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1.
Prolificacy assumes significance for development of high‐yielding baby corn hybrids. “Sikkim Primitive” is a native landrace of North‐Eastern Himalaya, and is the highest prolific maize germplasm. So far, the genetics of prolificacy in “Sikkim Primitive” has not been deciphered. Here, a prolific inbred (MGU‐SP‐101) developed from “Sikkim Primitive” was crossed with four non‐prolific inbreds viz., LM13, BML7, HKI161 and HKI1128. Six generations (P1, P2, F1, F2, BC1P1 and BC1P2) of the crosses were evaluated at two locations during rainy season 2018. MGU‐SP‐101 possessed 2.50–3.78 ears per plant compared to 1.06–1.86 among non‐prolific inbreds. The variation for ears was the highest in F2s (1–8), followed by BC1P1 (1–7) and BC1P2 (1–5). The quantitative inheritance pattern of prolificacy with prevalence of non‐allelic interactions of duplicate epistasis type has been observed. Dominance × dominance effect was predominant over additive × additive and additive × dominance effects. Total number of major gene blocks ranged from 0.41 to 2.86, thereby suggesting the involvement of at least one major gene/QTL governing the prolificacy. This is the first report of genetic dissection of prolificacy in “Sikkim Primitive”.  相似文献   

2.
Sorghum shoot fly, Atherigona soccata is an important pest of sorghum during the seedling stage, which influences both fodder and grain yield. To understand the nature of inheritance of shoot fly resistance in sorghum, we performed generation mean analysis using two crosses IS 18551 × Swarna and M 35-1 × ICSV 700 during the 2013–2014 cropping seasons. The F1, F2, BC1 and BC2 progenies, along with the parental lines were evaluated for agronomic and morphological traits associated with resistance/susceptibility to sorghum shoot fly, A. soccata. The cross IS 18551 × Swarna exhibited significant differences between the parents for shoot fly deadhearts (%) in the postrainy season. The progenies of this cross exhibited lower shoot fly damage, suggesting that at least one of the parents should have genes for resistance to develop shoot fly-resistant hybrids. Leaf glossiness, leafsheath pigmentation and plant vigor score during the seedling stage exhibited non-allelic gene interactions with dominant gene action, whereas 100 seed weight showed both additive and dominant gene interactions. Presence of awns showed recessive nature of the awned gene. Generation mean analysis suggested that both additive and dominance gene effects were important for most of the traits evaluated in this study, but dominance had a more pronounced effect.  相似文献   

3.
Gene effects were analyzed using mean spike length of 12 populations, viz., both parents, F1, F2, first back cross generation, BC1 and BC2, second backcross generations, BC11,BC12, BC21 and BC22 along with BC1 self and BC2 self derived by selfing BC1 and BC2populations of three crosses involving six diverse cultivars of Triticum durumto determine the nature of gene actions governing spike length through generation mean analysis under normal and late sown environments. The six-parameter model was adequate in most of the cases to explain genetic variation among the generation means under both the sowing environments. Additive (d) gene effect was significant in all the cases, whereas dominance (h) gene effect was not so frequently observed significant. Epistatic effects, particularly digenic types were predominant over additive and dominance effects in most of the cases under both normal and late sown environments except in the cross Cocorit 71 × A-9-30-1 (normal sown).Additive × dominance × dominance (y), trigenic interaction played significant role in controlling the inheritance of this trait in the cross HI 8062 × JNK-4W-128under late sown condition. Duplicate epistasis was observed in the cross HI 8062× JNK-4W-128 (normal sown). Non-fixable gene effects were of higher magnitude than fixable gene effects in almost all cases, confirmed the major role of non-additive gene effects to control the inheritance of spike length in durum wheat. Significant heterosis over better parent was not observed. Similarly, inbreeding depression was not commonly observed. Favourable and suitable environment must be considered before finalizing breeding programme for its simple inheritance to get desirable improvement for high grain yield. Hybridization systems, such as biparental mating and / or diallel selective mating, which exploit both additive and non-additive gene effects, simultaneously, could be useful in the improvement of spike length in durum wheat. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

