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1.
Summary Selection criteria for agronomic characters in a potato breeding program at the diploid (2x) level may differ from selection criteria used when selecting breeding lines at the tetraploid (4x) level. Differences between selection criteria are expected, (1) when expression of the characters is different at both ploidy levels and/or (2) when the effect of diploid breeding lines on agronomic characters of tetraploid progenies is different from the effect of tetraploid breeding lines. In this investigation sets of diploid and tetraploid progenies, each set derived from the same 2x.2x cross, were compared as to the expression of six agronomic characters. Diploid progenies had significantly lower yields (due to smaller tubers) and significantly higher under water weights than tetraploid progenies. Vine maturity and chip colour were similarly expressed at both ploidy levels. Correlations between yield and yield components, and between under water weight and chip colour were similar at both ploidy levels. The lower yields and higher under water weights found in diploids point to the need of different selection criteria for selecting diploid and tetraploid breeding lines.  相似文献   

2.
B. Maris 《Euphytica》1990,46(1):15-33
Summary To determine whether in potatoes the tetraploid level is preferable to the diploid level, especially regarding tuber yield, four diploid (2n=2×=24) Solanum phureja x dihaploid S. tuberosum hybrid parents and their vegetatively doubled, tetraploid (2n=4×=48) counterparts were intermated, which resulted in two F1 hybrid families at both levels of ploidy. The parents and clones of the F1 families and their offspring were used in crosses in such a way that in addition Sib1, Sib2, F1×Sib1, BC1 and Sib1×Sib1 families were produced. Of the first clonal generation of the 12 2 x families and their 12 counterpart 4 x families two tubers per clone were planted in three replications in a field experiment at Sturgeon Bay in 1969; of the parents six tubers were planted in each replication. Data were recorded on 16 characters, including plant height at four different times.The ANOVA's showed significant clone effects within each family for all characters. Computed from all family means as well as from the family means per ploidy level, differences due to family were also significant for all characters except one.As at the 2 x level and at the 4 x level of ploidy the mean phenotypic correlations between characters were of similar magnitude, it is concluded that they are independent of ploidy level.With the exception of eye depth, the mean coefficient of variation was greater at the 2 x than at the 4 x level of ploidy, indicating the greatest response to selection for those characters at the 2 x level. From the differences in family means between the 4 x and the 2 x level of ploidy it was apparent that the 4 x families generally had significantly taller plants, later maturity, fewer tubers, higher mean tuber weight, more tuber yield and more dry matter yield than their counterpart 2 x families. In contrast, the 4 x parents had on the average shorter plants, lower mean tuber weight, much lower tuber yield and lower dry matter yield than their 2 x counterparts.The phenotypic correlation and Spearman's rank correlation between the family means of the 2 x and the 4 x level of ploidy were positive for almost all characters and significant for nearly half of them.From the results it is concluded that 1. in potatoes the 4 x level of ploidy is preferable to the 2 x level, and 2. the performance of 4 x families is predictable from the performance of their counterpart 2 x families.Based on results mentioned in the literature and on the present results, a continued use of S. tuberosum dihaploids in potato breeding needs to be dissuaded.  相似文献   

3.
The study examined the effect of ploidy elevation through unreduced gametes on transgene expression in potato. Tetraploid transgenic progenies were obtained from one tetraploid potato cultivar crossed with 2n pollen producing diploid clones harbouring an exogenous transgene (cry3Aa). Both single‐ and multiple‐insert diploid transgenic lines that were regenerated by Agrobacterium tumefaciens leaf disc inoculation were used in crosses. A DAS‐ELISA system and no‐choice feeding bioassay enabled characterization of the parental lines as either ‘high’ or low’ expressers of the Cry3Aa protein. High Cry3Aa expression was observed for both single‐insert transgenic diploids and their 4x‐2x progeny. On the contrary, 68% of 4x‐2x progeny derived from a multiple‐insert, diploid transgenic had significantly reduced Cry3Aa expression compared with the parent, with 32% demonstrating nearly complete silencing of the transgene. Multiple copies of a transgene, like homologous native genes, may be susceptible to transgene silencing following polyploidization. Therefore, incorporation of exogenous transgenes into a true potato seed (TPS) production system is feasible if a single‐insert diploid parent is used. Gene‐centromere mapping of the cry3Aa transgene demonstrated that a non‐transgenic refuge might be naturally created in a TPS hybrid system through genetic recombination.  相似文献   

