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1.
The genetic analysis of 5 tomato hybrids (Danubius F 1, Luna F 1, Lido F 1, Balkan F 1 and Mi-10 F 1) was made. We produced their F 1, F 2, BC 1 and BC 2 generations and analysed their yield (on the first three flower branches) as well as some of the yield components of tomato
fruits (mean fruit weight, mean fruit weight on the first flower branch, fruit length, fruit width, and number of locules).
In order to estimate the gene effects, we applied the additive-dominance mode with three and six parameters. Epistatic gene
effects were estimated by applying the six-parameter mode (Mather and Jinks 1982). As for yield and yield components, there
were significant differences between the mean values of parents and their progeny. On the basis of the investigated genetic
parameters, the obtained results suggested that the additive and dominance gene effects prevailed in the yield and yield components
(Danubius F 1, Luna F 1, Lido F 1, Mi-10 F 1), whereas epistatic gene effects were excluded. As for the hybrid Balkan F 1, we recorded significant gene effects, both the additive and the dominance ones in the yield inheritance: additive x additive
and dominance x dominance (with the negative sign). The estimated values of the epistatic gene effects were the most prominent
in inheriting the feature average fruit weight on the first flower branch — additive x dominance gene effects. They represented
the most frequent type of the interallele interaction recorded in the investigated hybrids. 相似文献
2.
Six generations, consisting of three resistant parents, three susceptible parents, their 15 possible F 1 crosses, 15 F 2's, 15 BC 1's (F 1 x resistant female parent) and 15 BC 2's (F 1 x susceptible male parent) were analysed following Hayman (Heredity 12: 371–390, 1958) to evaluate the nature and type of gene action governing resistance to H. turcicum. The results showed that all types of gene effects, viz., additive, dominance and epistasis (i.e., additive x additive, additive x dominance and dominance x dominance) were operating in one cross or the other in controlling resistance. However, it was additive gene action and dominance x dominance type of epistasis with duplicate nature that were important in controlling resistance in most crosses. Depending upon the final objectives, one of the breeding methods, viz., recurrent selection, heterosis breeding, back-cross method or full-sib selection (bi-parental mating) may be followed. 相似文献
3.
The level of transgene expression in crop × weed hybrids and the degree to which crop-specific genes are integrated into hybrid populations are important factors in assessing the potential ecological and agricultural risks of gene flow associated with genetic engineering. The average transgene zygosity and genetic structure of transgenic hybrid populations change with the progression of generations, and the green fluorescent protein (GFP) transgene is an ideal marker to quantify transgene expression in advancing populations. The homozygous T 1 single-locus insert GFP/ Bacillus thuringiensis (Bt) transgenic canola ( Brassica napus, cv Westar) with two copies of the transgene fluoresced twice as much as hemizygous individuals with only one copy of the transgene. These data indicate that the expression of the GFP gene was additive, and fluorescence could be used to determine zygosity status. Several hybrid generations (BC 1F 1, BC 2F 1) were produced by backcrossing various GFP/Bt transgenic canola ( B. napus, cv Westar) and birdseed rape ( Brassica rapa) hybrid generations onto B. rapa. Intercrossed generations (BC 2F 2 Bulk) were generated by crossing BC 2F 1 individuals in the presence of a pollinating insect ( Musca domestica L.). The ploidy of plants in the BC 2F 2 Bulk hybrid generation was identical to the weedy parental species, B. rapa. AFLP analysis was used to quantify the degree of B. napus introgression into multiple backcross hybrid generations with B. rapa. The F 1 hybrid generations contained 95–97% of the B. napus-specific AFLP markers, and each successive backcross generation demonstrated a reduction of markers resulting in the 15–29% presence in the BC 2F 2 Bulk population. Average fluorescence of each successive hybrid generation was analyzed, and homozygous canola lines and hybrid populations that contained individuals homozygous for GFP (BC 2F 2 Bulk) demonstrated significantly higher fluorescence than hemizygous hybrid generations (F 1, BC 1F 1 and BC 2F 1). These data demonstrate that the formation of homozygous individuals within hybrid populations increases the average level of transgene expression as generations progress. This phenomenon must be considered in the development of risk-management strategies.Communicated by J. Dvorak 相似文献
4.
