首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Larger particle volume is beneficial for many aspects of maize starch processing, and may improve the performance of some starch attributes. Of the numerous endosperm carbohydrate mutants, the soft starch (h) mutant appears to have the greatest influence on starch particle volume. The objective of this study was to determine the gene dosage effect upon starch particle volume at the h locus. Two inbreds, B37 and Oh43, were studied in 1992 and 1993, and their hybrid B37 × Oh43 was studied in 1993. Appropriate crosses were made to establish four endosperm genotypes ++/+, ++/h, hh/+ and hh/h. Starch was extracted from mature kernels collected for each endosperm genotype and analysed for particle volume. The source of variation attributable to fitting two straight regression lines on number of h alleles was highly significant (P < 0.01) in all experiments, resulting in a horizontal‐line relationship among the three normal genotypes (++/+,++/h and hh/+) at 14.452 μm33 and a regression line of slope 1.622 μm3 passing from hh+ to hh/h. There is no dosage effect of starch particle volume at the h locus; complete recessiveness of the h allele for starch particle volume is the same as the visual phenotypic observation of soft starch.  相似文献   

2.
Development of cytoplasmic-genic male sterility in safflower   总被引：1，自引：0，他引：1  
K. Anhani 《Plant Breeding》2005,124(3):310-312
An interspecific cross was made between Carthamaus oxyacantha and the cultivated species C. tinctorius to develop a cytoplasmic‐genic male sterility (CMS) system in safflower. C. oxyacantha was the donor of sterile cytoplasm. The 3: 1 segregation pattern observed in BC1F2 suggested single gene control with dominance of male‐fertility over male‐sterility. The information obtained from crossing male sterile X male fertile plants in BC1F3 and BC1F4 generations showed statistically significant single gene (1: 1) segregation for male sterility vs. male fertility. The results demonstrated that C. tinctorius possesses a nuclear fertility restorer gene and that a single dominant allele restored fertility (Rf) in progeny carrying CMS cytoplasm of C. oxyacantha. Male sterility occurred with the homozygous recessive condition (rfrf) in a sterile C. oxyacantha cytoplasm background and not in the normal cytoplasm of C. tinctorius. The genetic background of different restorer lines of C. tinctorius having normal cytoplasm did not effect fertility restoration. The absence of male sterile plants in C. tinctorius populations ruled out the possibility of genetic male sterility. Normal meiosis in F1 and BC1F2 ruled out a cytogenetic basis for the occurrence of male sterility.  相似文献   

3.
To combine high yield and improved cold tolerance (CT) in a japonica rice variety, ‘Chaoyou1’ (CY1), 324 BC2F5 introgression lines (ILs) selected for CT from 11 CY1 BC2F4 populations were evaluated in replicated experiments for their CT at the reproductive and seedling stages. A mean realized heritability of 0.747 was achieved in this study for CT. Evaluation of 116 ILs from five BC populations in replicated experiments under stress and normal conditions identified 18 promising ILs that had greatly improved CT and yield compared with CY1. Detailed comparisons between the ILs and CY1 for CT and yield‐related traits under stress and non‐stress conditions provided useful information and better understanding of important issues such as donor selection, selection efficiency and associated changes in non‐target traits in the BC breeding process. The large numbers of CT ILs developed provide useful materials for genetic, physiological and molecular dissection of CT and yield traits using DNA markers and ‐omic tools, and as parents for further improving these traits by designed QTL pyramiding.  相似文献   

