Production of intraspecific aneuploids in the genus Solanum. 1. Doubling the chromosome number of seven diploid species

Summary The variation which persisted in interspecific aneuploids even after one or two generations of backcrossing prevented the morphological distinction of the aneuploids from their diploid sibs. An attempt was made to unmask the effects of aneuploidy by producing aneuploids within the more uniform genetic background of a single species.The procedure to produce trisomics and aneuploids of diploid species was to vegetatively double clones or seed of the species with colchicine, cross the induced tetraploids to diploids to produce triploids, and then cross the triploids to the original diploids. An attempt was made to use the same diploid clone and/or introduction of a species in all successive stages of the procedure in order to obtain as much uniformity as possible. This was largely unsuccessful because self-incompatibility and inbreeding reduced seed set. Seventy-three different tetraploids were obtained from seven species. Tuber treatments were noticeably unsuccessful in producing doubled plants. The two vegetative treatments were most successful and produced 41 different tetraploid clones while 30 doubled plants were obtained from four seed treatments.Morphologically the tetraploids resembled the diploid and there was no noticeable increase in size of leaflets and floral parts in the tetraploid. The average number of chloroplasts in ten pairs of guard cells was a distinctive feature which could efficiently be used in distinguishing the induced tetraploid plants from diploids. The tetraploids were generally less fertile than their diploid counterparts and the majority of them exhibited self-compatibility in comparison to self incompatibility of the diploids.Cooperative investigations of the Agricultural Research Service, U.S. Department of Agriculture and the Wisconsin Agricultural Experiment Station. Supported in part by grants from the Research Committee of the Graduate School, University of Wisconsin.     

Evidence for possible selective survival and function of gametes on progeny characteristics of Bromus inermis Leyss

Summary Approximately 85% of the S₁, S₂ and S₃ plants in 142 smooth bromegrass progenies were morphologically similar within lines. Progenies developed from diallel crosses possessed greater uniformity than was expected from hybridization of S₁ octaploid smooth bromegrass. Behaviors observed are interpreted on the basis of selective survival and functioning of gametes and can be explained by the fusion of like gametes.Results of cooperation between the Crops Research Division, Agricultural Research Service, US Department of Agriculture, and the Research Division, College of Agricultural and Life Sciences, University of Wisconsin, Madison, Wisconsin 53706.Geneticist (deceased).     

Cytology of Phleum sp. affin. P. montanum C. Koch

Diploid, tetraploid, and hexaploid plants occurred in foreign plant introductions of P. sp. affin. P. montanum from Turkey and Iran. Within-progeny variations in polyploid levels indicate that divergent races occurred as interspersed but natural populations. One to six B-chromosomes of varying sizes in addition to the normal chromosome complement were present in some plants. Their behaviours appeared essentially similar to those recorded for other species. Certain of the plants examined exhibited cytological features similar to those observed in known hybrids. These included prophase pycnosis, stickiness, split metaphase I plates, unoriented chromosomes at M-1, and low levels of pollen stainability. These features were absent in microsporocytes of other plants. Low open-pollination seed set characterized all plants examined. This may be due to hybridity or possibly to response to ecological conditions of the new environment.Results of co-operative work of the Crops Research Division, A.R.S., U.S. Department of Agriculture, and the Wisconsin Agricultural Experiment Station, Madison, Wisconsin.Former Graduate Student, Department of Agronomy, Wisconsin Agricultural Experiment Station, and Geneticist, Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture.     

Cytogenetics of a tetraploid form of Phleum pratense L.

A tetraploid form of Phleum pratense from southwestern Europe was found to behave cytogenetically as an autotetraploid. Inheritance patterns in inbred seedlings artificially inoculated with stem rust agreed with this interpretation if chromosome and chromatid assortment are assumed.Results of cooperative investigations of the Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture, and the Wisconsin Agricultural Experiment Station.Geneticist, Crops Research Division, A.R.S., U.S. Department of Agriculture, and former Graduate Assistant, Agronomy Department, Wisconsin Agricultural Experiment Station, Madison, Wisconsin.     

Investigations on the breeding behaviour of aneuploids of guava

Summary The breeding behaviour of aneuploids of guava (Psidium guajava L.) such as trisomic, tetrasomic, and higher aneuploids has been studied. Reciprocal crosses between aneuploids and diploids indicated less than 100% crossability. The aneuploids when used as male parents crossed less frequently than as female parents and certain aneuploids crossed more readily than others. Differences were observed in fruit size, fruit weight, and seed number in the reciprocal crosses.The extra chromosome was found to be transmitted through both the egg cell and the pollen. However, the frequency of transmission was greater through the egg cell than the pollen. As high as 26% transmission of extra chromosomes were obtained through the egg cell. There was no clear cut difference between trisomics and higher aneuploids with regard to the frequency of transmission of extra chromosomes.     