In two previous quantitative trait locus (QTL) mapping studies conducted in Lycopersicon esculentum x L. pimpinellifolium BC 1 and BC 2 populations we had localized a major QTL for fruit shape, fs8.1, to a ca. 20 cM interval on the short arm of chromosome 8, flanked by markers TG176 and CT92. At this QTL the allele from the wild species reduces the length of fruit, giving round-shaped fruit. In order to define more precisely the location of fs8.1, near-isogenic lines (NILs) segregating for the region of interest were developed. The results from substitution mapping show that no recombination occurred between fs8.1 and the marker CD40 in 322 meioses. The gene action for fs8.1 was determined in a BC 4F 3 population to be partial dominance. The main effect of fs8.1 is exerted on fruit length while fruit diameter is not significantly affected. A highly significant correlation ( r=0.89; P<0.01) was found between fruit shape and ovary shape indicating that the fs8.1 gene product acts early in ovary development (preanthesis). Implications for the evolution of fruit shape and the feasibility of map-based cloning of this QTL are discussed. 相似文献
5.
Scutellum derived calli of recalcitrant indica rice variety ASD-16 are subjected to qualitative and quantitative changes using different callus induction media (CIM). The suitable media for generation of regenerating calli by evaluating the increase in size of these calli as a function of time (MeazureTM2.0 software), were recorded (till 25-days post-inoculation). After 10-days post-inoculation significant differences which ranged from 5 mm to 6.5 mm and 30% variation in calliQuery size were recorded for different CIM. Improved regeneration achieved by reducing the time on callusing media to 5-days and 10-days. Also, the insights are provided for the role of cationic and anionic strength, phenomics of somatic embryogenesis, and also browning of the calli for recalcitrant indica rice variety ASD-16. The statistical analysis of size of calli with ionic strength of cations K+, H+, NH4+, Mg2+, Ca2+ and anions PO43?, NO3?, Cl? (statistical analysis tool “The Unscramble X”) shows positive correlation. The loss of scutellum derived calli due to browning was reduced by allowing the mature seed used for generation of calli to be attached to the growing calli. The browning of the calli was monitored in different media for the pattern, and statistical evidences are provided for the important role played by ionic ratios of media constituent namely, NH4+/NO3? and SO42?/PO43? (reported here for the first time). Maximum healthy calli obtained (80%) were on CIM-2 whereas maximal browning (60%) was obtained on CIM-4 after 15-days post-inoculation. Successful regeneration is achieved for recalcitrant indica rice variety ASD-16. 相似文献
6.
Transgene flow from engineered Brassica napus to wild weed relatives could potentially have an environmental effect. To evaluate the introgression of transgenic B. napus into wild Brassica juncea, the hybrid F 1 and backcross progenies derived from B. juncea (genome constitution AABB) and transgenic B. napus (AACC) crosses were investigated. C-genome-specific simple sequence repeat (SSR) markers corresponding to linkage groups N11–N19 in B. napus were screened and used to estimate the marker frequency in hybrid F 1 and backcross progenies. C-genome-specific markers could be stably detected in hybrid F 1 and backcross BC 1 plants, but were only rarely found in the BC 2–BC 5 generations. For example, a specific SSR marker for linkage group N12 segregated in BC 2 generation but were completely lost in BC 3–BC 5, while a specific SSR marker of linkage group N15 segregated in BC 1, BC 2 and BC 3 generations and was absent in more advanced backcrossed generations (BC 4 and BC 5). The results indicate that a certain gene regions in Brassica napus plants are transmitted at a relatively lower frequency to wild relatives, and more rapidly disappeared in subsequent backcross generations. We propose that a foreign gene or transgene that is integrated in the C-chromosome of Brassica napus could reduce the risk of introgression in nature. 相似文献
7.