4.
Non‐pungent bell pepper (Capsicum annuum L.) lacks the cytoplasmic male sterility (CMS) nuclear restorer allele, Rf, and CMS cannot be employed in its F1 hybrid seed production. To demonstrate that the genic male sterility (GMS) system in non‐pungent bell pepper can be converted to the CMS male sterility system, the conversion of GMS to CMS for non‐pungent bell pepper line GC3 was conducted by introgression of S‐type cytoplasm and the Rf allele from tropical pungent donors. After morphological traits were evaluated, two lines from BC1F1 containing S‐type cytoplasm and four lines from BC2F2 containing Rf allele, phenotypically similar to GC3, were obtained and could be employed as CMS male sterile lines and restorer lines for non‐pungent bell pepper. Four molecular markers potentially linked to traits of interest were also evaluated in BC1F1 and BC1F2 populations. This is the first time that GMS has been successfully converted to CMS in bell pepper, a significant contribution for bell pepper hybrid seed production.  相似文献   

5.
The genetic behaviour of a yellow-green leaf sweetpotato mutant, a269, was analysed to prepare for genetic mapping and cloning of this mutant and to elucidate the regulation of its molecular mechanisms. The phenotypic stability of the mutant was observed under natural conditions, and photosynthetic pigments in mature leaves were measured. GN1323 and a269 were crossed and backcrossed. Genetic behaviour was assessed using phenotypic expression and segregation in F1, BC1 and BC2. The a269 leaves were yellow-green at all stages after germination. The thylakoid lamellae of a269 were disorganized, had incomplete grana and were fewer compared with GN1323. The direct and reciprocal F1 populations had normal leaf colour, whereas the BC2 populations had yellow-green leaves. Segregation of plants with normal- and yellow-green leaf colour in the four BC1 populations satisfied the backcross segregation ratio of 11 : 1 for auto-allohexaploids. The a269 mutant is stable, and its trait is controlled by one recessive nuclear locus.  相似文献   

6.
A pubescent mutant of Ethiopian mustard (Brassica carinata A. Braun), N2-9531, was developed from the glabrous line C-101. The objective of this research was to study the inheritance of trichome density in this mutant. Plants of N2-9531 and C-101 were reciprocally crossed and F1, F2, and BC1F1 generations were analysed for trichome density. The average trichome density differed in the reciprocal F1 and F2 generations, indicating partial cytoplasmic effects. The trichome density of F1 plants was lower than the midparent value, revealing a partial dominance of absence over high trichome density. Segregation in the F2 and BC1F1 generations approximated 1:4:6:4:1 and 1:2:1 ratios, respectively indicating that two independent loci (H 1 and H 2) acting in an additive manner contributed equally to the expression of trichome density. The proposed genotypes were h 1 h 1 h 2 h 2 for N2-9531 and H 1 H 1 H 2 H 2 for C-101. The simple inheritance of this trait should facilitate the transfer of leaf pubescence to other Ethiopian mustard lines. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

7.
Interspecific hybrids between Trifolium uniflorum and cultivated white clover (Trifolium repens) have highly useful characteristics for temperate pastoral systems derived from both parent species. However, the early hybrids (F1 and BC1) also have unacceptably poor seed production for commerce. This study analysed the basis for the poor seed production and investigated breeding strategies for overcoming the problem. The BC1F1 generation produced lower‐than‐expected numbers of heads per plant and seeds per floret. Backcrossing of selected hybrids to white clover corrected these deficiencies and created new variation. Seed numbers were also returned to near target levels by recurrent selection within the BC1 generation. Thus, it was possible to retain a theoretical average of 25% of T. uniflorum genome and still achieve high seed production per plant. The BC1F2 and BC2F1 generations produced high seed numbers per plant, along with reasonable variation. Both of these second‐generation hybrid forms have high reproductive potential and should be the focus for the selection of the desired combinations of agronomic and seed production traits.  相似文献   