4.
A total of 45 tetraploid-diploid (4x—2x) hybrid progenies were obtained by crossing each of ten diploid parents as males to each of five tetraploid parents. A relatively low degree of determination (R2) of both 4x and 2x parents on the performance of their 4x—2x hybrid progenies was found for all six traits studied. This implies that test crossing and subsequent progeny analysis is necessary before such parents can be used in a breeding program. Since marketable yield was found to have a higher predictability than total yield, it is the preferred yield trait to be measured. Diploids which produce 2n gametes via FDR usually give rise to 4x progenies with a greater amount of heterosis than similar progenies derived from diploids which produce 2n gametes via SDR, although such heterosis is not necessarily expressed in terms of marketable yield.  相似文献   

5.
Summary Resistance to bacterial wilt (Pseudomonas solanacearum) found in tuber-bearing Solanum species was transferred into a diploid potato breeding population. Simultaneous selections were made for agronomic characters, production of first division restitution (FDR) 2n pollen, and resistance. Diploid resistant genotypes were identified via inoculation with a virulent isolate (CIP-204) of race 3 of Pseudomonas solanacearum. These resistant diploid genotypes were crossed to susceptible tetraploid potatoes. An investigation was made to assess whether resistant diploid genotypes transmit resistance to bacterial wilt, which is a quantitatively inherited trait, to tetraploid potatoes via FDR 2n pollen. Tetraploid seedlings from 4x×2x crosses were inoculated with the same isolate CIP-204, and the percentage of surviving seedlings was scored. Some 4x×2x families from resistant diploid genotypes demonstrated a high level of survival rate. The transmission of bacterial wilt resistance was achieved by the use of FDR 2n pollen. It was speculated that a female x male interaction effect on the survival rate of the evaluated progeny may exist. Selecting proper 4x and 2x parents would be important for obtaining a higher frequency of transmission of resistance to bacterial wilt in the progeny.  相似文献   

6.
Difficulties in obtaining new breeding lines of Brachiaria (Trin.) Griseb., an important forage grass in Brazil, are mostly related to differences in ploidy among the accessions, and to apomixis, an asexual mode of reproduction. Usually, sexual accessions are diploid while apomicts are polyploid. Induced tetraploids of Brachiaria brizantha (A. Rich.) Stapf have been successfully obtained and this paper presents the results of a study of their reproductive modes and fertility. Despite frequent meiotic aberrations during microspore development, the induced tetraploids produced viable pollen and produced progeny after controlled self-pollination. Similarly to the original diploid sexual progenitor, embryo sacs of the Polygonum type with confirmed meiotic origin were present in the induced tetraploids suggesting chromosome doubling did not alter the reproductive mode. The embryo sac of the Polygonum type was also observed in progenies obtained after self and open pollination. Nevertheless, embryo sacs of the Polygonum and the Panicum types within the same ovule were observed in some progenies obtained after open pollination, probably having resulted from hybridization with tetraploid, apomictic plants. Indeed, the compatibility of the progeny with tetraploid, apomictic B. brizantha was confirmed by the formation of mature caryopses after controlled pollination. Evidence is presented that the induced tetraploids and their progeny are sexual plants and that they are compatible with natural tetraploid B. brizantha. The induced tetraploids will be useful for analyses of apomictic inheritance as well as in the development of sexual tetraploid lines in Brachiaria breeding programs.  相似文献   

7.
Seven tetraploid watermelon lines developed by colchicine treatments were compared with their diploid counterpart for plant, flower, fruit, seed and qualitative characteristics. Tetraploid genotypes attained statistically higher vine thickness (8.04 mm), leaf area (298.9 cm2) and chlorophyll content (55.6) while internode length and chlorophyll fluorescence was similar to their corresponding diploid. Both pistillate and staminate flower organs (pedicel, anther, ovary, stigma, petals) were larger in tetraploid plants; however, the percent increase in flower components varied across the tetraploid lines. Fruit weight and total sugar content (∘Brix) in both ploidy fruits was similar. Rind thickness in fruits varied significantly and averaged 12.7 and 17.2 mm in diploid and tetraploid fruits, respectively. Tetraploid genotypes showed sterility, yielded lower number of seed per fruit (37.9), and tetraploid seed was larger and thicker than diploid seed. Overall β-carotene (0.89), lycopene (1.16), fructose (5.43%) and glucose (2.38%) contents were higher in tetraploid than diploid fruits.  相似文献   

