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1.
The occurrence of somaclonal variation among regenerants derived through indirect shoot organogenesis from leaf explants of three Dieffenbachia cultivars Camouflage, Camille and Star Bright was evaluated. Three types of somaclonal variants (SV1, SV2, and SV3) were identified from regenerated plants of cv. Camouflage, one type from cv. Camille, but none from cv. Star Bright. The three variants had novel and distinct foliar variegation patterns compared to cv. Camouflage parental plants. Additionally, SV1 was taller with a larger canopy and longer leaves than parental plants and SV2. SV2 and SV3 did not produce basal shoots (single stem) but basal shoot numbers between SV1 and parental plants were similar ranging from three to four. The variant type identified from regenerated cv. Camille had lanceolate leaves compared to the oblong leaves of the parent. This variant type also grew taller and had a larger canopy than parental plants. The rates of somaclonal variation were up to 40.4% among regenerated cv. Camouflage plants and 2.6% for regenerated cv. Camille. The duration of callus culture had no effect on somaclonal variation rates of cv. Camouflage as the rates between plants regenerated from 8 months to 16 months of callus culture were similar. The phenotypes of the identified variants were stable as verified by their progenies after cutting propagation. This study demonstrated the potential for new cultivar development by selecting callus-derived somaclonal variants of Dieffenbachia.  相似文献   

2.
Several hundred somaclones established from plants regenerated from embryogenic callus cultures of six high tannin sorghum lines were screened for variants with altered levels of polyphenols in the grain. Grain from over 6000 plants including the R 1 (primary), R2, and R3 generations were analyzed for total phenols, flavan-4-ols, and proanthocyanidins (condensed tannins). Although many variants which had lost the ability to synthesize chlorophyll were found, none of the somaclones tested had lost or greatly reduced the ability to synthesize any of the polyphenols assayed. However, we did observe statistically significant differences in polyphenol concentration between tissue culture-derived R1 plants and the parental controls. In the R2 generation the proportion of somaclones which differed significantly from the parents varied from 47% to 68% depending upon genotype. The average somaclonal variation rate and somaclonal variant frequency estimated in the tested population for the three polyphenol characteristics ranged from 37.3% to 40.7% and 5.3% to 7.8%, respectively. Variants with decreased levels of polyphenols were usually epigenetic and reverted back to normal levels in subsequent generations, but those with increased levels usually persisted after two meiotic cycles, indicating they are heritable. Variants with polyphenol levels increased up to 80% or decreased by 30% were selected for in the R3 generation.  相似文献   

3.
Summary Plants were regenerated from leaf, cotyledon, and hypocotyl explants of tomato cv Moneymaker. Various phenotypic alterations were observed among regenerated plants (R1), but were not transmitted to the progenies, except for ploidy variation. Variation in ploidy level, mainly tetraploidy, occurred in R1 plants and their R2 progenies, and the frequency of polyploid plants depended on the explant source. More than 50% of the regenerants derived from hypocotyl explants were found to be polyploid. A correlation was observed between the percentage of polyploid cells present in the explant material in vivo and the frequency of polyploid plants. Several monogenic mutations were recovered in the R2, four of which were shown to be allelic to known, recessive, single-gene mutants. No significant effect of explant source or duration of tissue culture period on mutant frequency or spectrum was found. For several mutant types that could be scored unambiguously, somaclonal variation was compared to variation induced by treatment of seeds with ethyl methane sulphonate (EMS). The results showed that the mutant frequencies were higher after EMS treatment than those generated through tissue culture. With respect to the mutant spectrum, no clear differences were observed between the spectra obtained after EMS treatment and those after tissue culture. However, tissue culture gave rise to polyploid plants, whereas no ploidy variants occurred after EMS treatment.  相似文献   

4.
Two successive cycles of mature embryo-derived callus culture separated by one cycle of sexual reproduction of R0 regenerated plants were performed using two rice (Oryza sativa L.) cultivars in order to gain information upon the nature of somaclonal variation in this species. Plants regenerated after one cycle of tissue culture exhibited higher variability and lower performances than those of initial cultivar. A second cycle performed using R1 embryos as explants showed that the cellular component of salt resistance in terms of growth and regenerating abilities selected during the first cycle could be transmitted to the progenies. The extent and the nature of somaclonal variation depended on the identity of R0 mother plant and culture conditions, somaclonal variation being strongly reduced in some families obtained from salt-treated calli.  相似文献   

