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1.
M. R. Simón 《Euphytica》1994,76(3):235-238
Summary Gene action and heritability for photosynthetic activity were estimated from generation means in two wheat crosses during two stages (5 th leaf and flag leaf between 2 and 5 days after anthesis). Six generations were available for each cross: parents (P1 and P2), F1, F2 and backcrosses (BC1 and BC2).Correlations between some morphophysiological characters and photosynthetic activity of the flag leaf was also determined. The joint scaling test described by Mather & Jinks was used to determine the gene action. It showed that them; [d]; [h]; [i], [l] (mean, additivity, dominance, additive x additive interallelic interaction effects, dominance x dominance interallelic interaction effects) model fits the two crosses at both measurement times. All the model genetic components were significant for the flag leaf, however for the 5 th leaf only [h]; [i] and [l] were significant. The presence of additive and additive x additive effects suggested the possibility of selecting for this character using the flag leaf so as to obtain pure inbred lines. Dominance effects [h] were negative and dominance x dominance effects [l] were positive. Broad sense heritability values were medium to low. There were no correlations between the studied morphophysiological characters and the photosynthetic activity.  相似文献   

2.
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   

3.
A study was made on the quantitative inheritance of seven characters viz., flowering time, plant height, leaf length, leaf width, number of curable leaves, green weight and cured weight for two crosses of flue-cured tobacco Chatham x Delcrest and 232 x Hicks. Six genetic populations P1, P2, F1, F2, B1 and B2 were observed in each cross.Small and significant values of heterosis were observed for almost all the characters for the two crosses. Significant average inbreeding depression was found for all the characters in both the crosses.Significant additive and dominant effects were found for the various characters in the cross Chatham x Delcrest in which the dominance gene effects were high. While in 232 x Hicks cross, additive gene effects contributed much in controlling the characters studied.Significant epistatic effects were found for leaf length and number of leaves in the cross Chatham x Delcrest, flowering time and plant height in 232 x Hicks by 2 test. Indications of exploiting these above two characters in plant breeding were revealed by these studies and a systematic approach in planning for such exploitation would be possible by further investigations.  相似文献   

4.
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   

5.
V.J. Joshi  S.D. Ugale 《Euphytica》2002,127(2):149-161
Inheritance of downy mildew [Sclerospora graminicola (Sacc.) Schrot]resistance was studied using generation mean analysis in pearl millet [Pennisetum glaucum (L.) R.Br.]. Eleven basic generations, namely, P1, P2, F1, F2, B1, B2, B1F2, B2F2, L1, L2 and L3 of three crosses involving six diverse lines for downy mildew incidence were evaluated under artificial epiphytotic conditions over two environments. The downy mildew incidence was best fitting for digenic, trigenic and tetragenic ratios when fitted into classical Mendelian ratios demonstrating involvement of two or more genes. Digenic and trigenic interaction models were adequate in the case of crosses I and III respectively, to account for the total variability in generation means. Unlike severity, comparative estimates of gene effects over two environments were mostly consistent in all crosses for prevalence. Most of the epistatic and major gene effects were found significant in all crosses for both the disease traits. Non-allelic interactions particularly at three-gene loci viz., w (additive × additive × additive) and y (additive × dominance × dominance) in cross II and all trigenic interactions in cross III were predominant. Duplicate dominance (cross I) and complementary epistasis (crosses II and III) were observed for both the traits revealing inconsistency of gene effects over crosses. The gd1 (interaction of additive gene effect with e1) and gh1(interaction of dominant gene effect with e1) were significant in crosses I and II, indicating interaction of additive and dominance gene effects with environments. Thus a breeding method that can mop up the resistant genes to form superior gene constellations interacting in a favorable manner against pathotype I would be more suitable to accelerate the pace of resistance improvement. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

6.
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   

7.
The genetic nature of early blight resistance in tomato was studied in three crosses at seedling and adult plant stages. A six generation mean analysis of the cross Arka Saurabh (susceptible) × IHR1939 (resistance) and its reciprocal cross revealed that the resistance to early blight was conferred by recessive polygenes at both seedling and adult plant stages. This polygenic early blight resistance revealed the importance of additive and additive × additive gene effects at seedling stage and higher magnitude of dominance and dominance× dominance gene effects at adult plant stage. Evaluation of parents, F1, F2 and backcross generations of IHR1816 (resistance) × IHR1939 (resistance) revealed that the early blight resistance genes in IHR1816 (Lycopersicon esculentum NCEBR-1) and IHR1939 (Lycopersicon pimpinellifolium L4394) are independent. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