Inheritance of resistance to blackmold, a disease of ripe tomato fruit caused by Alternaria alternata, was studied in two interspecific crosses. The parents, F 1 and F 2 generations of a cross between the susceptible Lycopersicon esculentum Mill. cultivar Hunt 100 and the resistant L. Cheesmanii f. typicum Riley accession LA 422, and the parents, F 1, F 2, F 3, and BC 1 P 2 generations of a cross between the susceptible L. Esculentum cv. VF 145B-7879 and LA 422 were evaluated. The following disease evaluation traits were used: symptom rating (a symptom severity rating based on visual evaluation of lesions), diseased fruit (the number of diseased fruits divided by the total number of fruit scored), and lesion size (a function derived from the actual lesion diameter). Generation means analysis was used to determine gene action. The data of the Hunt 100 × LA 422 cross fit an additive-dominance model for all three traits. The VF 145B-7879 × LA 422 cross data best fit a model that included the additive × additive and additive × dominance interaction components for the trait diseased fruit, whereas higher-order epistatic models would have to be invoked to fit the data for the traits symptom rating and lesion size. A minimum of one gene segregated for all three traits. Broad-sense heritability estimates ranged from 0.09 to 0.16 for all three traits, indicating that selection for improved resistance to blackmold will require selection on a family performance basis. 相似文献
8.
Larval feeding was assayed in a generalist caterpillar ( Heliothis virescens (F.)), a specialist caterpillar ( Heliothis subflexa (Gn.)), their F 1 hybrids and a backcross with H. s. to gain a preliminary understanding of the genetic basis of host use in H. v. Plants used in these experiments were tobacco ( Nicotiana tabaccum), cotton ( Gossypium hirsutum), soybean ( Glycine max) (hosts of H. v.) and ground cherry ( Physalis pubescens) (host of H.s.).
A feeding study of H.v., H.s. and their reciprocal hybrids showed that, after the first eight days of feeding, H.v. had its highest survival and weight gain on soybean and had lowest survival and weight gain on its non-host, Physalis. H.s. had its highest survival and weight gain on its host plant, Physalis, and performed very poorly on the three non-host plants. The two F 1 hybrids were SV 0 (offspring of H.s. female and H.v. male) and VS 0 (offspring of H.v. female and H.s. male). The hybrids did not differ from each other, indicating no sex linkage or maternal effects, except that VS 0 had greater weight gain on tobacco than did SV 0. The hybrids, unlike their parents, survived well on all four host plants and their weight gain was intermediate on all four
host plants.
In a separate experiment the VS 0 hybrid was mated to the specialist to produce the VS 1 backcross. In contrast to the F 1, the backcross had significantly lower survival than the generalist on soybean, cotton, tobacco and weight gain was lower
on soybean, cotton and tobacco but higher on Physalis. Survival and weight gain on cotton and tobacco were inherited as partially dominant traits; on Physalis there was overdominance for survival and complete dominance for weight gain; on soybean both survival and weight gain were
additive. Survival on cotton, Physalis, soybean and tobacco and weight gain on Physalis could not be completely explained by a model that included only dominance and additive effects. These traits may be influenced
by epistatic and/or environmental effects. 相似文献
9.
The valuable genes of Aegilops biuncialis, Ae. ovata, Ae. kotschyi, and Ae. variabilis were transferred to rye, by crossing Aegilops-rye amphiploids with tetraploid and diploid substitution rye. The C-banded karyotype of the BC 1 and BC 2 generations of amphiploids with 4 x substitution rye and BC 1 with 2 x substitution rye showed great variation in chromosome number and composition. In the BC 1 generation of amphiploids with 4 x and 2 x substitution rye, seed set success rate and germination rate varied depending on origin. However, plant sterility in all
cross combinations of amphiploids with 4 x and 2 x substitution rye resulted in their elimination from further experiments in the BC 3 and BC 2 generations, respectively. In backcrosses of 4 x substitution rye with amphiploids Ae. variabilis × rye 4 x, fertile 4 x rye plants containing Aegilops chromatin were produced in the BC 2 generation. 相似文献
10.