4.
M.A. Rahman  M.S. Saad 《Euphytica》2000,114(1):61-66
Inheritance of yield and yield contributing characters were investigated using generation mean analysis, utilising the means of six basic populations viz., P1, P2, F1, F2, BC1P1 and BC1P2 in four crosses of Vigna sesquipedalis. The analysis reiterated that the importance of dominance (h) gene effects for pod yield/plant and pods/plant as compared to additive (d) gene effects. However, significant and positive additive effects were noticed for pod yield/plant, pods/plant, pod weight and seed weight in different crosses. The three types of gene interactions (additive, dominance and epistasis) were significantly involved for pods/plant in cross KU 7 ×KU 8. Among the digenic epistatic interactions, both additive ×additive (i) and dominance × dominance (l) contributed more for pod yield/plant and pods/plant, however, it varied among the crosses. Populations having earliness can be developed as indicated by reducing dominance effects. Pedigree selection and heterosis breeding is suggested to exploit the fixable and non fixable components of variation respectively in Vigna sesquipedalis. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

5.
Six blast‐resistant pearl millet genotypes, ICMB 93333, ICMB 97222, ICMR 06444, ICMR 06222, ICMR 11003 and IP 21187‐P1, were crossed with two susceptible genotypes, ICMB 95444 and ICMB 89111 to generate F1s, F2s and backcrosses, BC1P1 (susceptible parent × F1) and BC1P2 (resistant parent × F1) for inheritance study. The resistant genotypes were crossed among themselves in half diallel to generate F1s and F2s for test of allelism. The F1, F2 and backcross generations, and their parents were screened in a glasshouse against Magnaporthe grisea isolates Pg 45 and Pg 53. The reaction of the F1s, segregation pattern of F2s and BC1P1 derived from crosses involving two susceptible parents and six resistant parents revealed the presence of single dominant gene governing resistance in the resistant genotypes. No segregation for blast reaction was observed in the F2s derived from the crosses of resistant × resistant parents. The resistance reaction of these F2s indicated that single dominant gene conferring resistance in the six genotypes is allelic, that is same gene imparts blast resistance in these genotypes to M. grisea isolates.  相似文献   

6.
Hailu Tefera  W.E. Peat 《Euphytica》1997,96(2):185-191
Quantitative genetics of grain yield and other agronomic characters of t'ef (Eragrostis tef) were studied using the F1, F2, BC1, and BC2 of the cross Fesho × Kay Murri. The study was carried out to estimate gene effects controlling the inheritance of grain yield and related agronomic characters. Significant additive [d] and dominance × dominance [l] interaction effects were detected for grain yield. The variations of yield per panicle and panicle weight were explained in terms of [d], dominance [h], and additive × additive [i] interactions. Non-allelic gene interactions were also detected for kernel weight, harvest index, tiller number, plant height, days to heading and days to maturity. The simple additive-dominance model explained the variation for panicle length, culm diameter and plant weight, allowing unbiased estimates of additive (D) and dominance (H) variance components. Large dominance variances (H) were estimated for grain yield, yield per panicle, and panicle weight. The additive variances for plant height, panicle length, days to heading and days to maturity were higher than the respective dominance variances. High narrow-sense heritability (h2) values (> 0.50) were estimated for plant height, panicle length, days to heading and days to maturity. The lowest h2 (0.09) was obtained for kernel weight for which there was little variability. Since grain yield and several important agronomic characters of t'ef are influenced by non-allelic gene interaction, it is advisable to delay selection for yield to later generations with increased homozygosity. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