8.
Understanding the genetic basis of tolerance to high temperature is important for improving the productivity of wheat (Triticum aestivum L.) in regions where the stress occurs. The objective of this study was to estimate inheritance of heat tolerance and the minimum number of genes for the trait in bread wheat by combining quantitative genetic estimates and molecular marker analyses. Two cultivars, Ventnor (heat-tolerant) and Karl92 (heat-susceptible), were crossed to produce F1, F2, and F3populations, and their grain-filling duration (GFD) at 30/25 °C 16/8 h day/night was determined as a measure of heat tolerance. Distribution of GFD in the F1 and F2 populations followed the normal model (χ2, p > 0.10). A minimum of 1.4 genes with both additive and dominance effects, broad-sense heritability of 80%, and realized heritability of 96%for GFD were determined from F2 and F3 populations. Products from 59primer pairs among 232 simple sequence repeat (SSR) pairs were polymorphic between the parents. Two markers, Xgwm11 andXgwm293, were linked to GFD by quantitative trait loci (QTL) analysis of the F2 population. The Xgwm11-linked QTL had only additive gene action and contributed 11% to the total phenotypic variation in GFD in the F2population, whereas the Xgwm293-linked QTL had both additive and dominance action and contributed 12% to the total variation in GFD. The results demonstrated that heat tolerance of common wheat is controlled by multiple genes and suggested that marker-assisted selection with microsatellite primers might be useful for developing improved cultivars. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

9.
Summary The genetics of stem elongation ability in rice was studied in parents, F1, F2 and backcross generations of six crosses. Segregation analysis indicated dominance for stem elongation ability. Estimation of genetic parameters under epistatic model indicated more than one locus control stem elongation ability and both additive and nonadditive gene effects were important. Epistatic effects were predominant over additive and dominance effects with an important role of duplicate type of epistasis. The occurrence of significant additive and additive x additive types of genetic variation and the moderately high broad sense heritability indicated the possibility of selection for an increased manifestation of stem elongation ability.  相似文献   

10.
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   

11.
T. Danon  Z. Eyal 《Euphytica》1990,47(3):203-214
Summary All possible crosses (including reciprocals) were made among four winter bread (Aurora, Bezostaya 1, Kavkaz, and Trakia) and two Israeli spring wheat cultivars (spring x winter diallel), and among two South American spring wheats (Colotana and Klein Titan) with the same Israeli cultivars (spring x spring diallel) to study the inheritance of resistance to septoria tritici blotch. Parents, F1, F2 and backcrosses were grown in two separated blocks in the field over two years. One block was inoculated with isolate ISR398A1 and another with ISR8036. Each plant was assessed for plant height (cm), days to heading (from emergence or transplanting), and percent pycnidia coverage on the four uppermost leaves. Plant height and maturity had insignificant effects on pycnidia coverage. No cytoplasmic effects could be detected. In the spring x winter diallel general combining ability (GCA) was the major component of variation. Significant specific combining ability (SCA) was present in all cases. Partial dominance was operative in populations inoculated with ISR398A1. Resistance in the winter wheats was controlled by a small number of genes (usually two). The four winter wheats derive their resistance to ISR398A1 from their common parent Bezostaya 1 which lacks the 1B/1R wheat-rye translocation. Their resistance is readily overcome by ISR8036. Inheritance of the South American wheats can be explained by additive effects, with a small number of genes of recessive mode affecting resistance to both isolates. Breeding strategies that favor additive, and additive x dominance gene action should be pursued.  相似文献   

