The association among herbivory tolerance,ploidy level,and herbivory pressure in <Emphasis Type="Italic">cardamine pratensis</Emphasis>

We tested whether differences in ploidy level and previous exposure to herbivory can affect plant tolerance to herbivory. We conducted a common garden experiment with 12 populations of two ploidy levels of the perennial herb Cardamine pratensis (five populations of tetraploid ssp. pratensis and seven populations of octoploid ssp. paludosa). Earlier studies have shown that attack rates by the main herbivore, the orange tip butterfly Anthocharis cardamines, are lower in populations of octoploids than in populations of tetraploids, and vary among populations. In the common garden experiment, a combination of natural and artificial damage significantly reduced seed and flower production. We measured tolerance based on four plant-performance metrics: survival, growth, seed production and clonal reproduction. For three of these measurements, tolerance of damage did not differ between ploidy levels. For clonal reproduction, the octoploids had a higher tolerance than the tetraploids, although they experience lower herbivore attack rates in natural populations. Populations from sites with high levels of herbivory had higher tolerance, measured by seed production, than populations with low levels of herbivory. We did not detect any significant costs of tolerance. We conclude that high intensity of herbivory has selected for high tolerance measured by seed production in C. pratensis.     

Cytomorphology of induced octoploid Chili pepper (Capsicum annuum L.)

Summary Octoploidy was induced in Chili pepper (Capsicum annuum cultivar cerasiformis) through the application of colchicine and the cytomorphological features of two octoploid plants were described. In general, the octoploids did not exhibit gigas characters when compared to the tetraploids; on the contrary they were less vigorous, suggesting that the optimum and desirable ploidy level for Capsicum is probably tetraploid. Chromosome associations such as octovalents and hexavalents, in addition to IVs, IIIs, IIs and Is, were recorded at diakinesis and metaphase I. Meiosis was highly irregular and the pollen and seed fertility was very low. Cytological features of octoploid Chili peppers are compared with octoploids of Physalis and Petunia.     

Plant ploidy level influences selection by butterfly seed predators

Polyploidization is a common route to plant diversification. Polyploids often differ from their progenitors in size, flower number, flower size and flowering phenology. Such differences may translate into differences in the intensity of interactions with animals. Here we investigated the impact of the ploidy-related differences in tetraploids and octoploids of the perennial herb Cardamine pratensis on pre-dispersal seed predation by the butterfly Anthocharis cardamines . The probability of escaping attack was lower for octoploids than for tetraploids, even after accounting for the fact that octoploids were larger and had fewer flowers than tetraploids. Flower shoot size was correlated with probability of attack in tetraploids but not in octoploids. Differences in plant traits associated with polyploidization can alter interactions with animals, and animal-mediated differences in trait selection between ploidy types can contribute to their further divergence.     

Cytogeographic Distribution and Genome Size Variation in Prairie Cordgrass (Spartina pectinata Bosc ex Link)

Prairie cordgrass plants (Spartina pectinata Bosc ex Link) were examined from 61 locations representing the geographic distribution of prairie cordgrass in the U.S. Using flow cytometry, the genome size of 183 individual plants of prairie cordgrass was determined, and the chromosome counts were obtained. Three distinct ploidy levels were observed: tetraploid ( $ \overline x = {1}.{56} {\text{pg}},{2}n = {4} \times = {4}0 $ ), hexaploid ( $ \overline x { = 2}.{33} {\text{pg}},{2}n = {6} \times = {6}0 $ ), and octoploid ( $ \overline {\text{x}} { = 3}.0{6} {\text{pg}},{2}n = {8} \times { = 8}0 $ ). In the sampled areas, the tetraploid populations extended from the East North Central to the New England regions of the U.S., while the octoploid cytotypes were mostly distributed in the West North Central regions. Populations of the tetraploids and octoploids were found in close proximity in the West North Central (Iowa and Kansas) and the West South Central (Oklahoma) regions. The hexaploid cytotype was found in one mixed population (4x?+?6x) occurring in Illinois. No statistically significant intraploidy genome size variation was found in the tetraploid populations, while significant intraploidy genome size variation was found in the octoploid populations. This study precisely defined the geographic distribution of cytotypes in prairie cordgrass throughout the different regions of the U.S. These results provide critical genome size and ploidy distribution information needed to design efficient breeding schemes for high yielding cultivars of prairie cordgrass with local adaption.     