7.
Heterosis, or hybrid vigour, has been used to improve seed yield in several important crops for decades and it has potential applications in soybean. The discovery of over‐dominant quantitative trait loci (QTL) underlying yield‐related traits, such as seed weight, will facilitate hybrid soybean breeding via marker‐assisted selection. In this study, F2 and F2 : 3 populations derived from the crosses of ‘Jidou 12’ (Glycine max) × ‘ZYD2738’ (Glycine soja) and ‘Jidou 9’ (G. max) × ‘ZYD2738’ were used to identify over‐dominant QTL associated with seed weight. A total of seven QTL were identified. Among them, qSWT_13_1, mapped on chromosome 13 and linked with Satt114, showed an over‐dominant effect in two populations for two successive generations. This over‐dominant effect was further examined by six subpopulations derived from ‘Jidou12’ × ‘ZYD2738’. The seed weight for heterozygous individuals was 1.1‐ to 1.6‐fold higher than that of homozygous individuals among the six validation populations examined in different locations and years. Therefore, qSWT_13_1 may be a useful locus to improve the yield of hybrid soybean and to understand the molecular mechanism of heterosis in soybean.  相似文献   

8.
Seed size, determined by 100-seed weight, is an important yield component and trade value trait in kabuli chickpea. In the present investigation, the small seeded kabuli genotype ICC 16644 was crossed with four genotypes (JGK 2, KAK 2, KRIPA and ICC 17109) and F1, F2 and F3 populations were developed to study the gene action involved in seed size and other yield attributing traits. Scaling test and joint scaling test revealed the presence of epistasis for days to first flower, days to maturity, plant height, number of pods per plant, number of seeds per plant, number of seeds per pod, biological yield per plant, grain yield per plant and 100-seed weight. Additive, additive?×?additive and dominance?×?dominance effects were found to govern days to first flower. Days to maturity and plant height were under the control of both the main as well as interaction effects. Number of seeds per pod was predominantly under the control of additive and additive?×?additive effects. For grain yield per plant, additive and dominance?×?dominance effects were significant in the cross ICC 16644?×?KAK 2, whereas, additive?×?additive effects were important in the cross ICC 16644?×?JGK 2. Additive, dominance and epistatic effects influenced seed size. The study emphasized the existence of duplicate epistasis for most of the traits. To explore both additive and non-additive gene actions for phenological traits and yield traits, selection in later generations would be more effective.  相似文献   

9.
M. N. Barakat 《Euphytica》1996,87(2):119-125
Summary Estimates of gene actions were obtained for five in vitro traits of immature wheat (Triticum aestivum L.) embryo cultures from a cross of two wheat cultivars and the resulting reciprocal, F1, F2 and backcross populations. The contribution of additive gene effects to in vitro traits was not as important as the dominance gene effects. Epistatic gene effects were relatively more important than either additive or dominance gene effects. Of the individual types of digenic epistatic effects, the dominance x dominance estimates were relatively larger in magnitude for all in vitro culture traits measured. The maternal effect played a minor role in the inheritance of the in vitro studied traits since the difference among the reciprocal values was not significant. It is shown from the generation mean method that epistasis played a major role in the inheritance of most of the traits under study. The negative values of additive and dominance genetic variance were estimates of zero. Heritability estimates, in broad sense, were relatively high for the in vitro studied traits. In some cases, heritability estimates in broad and narrow senses are almost equal since the estimation of dominance genetic variance led to negative values. According to the results of the gene effects, dominance and epistasis were important for the shoot formation trait. Selection would be effective among the isolated genotypes on individual basis.  相似文献   

10.
Striga hermonthica can cause as high as 100% yield loss in maize depending on soil fertility level, type of genotype, severity of infestation and climatic conditions. Understanding the mode of inheritance of Striga resistance in maize is crucial for introgression of resistance genes into tropical germplasm and deployment of resistant varieties. This study examined the mode of inheritance of resistance to Striga in early‐maturing inbred line, TZdEI 352 containing resistance genes from Zea diploperennis. Six generations, P1, P2, F1, F2, BC1P1 and BC1P2 derived from a cross between resistant line, TZdEI 352 and susceptible line, TZdEI 425 were screened under artificial Striga infestation at Mokwa and Abuja, Nigeria, 2015. Additive‐dominance model was adequate in describing observed variations in the number of emerged Striga plants among the population; hence, digenic epistatic model was adopted for Striga damage. Dominance effects were higher than the additive effects for the number of emerged Striga plants at both locations signifying that non‐additive gene action conditioned inheritance of Striga resistance. Inbred TZdEI 352 could serve as invaluable parent for hybrid development in Striga endemic agro‐ecologies of sub‐Saharan Africa.  相似文献   