12.
G.-L. Jiang    R. W. Ward 《Plant Breeding》2006,125(5):417-423
Fusarium head blight (FHB or scab) caused by Fusarium graminearum is a worldwide serious disease in wheat. Exploitation and genetic studies of elite resistance sources can speed up the development of resistant cultivars. To characterize the inheritance of host plant resistance in two new lines, ‘CJ 9306’ and ‘CJ 9403’, developed from a recurrent selection programme in China, six generations P1, P2, F1, F2, B1 and B2 of four crosses and 137 F6 : 7 recombinant inbred lines (RILs) from one cross were evaluated in the greenhouse for scab resistance using single‐floret inoculation. The data of area under disease progress curve (AUDPC) in F2, backcross (BC) and RIL populations exhibited mono‐modal distributions without clear‐cut demarcations and skewing towards resistance. An additive–dominance model was well‐fitted, additive effects played a predominating role, and dominance effects were also significant. Continuous distributions with two major peaks and one minor peak for the number or percentage of scabby spikelets (NSS or PSS) in segregating populations implied the existence of major genes or quantitative trait loci (QTL) for resistance. The estimates of broad‐sense and narrow‐sense heritabilities based on the six‐generation experiment were 56–76% and 26–67% respectively. The estimates of broad‐sense heritabilities based on anova with RILs were 89–90%. These two improved lines with excellent scab resistance and good agronomic traits are of interest for wheat breeding and production.  相似文献   

13.
油菜半矮杆新品系10D130株型性状的遗传分析   总被引:5,自引:0,他引:5  
株型改良是油菜高产、优质育种的主攻方向之一。矮杆及半矮杆株型有利于提高植株抗倒伏能力和经济系数、减少收获难度。10D130是一个半矮杆新品系, 用10D130和常规优良品种中双11杂交, 构建6世代遗传群体(P1、F1、P2、B1、B2和F2), 以主基因+多基因混合遗传模型对该组合株高及其关联性状进行遗传分析。结果表明, 10D130×中双11组合株高、分枝部位、主花序长度的遗传均受到1对加性-显性-上位性主基因+加性-显性-上位性多基因控制(D-0模型)。其中, 株高性状加性效应值为–8.58, 显性效应值为7.44, 主基因遗传率在B1、B2和F2中分别为23.52%、0.91%和17.81%;一次有效分枝起始部位的1对主基因加性效应值为–22.11, 显性效应值为3.13, 主基因遗传率在B1、B2和F2中分别为49.95%、40.85%和61.15%;主花序长的主基因加性效应值为–2.21, 显性效应值为1.6, 主基因遗传率在B1、B2和F2中分别为0.68%、47.94%和40.07%。一次有效分枝间距的最适宜遗传模型为E-1模型(2对加-显-上位性主基因+加-显-上位性多基因混合遗传模型), 其中第1对主基因加性效应值为–0.55、显性效应值为–1.66, 第2对主基因加性效应值为0.74、显性效应值为–1.29, 均表现超显性遗传, 主基因遗传率在B1、B2和F2三个分离世代群体中分别为10.99%、38.65%和44.10%。一次有效分枝部位高度、主花序长、有效分枝节间距和有效分枝数与株高均呈显著正相关。  相似文献   

14.
Summary Crosses were made among ten winter wheat genotypes representing different levels of resistance to Fusarium head blight to obtain F1 and F2 generations. Parents, F1 and F2 were inoculated with one strain of Fusarium culmorum. Data on incidence of head blight 21 days after first inoculation were analyzed. Broad-sense heritabilities averaged 0.39 and ranged from 0.05 to 0.89 in the individual F2 families. The joint-scaling test indicated that the inheritance of Fusarium head blight resistance was adequately described by the additive-dominance model, with additive gene action being the most important factor of resistance. With respect to the non-additive effects, dominance of resistance predominated over recessiveness. The number of segregating genes governing resistance in the studied populations was estimated to vary between one and six. It was demonstrated that resistance genes differed between parents and affected resistance differently.  相似文献   

15.
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   

16.
Summary A population of 2xms sugar beets was crossed with 4x Beta lomatogona F. et M. The 3x F1-plants were male sterile and were backcrossed with 2x and 4x sugar beets and multiplied without pollination as well. After the 1st backcross mainly 3x apomict types arose again and, among others, a small number of successful 4x backcrosses. After pollination by 4x sugar beets this 4x F1 B1 produced. besides predominatly apomictically multiplied 4x plants, also about 7% haploid 2x hybrids. The latter probably possess 1 genome from B. vulgaris and 1 genome from B. lomatogona. In the meiosis of the PMC's a certain amount of homeology between a number of chromosomes of both species could be established. The amphihaploid hybrids can be used as breeding parents for the creation of types in which introgession can occur. During hybridization in addition to 2x and 4x B. vulgaris types a number of 2x-, 3x-, 5x- and 6x-hybrids arose. This is presumably caused by the presence of gametes with the somatic number of chromosomes and the occurrence sometimes of haploid apomictic multiplication.The presence of large numbers of bolters in the F1 and F1 B1 suggests that the bolting tendency of both species is based on different genes.  相似文献   