A cytotaxonomic study of theCalamagrostis purpurea —langsdorffii—canadensis complex in the lowlands of hokkaido

A chromosome survey of 278 individuals from 52 localities confirmed, that the principal components of theCalamagrostis purpurea—langsdorffi—canadensis complex in the lowlands of Hokkaido are tetraploid (2n=28) and octoploid (2n=56). A few hexploids (2n=42), were also found, but they may be either a triploid of the tetraploid plants or a hybrid between the tetraploid and octoploid plants. These hexaploids clearly differ in origin from the North American plants with 2n=42 which are generally placed underC. canadensis. The tetraploids and the octoploids are significantly different in pollen size but resemble each other in other morphological features and ecological requirements. These two races are also not disparate in distribution within Hokkaido. The tetraploids in Hokkaido are closely related to the tetraploids known in Alaska, and these tetraploid plants may be continuously distributed from Hokkaido to Alaska. The octoploids in Hokkaido have shown good pollen. They seem to have had a somewhat different course of evolution fromC. purpurea s. str. which principally reproduces in an apomictic manner.     

Do ploidy level and nuclear genome size and latitude of origin modify the expression of <Emphasis Type="Italic">Phragmites australis</Emphasis> traits and interactions with herbivores?

We studied the relationship between genome size and ploidy level variation and plant traits for the reed grass Phragmites australis. Using a common garden approach on a global collection of populations in Aarhus, Denmark, we investigated the influence of monoploid genome size and ploidy level on the expression of P. australis growth, nutrition and herbivore-defense traits and whether monoploid genome size and ploidy level play different roles in plant trait expression. We found that both monoploid genome size and latitude of origin contributed to variation in traits that we studied for P. australis, with latitude of origin being generally a better predictor of trait values and that ploidy level and its interaction with monoploid genome size and latitude of origin also contributed to trait variation. We also found that for four traits, tetraploids and octoploids had different relationships with the monoploid genome size. While for tetraploids stem height and leaf water content showed a positive relationship with monoploid genome size, octoploids had a negative relationship with monoploid genome size for stem height and no relationship for leaf water content. As genome size within octoploids increased, the number of aphids colonizing leaves decreased, whereas for tetraploids there was a quadratic, though non-significant, relationship. Generally we found that tetraploids were taller, chemically better defended, had a greater number of stems, higher leaf water content, and supported more aphids than octoploids. Our results suggest trade-offs among plant traits mediated by genome size and ploidy with respect to fitness and defense. We also found that the latitude of plant origin is a significant determinant of trait expression suggesting local adaptation. Global climate change may favor some genome size and ploidy variants that can tolerate stressful environments due to greater phenotypic plasticity and to fitness traits that vary with cytotype which may lead to changes in population genome sizes and/or ploidy structure, particularly at species’ range limits.     

The effect of ploidy level on fitness in parthenogenetic flatworms

Although polyploidy plays an important role in speciation, its impact on fitness is still debated. One problem is that its adaptive significance can only be inferred by comparing forms with different ploidy that are identical in all other traits. This situation is uncommon, presumably because ploidy types often differ in reproduction mode, genetic background or habitat. Here we compare fitness in a system of triploid and tetraploid karyotypes of the planarian flatworm Schmidtea polychroa . Both types have the same type of sperm-dependent parthenogenesis and share the same genetic background and habitat. Hence, fitness differences, if any, can be attributed to different ploidy levels only. Contrary to the general assumption of a positive correlation between fitness and ploidy level, we showed that triploids produced 58% more offspring than tetraploids. Within each ploidy type, we identified groups of highly related clones using microsatellites. Significant variation among clonal groups in body size, offspring and cocoon number and hatching time indicated a genetic basis for variance in these traits. A small model shows that despite low fitness of tetraploids, stable coexistence of triploids and tetraploids can be explained by the recurrent origin of triploids from tetraploids and vice versa.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 85 , 191–198.     