11.
Phytophthora root and stem rot caused by Phytophthora sojae, is one of the most damaging diseases of soybean, for which management is principally done by planting resistant cultivars with race specific resistance which are conferred by Rps (Resistance to Phytophthora sojae) genes. The Rps8 locus, identified in the South Korean landrace PI 399073, is located in a 2.23 Mbp region on soybean chromosome 13. In eight cv. Williams (rps8/rps8) × PI 399073 (Rps8/Rps8) populations, this region exhibited strong segregation distortion. In a cross between the South Korean lines PI 399073 (Rps8/Rps8) and PI 408211B (multiple Rps genes) this region segregated in a Mendelian fashion. In this study, microsporogenesis was evaluated to identify meiotic abnormalities that may be associated with the segregation distortion of the Rps8 region. Pollen was collected from greenhouse-grown plants of the parental genotypes: Williams, PI 399073, and PI 408211B; as well as selected Rps8/rps8 RILs from Williams × PI 399073 BC4F2:3 and PI 399073 × PI 408211B F4:5 populations. There were no differences for pollen viability among the genotypes. However, for PI 399073, a mix of dyads, triads, tetrads and pentads was observed. A high frequency of meiotic abnormalities including fragments, laggards, multinucleated microspores; and microcytes containing DNA was also observed in Rps8/rps8 Williams × PI 399073 BC4F2:3 RILs. These meiotic abnormalities may contribute to the high degree of segregation distortion present in the Williams × PI 399073 populations.  相似文献   

12.
The resistant accession, LA1312, and the susceptible cultivar ‘Peto 343′, were crossed to develop F1, F2 and BC1 populations for genetic analysis of resistance in tomatoes to Phytophthora parasitica Dastur, the causal agent of Phytophthora root rot. There was no maternal effect on resistance. Generation means analysis indicated that tolerance to Phytophthora root rot was under genetic control with both simple (additive and dominance) and digenic interaction (additive × additive and additive × dominance) effects contributing to the total genetic variation among generation means. Weighted least square regression analysis indicated that the majority (ca. 96 %) of the genetic variation could be explained by simple additive effects alone. Narrow sense heritability was estimated as 0.22. Based on effective factor formulae, at least five effective factors controlled the resistance. Implications for breeding procedures are discussed.  相似文献   

13.
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14.
The peach root‐knot nematode, Meloidogyne floridensis (MF), infects majority of available nematode‐resistant peach rootstocks which are mostly derived from peach (Prunus persica) and Chinese wild peach (P. davidiana). Interspecific hybridization of peach with its wild relative, Kansu peach (P. kansuensis), offers potential for broadening the resistance spectrum in standard peach rootstocks. We investigated the inheritance of resistance to MF in segregating populations of peach (‘Okinawa’ or ‘Flordaguard’) × P. kansuensis. A total of 379 individuals from 13 F2 and BC1F1 families were challenged with a pathogenic MF isolate “MFGnv14” and were classified as resistant (R) or susceptible (S) based on root galling intensity. Segregation analyses in F2 progeny revealed the involvement of a major locus with a dominant or recessive allele determining resistance in progeny segregating 3R:1S and 1R:3S, respectively. Testcrosses with a homozygous‐susceptible peach genotype (‘Flordaguard’ or ‘UFSharp’) confirmed P. kansuensis as a source of new resistance and the heterozygous allelic status of P. kansuensis at the locus conferring resistance to MF. We propose a single‐locus dominant/recessive model for the inheritance of resistance.  相似文献   

