterozygous for blood group Kidd genes or homozygous for the Jkb gene than in pairs who were homozygous for the Jkb gene. The difference between the two categories of homozygotes was significant at the 2% level. The analyses suggest that the main reason for the difference observed is a restrictive effect of the Jkb gene on total cholesterol variability. No effect on triglycerides or HDL cholesterol variability was detected and there was no association between Kidd blood groups and sex and age-adjusted levels of cholesterol, triglycerides or HDL cholesterol. The present data confirm findings we reported when we introduced the study of within-pair variability in MZ twins as a method to analyse gene-environment interactions and validate the “variability gene” concept. A person's net risk for coronary heart disease may depend on his or her combination of “level genes” and “variability genes” as well as on environmental or life-style factors.

Six populations — P1,P2,F1,F2,B1 and B2 — each of five Upland Cotton (Gossypium hirsutum L.) crosses were used to evaluate gene effects in the inheritance of fibre properties by Gamble's six-parameter model for the analysis of generation means. Partial dominance of long fibres over short fibres and of mature fibres over immature fibres was found in the material studied. Overdominance in gene action governed fibre fineness while additive gene action governed the fibre strength. Besides additive and dominance effects, significant epistasis was present in all crosses. These results indicate a significant potential for improving fibre properties through reciprocal recurrent selection.

Studies by computer simulation to determine applicability of the theory of the distribution of gene frequencies at the steady state of decay to small populations and the effect of linkage on the distribution revealed: 1. For random genetic drift with no selection theory and observations agree well for independent assortment and linkage. 2. For random genetic drift with selection theory and observations agree well for independent assortment and full dominance. Linkage with relatively large N s decreased the mean gene frequency of unfixed classes and the steady rate of fixation of the favorable allele. 3. With independent assortment and additive gene effects agreement between theory and observations for the rates of fixation and loss at the terminal classes was good only for effective population number of at least 42. Small effective population numbers increased variance and decreased the steady rate of fixation and loss at the terminal classes. Linkage had no effect for small N s, but for relatively large N s, it decreased the mean of gene frequencies and increased the steady rate of fixation and loss at the terminal classes from that of independent assortment.