Phytogeographical studies ofCalamagrostis sachalinensis (Gramineae)

Chromosome numbers were determined on 223 collections ofCalamagrostis sachalinensis from 18 localities in Japan. The plants were found to be tetraploid (2n=28), hexaploid (2n=42) or octoploid (2n=56). A few collections were found to include one or two B-chromosomes. The tetraploid collections were made from central Honshu and Mt. Apoi in Hokkaido, while the hexaploids and the octoploids were detected in many localities. Pollen examination of these collections showed that the tetraploids with but one exception have good pollen and the hexaploids and the octoploids have no pollen or have bad pollen with stainability less than 10%. With the help of pollen examination of a number of herbarium specimens, the distribution of the tetraploids and that of the assemblage of the hexaploids and octoploids were delineated. Morphological studies indicated that the tetraploid, hexaploid and octoploid plants can not be separated in gross and spikelet morphology and that the tetraploids in central Honshu and those in Mt. Apoi are significantly different in leaf features. It was concluded thatC. sachalinensis represents an apo-amphimictic complex, which includes the following four races: 1) tetraploid, amphimictic, having thin leaf blades 5–10 mm broad and growing on the subalpine conifer forest belt and the conifer forest-alpine ecotone in the mountains of central Honshu; 2) tetraploid, amphimictic, having hard leaf blades 2–6 mm broad and growing on the stony, arid and exposed alpine belt on Mt. Apoi in Hokkaido; 3) hexaploid, mainly apomictic, the most variable ecologically, widely distributed; 4) octoploid, mainly apomictic, frequent in the upper montane to alpine belts, probably widely distributed.     

A new cytotype of Jacobaea vulgaris (Asteraceae): frequency,morphology and origin

Jacobaea vulgaris subsp. vulgaris (syn. Senecio jacobaea subsp. jacobaea) constitutes an intricate polyploid complex distributed in Europe. Four cytotypes have been reported in this species, three with euploid (diploid, tetraploid and octoploid; 2n=20, 40 and 80) and one with aneuploid (2n=32) chromosome numbers. Here we report that the diploid chromosome number (2n=20) reported from Bulgaria is due to misidentification with Jacobaea aquatica. On the other hand, we have discovered a new, hexaploid (2n=6x=60) cytotype within J. vulgaris subsp. vulgaris using flow cytometry. The new cytotype occurs within four sympatric populations of otherwise tetraploid and octoploid plants in Pannonia (one locality in the eastern Czech Republic and two localities in southwestern Slovakia) and in Podillya (one locality in western Ukraine). The frequency of hexaploid individuals within 76 studied populations is very low (only 10 of 693 analysed plants), and hexaploids probably represent hybrids between tetraploid and octoploid plants. Three mixed populations with hexaploid plants were subjected to detailed morphological and pollen fertility analyses. Multivariate morphometric analysis reveals partial separation of tetraploid and octoploid plants, whereas hexaploid individuals are similar in morphology to octoploids. In comparison with tetraploids, octoploids and hexaploids exhibit slightly longer ray florets, involucral bracts and tubular florets and more hairy outer achenes. Hexaploid plants display larger pollen grains and lower pollen fertility compared to tetraploids and octoploids.     

Occurrence of tetraploid and octoploid cytotypes in Senecio jacobaea ssp. jacobaea (Asteraceae) in Pannonia and the Carpathians

Four different cytotypes have been reported for Senecio jacobaea L. ssp. jacobaea throughout Europe, with the most common occurrence of tetraploids (2 n  = 40). Here we present a survey of previously published chromosome number data on this subspecies and its geographical distribution, and focus on populations from Pannonia and the Carpathians. Two ploidy levels have been determined in the study area, using chromosome counting and flow cytometry: tetraploid (2 n  = 40) and octoploid (2 n  = 80). Fifty-one populations originating from Slovakia, Austria, the Czech Republic, Hungary, Ukraine and Romania have been analysed. Multivariate morphometric analyses have been performed on 39 populations to study morphological differentiation between these two cytotypes. Despite slight morphological tendencies expressed on the level of populations, tetraploid and octoploids cannot be reliably distinguished morphologically and they are not taxonomically classified formally here.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 153 , 231–242.     

Context-dependent resistance against butterfly herbivory in a polyploid herb

Spatial variation in biotic interactions and natural selection are fundamental parts of natural systems, and can be driven by differences in both trait distributions and the local environmental context of the interaction. Most studies of plant–animal interactions have been performed only in natural settings, making it difficult to disentangle the effects of traits and context. To assess the relative importance of trait differences and environmental context for among-population variation in plant resistance to herbivory, we compared oviposition by the butterfly Anthocharis cardamines on two ploidy types of the herb Cardamine pratensis under experimentally controlled conditions with oviposition in natural populations. Under controlled conditions, plants from octoploid populations were significantly more preferred than plants from tetraploid populations. This difference was largely mediated by differences in flower size. Among natural populations, there was no difference in oviposition rates between the two ploidy types. Our results suggest that differences in oviposition rates among populations of the two cytotypes in the field are caused mainly by differences in environmental context, and that the higher attractiveness of octoploids to herbivores observed under common environmental conditions is balanced by the fact that they occur in habitats which harbor lower densities of butterflies. This illustrates that spatial variation in biotic interactions is the net result of differences in trait distributions of the interacting organisms and differences in environmental context, and that variation in both traits and context are important in understanding species interactions.     