17.
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   

18.
Summary The first backcross and F2 progenies from triploid F1 and tetraploid F1 hybrids between B. napus and 2x and 4x B. oleracea ssp. capitata (cabbage) were studied for their general morphology, resistance to race 2 of the clubroot pathogen, chromosome number and meiotic chromosome behavior. No linkage was apparent between resistance and the major morphological characters. Unreduced gametes played a large part in the successful formation of seed of the B1 and F2 progeny. B1 plants with low chromosome numbers were selected for use in recurrent backcrosses. The potential use of anther culture to extract gametic progenies from resistant B1 and F2 plants with higher chromosome numbers was suggested. The presence of homoeologous pairing observed in all the plants is considered advantageous for selecting suitable progeny in later generations.  相似文献   

19.
Summary Crossability and cytology were examined in F1, F2, B1 and hybridsplants of F1 hybrids of Brassica campestris and three wild relatives of B. oleracea, B. bourgeaui, B. cretica and B. montana, respectively. The F2 plants were obtained after self-and open pollination of the F1 hybrids. The B1 and hybrid plants were produced after the F1 hybrids backcrosses with B. campestris and crossed with B. napus, respectively. After crossing the F1 hybrids, many seeds of the F2, B1 and hybrid plants were harvested. Multivalent formation was high in the chromsome configuration for the PMCs of F2, B1 and hybrid plants, suggesting that crossing over might occur between them. Many different types of aneuploids were obtained in the progenies of the F2, B1 and hybrid plants. It is suggested that different types of normal egg cells may be produced by one-by-one or little-by-little chromosome addition. The possibility is discussed of gene transfer from B. bourgeaui, B. cretica and B. montana, to cultivated plants, B. campestris and B. napus.  相似文献   

20.
One thousand four hundred and seven spring wheat germplasm lines belonging to Indian and CIMMYT wheat programs were evaluated for stay green (SG) trait and resistance to spot blotch caused by Bipolaris sorokiniana during three consecutive crop seasons, 1999–2000, 2000–2001 and 2001–2002. Disease severity was recorded at six different growth stages beginning from tillering to late milk stage. SG trait was measured by following two approaches: difference for 0–9 scoring of green coloration (chlorophyll) of flag leaf and spike at the late dough stage (GS 87) and a new approach of leaf area under greenness (LAUG). Germplasm lines showed a wide range (7–89) for LAUG and were grouped into four viz., SG, moderately stay green, moderately non-stay green and non-stay green (NSG). However, very few (2.2%) lines showed high expression of SG trait, i.e., LAUG >60. LAUG appeared to be a better measure of SG trait than a 0–9 scale. Mean spot blotch ratings of SG genotypes were significantly lower than those of NSG genotypes at all growth stages. Two spot blotch resistant genotypes (Chirya 3 and Chirya 7) having strong expressions of SG trait were crossed with NSG, spot blotch susceptible cv. Sonalika. Individually threshed F2 plants were used to advance the generations. SG trait and spot blotch severity were recorded in the parents and F1, F3, F4, F5, F6 and F6–7 generations under disease-protected and inoculated conditions. SG trait in the F1 generation was intermediate and showed absence of dominance. Evaluation of progenies (202–207) in the segregating generations revealed that SG trait was under the control of around four additive genes. Lines homozygous for SG trait in F4, F5, F6 and F6–7 generations showed significantly lower mean area under disease progress curve (AUDPC) for spot blotch than those with NSG expression. A positive correlation (0.73) between SG trait and AUDPC further indicated a positive influence of SG on severity of spot blotch. The study established that variation for SG trait exists in spring wheat; around four additive genes control its inheritance in the crosses studied and there is positive association between SG trait and resistance to spot blotch.  相似文献   

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