5.
Quantitative trait variation in phenotypically normal regenerants of cotton   总被引:11,自引:0,他引:11  
Summary Somaclonal variation for quantitative traits could affect the practical utilization of regenerants in cotton improvement. Three groups of experimental lines were derived to analyze variation, including one control group from the explant-source cultivar and two groups of R3 somaclones from different R0’s (R0 = initial regenerant) free of observable chromosomal rearrangements. A three-environment field trial was conducted to evaluate group means, genetic variance, and line performance. Mean seedcotton yields of the somaclonal groups were reduced by 21 and 26% relative to the Coker 310 standard at two locations, but lint percentage and certain fiber properties were improved. Group-by-environment interactions were significant (P<0.05) for 10 of the 12 measured traits. Genetic variance tended to decrease in the somaclones, plant height being an exception. Line performance of the somaclones indicated that 50-boll weight, seed index, and fiber length did not reach the Coker 310 group means. These data suggest that genetic gain will be improved if regenerants of cotton are self-pollinated and the progenies evaluated for quantitative traits before crossing somaclones with the explantsource cultivar or other elite germplasm.  相似文献   

6.
Summary Sugar, fodder and garden beet (Beta vulgaris L.) plants have been regenerated in culture from a range of expiant material. Of the regenerants 764 were subjected to isozyme analysis using eight enzyme-specific stains, and 60 were subjected to RFLP analysis using three cDNA probes. Both molecular techniques allowed the identification of somaclonal variant plants. Assessment of the numbers of variant isozymes and restriction fragments has allowed the calculation of the approximate percentage of variant alleles occurring in any one somaclonal regenerant, namely between 0.05% and 0.1%.  相似文献   

7.
Somaclonal variant plants may be of use in broadening the germplasm base of plant species and providing useful stocks for cytogenetic investigations. This study was conducted to compare morphologic, cytogenetic and enzymatic characteristics of 21 R1 (initial regenerate) bluestem,Bothriochloa sp., plants, visibly identified in a field-grown population of 522 plants as probable variants, with their respective R0 (explant donor) progenitor. An R2 seedling population was grown to ascertain the transmission of the variant R1 phenotypes. All R1 plants differed from their respective R0 progenitors in one or more morphological characters. Foliage colour was the most pronounced difference in most cases. Four of the plants, three of which were dwarfed, produced no inflorescences. The R1 plants tended to be shorter than R0 progenitors and had corresponding decreases in lengths on inflorescences and lowest racemes. All R1 plants of accessions 8911C and 8793 had an increase in chromosome number from2n=4x=40 to2n=5x=50. Three dwarfed R1 plants, derived from accession 8873B, were aneuploids, two having2n=48 chromosomes and the third being a probable mixoploid with 55–58 chromosomes. Other plants of accession 8873B had the R0 chromosome number. Fertility, as estimated by pollen stainability and seed set, generally was reduced in R1 plants relative to the R0. This reduction was not drastic, however, with all flowering plants having 45% or higher seed set. Apomixis apparently maintained fertility in all R1 plants, including those with a pentaploid chromosome number. All R1 plants differed from their respective R0 plants in peroxidase and esterase banding patterns. All R1 plants of accessions 8911C, and 8793, respectively, had identical peroxidase and esterase bands. For both enzyme systems two banding patterns were present in R1 plants of accession 8873B, with 12 of 13 plants exhibiting common patterns. Examination of R2 progeny plants confirmed the genetic transmission of the variant phenotypes and, by virtue of uniformity, indicated apomictic reproduction in the R1 plants. The results demonstrate the production of potentially useful genetic and cytogenetic variant plants via tissue culture in these apomictic species.  相似文献   

8.
Summary Tissue culture of the Zea mays inbred line A188 resulted in the regeneration of plants having a high level of phenotypic variation compared to seed-grown control plants. To determine how such variation was induced and whether this could be related to specific in vitro culture methods, callus cultures were established and maintained on different, commonly used culture media. Plants were regenerated and the genomic DNA of callus cultures and regenerants analysed for RFLP differences. The results show that regardless of the gene probe used, callus formation resulted in significant deviations from the DNA pattern normally found in seed-grown control plants. Alterations in gene copy number also occurred. As differentiation and organogenesis began, the level of DNA variation fell, and most of the regenerated plants showed a genetic similarity to the controls; those with RFLP differences were the somaclonal variants.  相似文献   