8.
Summary The objectives of this research were to evaluate the response to day length and the yield stability of environments of 4x families from 4x×2x crosses in potato. Twenty families from crosses between 4x female parents with different genetic backgrounds and 2x parents, which formed 2n pollen by first division restitution and were selected under short days, were evaluated in four locations in Peru (short days) and during two years at Rhinelander, USA (long days). Results from the USA indicate that the 4x progeny from 4x×2x crosses were very late maturing and poor yielding.Further, vine maturity, tuber size and tuber number are highly correlated with the percentage of Tuberosum germplasm in the parentage. Results from Peru indicate that most 4x×2x families had high tuber yield, stability for yield and high dry matter content. The lack of correlation between rank order of the parental value, based on progeny testing, of the male and female parents among short day locations and between short and long day environments indicates that selection of parents must be done in each location in which the final product, either a family or a clone, will be used.International Potato Center (CIP)  相似文献   

9.
The objectives of this study were to evaluate the use of potato (Solanum tuberosum L.) late blight (Phytophthora infestans (Mont.) de Bary) resistant parents in cultivar development and identify superior clones possessing moderate to high late blight resistance combined with acceptable maturity and tuber quality. Ninety-five crosses were made between eight unadapted parents with reported late blight resistance (B0718-3, Bertita, Bzura, Greta, Libertas, Stobrawa, Tollocan and Zarevo) and susceptible parents (cultivars or advanced breeding clones) adapted to North American growing conditions. A total of 408 field selected clones were assessed for late blight resistance in the greenhouse and in the field using a mixture of US8 P. infestans isolates (A2 mating type, metalaxyl resistant) that overcame all known R-genes except R8 and R9. Clones with ≤ 10% infected foliar area in the greenhouse test or ≤ 0.30 RAUDPC (relative area under the disease progress curve) value in the field in 1998 were re-tested in 1999. A total of 118 (29% of 408) putative late blight resistant clones were selected. The eight late blight resistant parents differed in both the ability to transmit late blight resistance and in the level of resistance transmitted to the progeny. The Tollocan and B0718-3 families (half-sib progeny) had the greatest degree of resistance and frequency of resistant clones. Scott-Knott cluster analysis ranked 79 clones (67% of 118) in the high and moderate late blight resistant groups. Among these 79 clones, 19 clones had vine maturity equal to or earlier than mid-season combined with acceptable tuber quality. Further selection in 2000 resulted in eight advanced selected clones (six from Tollocan and two from B0718-3 families) with the same level of resistance as the parent combined with vine maturity and tuber quality equivalent to Atlantic, a standard cultivar for chip processing in North America. The results indicate that this breeding approach can be used to select parents for late blight resistance breeding and to identify superior clones with high levels of late blight resistance and marketable vine maturity and tuber quality. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

10.
Early blight (Alternatia solani) is a fungal disease in hot and humid environments, which causes leaf, stem and tuber lesions. Early blight resistance should be incorporated into potato cultivars because the fungicide spraying is an expensive solution for developing countries. The diploid cultivated species Solanum tuberosum group Phureja and group Stenotomum are sources of resistance alleles. The elucidation of the inheritance for early blight resistance must help to decide what could be the best breeding procedure to improve this diploid germplasm and transfer the resistance to the tetraploid level. Three experiments were carried out under controlled and field conditions to determine the heritability of this trait using nested and diallel mating designs with haploid, species and haploid-species hybrids. The narrow-sense heritability estimates were relatively high (0.64–0.78). This means that additivity was the most important type of gene action for determining resistance to early blight at the diploid level. The results suggested that diploid parents showing highest levels of resistance, throughout the cycle of disease development, can be used in 4x×2x crosses to obtain resistant tetraploid progenies to this fungal disease.  相似文献   

11.
西瓜抗枯萎病育种的分子辅助选择   总被引：2，自引：1，他引：1  
利用中国国内公开发表的西瓜抗枯萎病生理小种1基因紧密连锁标记4451_fon,首次对抗枯萎病育种创新的二倍体和四倍体种质进行分子鉴定。结果表明,全部二倍体单系和除编号D16、D17外的四倍体单系均表现为抗病基因型,判定为抗病材料,与人工接种鉴定结果完全一致;分子鉴定还表明,这些抗病单系为抗病纯合体,在以后的自交纯化过程中抗性基因不再分离和丢失,因此不必继续对其自交后代进行抗性选择。研究结果认为dCAPS标记4451_fon可以作为西瓜抗枯萎病分子辅助选择(molecular marker assisted selection,MAS)的重要工具,能够实现提高选择效率、加速育种进程的目的。  相似文献   