15.
Despite being one of the important characteristics in determining pasta quality in durum wheat (Triticum turgidum ssp. durum), there is no direct report on inheritance of β-carotene concentration. The objectives of this study were to determine the inheritance of β-carotene concentration and the number of genes involved in six crosses of durum. For the cross PDW-233 (P1) × Bhalegaon-4 (P2), F1, F2, BCP1 and BCP2 populations were developed. For all other crosses, only the F1 and F2 populations were developed. β-carotene concentration was determined for all populations and parents of each cross grown at Hol, Maharastra, India. The cross PDW-233 × Bhalegaon-4 was also evaluated at Dharwad, Karnataka, India. Low β-carotene concentration was partially dominant in most of the crosses. Broad sense heritability was 67 and 91% at Dharwad and Hol, respectively, for the cross PDW-233 × Bhalegaon-4 and varied from 74 to 93% for the other five crosses indicating the presence of additive gene effects. The frequency distributions of the trait in the F2 populations were not normal and were skewed towards the lower parent. Segregation of β-carotene concentration in the six F2 populations indicated that at least two major genes and two or three minor genes with modifying effects govern the trait. Analysis of variance indicated that environment had comparatively little influence on the trait and this should allow for easy selection. The joint scaling test revealed additive × additive, additive × dominance and dominance × dominance epistatic interactions in the cross PDW-233 × Bhalegaon-4. These authors contributed equally.  相似文献   

16.
Understanding of mungbean yellow mosaic disease resistance is crucial to develop resistant varieties to combat worldwide threat of the disease epidemics. This study was aimed to determine nature of disease resistance in terms of number of genes governing it and genetics of related traits. Experimental site was located on 31.43°N and 73.06°E with an elevation of 186 m, and evaluation trials were conducted during spring season due to high disease epidemics in this season. Two contrasting genotypes, that is, NM 6‐68‐2 (resistant) and NM 1‐32‐1 (highly susceptible), were crossed to raise six populations, that is, P1, P2, F1, F2, BC1 and BC2 for evaluation under protected and unprotected field conditions using chi‐square test and generation mean and variance analysis. It was discovered that disease resistance was governed by two major genes with additive effects. Disease resistance can easily be incorporated through backcrossing and direct selection following hybridization. Direct selection should be practised at earlier generation for plant height, chlorophyll contents and number of seeds per pod due to preponderance of additive effects whereas at later generations for seed yield per plant, 100 seed weight, harvest index, number of pods per plant and pod length due to involvement of duplicate epistasis.  相似文献   

17.
Grain moulds are a major constraint to sorghum production and to adoption of improved cultivars in many tropical areas. Information on the inheritance of grain mould reaction is required to facilitate breeding of resistant cultivars. The genetic control of grain mould reaction was studied in 7 crosses of 2 resistant sorghum genotypes. P1, P2, F1, F2, BC1 and BC2 families of each cross were evaluated under sprinkler irrigation for field grade and threshed grade scores and subjected to generation mean analysis. Frequency distributions for grain mould reaction were derived and F2 and BC1 segregation ratios were calculated. Grain mould reaction in crosses of coloured grain sorghum was generally controlled by two or three major genes. Resistance to grain moulds was dominant. Significant additive gene effects were also found in all cross/season combinations. Significant dominance effects of similar magnitude to additive effects were also observed in five out of ten cross/season combinations. Gene interactions varied according to the parents with both resistant and susceptible parents contributing major genes. Choice of parents with complementary resistance genes and mechanisms of resistance will be critical to the success of resistance breeding. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

18.
Larger particle volume is beneficial for many aspects of maize starch processing, and may improve the performance of some starch attributes. This study focused on the soft starch (h) locus to identify its potentially influential role in starch particle volume distribution. The objectives were to study the genetic expression of starch particle volume of the h locus in different genetic backgrounds and the gene action conditioning starch particle volume of other loci in both normal‐starch and h‐starch backgrounds. Forty‐five populations (five intra‐inbred F1s, 10 hybrid F1s 10 F2s, 10 BC1F1s to h/h parent, and 10 BC1 to h:h conversion of normal parent) were planted in 1993 at two locations and in 1995 at one location. Selfed heterozygotes (±/h) in all generations provided intra‐ear comparisons of normal and h starch, and F3 and BC1F2 generations provided inter‐ear comparisons. Significant differences were found between normal and h:h genotypes in all intra‐ear and inter‐ear comparisons. In all cases, general combining ability effects were highly significant, suggesting the presence of additive gene effects. Generation mean analysis of normal and h:h starch materials yielded similar results, indicating the predominance of additive and some dominance effects for other loci on starch particle volume. These results indicate the usefulness of the soft starch gene and additional genetic variation among inbreds in the improvement of starch particle volume for increased starch recovery in wet milling.  相似文献   