Inheritance of incompatibility in hybrids between Solanum tuberosum haploids and diploid species

The inheritance of self-incompatibility in two South American cultivated diploid species, Solanum phureja and S. stenotomum subsp. stenotomum, conforms with the Nicotiana scheme of oppositional S alleles. Similar studies in hybrids between S. phureja and a haploid (US-W 253) derived from S. tuberosum subsp. andigena were explained on the assumption of S alleles at homologous loci. The cut-stem technique employed in haploid extraction was used to facilitate the analyses. Maintenance of a series of heterozygous S allele testers is accomplished via matings with a clone homozygous for the S allele common to the series. True seed obtained from such crosses consists of only the desired S genotype.Departments of Horticulture and Genetics, University of WisconsinPaper No. 951 from the Department of Genetics, College of Agriculture, University of Wisconsin. Supported in part by the National Science Foundation and the Research Committee of the Graduate School from funds supplied by the Wisconsin Alumni Research Foundation.     

Identification of primary trisomics and other aneuploids in foxtail millet

A complete set of nine primary trisomics (2n+ 1) for cv.‘Yugu No. 1’of foxtail millet, Setaria italica (L.) Beauv. (2n= 2x= 18), was identified cytologically from progenies derived from crosses between autotriploids(2n= 2x= 27) and their diploid counterparts. Five autotriploid plants were identified from 2100 seedlings derived from 4x-2x crosses; the reciprocal crosses (2x-4x) failed to produce autotriploids. Autotriploids grew vigorously and were morphologically very similar to diploids. Theprimary trisomics (2n= 2x= 19) constituted ?32.5% of the total progeny from the 3x-2x crosses, whereas 59.8% of the descendants were aneuploids with chromosome numbers ranging from 20 (double trisomics and tetrasomics) to 37 (2n= 4x+ 1; or autotetraploid with one additional chromosome). The nine primary trisomics identified were self-fertile; seven had characteristic morphology, whereas trisomics VIII and IX resembled the disomics. The seed set for trisomic V was the lowest (20%), and trisomic VIII the highest (74%). Other aneuploids with 20 or more somatic chromosomes were either self-sterile or partially fertile with various, but low, levels of seed set. Each of the primary trisomics showed its unique transmission rate when self-pollinated; trisomic IX had the highest (45.8%), whereas trisomic V had the lowest (19.6%) transmission rate.     

Cytology of tetraploid x hexaploid timothy (Phleum pratense L.)

Ten pentaploids were isolated from seedling populations developed from seed of tetraploid plants grown in association with hexaploid timothy. About 80% of the prophase sporocytes exhibited severe or moderate pycnosis. These pycnotic accumulations appear to arrest the meiotic processes and apparently result in sporocyte lethality. Surviving sporocytes at diakinesis possessed nuclei with configurations that varied from 1 VI+14 II+1 I to 9 II+17 I. It is suggested that the conventional sorts of irregularities (univalents, inversions and translocations) cannot account for the low percentages of stainable pollen. Pairing relations indicated that considerable duplication and/or autosyndesis occurred in the genomes combined, and suggest that even though the tetraploid (2n=28) and hexaploid (2n=42) forms of Phleum pratense are closely related they are not identical. A portion of the sterility observed may be due to nuclear-cytoplasmic interaction.Results of co-operative work of the Crops Research Division, A.R.S., U.S. Department of Agriculture, and the Wisconsin Agricultural Experiment Station, Madison, Wis.Geneticist, Crops Research Division, A.R.S., U.S. Department of Agriculture, and Graduate Assistant, Department of Agronomy, Wisconsin Agricultural Experiment Station.     

Chlorophyll inheritance patterns and extent of natural self-pollination in timothy

Three hundred sixty-five S₁ and 234 S₂ seedling populations of timothy (Phleum pratense L.) were examined for their segregations for chlorophyll deficiencies. Arrays of both self-and open-pollination families indicated a lack of concentration at definite levels, with ratios expressed forming a continuous series from 4.6:1 to 572:1 for green: chlorophyll-deficient types in the S₁ generation. The S₂ populations examined ranged from 1.8:1 to 244:1. Arrays were very similar in their distributions.Sixty-three plants yielded chlorophyll-deficient types in both S₁ and S₀ populations. From these, it was calculated that 7 to 8 percent of natural self-pollination may occur in timothy.Except at two levels (28:1 and 143:1 tetradisomic) assumption of tetradisomic or simpler inheritance patterns resulted in lower calculated percentages of natural self-pollination than resulted from assumed hexasomic inheritance. No apparent explanation is available to account for these divergences from the regular pattern encountered.Results of cooperative work of the Crops Research Division, Agriculture Research Service, U.S. Department of Agriculture and the Wisconsin Agricultural Experiment Station, Madison.Research Agronomist, Crops Research Division, Agriculture Research Service, U.S. Department of Agriculture and Associate Professor, and Professor of Agronomy, Wisconsin Agricultural Experiment Station, respectively.     