When sexual meets apomict: genome size,ploidy level and reproductive mode variation of Sorbus aria s.l. and S. austriaca (Rosaceae) in Bosnia and Herzegovina

Background and Aims Allopolyploidy and intraspecific heteroploid crosses are associated, in certain groups, with changes in the mating system. The genus Sorbus represents an appropriate model to study the relationships between ploidy and reproductive mode variations. Diploid S. aria and tetraploid apomictic S. austriaca were screened for ploidy and mating system variations within pure and sympatric populations in order to gain insights into their putative causalities.Methods Flow cytometry was used to assess genome size and ploidy level among 380 S. aria s.l. and S. austriaca individuals from Bosnia and Herzegovina, with 303 single-seed flow cytometric seed screenings being performed to identify their mating system. Pollen viability and seed set were also determined.Key Results Flow cytometry confirmed the presence of di-, tri- and tetraploid cytotype mixtures in mixed-ploidy populations of S. aria and S. austriaca. No ploidy variation was detected in single-species populations. Diploid S. aria mother plants always produced sexually originated seeds, whereas tetraploid S. austriaca as well as triploid S. aria were obligate apomicts. Tetraploid S. aria preserved sexuality in a low portion of plants. A tendency towards a balanced 2m : 1p parental genome contribution to the endosperm was shared by diploids and tetraploids, regardless of their sexual or asexual origin. In contrast, most triploids apparently tolerated endosperm imbalance.Conclusions Coexistence of apomictic tetraploids and sexual diploids drives the production of novel polyploid cytotypes with predominantly apomictic reproductive modes. The data suggest that processes governing cytotype diversity and mating system variation in Sorbus from Bosnia and Herzegovina are probably parallel to those in other diversity hotspots of this genus. The results represent a solid contribution to knowledge of the reproduction of Sorbus and will inform future investigations of the molecular and genetic mechanisms involved in triggering and regulating cytotype diversity and alteration of reproductive modes.     

Ploidy effects in isogenic populations of alfalfa : I. Ribulose-1,5-bisphosphate carboxylase, soluble protein, chlorophyll, and DNA in leaves

The influence of polyploidization on ribulose-1,5-bisphosphate carboxylase (RuBPCase), buffer-soluble protein (BSP), chlorophyll (Chl), and DNA was examined in fully expanded leaves of isogenic diploid-tetraploid (DDC 2X-4X) and tetraploid-octoploid (IC 4X-8X) sets of alfalfa (Medicago sativa L.). The concentration of RuBPCase in leaf extracts was determined by rocket immunoelectrophoresis. Activities of RuBPCase, expressed per milligram protein or per milligram Chl, and leaf tissue concentrations of RuBPCase, BSP, Chl, and DNA were similar between ploidy levels of the DDC 2X-4X set. Tetraploids and octoploids were similar in RuBPCase activities, expressed per milligram protein or per milligram Chl, and in leaf tissue concentrations of RuBPCase and DNA. Octoploids were significantly lower than tetraploids in concentrations of Chl and BSP.

When compared on a per leaf basis, tetraploids were 80% higher in BSP and essentially double comparable diploids in fresh weight, RuBPCase, Chl, and DNA. The observation that leaves of the DDC tetraploid population contain twice as much DNA as comparable diploids suggests that leaves of both ploidy levels contain similar numbers of cells. Leaves of the octoploid population were 33% to 80% higher than corresponding tetraploids in BSP, fresh weight, RuBPCase, Chl, and DNA. Ratios of RuBPCase to DNA and Chl to DNA were similar across ploidy levels of both isogenic sets suggesting that cellular content of Chl and RuBPCase increases proportionately with the amount of DNA per cell.