9.
Alfalfa plants were regenerated from callus cultures of three source plants that differed in resistance to anthracnose, caused by Colletotrichum trifolii. All regenerant plants were evaluated for variation in resistance to disease caused by races 1 and 2 of the pathogen. Of eighty-two plants that were regenerated and evaluated, no plants responded differently to inoculation with race 1 of C. trifolii, but two plants (2.4%) differed in resistance when inoculated with race 2. The source plant of these regenerants was resistant to races 1 and 2 of the pathogen but the regenerants were resistant to race 1 and susceptible to race 2. No variants to race 1 were detected. The susceptible response of the variant plants to race 2 was confirmed by cytological analysis and was consistent with the response of nonregenerant susceptible plants. These plants represent a near-isogenic plant model for studying the molecular biology of resistance and susceptibility to anthracnose of alfalfa.  相似文献   

10.
Somaclonal lines of linseed from the parent cultivar Norlin were produced from a callus-based in oitro regeneration system (the R0 generation). In field trials conducted over two seasons, 47 R1 (plants produced from the R0 generation) and 20 R2 somaclonal lines (plants produced from the R1 generation) were compared to the parent cultivar Norlin for quantitative characters. Irrespective of the genotype, traits in R1's and R2's were assessed on the basis of regression analysis as showing heritabilities of between 28% and 64%. Generally, the somaclonal variation assessed during these early generations revealed some detrimental traits, e.g. lower seed yield than the parent (control) cultivar and reduced 1000 seed weights, but a few lines were identified which had early or late flowering dates, improved seed yield and increased 1000 seed weights. It is concluded that somaclonal variation could be of value as an adjunct to classical breeding.  相似文献   

11.
Comparative hybridization analyses of total DNA from fertile and cytoplasmic male-sterile (CMS) triticale plants which had been regenerated from embryogenic callus cultures revealed the organization and variation of the mitochondrial atp6 gene region. In order to compare different developmental phases, we analysed mitochondrial DNA (mtDNA) from both the shoots and full-grown regenerants. Somaclonal variants were identified on the basis of differences in the mtDNA from fertile and CMS triticale. Several shoots as well as all of the full-grown plants analysed showed somaclonal variation. This phenomenon could be traced back to having primarily orginated from the influence of the nuclear background, which give rise to a stoichiometric increase in a rye-specific orf25 gene copy, and a tissue culture-induced combination of fertile and CMS-specific mtDNA organization of the atp6 gene area. The latter event is probably caused by the homologous recombination of repetitive sequences that may be accompanied by selective amplifications.  相似文献   

12.
Some somaclonal variants derived from a landrace rice variety, Indrayani, were shown to be high yielding and resistant to multiple diseases in previous analysis carried out in our laboratory. An attempt was made to assess the effect of culturing and regeneration of rice plants on DNA variation at microsatellite loci in R2 progeny of callus-derived rice plants. Different somaclones of the rice line Indrayani differing in yield and disease response (high, low and no change in yield, as compared to the original genotype) were used as genetic material for these analyses. Analysis of microsatellite loci was accomplished by digesting DNA from regenerated rice somaclones and assaying for polymorphisms at microsatellite loci by in-gel hybridization with synthetic oligonucleotide probes such as (GATA)4, (CAC)5 and (TG)10. Specific variation at a PCR-amplified locus containing three internal microsatellite repeats (1E6) using restriction site fingerprinting was also investigated. The locus-specific amplification of a sequence-tagged microsatellite marker followed by digestion with HinfI and Sau3AI restriction endonucleases showed differences in some somaclonal variants. The technique used in this study enables monitoring of DNA changes in successive generations of somaclonal variants as a measure of DNA variability and possibly to identify the regions which are responsible for specific traits. Received: 7 November 1997 / Revision received: 22 April 1997 / Accepted: 5 June 1998  相似文献   

13.
Summary Five hundred and twenty-four plants of a triploid, sexually sterile hybrid napiergrass (Pennisetum americanum x P. purpureum; 3x=21) were regenerated from embryogenic callus cultures obtained from segments of young inflorescences. Replicated field trials were conducted for two consecutive years to compare the biomass yield, phenotype and cytology of tissue culture regenerants (TC) and vegetatively propagated (V) plants. In the first year total biomass yield of TC plants was significantly greater than V plants but there was no significant difference in the second year. TC plants had more tillers compared to V plants. V plants did not show any morphological variability. The TC population also exhibited a high degree of phenotypic stability (96%). There were 23 phenotypic variants in the TC population of 524, most of them being more dwarf and late-flowering. Detailed morphological analysis of the TC-variant plants suggests that they very likely arose from only a few variant cell lines. Cytological analysis indicated stability of the triploid status in randomly selected regenerants. Two of the morphological variants were hexaploids (6x=42). It is concluded that embryogenic callus cultures can provide useful alternative for the rapid propagation of hybrid napier-grass which is commonly propagated by cuttings.  相似文献   