Summary Three flint and three dent maize ( Zea mays L.) inbred lines, their possible F 1 crosses, F 2 and backcross progenies, and all possible three-way crosses were evaluated in a three-year experiment for yield, ear moisture, and plant height. The purpose was to estimate genetic parameters in European breeding materials from (i) generation means analysis, (ii) diallel analysis of generation means, and (iii) analysis of F 1 and three-way cross hybrids. Method (i) was based on the F -metric model and methods (ii) and (iii) on the Eberhart-Gardner (1966) genetic model; both models extended for heterotic maternal effects.Differences among generation means for yield and plant height were mainly attributable to dominance effects. Epistatic effects were significantly different from zero in a few crosses and considerably reduced heterosis in both traits. Additive x additive and domiance x dominance effects for yield were consistently positive and negative, respectively. Significant maternal effects were established to the advantage of generations with a heterozygous seed parent. In the diallel analysis, mean squares for dominance effects were greater than for additive effects for yield and plant height but smaller for ear moisture. Though significant for yield and plant height, epistatic variation was small compared to additive and dominance variation. Estimates of additive x additive epistasis for yield were significantly negative in 11 of 15 crosses, suggesting that advantageous gene combinations in the lines had been disrupted by recombination in the segregating generations. The analysis of hybrids supported the above findings regarding the analysis of variance. However, the estimates of additive x additive epistasis for yield were considerably smaller and only minimally correlated with those from the diallel analysis. Use of noninbred materials as opposed to materials with different levels of inbreeding is considered the main reason for the discrepancies in the results. 相似文献
11.
Summary Genetical studies on grain yield and its contributing traits were made in a six parent complete diallel in the F 1 and F 2 generations of one of the most widely grown grain species of grain amaranths ( Amaranthus hypochondriacus L.). Graphical analysis indicated that epistasis exists for 1,000-grain weight in the F 1. Grain weight/panicle, yield/plant and harvest index indicated absence of non-allelic gene interaction. The harvest index in the F 1 and F 2 and grain weight/ panicle, 1,000-grain weight, yield/plant in the F 2 appeared to be controlled by overdominance effects. Higher grain yield appeared to be associated with dominant genes. Both additive and non-additive gene effects were responsible for the genetic variation in the diallel population. However, dominance variance was more important than additive variance in grain yield/ plant and harvest index in the F 1 and F 2. For 1,000-grain weight additive genetic variance was more important in the F 1 and non-additive in F 2. There was overdominance of a consistent nature in the two analyses for harvest index in the F 1 and F 2, grain weight/ panicle, 1,000-grain weight and yield/plant in the F 2 and partial dominance for 1,000-grain weight in the F 1. 相似文献
12.
Summary A series of experiments was conducted to determine the inheritance of seed weight in cucumber. Matings between a Cucumis sativus var. sativus (Cs) L. inbred line (USDA WI 1606; P 1) and a C. sativus var. hardwickii (Royle) Kitamura (Ch) collection (PI 215589; P 2) were made to produce seed of reciprocal F 1, F 2, and BC 1 families. Families were grown under field and greenhouse conditions, and seeds were extracted from fruit 55 to 60 days post-pollination. Seed of F 1 and F 2 families was obtained using the Cs inbred WI2808 (P 12) and the Ch collection LJ 90430 (P 10), and seed of F 1 families were produced using a North Carolina Design II mating scheme in which three Cs (P 3= GY-14; P 4=WI 1379; P 5=WI 1909) inbreds were used as maternal parents and seven Ch collections (P 2; P 6= PI462369; P 7=486336; P 8=LJ91176; P 9=273469; P 10= 2590430; P 11=PI187367) were used as paternal parents. Mean seed weights of F 1 progeny reflected the dominance of genes of the C. sativus var. sativus parent. Transformation to number of seeds per unit weight resulted in increased variance homogeneity within generations and a broad-sense heritability ranging between 26% to 56%. Additive and dominance effects were important in the expression of seed weight in P 1×P 2 progeny produced in the greenhouse and additive effects were important in field grown progeny resulting from P 1×P 2 and P 10×P 12 matings. The estimated number of factors or loci involved ranged between 10 to 13, depending on the method of calculation. 相似文献
13.