     

Fine-scale comparisons of genetic variability in seed families of asexually and sexually reproducing Crataegus (hawthorn; Rosaceae)

The reproductive system is one of the key mechanisms that determine genetic diversity at different biological levels. However, few attempts have been made to assess the consequences of asexual reproduction by comparing genetic structure and fecundity of seed families in asexually and sexually reproducing individuals. We have examined two similar hawthorn species, Crataegus crus-galli and C. punctata, that differ in ploidy level and breeding system. Fecundity (per-fruit seed set) and microsatellite genotypes for five loci were determined in 18 and 26 seed families of C. crus-galli and C. punctata (totals of 83 and 118 embryos), respectively. Compared with the sexual diploid C. punctata, tetraploid C. crus-galli shows similar fecundity, but lower genotypic diversity within and between seed families. Reproduction in the tetraploid, while predominantly apomictic, is nevertheless accompanied by outcrossing and selfing. We conclude that in C. crus-galli pollen flow between conspecific individuals is limited, and the combination of pollen fertility, self-compatibility, and pseudogamous apomixis provides reproductive assurance in these tetraploids. Reproductive assurance, in turn, may explain the derived floral architecture seen in most North American tetraploid hawthorns. We also discuss analytical approaches for inferring mating-system parameters in tetraploids and for comparing microsatellite variation across ploidy levels.     

Polyploidy: a missing link in the conversation about seed transfer of a commonly seeded native grass in western North America

The use of local, native plant materials is now common in restoration but testing for polyploidy in seed sources is not. Diversity in cytotypes across a landscape can pose special seed transfer challenges, because the methods used to determine genetically appropriate materials for seed transfer do not account for cytotypic variation. This lack of consideration may result in mixing cytotypes through revegetation, which could reduce long‐term population viability. We surveyed nine populations of a native bunchgrass, Pseudoroegneria spicata, in three EPA Level III Ecoregions in the western United States to determine the frequency of polyploidy, whether there are differences in traits (phenotype, fecundity, and mortality) among plants of different cytotypes, and whether cytotype frequency varies among ecoregions. We assessed trait variation over 2 years in a common garden and determined ploidy using flow cytometry. Polyploidy and mixed cytotype populations were common, and polyploids occurred in all ecoregions. Four of the nine populations were diploid. The other five had tetraploids present: three had only tetraploid individuals whereas two had mixed diploid/tetraploid cytotypes. There was significant variation in traits among cytotypes: plants from tetraploid populations were larger than diploid or mixed populations. The frequency and distribution of cytotypes make it likely that seed transfer in the study area will inadvertently mix diploid and polyploid cytotypes in this species. The increasing availability of flow cytometry may allow ploidy to be incorporated into native plant materials sourcing and seed transfer.     

Reproductive differentiation into sexual and apomictic polyploid cytotypes in Potentilla puberula (Potentilleae, Rosaceae)

Background and Aims

Intraspecific reproductive differentiation into sexual and apomictic cytotypes of differing ploidy is a common phenomenon. However, mechanisms enabling the maintenance of both reproductive modes and integrity of cytotypes in sympatry are as yet poorly understood. This study examined the association of sexual and apomictic seed formation with ploidy as well as gene flow towards sexuals within populations of purely polyploid Potentilla puberula.

Methods

The study is based on 22 populations representing various combinations of five polyploid cytotypes (tetraploid–octoploid) from East Tyrol, Austria. Embryo ploidy and the endosperm/embryo ploidy ratio obtained by a flow cytometric seed screen were used to infer reproductive modes of seed formation and to calculate the male and female genomic contributions to the embryo and endosperm. Self-incompatibility (SI) patterns were assessed and a new indirect approach was used to test for the occurrence of intercytotype matings based on the variation in the male genomic contribution to sexually derived embryos on the level of developed seed.

Key Results

Tetraploids formed seeds almost exclusively via sexual reproduction, whereas penta- to octoploids were preferentially apomictic. Non-random distribution of reproductive modes within maternal plants further revealed a tendency to separate the sexual from the apomictic mode among individuals. Self-incompatibility of sexuals indicated functionality of the gametophytic SI system despite tetraploidy of the nuclear genome. We found no indication for significant cross-fertilization of tetraploids by the high polyploids.

Conclusions

The study revealed a rare example of intraspecific differentiation into sexual and apomictic cytotypes at the polyploid level. The integrity of the sexual tetraploids was maintained due to reproductive isolation from the apomictic higher polyploids. Functionality of the gametophytic SI system suggested that the tetraploids are functional diploids.     