14.
Diseases affecting strawberry (Fragaria × ananassa Duch.) have been of major concern in recent years because of their widespread occurrence and potential for yield loss. Anthracnose, caused by the fungus Colletotrichum acutatum, is one of the most serious diseases of strawberry worldwide. Tissue-culture induced (somaclonal) variation provides one strategy for generating disease-resistant genotypes. As part of a program to generate strawberry germplasm resistant to anthracnose, an in vitro screening system was used to evaluate several commercial cultivars, Chandler, Delmarvel, Honeoye, Latestar, Pelican and Sweet Charlie propagated in vitro, and shoots regenerated from leaf explants of these cultivars for resistance to C.␣acutatum isolate Goff (highly virulent). Regenerants with increased levels of resistance were identified from all of the cultivars. The greatest increases in disease resistance were observed for regenerants from leaf explants of cultivars Pelican and Chandler that exhibited 17.5- and 6.2-fold increases in resistance, respectively. The highest levels of anthracnose resistance (2 to 6% leaf necrosis) were exhibited by regenerants from explants of cultivars Pelican and Sweet Charlie. These studies suggest that generating somaclonal variation may be a viable approach to obtaining strawberry plants with increased levels of anthracnose resistance.  相似文献   

15.
We present data on the morphological, cytological, biochemical and genetic characteristics of tomato regenerants obtained through anther culture. As a result of induced androgenesis, more than 6,000 rooted regenerants were developed that differed both from the donor plants and among each other with respect to habitus and leaf, flower and inflorescence morphology. Cytological analysis revealed a great variability in chromosome number in the cells of the regenerated plants. While most of the regenerants were mixoploid, the majority of the cells had a haploid chromosome number. R1 and R2 progenies were tested for their resistance to Clavibacter michiganense subsp. michiganense (Cmm 7). Some of the regenerants were resistant to the pathogen. A biochemical analysis of fruit from R3 and R4 plants showed a higher content of dry matter, sugars and vitamin C in the regenerant plants obtained from the hybrids than in those from the cultivars and control plants. The values of the parameters of hybrid regenerants grown in the greenhouse were about 1.5-fold higher than those of the hybrid regenerants grown in the field, and this trend is clearly expressed in all of the hybrid regenerants. The results obtained suggest that induced androgenesis and gametoclonal variation may be used as an additional tool to create a large range of new forms. The application of the latter in breeding programs would accelerate the development of tomato lines and varieties that would be more productive, disease-resistant, highly nutritive and flavour-acceptable.Abbreviations BAP N6-Benzylaminopurine - Cmm Clavibacter michiganense subsp. michiganense - cfu Colony-forming units - GA 3 Gibberellic acid - IBA Indole-3-butyric acid - ms Male sterility - PDA Potato dextrose agar Communicated by H. Lörz  相似文献   

16.
A study was conducted to examine the extent of somaclonal variation of soybean plants, Glycine max (L.) Merrill cv. McCall, regenerated via somatic embryogenesis from cultured immature cotyledons using two different protocols. The sexual progeny of regenerants were compared with normal, seed-derived populations for morphological characteristics and fatty acid composition of seeds. First generation progeny of regenerants showed greater phenotypic variation than the control population, but this variation was not observed in the second generation. No stable somaclonal variants for fatty acid composition of the seed oil or morphological characteristics were observed, indicating that this somatic embryogenesis system should be adaptable for transformation with minimal generation of unwanted variation.Abbreviations NAA 1-naphtaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - IBA indolebutyric acid Contribution from the Department of Agronomy, University of Kentucky, Lexington, KY 40546. The research, was supported by the American Soybean Association and the Lubrizol Genetics Company, published with the approval of the director of the Kentucky Agricultural Experiment Station as Journal Article Number 88-3-264. Offprint requests to: D.F. Hildebrand  相似文献   