12.
To study the origin of unreduced (2n) gametes in diploid Vitis cultivars, we surveyed the occurrence of tetraploid hybrid seedlings from 40 interploid crosses with five tetraploid and seven diploid cultivars. A total of 250 seedlings from the interploid crosses were established through embryo culture and by seed sowing. In 20 2x × 4x crosses, no tetraploid hybrid seedlings were derived from 8,902pollinations. In 20 4x × 2x crosses, two tetraploid hybrid seedlings were obtained from 8,057 pollinations. Investigation of isozyme genotypes of the two tetraploid seedlings using three variable enzyme systems indicated that one of the two seedlings resulted from the union of a diploid egg with a 2n male gamete and that failure of second meiotic division resulted in the formation of the 2n male gamete. The percentage of giant pollen grains in `Muscat Bailey A', a pollen parent of the tetraploid seedling, was relatively high(about 5.9%) and 10.9% of the giant pollen grains germinated on agar medium. These results suggested that 2n pollen of diploid cultivars are useful for breeding tetraploid grape. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

13.
J. Chat    P. Y. Dumoulin    Y. Bastard  R. Monet 《Plant Breeding》1996,115(5):378-384
Interspecific crosses between Actinidia arguta (In = 4x) and A. deliciosa (2n = 6x) were carried out in order to transfer cold resistance from a wild to the cultivated kiwifruit species. Of the 65 progenies obtained and analysed by flow cytometry, 16 were diploid, one was tetraploid and 48 were, as expected, pentaploid. Morphologically, the diploids can be distinguished from the pentaploids by their longer lamina. The existence of 5x progenies confirms the existence of gene flow between A. arguta and A. deliciosa, whereas the existence of 2x and 4x progenies provides evidence for parthenogenesis within the Actinidia genus following an interspecific cross. The study demonstrates the utility of flow cytometry for genomic analysis of progenies derived from interspecific crosses. Possible uses of both sexual and parthenogenetic progenies in the breeding and genetics of kiwifruit are discussed.  相似文献   

14.
Summary The possibility of combining anew the genomes of wild and cultivated progenitors of triploid S. x juzepczukii and pentaploid S. x curtilobum by following the known evolutionary pathway of these species was investigated.The resynthesis of S. x juzepczukii was easy, and a wide range of synthetic forms was bred. Among these were forms with higher frost resistance (-5°C) than has been found in natural S. x juzepczukii. The total tuber glycoalkaloid content of several synthetic hybrids was lower than or as low as that of natural clones. Most synthetic hybrids were more vigorous than natural S. x juzepczukii and produced about the same types of tubers as are found in the natural range of variation. The best diploid parents were found in the species S. goniocalyx.The attempt to resynthesize pentaploid S. x curtilobum has not been successful but tetraploid plants were obtained in the process. An explanation for the occurrence of tetraploids resulting from triploid x tetraploid and/or diploid crosses is offered.The newly bred tetraploids contain at least one genome from S. acaule (possibly two) and hybridize easily with ssp. andigena. They thus provide a means for the transfer of S. acaule germ plasm into the tetraploid cultivated gene pool which would profit from the frost resistance of S. acaule.  相似文献   

15.
Genetic resistance to potato cyst nematode is considered as one of the most effective means of increasing yield and reducing nematode infestation levels in potato fields. In this study, resistance to this nematode was successfully transferred from diploid tuber-bearing Solanums to the tetraploid gene pool using a 4x-2x breeding approach. More specifically, resistance from Solanum vernei, S. sparsipilum and haploids of S. tuberosum group Andigena was introgressed into conventional tetraploid clones, using first division restitution (FDR) 2n gametes. Furthermore, some of the FDR diploid parents had similar breeding values as advanced resistant tetraploid clones which were developed only after several cycles of selection against the potato cyst nematode. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

16.
Crosses were carried out between tetraploid Dianthus caryophyllus cv ‘Butterfly’ (2n = 4×= 60) and seven diploid cultivars (2n = 2×= 30). Fewer seeds were obtained and the low seed germination was found which suggested the post-fertilization barrier in 4×–2× crosses. 12 progeny were obtained from 5 crossing combinations. Chromosome analysis revealed that they consisted of 5 triploid hybrid plants and 7 tetraploid hybrid plants, suggesting that unreduced male gamete maybe be involved in polyploid formation. Various flower shapes and colours were observed in the polyploid progenies, showing that sexual polyploidization results in greater variability and fitness. The hybrids obtained by 4×–2× crosses showed the flower-size intermediate between the parents or larger than the parents. Some favourable characters of parents such as flower shape, flower colour and resistance to Fusarium oxysporum, were successfully transmitted to the hybrids. Since polyploid hybrids have some of the profitable characters of the parents, they are expected to be used for future breeding in carnation.  相似文献   