8.
Summary Interspecific substitutions of the nucleus of Helianthus annuus (2n=34) into the cytoplasm of H. petiolaris (2n=34) were obtained by successive backcrossing using cultivated sunflower, H. annuus, as the recurrent pollen parent.Meiosis in the F1 was characterized by multivalents, suggesting that 10 of the 34 chromosomes were heterozygous for chromosomal interchanges. An additional pair of chromosomes also contained a paracentric inversion. Continued backcrossing resulted in rapid elimination of the meiotic aberrations evident in the F1. In the BC1, 1 of 11 plants had normal meiosis and by the BC2, only 13 of 54 plants had meiotic aberrations similar to those of the F1. However, trisomic progeny (2n=35) were found in 3 of the 11 BC1 plants and 20 of the 54 BC2 plants. No meiotic aberrations were observed in BC3 or BC4 plants. Plants with indehiscent anthers, and considered to be male sterile (M.S.), first occurred in the BC1 and, by the BC2, 51 of 54 plants were M.S. All 19 BC3 and 16 BC4 plants were M.S. Preliminary investigations suggest that the pollen from such plants is sterile and that the sterility is cytoplasmic rather than genetic.Disc-flower measurements were a useful technique for selecting samples at the correct stage of microsporogenesis, but could not be used to distinguish between successive backcrosses.  相似文献   

9.
Safflower (Carthamus tinctorius L.) possesses the highest amount of linoleic acid among the 10 major vegetable oil crops of the world. Very high linoleic acid content is controlled by recessive alleles at a single locus Li. However, deviated segregations from the expected monogenic inheritance have been observed in crosses involving nuclear male‐sterile (NMS) lines. The present research was undertaken to study the inheritance of very high linoleic acid content in safflower and its relationship with nuclear male sterility. F1, F2, F3, BC1F1 and BC1F2 seed generations were evaluated in a cross between CR‐142 (a line with very high linoleic acid content, 88%) and CL1 (an NMS line with wild‐type linoleic acid content, 74%). The genetics of linoleic acid content in male‐sterile plants was determined by testcrossing with CR‐142. The results confirmed monogenic inheritance. The analysis of the F3 and BC1F2 to CL1 seed generations demonstrated a repulsion‐phase linkage between Li and Ms loci, the latter conferring the NMS trait. The recombination rate between Li and Ms was estimated to be 0.09.  相似文献   

10.
The entire USDA‐ARS maintained collection of 650 accessions of proso millet (Panicum miliaceum L.) was evaluated for the presence of accessions with waxy (amylose‐free) endosperm starch. Six accessions, five of which derived from mainland China, were identified. Segregation ratios for waxy endosperm were evaluated in F2 and F3 populations derived from crosses between two waxy accessions, PI 436625 (Lung Shu 16) and PI 436626 (Lung Shu 18), and several wild‐type accessions. The waxy trait was found to be under the control of duplicate recessive alleles at two loci, herein designated wx‐1 and wx‐2. Wild‐type alleles at these loci were designated Wx‐1 and Wx‐2. Iodine‐binding revealed a mean grain‐starch amylose concentration of 3.5% in waxy lines and 25.3% in wild‐type proso. Expression of the granule‐bound starch synthase (waxy protein) in waxy lines was reduced to approximately one‐tenth that of wild‐type accessions. The waxy accessions identified now are available for the introgression of this trait into breeding lines adapted to the Great Plains of North America.  相似文献   

11.
Although the wild sunflower species Helianthus laevigatus has not been extensively studied it may be considered for sunflower breeding as a potential source of desirable genes for Sclerotinia stalk rot resistance and high contents of proteins and linoleic acid in the seed. A set of six H. laevigatus populations was crossed to cultivated sun~ower lines and produced nine F1 (2-14 plants) and 66 BC1F1 hybrid combinations (1-13 plants). Male sterility occurred in F1 and BC1F1 hybrid combinations and pollen viability was lower in the progenies than in the parents (51.6-77.2%in F1 and in F1 and 4.8-34.0% in BC1F1). Meiosis was normal in the H. laevigatus populations It was found that this tetraploid species also occurred in a hexaploid form Numerous irregularities were observed in the meiosis of the F1 interspecific hybrids During diakinesis, quadrivalents and hexavalents were recorded in addition to bivalents Dislocated chromosomes and chromosome bridges were present in the other phases The chromosome number in F1 was 68 (tetraploid). Irregularities in chromosome pairing were observed in the interspecific hybrids at BC1F1. There were many univalents, and trivalents quadrivalents and hexavalents were also present The chromosome number in the BC1F1 generation ranged from 34 to 60. The occurrence of meiotic irregularities in the F1 and BC1F1 interspecific hybrids indicates that H. laevigatus and the cultivated sunflower differ in genome constitution.  相似文献   