17.
Summary Genetic analysis was conducted on the qualitative and quantitative traits of sexual progeny derived from embryogenic cultures of two inbred lines of Pennisetum glaucum (L.) R. Br. (pearl millet). These lines included a genetically stable inbred of Tift 23 BE and a genetic marker line, derived from Tift 23BE, which bore qualitative genetic markers for a dominant purple plant trait (P) and two recessive traits, early flowering (e1) and yellow stripe (ys). Tissue culture regenerant populations (R0) and progeny populations (R1) produced from these plants by selfing showed no qualitative genetic variation when derived from the genetically stable inbred Tift 23BE. In contrast, stably inherited qualitative variation for a number of genetic markers was observed in R0, R1, and R2 progeny of the genetic marker line. In a population of 1,911 plants regenerated over a 12-month period, 0.02% of the population lost or showed reduced expression of the purple plant trait and 92% of plants were chlorophyll deficient. Plants showing reduction or loss of anthocyanin synthesis also flowered later. None of the purple plants showed any significant variation in flowering time. The incidence of chlorophyll deficiency increased with time in culture, 51 % of the progeny regenerated after 1 month were chlorophyll deficient, while 100% of the plants regnerated after 12 months were chlorophyll deficient. Qualitative variation was also observed in control populations of the genetic marker line where 1 plant in a total of 1,010 lacked purple pigmentation and a total of 6% showed chlorophyll variation in the first generation (S0). The presence of qualitative variation in controls suggests that the inherent variation present in the original explant was expressed and perpetuated in vitro. Quantitative variation was observed for a number of traits in the first sexual cycle (R1) of the marker line but did not occur in a subsequent generation, suggesting that this variation was epigenetic.  相似文献   

18.
The mitochondrial DNA (mtDNA) organization of primary hexaploid cytoplasmic male-sterile (CMS) triticale regenerants containing Triticum timopheevi cytoplasm was analysed by hybridization experiments and compared with the mitochondrial genome organization of the corresponding regenerants with maintainer cytoplasm. Callus cultures had been derived from immature embryos, and 623 triticale plants were regenerated via somatic embryogenesis after three to four subcultures. The chondriome of 159 regenerants was investigated with regard to somaclonal variation. Six different mitochondrial gene probes and four different restriction enzymes were used for Southern blot analyses by the non-radioactive digoxigenin labeling technique. Alloplasmic regenerants showed a gain or loss of hybridization signals up to a high percentage, while euplasmic ones revealed only minor variability with respect to band stoichiometries. In 24 cases rearrangements in the mtDNA were proved. We suppose that recombination processes and selective amplification events are responsible for these findings.  相似文献   

19.
A simple tissue culture protocol was developed for efficient plant regeneration from young inflorescence-derived calli in wild barley, Hordeum brevisubulatum (Trin.) Link, an important pasturage grass. Genetic and epigenetic instabilities in the regenerated plants (regenerants) were assessed by three molecular markers AFLP, S-SAP and MSAP. Two pools of calli derived from young inflorescences of a single donor plant and 44 randomly chosen regenerants were subjected to AFLP analysis. Results showed that 74 out of 793 scored bands were polymorphic among the studied samples, giving rise to a genetic variation frequency of 9.3%. The number of variant bands as compared to the donor plant varied greatly among the regenerants, with a small number of regenerants accumulated a large number of variant bands (maximum 55), while the majority of regenerants showed only 2–3 variant bands. A subset of regenerants together with the two pools of calli were selected for S-SAP and MSAP analysis to detect possible retrotranspositional activity of a prominent retroelement family, BARE-1, in the genomes of Hordem species, and possible alterations in cytosine methylation. S-SAP analysis showed that of the 768 scored bands, 151 were polymorphic among the analyzed samples, giving rise to a genetic variation frequency of 19.7%, albeit no evidence for retrotranspositional event was obtained based on locus-specific PCR amplifications. MSAP analysis revealed that tissue culture has caused cytosine methylation alterations in both level and pattern compared with the donor plant. Sequencing of selected variant bands indicated that both protein-coding genes and transposon/retrotransposons were underlying the genetic and epigenetic variations. Correlation analysis of the genetic and epigenetic instabilities indicated that there existed a significant correlation between MSAP and S-SAP (r = 0.8118, 1,000 permutations, P < 0.05), whereas the correlation between MSAP and AFLP (r = 0.1048) is not statistically significant. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Xiaoling Li and Xiaoming Yu contributed equally to this work.  相似文献   

20.
A random amplified polymorphic DNA (RAPD) analysis of spineless (variant phenotype) plants obtained from micropropagated dormant pineapple (Ananas comosus L., Merr.) axillary buds was performed using arbitrary 10-mer oligonucleotide primers. This was done to investigate the genetic fidelity of the regenerants and to distinguish these variants from regenerants bearing the normal spined phenotype. Of the 58 arbitrary primers used, 29 produced bands unique to the spineless phenotype, and 30 produced bands unique to the spined phenotype. A total of 914 bands were scored, 55 of which were polymorphic to the spineless phenotype and 51 of which were polymorphic to the spined phenotype. On the basis of RAPD amplification products, genetic similarity was estimated in both types of regenerants using similarity coefficients (Nei and Li, 1979). The characteristic finger-prints generated by each probe emphasize genetic variability of regenerants. This technique is suitable for analyzing variant regenerants induced in vitro.  相似文献   

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