Haploid induction in potato: Cytological basis for the pollinator effect

Summary A hexaploid endosperm is regularly associated with a haploid embryo following 4x–2x crosses in potato. One explanation for this is that a single 24-chromosome restitution sperm nucleus fuses with the central cell of the megagametophyte. This suggests that a superior pollinator may be one that produces a high frequency of restitution sperm nuclei. To test this, a technique was developed for observing pollen tube mitosis in vitro following germination of potato pollen in a 20% lactose-50 ppm boric acid solution. A single 24-chromosome restitution sperm nucleus was found in up to 38% of the pollen tubes from a superior pollinator. Moreover, pollen from an inferior pollinator soaked in a sucrose-boric acid-colchicine solution produced 100% restitution sperm nuclei in vitro and a haploid frequency from a tetraploid cultivar comparable to that normally induced by an untreated superior pollinator. The data indicate that the effectiveness of a pollinator in inducing haploids in potato is determined by the frequency of restitution sperm nuclei it produces.Cooperative investigations of the Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture, and the Wisconsin Agricultural Experiment Station. Part of a thesis submitted by the senior author in partial fulfilment of the requirements for the Ph. D. degree. Published with the approval of the Director of the Wisconsin Agricultural Experiment Station.Research Assistant, Department of Horticulture, University of Wisconsin, and Research Geneticist, Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture, Madison, Wisconsin 53706.     

Genetic variance of six agronomic characters in three lentil (Lens culinaris Medic) crosses

Summary Three lentil (Lens culinaris Medic) crosses (cross 1 = Chilean × PI 297784; cross 2 = Tekoa × PI 212611; cross 3 = Precoz × PI 212611) were advanced in a hierarchal design from the F₂ generation to the F₅ generation and tested in replicated field experiments. The purpose was to estimate the genotypic variances and covariances for several characters and to partition these into components due to additive, dominance, and additive × additive variances.Additive genetic variance was the major component of variance in cross 2 for all characters, except plant height and seed weight. Unexpectedly, estimates of dominance variance appeared to be high in crosses 1 and 3. Estimates of the additive × additive component seemed very small in all three populations. The dominance variance component estimates were consistently high for plant height in the three crosses and for seed weight in crosses 2 and 3. Where parental means were close, additive variance estimates were often low and in many cases negative. The unexpected high ratio of dominance variance to additive variance indicated that dominance variance was important in the crosses we studied.Cooperative investigations of Agricultural Research Service, US Department of Agriculture and the College of Agriculture, Washington State University, Pullman, Washington 99164, Work sponsored by Fellowship from Univ. of Jordan, Amman, Jordan. Scientific paper no. 5825.Formerly: Department of Agronomy and Soils, Washington State University, Pullman, WA., USA. Presently: Department of Plant Production and Plant Protection, University of Jordan, Amman, Jordan.Statistical Services, Washington State University, Pullman, WA 99164, USA.US Department of Agriculture, Agricultural Research Service, Washington State University, Pullman WA 99164, USA.     

Crossability relationships of andean potato varieties of three ploidy levels

Summary The formation of triploids in 4x×2x crosses was studied in primitive potato varieties from the Andes of Peru and Bolivia. Triploid frequencies were as high as 80–100% in some crosses, although the actual number of seeds was low. The triploid block varied according to the tetraploid parent, and was never entirely absent. The likelihood of triploid formation was studied in 4x×2x crosses where pollen from both tetraploids and diploids of known genotype was used. Even though the diploids were chosen for their non-production of 2n gametes, as detected in pollen grain size, 66% of the hybrids were tetraploid. The amount and probability of gene-flow between the tetraploid and diploid gene-pools, either directly through 2n gametes or through triploid bridges was examined. Most of the 20 cultivars of S. x chaucha produced seed in crosses with tetraploids and diploids, although the fertility of the latter crosses was four times higher. The female fertility of some of the triploids thus allows them to exchange genes with the tetraploids and diploids, although gene-flow occurs more rapidly through direct transfer from diploids to tetraploids via 2n gametes.     

