EXPERIMENTAL HYBRIDIZATION,CHROMOSOMAL DIVERSITY,AND PHYLOGENY WITHIN GAURA (ONAGRACEAE)

Patterns of interfertility for intersectional hybridizations in Gaura are generally consistent with current taxonomic hypotheses regarding the sectional division of the genus. Crossability is generally lower for intersectional crosses than for intrasectional, interspecific crosses. Average intersectional cross-success ranged from 0–14% among the eight sections, and a total of 54 intersectional hybrids were produced from 1,872 intersectional pollinations. Low rates of capsule-set and no intersectional hybrids were produced by G. mutabilis (section Gauridium), an early offshoot of a primitive ancestor of Gaura. Two species of section Xerogaura that are regarded as relicts of the primitive ancestor of all other Gaura showed low averages for cross-success, but did produce hybrids in combination with three relatively advanced sections (Campogaura, Stipogaura, Pterogaura). Low capsule-set and no intersectional hybrids were produced by G. parviflora (section Schizocarya). Extreme morphological specialization for autogamous reproduction has been accompanied by reproductive isolation of G. parviflora. Only three hybrids resulted from crosses using G. coccinea (section Campogaura), a polyploid complex. Each successful cross paired G. coccinea with a putative progenitor, either a species of section Xerogaura or G. villosa of section Stipogaura. Hybrids of G. coccinea with odd ploidy number showed reduced pollen staining. Species of Stipogaura produced only three hybrids, one each in combination with species of sections Xerogaura, Campogaura, and Pterogaura. Gaura drummondii (section Xenogaura) registered the highest average cross-success despite being a tetraploid. All 25 hybrids of G. drummondii resulted from crosses with G. suffulta, and were triploids that showed reduced pollen staining. Intersectional crosses fail to support the hypothesized relationships of G. drummondii either to G. coccinea or to species of section Stipogaura. Section Gaura produced moderate averages of cross-success, but all 20 hybrids resulted from crosses with G. suffulta. Fifty of the 54 intersectional hybrids were descended from a species of section Pterogaura. Crosses that used G. suffulta as one parent produced 49 of these hybrids. Four hybrids were from crosses with G. macrocarpa (section Xerogaura), and the remaining 45 were due to the recurrent success of crosses that paired G. suffulta as maternal parent with either G. drummondii or a species of section Gaura.     

Chromosome numbers in callirhoe (Malvaceae)

Forty-four chromosome counts from the North American genusCallirhoe are reported, including first-recorded counts ofC. alcaeoides, C. digitata, C. bushii, C. triangulata, andC. involucrata var.tenuissima. Information concerning chromosome numbers from present and previous reports is summarized and evaluated. Observations are presented on meiosis for the genus in general, for male sterile individuals of gynodioecious species, and for selected F₁ hybrids. Pollen fertility data are recorded for the latter. Chromosomally three species groups are recognized: an exinvolucellate, diploid species group withn=14; an involucellate, tetraploid and octoploid species pair,n=28 and 56; and an involucellate, diploid and tetraploid species group withn=15 and 30. Intrageneric relationships and those within the tribe Malveae subtribe Malvinae are discussed.     

Genetic diversity in and phylogenetic relationships of the Brazilian endemic cotton,Gossypium mustelinum (Malvaceae)

Gossypium mustelinum, one of five tetraploid species in the cotton genus, is geographically restricted to a few states in NE Brazil. Allozyme analysis was used to assess levels and patterns of genetic diversity inG. mustelinum and its relationship to the other tetraploid species. Genetic variation was low, with only 6 of 50 loci examined being polymorphic, a mean of 1.14 alleles per locus and a mean panmictic heterozygosity of 0.08. These estimates are low relative to other tetraploid cotton species, but are typical of island endemics. Interpopulational genetic identities were uniformly high, lending support to the concept of there being only one wild species of Brazilian cotton. The limited allelic diversity observed was correlated with geographical distribution, although variability is so limited in the species that geographically marginal populations are electrophoretically ordinary. Phylogenetic and phenetic analyses demonstrate thatG. mustelinum is isolated among polyploid cotton species, occupying one of the three basal clades resulting from an early radiation of polyploid taxa subsequent to polyploid formation. We suggest thatG. mustelinum represents a paleoendemic that presently exists as a series of widely scattered, relictual populations. Despite several centuries of sympatric cultivation ofG. barbadense andG. hirsutum, there was little evidence of interspecific introgression of alleles from cultivated cottons intoG. mustelinum.     