Summary Anther-culture response was examined among three spring wheat ( Triticum aestivum L.) cultivars to evaluate the genetic component of response and to determine whether androgenetic performance could be improved by selection. The three lines, the three possible F 1's among the three lines, their F 2's, and the backcrosses to the parents were evaluated for callus production and regeneration capacity. Significant variation was observed among the generations of the three crosses for callus formation. Genetic variation for regenerability was nonsignificant. Callus production was negatively correlated (-0.24) with regeneration capacity. The random variation in the study was too great to determine whether major-gene differences for antherculture response exist among the three lines by examining population distributions. When the material was evaluated for quantitative gene effects, the estimates for the additive gene effects were generally greater than the estimates for the dominance gene effects for callus formation. Only the Pavon x Chris cross, however, exhibited a significant narrow sense heritability estimate for callusing response (0.94). Due to the large component of random variation and the varying selection potential among crosses for androgenetic performance, improving anther-culture response in wheat by selection could prove difficult unless the anther-culture process itself selects for response traits at the gametic level. 相似文献
14.
In order to identify quantitative trait loci (QTLs) for leaf senescence and related traits in rice ( Oryza sativa L.), we developed two backcross populations, indica/japonica// japonica and indica/japonica//indica, using IR36 as the indica parent and Nekken-2 as the japonica parent. The QTLs were mapped using a set of simple sequence-repeat markers (SSRs) in the BC 1F 1 population. Senescence was characterized in these plants by measuring the leaf chlorophyll content 25 days after flowering (DAF), the reduction in chlorophyll content (the difference between the chlorophyll content at flowering and at 25 DAF), and the number of late-discoloring leaves per panicle at 25 DAF in five plants from each BC 1F 2 line. These plants were moved into a temperature-controlled growth cabinet at the time of flowering and allowed to mature under identical conditions. Eleven QTLs were detected in the two populations. The major of QTLs for senescence were found on the short arm of chromosome 6 and on the long arm of chromosome 9. Of these, one QTL on chromosome 6 and two on chromosome 9 were verified by confirming the effects of the genotypes on the phenotypes of the BC 1F 3 lines. The japonica parent was found to contribute to late senescence at all but one QTL. Based on a comparison of the effects of heterozygotes and homozygotes on the phenotypic values of each QTL genotype, we concluded that the differential senescence observed in the indica-japonica hybrid was not due to over-dominance; rather, it was the result of partial-dominance genes that were donated from either of the parents. 相似文献
15.
Summary Synthetic alloploid Brassica oxyrrhina (2n = 18, OO) x B. campestris (2n = 20, AA) was repeatedly backcrossed with B. campestris to place B. campestris nucleus in the cytoplasm of B. oxyrrhina. Alloplasmic plants, obtained in BC 5 generation, were stably male sterile but mildly chlorotic during initial development. Synthetic alloploid B. oxyrrhina-campestris was also hybridized with B. juncea to transfer B. oxyrrhina cytoplasm. Segregation for green and chlorotic plants was observed in BC 1 and BC 2 generations. By selection, however, normal green male sterile B. juncea was obtained in BC 3. Pollen abortion in both B. campestris and B. juncea is post-meiotic. 相似文献
16.
Summary
Oryza minuta J. S. Presl ex C. B. Presl is a tetraploid wild rice with resistance to several insects and diseases, including blast (caused by Pyricularia grisea) and bacterial blight (caused by Xanthomonas oryzae pv. oryzae). To transfer resistance from the wild species into the genome of cultivated rice ( Oryza sativa L.), backcross progeny (BC 1, BC 2, and BC 3) were produced from interspecific hybrids of O. sativa cv IR31917-45-3-2 (2n=24, AA genome) and O. minuta Acc. 101141 (2n=48, BBCC genomes) by backcrossing to the O. sativa parent followed by embryo rescue. The chromosome numbers ranged from 44 to 47 in the BC 1 progeny and from 24 to 37 in the BC 2 progeny. All F 1 hybrids were resistant to both blast and bacterial blight. One BC 1 plant was moderately susceptible to blast while the rest were resistant. Thirteen of the 16 BC 2 progeny tested were resistant to blast; 1 blast-resistant BC 2, plant 75-1, had 24 chromosomes. A 3 resistant: 1 susceptible segregation ratio, consistent with the action of a major, dominant gene, was observed in the BC 2F 2 and BC 2F 3 generations. Five of the BC 1 plants tested were resistant to bacterial blight. Ten of the 21 BC 2 progeny tested were resistant to Philippine races 2, 3, and 6 of the bacterial blight pathogen. One resistant BC 2, plant 78-1, had 24 chromosomes. The segregation of reactions of the BC 2F 2, BC 2F 3, and BC 2F 4 progenies of plant 78-1 suggested that the same or closely linked gene(s) conferred resistance to races 2, 3, 5, and 6 of the bacterial blight pathogen from the Philippines. 相似文献
17.