12.
H. M. Kamal    T. Takashina    H. Egashira    H. Satoh  S. Imanishi 《Plant Breeding》2001,120(2):179-181
This study was performed to introduce the distinct aromatic fragrance of Lycopersicon peruvianum LA 1554 into the cultivated tomato, Lycopersicon esculentum. The strong breeding barriers existing between these two distantly related species were circumvented by the ovule selection and culture method. A large BC1F1 population was developed and among 127 plants, 36 were self‐compatible and yielded fruits. Fruits of some of these selected plants were found to be enriched with a sweet aromatic flavour. Sensory evaluation of the fruit aroma of these selected plants was performed by a panel of 12 members against one of the best consumer‐rated Japanese commercial tomato cultivars, ‘Momotaro’. Although extensive variation was observed in fruit‐aroma in the BC1F1 population, panel opinion on ‘flavour‐desirability’ significantly favoured the BC1F1 fruits of some selected plants over the cv. ‘Momotaro’. Therefore, it can be concluded that the aromatic fragrance of a ‘L. peruvianum’ accession has successfully been introduced into the cultivated tomato gene pool.  相似文献   

13.
N. Inomata 《Plant Breeding》2002,121(2):174-176
In this cytogenetic study the progeny of all crosses were investigated in F1, F2 and backcross (BC1) hybrids. Brassica napus and F1 hybrids between B. napus and B. oleracea, and between B. napus and three wild relatives of B. oleracea (B. bourgeaui, B. cretica and B. montana). Each of the wild relatives has 18 somatic chromosomes. Interspecific F1 hybrids were obtained through ovary culture mean. These had 28 and 37 chromosomes and their mean pollen fertility was 10.7% and 93.0%, respectively. Many F2 and BC1 seeds were harvested from the F1 hybrids with 37 chromosomes after self‐pollination and open pollination of the F1 hybrids, and backcrossing with B. napus. Many aneuploids were obtained in the F2 and BC1 plants. It is evident from these investigations that the F1 hybrids may serve as bridge plants to improve B. napus and other Brassica crops.  相似文献   

14.
Fitness of sugary1 (su1) is affected by some critical traits that depend on the genotypes and environments, while their effects have not been quantified with convincing statistical methods. The objective of this work was to identify and quantify the critical factors of su1 fitness with different genotypes and environments. We used two pairs of field corn inbreds that differentially affected su1 viability to develop F1, F2, BC1 and BC2. After selfing, Su1 and su1 kernels were evaluated under controlled environmental conditions and in field trials. Multiple regressions showed that dry weight of juvenile plant was affected by early vigour (plant size, colour and health) and emergence in cold conditions; ear weight by plant appearance, number of plants and chlorophyll content; number of ears by plant appearance, number of plants, chlorophyll content and female flowering; and kernel weight by ear weight, number of plants, row number and ear length. The main critical factors for su1 fitness were early vigour and emergence under cold conditions at initial stages, while several adult traits were related with final fitness.  相似文献   