Other tetraploid species and conspecific diploids as sources of genetic variation for an autotetraploid

? Premise of the study: Most plants are polyploid and have more than two copies of the genome. The evolutionary success of polyploids is often attributed to their potential to harbor increased genetic variation, but it is poorly understood how polyploids can attain such variation. Because of their formation bottleneck, newly formed tetraploids start out with little variation. Tetraploids may attain genetic variation through a combination of new mutations, recurrent formation, and gene exchange with diploid ancestors or related tetraploid species. We explore the role of gene exchange and introgression in autotetraploid Rorippa amphibia, a species that harbors more genetic variation than its diploid ancestors. ? Methods: We crossed autotetraploid R. amphibia to diploid conspecifics and tetraploid R. sylvestris and backcrossed resulting F(1) hybrids. We used flow cytometry to determine the ploidy of all progeny. ? Key results: Tetraploids of R. amphibia and R. sylvestris were interfertile; F(1) hybrids were fertile and could backcross. Crosses between diploids and tetraploids yielded a small number of viable, often tetraploid progeny. This indicates that unreduced gametes can facilitate gene flow from diploids to tetraploids. We detected a frequency of unreduced gametes of around 2.7 per 1000, which was comparable between diploids and tetraploids. ? Conclusions: Introgression from tetraploid R. sylvestris provides a realistic source of variation in autotetraploid R. amphibia. Only in a scenario where other compatible partners are absent, for example immediately after tetraploidization, gene flow through unreduced gametes from diploids could be an important source of genetic variation for tetraploids.     

Patterns of cytotype distribution and genome size variation in the genus Sesleria Scop. (Poaceae)

Polyploidization has played an important role in the diversification of the genus Sesleria (Poaceae), which comprises c. 48 species and subspecies mostly distributed in Europe. The genus' centre of diversity clearly is the Balkan Peninsula, harbouring about 80% of the species, half of which are endemic to this area. We employed chromosome counts, measurements of absolute genome size and determination of relative DNA‐content for 460 populations belonging to 43 species of Sesleria. Our main aim was to provide essential baseline data for future molecular genetic reconstructions of the genus' evolutionary history. Relative genome size allowed for a mostly clear separation of four ploidy levels. The most frequent and widespread cytotypes are tetraploids followed by octoploids, while di‐ and dodecaploids were only found in a few species. We present first chromosome numbers for the tetraploid species S. doerfleri, S. phleoides, S. skipetarum and S. tuzsonii as well as for diploid S. ovata. Based on relative and partly also on absolute genome size measurements, ploidy level was determined in tetraploid S. rhodopaea and S. voronovii for the first time, and new cytotypes were identified in S. interrupta, S. kalnikensis and S. wettsteinii (tetraploids), S. caerulea, S. klasterskyi, S. latifolia, S. tenerrima, S. ujhelyii and S. vaginalis (octoploids), and S. albanica and S. vaginalis (dodecaploids). While most Sesleria species are ploidy‐uniform, several comprise two or even, in the case of S. vaginalis, three ploidy levels. Genome downsizing after polyploidization was confirmed by significant negative correlation between ploidy level and monoploid genome size. Finally, we found a significant increase in monoploid relative genome size towards the margin of the genus' distribution area, which may be triggered by increased activity of transposable element in populations exposed to environmental or genomic stress. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 126–143.     

Influence of wheat and rye parents on agronomic characters in primary hexaploid and octoploid triticale

Summary Thirty-five hexaploid and twenty octoploid primary triticales (xTriticosecale Wittmack) derived from homozygous wheat and rye inbred lines were used (1) to investigate the parental wheat, rye, and interaction effects and (2) to estimate quantitative genetic parameters for agronomic traits. The winter triticales were tested in four environments in a three-replicate split-plot design with drilled 1 m² plots. Superior performance of hexaploid triticales as compared to the octoploids was revealed. Substantial genetic variation and high heritability estimates were found for nearly all of the characters investigated. Estimates of wheat, rye, and wheat×rye interaction variance components disclosed parental main effects to be the most important source of genetic variation in primary triticales. The rye parent was dominant for all characters affecting fertility, and the wheat parent was more important for vegetative development. Character correlations were very similar for triticales of both ploidy levels. The lack of association between grain yield and tillering and the positive correlation between kernels per spike and thousand kernel weight indicated physiological disorders specific for primary triticales.