The two-spotted spider mite ( Tetranychus urticae Koch) is an important pest of tomato ( Lycopersicon esculentum Mill.) crops in temperate regions as this spider mite has a very large capacity for population increase and causes severe
tomato yield losses. There is no described tomato cultivar fully resistant to this pest, although resistant accessions have
been reported within the green-fruited tomato wild species L. pennellii (Corr.) D’Arcy and L. hirsutum Humb. & Bonpl. We observed a L. pimpinellifolium (Jusl.) Mill. accession, ‘TO-937’, which seemed to be completely resistant to mite attacks and we crossed it with the susceptible
L. esculentum cultivar. ‘Moneymaker’ to obtain a family of generations consisting of the two parents, the F 1, the F 2, the BC 1 to L. esculentum, and the BC 1 to L. pimpinellifolium. This family was evaluated for mite resistance in a polyethylene greenhouse using an experimental design in 60 small complete
blocks distributed along 12 double rows. Each block consisted of five F 2 plants in one row and one plant of each of the two parents, the F 1, the BC 1 to L. esculentum, and the BC 1 to L. pimpinellifolium in the adjacent row. Plants at the 10–15 leaf stage were artificially infested by putting on them two pieces of French bean
leaf heavily infested with T. urticae. After two months, evaluations of infestation were made by visual observation of mite nets and leaf damage. Plants that were
free of signs of mite reproduction on the top half were considered as resistant, plants with silky nets only on their basal
leaves, intermediate, and plants with mite reproduction on both basal and top canopies were scored as susceptible. Dominance
for resistance appeared because all the ‘To-937’, BC 1 to L. pimpinellifolium, and F 1 plants were resistant. Not all ‘Moneymaker’ plants behaved as susceptible because 35% of plants were intermediate. In the
BC 1 to L. pimpinellifolium and the F 2, most plants were scored as resistant, only 7 % BC 1 and 3 % F 2 plants were intermediate, and a single F 2 plant (0.3 %) was susceptible. With these figures, resistance seemed to be controlled by either four or two genes according
to whether segregation in the BC 1 or in the F 2, respectively, were considered. These results could in part be explained because of appearance of negative interplot interference
due to the high frequency of resistant genotypes within most of the generations. Therefore, the family was evaluated again
but using a different experimental design. In the new experiment, 16 ‘TO-937’, 17 ‘Moneymaker’, 17 F 1, 37 BC 1 to L. pimpinellifolium, 38 BC 1 to L. esculentum, and 125 F 2 plants were included. Each of these test plants was grown besides a susceptible ‘Moneymaker’ auxilliary plant that served
to keep mite population high and homogeneous in the greenhouse. Negative interplot interference was avoided with this design
and all the ‘TO-937’, F 1, and BC 1 to L. pimpinellifolium plants were resistant, all ‘Moneymaker’ test plants were susceptible, and 52 % BC 1 to L. esculentum and 25 % F 2 plants were susceptible, which fitted very well with the expected for resistance governed by a single dominant gene. The
simple inheritance mode found will favour sucessful introgression of mite resistance into commercial tomatoes from the very
close relative L. pimpinellifolium. 相似文献
18.