Association between groat protein percentage and certain plant and seed traits in interspecific oat crosses

Summary Ten interspecific crosses of Avena sativa L. x A. sterilis L. were used to study associations of groat protein percentage with selected seed and agronomic traits. Each cross was grown in a replicated experiment, and the genetic material consisted of parents and F₂-derived lines grown in the F₄ generation.No close associations were found between groat protein percentage and plant height, heading date, or 10-groat weight. Individual crosses did show significant correlations, but none of the 3 traits was sufficiently associated with groat protein generally so as to be beneficial or inhibitory to combining high groat-protein percentage with the maturity, plant height, and 10-groat weight appropriate for good agronomic cultivars of oats.High groat-protein percentage was closely associated with abscission spikelet separation and jointed awn, both of which are A. sterilis traits. Shattering and dark seed color (A. sterilis traits) were also associated with high groat protein percentage, but kernel pubescence was not. Only a few segregates within each cross were A. sativa type for all 5 of the seed traits, but when A. sativa types from all crosses were grouped together, there was a large range for groat-protein percentages.Journal Paper No J-6950 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project 1752. In cooperation with the Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture. Carried out with a grant from the Quaker Oat Co., Chicago, Illinois, USA.     

Characteristics of inbred progenies from morphologically unstable Sorghum plants

Progenies from 68 self-pollinated panicles of 10 somatically unstable sorghum-sudangrass hybrid sectors were grown. Data are presented for 25 progenies from three representative unstable plants. Highly uniform progenies were obtained from most panicles. Results indicate chromosome assortment was not always at random. Major distinctions between panicle progenies suggested that: (a) sorghum-like and sudangrass-like genomes functioned as units; (b) gene transfer and association were non-random further indicating that somatic chromosome substitution or somatic translocations, or other gross changes, may have occurred; and (c) other deviating behaviors implied genetic segregation.Results of cooperative work of the Crops Research Division, Agricultural Research Service, U. S. Department of Agriculture, and the Wisconsin Agricultural Experiment Station, Madison, Wisconsin 53706 U.S.A.     

Inheritance of groat protein percentage in Avena sativa L. × A. Fatua L. Crosses

Summary Gene action and heritability of groat protein percentage were determined in F₁, F₂, and F₃ generations of nine crosses between three Avena sativa L. cultivars and three A. fatua L. selections. Relationships among groat protein percentage, grain yield, and 100-seed weight also were evaluated. The three A. sativa parents were Dal (high grain yield and intermediate groat protein percentage), Goodland (low grain yield and high groat protein percentage), and Stout (high grain yield and low groat protein percentage). The three A. fatua parents were chosen for the study on the basis of vigorous plant growth and high groat protein percentage. The study was conducted at Madison, Wisconsin in 1979 and 1980.There was partial dominance towards low groat protein percentage. Narrow sense heritability estimates for groat protein percentage were low in Dal and Goodland crosses and intermediate in Stout crosses. In the F₂ generation, groat protein percentage was significantly higher in shattering than in nonshattering plants in 1979, but not in 1980. There were significant, positive correlations between groat protein percentage, 100-seed weight, and grain yield in F₁ and F₂ generations, but they were not large numerically. Relationships among these traits were either negative or nonsignificant in the F₃ generation. Although our results indicated that selection for higher groat protein percentage is possible when a low protein A. sativa cultivar is used, most of our simple cross progenies from A. sativa x A. fatua crosses had weak straw and were susceptible to crown rust (Puccinia coronata Cda. var. avenae Fraser and Led.).     

Combining ability in crosses within and between diverse groups of alfalfa introductions

Summary 144 alfalfa (Medicago sativa L.) introductions were classified into eight groups based on their origin, winterhardiness, leafhopper yellowing, and growth characteristics. We studied the performance of crosses within and between these groups. General (GCA) and specific combining ability (SCA) for persistence among the eight groups were about equal. The Chilean group had a high positive GCA for persistence, suggesting that it may be become a good source of germplasm for persistance and, perhaps, disease resistance.SCA for forage yield was about three times greater than GCA, indicating a large amount of non-additive gene action for yield in crosses between groups. In general, crosses between groups yielded more than crosses within groups. The Afghan group showed high GCA with all groups, suggesting that Afghan introductions may contribute to improved synthetic varieties. The Flemish introductions performed well in crosses within their group and also in crosses between groups.GCA for rapid recovery after cutting was six times greater than SCA, indicating largely additive gene action for this trait. Nonhardy and Afghan-like introductions contributed most to rapid recovery in hybrid combinations.GCA for fall growth was slightly larger than SCA. The nonhardy introductions showed a large positive GCA, along with a significant SCA for fall growth.The evidence of specific combining ability, particularly for forage yield, suggested that hybridization may be needed for adequate evaluation of alfalfa introductions. An introduction grown in a new environment often will perform poorly, but its hybrid progeny from crosses to other introduced or adapted strains may show superiority.Paper number 3992 of the Journal Series of the North Carolina State University Agricultural Experiment Station, Raleigh, N. C. in cooperation with the Agricultural Research Service, U.S. Department of Agriculture.Research Geneticist, Southern Region, Agricultural Research Service, U. S. Department of Agriculture, and Professor of Statistics, North Carolina State University, Raleigh, N.C. 27607.     