19.
J. E. Zalapa    J. E. Staub    J. D. McCreight   《Plant Breeding》2006,125(5):482-487
Unique architectural phenotypes have the potential for increasing yield in commercial melon (Cucumis melo L.). Therefore, a generation means analysis was conducted to investigate the inheritance of architectural traits (days to anthesis, primary branch number, fruit number and weight, and average weight per fruit). Progeny (F1, F2, BC1P1 and BC1P2) from a cross between US Department of Agriculture (USDA) line, USDA 846‐1 (P1) and ‘TopMark’ (P2) were evaluated at Arlington (AR) and Hancock (HCK), Wisconsin in 2001. Significant (P ≤ 0.05) environment effects and genotype × environment interactions (G × E) analyses necessitated analysis by location. Significant differences (P ≤ 0.05) among parents and generations were observed for all traits, and the two parental lines differed significantly for primary branch number, fruit number and average weight per fruit. Additive gene effects were most important in governing primary branch number and fruit number per plant, while dominance and epistatic genetic effects mainly controlled days to anthesis, fruit weight per plant and average weight per fruit. Narrow‐sense heritabilities were 0.62 (AR) for days to anthesis, 0.71 (AR) and 0.76 (HCK) for primary branch number, 0.68 (AR) and 0.70 (HCK) for fruit weight per plant, 0.33 (AR) and 0.45 (HCK) for fruit weight per plant, and 0.06 (AR) and 0.79 (HCK) for average weight per fruit. Estimations of the least number of effective factors for primary branch number were relatively consistent at both AR (approx. 4) and HCK (approx. 2). Results suggest that introgression of yield‐related genes from highly branched melon types (e.g. USDA 846‐1) into US Western Shipping germplasm may aid in the development of high‐yielding cultivars with concentrated fruit set suitable for machine and/or hand‐harvesting operations.  相似文献   

20.
Groundnut (Arachis hypogaea L.) is an important oilseed crop grown in more than 100 countries across wide range of environments. Frequent occurrence of drought is one of the limiting factors adversely affecting groundnut productivity, especially in rainfed areas, and hence genotypes having high water use efficiency (WUE) under limited available water need to be developed. In groundnut, WUE is correlated with SPAD chlorophyll meter reading (SCMR) and specific leaf area (SLA). These two traits, SCMR and SLA, can be used as surrogate traits for selecting for WUE. In order to improve SCMR and SLA, and in turn WUE in groundnut, a good knowledge of the genetic system controlling the expressions of these traits is essential for the selection of the most appropriate and efficient breeding procedure. The present investigation was conducted to determine the gene action controlling the inheritance of SCMR and SLA in two crosses, ICG 7243 × ICG 9418 and ICG 6766 × Chico, and their reciprocals. Six generations of each cross (P1, P2, F1, F2, BC1P1, and BC1P2) were evaluated for SCMR and SLA at two stages of the crop growth viz., 60 and 80 days after sowing (DAS). For SCMR at 80 DAS, additive effects were important in both the crosses whereas predominance of dominance effects with duplicate epistasis was observed for SCMR at 60 DAS and SLA at both stages in both the crosses. Predominance of additive effect for SCMR at 80 DAS suggested effective selection could be practiced even in early generations whereas for SCMR at 60 DAS and SLA at both stages in both crosses, it would be better to defer selection to later generations. Further, recording of SCMR and SLA should be done between 60 and 80 DAS for screening the germplasm lines for drought tolerance.  相似文献   

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