A cross within C. sativus var. sativus (GY14 x P1432860) and molecular markers were used to determine the number, magnitudes of effect, and overall variation described for genes conditioning the quantitatively inherited traits of length, diameter, seed-cavity size, color, L/D (length/diameter), and S/D (seed-cavity size/diameter). QTL effects were detected with MAPMAKER/QTL using 100 F 3 lines evaluated in a replicated field trial of two harvests over 2 years at one location. Multilocus models were constructed by fixing significant intervals and re-scanning using MAPMAKER/ QTL. Marker inclusion in multilocus models was compared to an ANOVA backward elimination procedure. Generally the same loci were associated with QTLs among the two methods of model construction. Heritabilities of individual QTLs were confirmed by analysis of related backcrosses (67 BC 1P 1 lines and 68 BC 1 P 2 lines). The majority of QTLs were confirmed in at least one backcross population. Pairs of backcrosses allowed overall additive variances and heritabilities to be calculated using a North Carolina Design III (NCIII design) and estimates were compared to overall variances attributable to markers. Heritability estimates using markers were comparable, but generally lower than additive variances estimated by co-variance relationships in the NCIII design. This suggests that neither the number nor the magnitude of QTL effects were overestimated. The utility of backcrosses to confirm individual QTLs and the overall variance described by QTLs is recommended to avoid false positives and over-estimation of effects. The number of QTLs, and/or the proportions of phenotypic variation described by markers and the mating design, agreed with previous reports of heritabilities employing similar germplasm. 相似文献
19.
The identification of molecular markers that are closely linked to gene(s) in Gossypium barbadense L. accession GB713 that confer a high level of resistance to reniform nematode (RN), Rotylenchulus reniformis Linford & Oliveira, would be very useful in cotton breeding programs. Our objectives were to determine the inheritance of
RN resistance in the accession GB713, to identify SSR markers linked with RN resistance QTLs, and to map these linked markers
to specific chromosomes. We grew and scored plants for RN reproduction in the P 1, P 2, F 1, F 2, BC 1P 1, and BC 1P 2 generations from the cross of GB713 × Acala Nem-X. The generation means analysis using the six generations indicated that
one or more genes were involved in the RN resistance of GB713. The interspecific F 2 population of 300 plants was genotyped with SSR molecular markers that covered most of the chromosomes of Upland cotton ( G. hirsutum L.). Results showed two QTLs on chromosome 21 and one QTL on chromosome 18. One QTL on chromosome 21 was at map position
168.6 (LOD 28.0) flanked by SSR markers, BNL 1551_162 and GH 132_199 at positions 154.2 and 177.3, respectively. A second
QTL on chromosome 21 was at map position 182.7 (LOD 24.6) flanked by SSR markers BNL 4011_155 and BNL 3279_106 at positions
180.6 and 184.5, respectively. Our chromosome 21 map had 61 SSR markers covering 219 cM. One QTL with smaller genetic effects
was localized to chromosome 18 at map position 39.6 (LOD 4.0) and flanked by SSR markers BNL 1721_178 and BNL 569_131 at positions
27.6 and 42.9, respectively. The two QTLs on chromosome 21 had significant additive and dominance effects, which were about
equal for each QTL. The QTL on chromosome 18 showed larger additive than dominance effects. Following the precedent set by
the naming of the G. longicalyx Hutchinson & Lee and G. aridum [(Rose & Standley) Skovsted] sources of resistance, we suggest the usage of Ren
barb1
and Ren
barb2
to designate these QTLs on chromosome 21 and Ren
barb3
on chromosome 18. 相似文献
20.
Anthers of Psidium guajava cultivated on either Murashige-Skoog's or Nitsch's basal medium (BM) or the BM supplemented with 10 −6 M benzylaminopurine (BAP) were observed to contain microspores undergoing androgenic segmentations as well as a few multicellular
microscopic embryoids. However, final morphogenic response from such cultured anthers was the development of calli. These
calli had restricted growth accompanied by their early browning. Suspecting the browning to be due to accumulation of polyphenols,
the culture medium was fortified with polyvinylpyrrolidone (PVP). PVP, increased sucrose concentration in the medium and cold
pretreatment of anthers decreased the proportion of anthers turning brown as well as delayed the browning of calli, but it
was not possible to maintain the calli for differentiation. Cold pretreatment significantly increased the percentage of callusing
anthers and also resulted in the early emergence of calli. 相似文献
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