15.
The development of soybean varieties that lack the β‐conglycinin α‐subunit is an attractive goal because the β‐conglycinin α‐subunit negatively influences the nutrition and gelation of tofu and is a major allergen. To remove this undesirable allergen and simultaneously improve the seed nutritional value and food‐processing quality, marker‐assisted background selection (MABS) was used in backcross breeding to incorporate cgy‐2, a null phenotype version of the gene encoding the β‐conglycinin α‐subunit, from the donor line ‘RiB’ into the genetic background of the Chinese cultivar ‘Dongnong47’ (DN47), a popular high‐oil superfine seed soybean cultivar from Heilongjiang Province, China. In each F2 (F2, BCnF2) generation of the breeding programme, the offspring that carried the introgressed cgy‐2 were identified by sodium dodecyl sulphate–polyacrylamide gel electrophoresis and rescreened by MABS using simple sequence repeat markers to accelerate recurrent parent genome recovery. Of the 49 advanced backcrossing breeding lines (ABLs), the three best lines, ABL1, ABL2 and ABL3, were selected from the BC1, BC2 and BC3 populations, respectively. The ABLs were evaluated for desirable agronomic characteristics, yield‐related traits, amino acid composition, free amino acid composition and tofu‐processing quality in the mature seeds. All of the ABLs lacked the α‐subunit but grew and reproduced normally without deleterious effects on physiological processes such as seed development and germination. The free amino acid content of ABL1 was significantly higher than that of ‘DN47’, with arginine (Arg) being particularly enriched. Compared to the recurrent parent ‘DN47’, the total protein content of the three ABLs was higher, the amino acid composition of the seed proteins was markedly modified and the yield and hardness of the tofu that was made from the ABLs were significantly increased. MABS combined with stringent phenotypic selection in a backcross breeding programme is a feasible strategy for the genetic engineering of seed protein components to produce allergenic subunit‐deficient variant alleles.  相似文献   

16.
The wheat progenitors and other wild relatives continue to be important sources of genes for agronomically desirable traits, which can be transferred into durum wheat (Triticum turgidum; 2n = 4x = 28; AABB genomes) cultivars via hybridization. Chromosome pairing in durum × alien species hybrids provides an understanding of genomic relationships, which is useful in planning alien gene introgression strategies. Two durum cultivars, ‘Lloyd’ and ‘Langdon’, were crossed with diploid wheatgrass, Thinopyrum bessarabicum (2n = 2x = 14; JJ), to synthesize F1 hybrids (2n = 3x = 21; ABJ) with Ph1. ‘Langdon’ disomic substitution 5D(5B) was used as a female parent to produce F1 hybrids without Ph1, which resulted in elevation of pairing between durum and grass chromosomes – an important feature from the breeding standpoint. The F1 hybrids were backcrossed to respective parental cultivars and BC1 progenies were raised. ‘Langdon’ 5D(5B) substitution × Th. bessarabicum F1 hybrids were crossed with normal ‘Langdon’ to obtain BC1 progeny. Chromosome pairing relationships were studied in F1 hybrids and BC1 progenies using both conventional staining and fluorescent genomic in situ hybridization (fl‐GISH) techniques. Multicolour fl‐GISH was standardized for characterizing the nature and specificity of chromosome pairing: A–B, A–J and B–J pairing. The A–J and B–J pairing will facilitate gene introgression in durum wheat. Multicolour fl‐GISH will help in characterizing alien chromosome segments captured in the durum complement and in their location in the A and/or B genome, thereby accelerating chromosome engineering research.  相似文献   

17.
Summary Cajanus platycarpus, an incompatible wild species from the tertiary gene pool of pigeonpea (C. cajan (L.) Millspaugh), has many desirable characteristics for the improvement of cultivated varieties. To necessitate such transfers, embryo rescue techniques were used to obtain F1 hybrids. The F1 hybrids were treated with colchicine to obtain tetraploid hybrids, that were selfed to obtain F2, F3 and F4 progenies. All of the hybrids and subsequent progenies had an intermediate morphology between the two parents. Backcrossing of the tetraploid hybrids with cultivated pigeonpea was not possible given embryo abortion, with smaller aborted embryos than those obtained in the F0 parental cross.As a route of introgression, diploid F1 hybrids were backcrossed with cultivated pigeonpea and BC1 progeny obtained by in vitro culture of aborting embryos. BC2 plants were obtained by normal, mature seed germination. Although embryo rescue techniques had to be used to obtain F1 and BC1 plants, it was possible to produce BC2 and subsequent generations through direct mature seed. Every backcross to cultivated pigeonpea increased pollen fertility and the formation of mature seeds.Special project assistant till December, 2003.  相似文献   