17.
Summary Three sugarbeet breeding lines partially resistant to the root-rotting fungus, Rhizoctonia solani, were converted to the tetraploid condition without selection. These three diploid and tetraploid lines were crossed with three diploid male-sterile lines to produce equivalent diploid and triploid hybrids. The triploid hybrids were significantly more resistant to Rhizoctonia than were the diploid hybrids. However, the tetraploid resistant limes were no different than their diploid equivalent lines. Reciprocal crosses provided no evidence of maternal effect on resistance. Cytoplasm that included the male-sterility factor had no influence on resistance. Triploid hybrids, where the resistant parent is tetraploid, should be advantageous in the breeding of rhizoctonia-resistant hybrid varieties.Joint contribution of the Agricultural Research Service, U.S. Department of Agriculture, the Colorado State University Experiment Station, and the Beet Sugar Development Foundation. Published with the approval of the Director of the Colorado State University Experiment Station as Scientific Paper Series No. 2072.  相似文献   

18.
Summary Somatic hybrids of diploid amylose-free (amf) Solanum tuberosum and diploid S. brevidens were made by Poly-Ethylene-Glycol (PEG) or electrofusion methods. For the isolation of interspecific hybrids the use of selection markers (kanamycin and hygromycin resistance) was useful but not essential. In this 2x+2x interspecific combination 4x and 6x somatic hybrids were obtained. Seed set was the best in 4x×4x (S. tuberosum) backcrosses, but seed germination was the best in 6x×4x combinations, using in vitro germination of unripe seeds harvested 25 days after pollination. A high degree of pollen stainability (30–40%) was observed in 7 tetraploid hybrids and very low in all hexaploids. After iodine staining, the recessive amf marker was expressed by a red colour instead of blue, visible in starch-containing cells like columella cells of root tips, (micro)tubers or microspores. As expected, complementation was observed in starch-containing cells of the fusion hybrids. Segregation of the amf marker was clearly observed in microspores of 4x and 6x hybrids. Segregation ratios in the 4x hybrids showed variable recombination frequencies. In the backcross progeny of hexaploid F12-5 with a tetraploid amf mutant one amylose-free recombinant among 67 plants was found, indicating the occurrence of meiotic recombination in the megaspore mother cells.  相似文献   

19.
I. Ho    Y. Wan    J. M. Widholm  A. L. Rayburn 《Plant Breeding》1990,105(3):203-210
The usefulness of using the chloroplast number in epidermal guard cells as an indirect ploidy indicator was evaluated on seed-grown and tissue culture-derived maize plants. For seed-grown plants, two maize genotypes (B89 and R75) which had both diploid and tetraploid seeds available were used as experimental materials. The ploidy levels of seed-grown plants were confirmed by flow cytometric analysis of nuclear suspensions from these plants. For regenerated plants, haploid and diploid levels were examined and the ploidy levels of these plants were determined by chromosome counts of cells from root tips. A positive relationship between the chloroplast number and ploidy level was observed for both seed-grown and regenerated plants. The stomatal guard cells of tetraploid plants had nearly double the number of chloroplasts as the diploid plants. Similar results were found from the regenerated plants. The differences in the mean chloroplast number between diploid and tetraploid seed-grown plants and between haploid and diploid regenerated plants were highly significant. The results of this study demonstrate that counting chloroplasts in guard cells can be an efficient means of screening a large number of plants for ploidy levels. In addition, this study suggests the possibilities of using this method for detecting contaminated seed lots by different ploidy seed and for distinguishing plants of different genotypes.  相似文献   

20.
Summary Diploid potato clones selected for their reaction to common scab and their ability to produce 2n male gametes were used in a series of crosses to a susceptible tetraploid female parent (cv. Shepody). In addition, two tetraploid clones were also selected for their reaction to common scab and crossed with Shepody as a female parent. Results indicated that resistance to common scab can be effectively transmitted from the diploid to the tetraploid level via 4x-2x crosses. Diploid parents producing 2n pollen via either first division or second division restitution can be used to transmit scab resistance. A relatively small proportion of resistant individuals could be recovered from susceptible x susceptible crosses in both 4x-2x and 4x-4x combinations. The data support a previously developed hypothesis that scab resistance is relatively simply inherited.  相似文献   

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