Cytogenetic studies and the occurrence of triploidy in the wild potato species Solanum commersonii Dun.

Summary The South American wild potato species Solanum commersonii Dun. exists as two subspecies, subsp. commersonii and subsp. malmeanum (Bitter) Hawkes and Hjerting, and as both diploid and triploid cytotypes. The two subspecies were completely cross fertile but there were reciprocal differences in the number of seeds set per berry and the mean seed weight. Crosses between diploids and colchicine-induced autotetraploids yielded only a few seeds per berry, but 16 of the 18 germinated seeds were triploid or nearly so. Such a high proportion of triploids is unusual for such crosses in potatoes. Some triploids has a high percentage of stainable pollen. The origin of naturally occurring triploids is discussed in the context of 2n gametes, a triploid block, and endosperm balance numbers.     

The production of aneudihaploids in Solanum tuberosum L. group Tuberosum (the common potato)

Summary Trisomic cytotypes were produced in dihaploid (diploid) plants of Solanum tuberosum L. Group Tuberosum, the common potato, according to two methods. Firstly, the aberrant types were selected, through chromosome counting, from parthenogenic dihaploid offspring of tetraploid-diploid crosses. In dihaploid populations from twelve tetraploid potato varieties the frequencies of aneuploids ranged from 3.5 to 11.0%. About 95% of these aneuploids had only one, and the others not more than two extra chromosomes. Secondly, the aneuploids were produced from triploid-diploid crosses. Seedset strongly depended on the crossability of the parental plant material, and the best results were obtained when the motherplants were grafted onto tomato. On avarage the three most successful cross combinations resulted in approximately 0.7 berries per pollination and 6 seeds per berry. With regard to seedsize the seed could be divided in two groups, viz, normal and small seeds. Half of the seed did not germinate or produced inviable seedlings, especially among the small seed group. About 93% of the plants was neuploid, with 25, 26 and 27 being the predominant chromosome number. It was concluded that the production of trisomics was the most successful through triploid-diploid crosses. The results were discussed with reference to the chromosomal behaviour in the meiosis in triploid plants (Lange & Wagenvoort, 1973a). It thus was possible to relate the low seedset to the distribution of chromosomes in the meiotic anaphases. On the one side this distribution resulted in a limitation of the avalability of gametes with monohaploid and near-monohaploid chromosome numbers, while on the other side the macrospores with higher chromosome numbers seemed to be inviable. Finally a crossing scheme was presented for transmitting the trisomic condition into a genetic background with better homogeneity and more homozygosity.Extended version of a lecture presented at a Eucapia meeting about Potato Dihaploids, held at Wageningen (Netherlands). See Lange and Wagenvoort, 1973b.     

Polyploid and maternal effects on Rhizoctonia root rot resistance in sugarbeet

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.     

Variation in seed and seedling charactes of smooth bromegrass,Bromus inermisLeyss,in relation to environment

Summary Soil type, seedling depth, soil moisture, nitrogen and seed lot all affected seedling stand and early vigor. The first two aspects caused significant variations only when other factors were limiting.Individual plant progenies were found to differ in rate of emergence and maximum stand, vigor and height.Seed weight was an important factor among individual plant progenies, with heavy seed being superior. Individual plant progenies similar in seed weight differed in each of the factors fo establishment, indicating that not all of the differences observed among progenies could be ascribed to seed weight. Age and condition of seed, diseases and soil temperature were found to affect stand and vigor.Fifteen selected plant progenies and an experimental synthetic were superior in germination and seedling vigor to the rour commercial varieties tested as checks.Contribution from the Department of Agronomy, University of Wisconsin. Supported in part by the Research Committee of the Graduate School. Published wit the approval of the Director of The Wisonsin agric. Exp. Stn., Madison, Wis., USA.