18.
Historically, conventional breeding has been the primary strategy used to develop a number of Striga‐resistant varieties currently grown in the Sahel of Western Africa. In this study, we have successfully developed and applied a marker‐assisted selection strategy that employs a single backcross programme to introgress Striga resistance into farmer preferred varieties of cowpea for the Nigeria savannas. In this strategy, we have introduced the Striga resistance gene from the donor parent IT97K‐499‐35 into an elite farmer preferred cowpea cultivar ‘Borno Brown’. The selected 47 BC1F2 populations confirmed the recombinants with desirable progeny having Striga resistance gene(s). The 28 lines selected in the BC1F2:4 generation with large seed size, brown seed coat colour and carrying marker alleles were evaluated in the field for resistance to Striga resistance. This led to the selection of a number of desirable improved lines that were immune to Striga having local genetic background with higher yield than those of their parents and standard varieties.  相似文献   

19.
Sixteen‐hundred BC1 plants of a cross between an early blight (EB) susceptible tomato (Lycopersicon esculentum Mill.) breeding line (‘NC84173’ maternal and recurrent parent) and a resistant accession (‘PI126445’) of the tomato wild species Lycopersicon hirsutum Humb. and Bonpl. were grown in a field in 1998. This population was segregating (among other traits) for growth habit, self‐incompatibility and earliness in maturity. To eliminate confounding effects of these factors on disease evaluation and h2 estimation, plants that were self‐incompatible, indeterminate and/or late‐maturing were eliminated. The remaining plants (146), which were self‐compatible and determinate (sp./sp.) in growth habit, with early‐ to mid‐season maturity, were evaluated for EB resistance and self‐pollinated to produce BC1S1 seed. The 146 BC1S1 progeny families, consisting of 30 plants per family, were grown in a replicated field trial in 1999 and evaluated for EB resistance and plant maturity. For each of the 146 BC1 plants and corresponding BC1 families, the area under the disease progress curve (AUDPC) and final disease severity (final percentage defoliation) were determined and used to measure disease resistance. The distributions of the AUDPC and final percentage defoliation values in the BC1 and BC1S1 generations indicated that resistance from ‘PI126445’ was quantitative in nature. Estimates of h2 for EB resistance, computed by correlation between BC1S1 progeny family means and BC1 individual plant values, ranged from 0.69 to 0.70, indicating that EB resistance of ‘P1126445’ was heritable. Across BC1S1 families, a small, but significant, negative correlation (r = ‐0.26, P < 0.01) was observed between disease resistance and earliness in maturity. However, several BC1S1 families were identified with considerable EB resistance and reasonably early maturity. These families should be useful for the development of commercially acceptable EB‐resistant tomato lines.  相似文献   

20.
Summary Strong resistance to the cane diseases Elsinoë veneta, Didymella applanata and Botrytis cinerea, and to Sphaerotheca macularis, occurred in F1 and BC1 derivatives of an accession of Rubus coreanus. Resistance to cane spot (E. veneta) was polygenic.In eight out of ten BC1 progenies, average grades for cane spot infections were significantly higher in white-flowered (an 1) than pink-flowered (An 1) plants and in hairy-caned (H) than in glabrous (h) seedlings. It is postulated that in R. coreanus factors controlling resistance are linked with An 1 and. probably, with h.Average grades for spur blight (D. applanata) were significantly higher in white-flowered plants in nine out of ten BC1 progenies. Spininess (S) was associated with greater susceptibility in six out of eight BC1 families, although this difference was not statistically significant.Plants with the phenotype hAn 1 on average provided the best source of resistance to both cane spot and spur blight.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号