New chromosome numbers for plant taxa endemic to the Balearic Islands

Mitotic chromosome numbers are reported from 25 vascular plant taxa, endemic to the Balearic Islands that are poorly known cytogenetically. The chromosome numbers ofAnthyllis vulneraria subsp.balearica (2n=12),Cymbalaria fragilis (2n=56), andPolygonum romanum subsp.balearicum (2n=40) were determined for the first time. A new chromosome number was found in several populations ofAnthyllis hystrix (2n=70) suggesting that this species is decaploid, in contrast to an earlier work reporting a higher ploidy level (2n=12x=84). The new chromosome number 2n=32 was reported inHypericum hircinum subsp.cambessedesii. It is suggested that the previous count (2n=40) could be explained by the presence of anomalous pentaploid cells in some tissues, contrating with the presence of a regular tetraploid complement (2n=32). Cytogenetic observations suggest thatSibthorpia africana has a diploid chromosome complement of 2n=18, with 0–2 accessory chromosomes. Accessory chromosomes are also reported forPhlomis italica, being the first record of B chromosomes in this genus. Chromosomal instability was found inGalium crespianum andG. friedichii species, with three numbers 2n=44, 55 and 66. Two cytotypes differing in ploidy level were documented within single plants. It is suggested that both species share a regular complement of 2n=44 and that the past hybridization events and formation of regenerating roots from the typical rootstock ofG. crespianum andG. friedrichii could be involved in the genesis of chromosome variants through partial endopolyploidy and concomitant somatic segregation.     

Allozyme analysis ofLuzula sect.Luzula (Juncaceae) in Ireland: Evidence of the origin of tetraploids

Luzula campestris, L. pallidula and tetraploi plants of this section from Ireland were studied electrophoretically. A hypothesis of alloploid origin for the Irish tetraploids from a hybrid betweenL. campestris andL. pallidula, based on the morphology, and karyology of the relevant taxa, has been tested. The presumed parental taxa are divergent in several loci,L. pallidula being highly homozygous andL. campestris moderately heterozygous. The Irish tetraploid combines the alleles of the putative parents, has no unique alleles, and exhibits a high frequency of heterozygotes, inAdh-2 andGpi-1, with invariably additive patterns. The Irish tetraploid has a low genotype diversity. The allozyme data support the hypothesis of alloploid origin for the Irish tetraploid withL. campestris andL. pallidula as possible parents.     

Chromosome numbers of Panamanian Lecythidaceae and their use in subfamilial classification

Nine species of Lecythidaceae subfamily Lecythidoideae in four genera whose chromosome numbers were previously unknown, have 17 as their basic chromosome number:Eschweilera pittieri, three other unidentified species ofEschweilera, Grias cauliflora, Gustavia dubia, G. superba, Lecythis minor, andL. tuyrana. All are diploid exceptGustavia superba, which is tetraploid.Couroupita guianensis, which was previously—and probably incorrectly—reported to have a gametic chromosome number of 18, also hasn = 17. The known chromosome numbers support recognizing at least three of Niedenzu’s subfamilies: Planchonioideae withx = 13, Napoleonaeoideae withx = 16, and Lecythidoideae withx = 17. His fourth subfamily, Foetidioideae, with one genus of five species, has not been counted. Cytological data have been and probably will be useful in indicating to what subfamily problematic genera belong and in showing interesting phytogeographic patterns within the family. On the other hand, cytological data provide no recognizable clues relating the Lecythidaceae to other families.     

A CYTOTAXOXOMIC SURVEY OF MELAMPODIUM (COMPOSITAE-HELIANTHEAE)

Turner , B. L.. and R. M. King . (U. Texas, Austin.) A cytotaxonomic survey of Melampodium (Compositae-Heliantheae). Amer. Jour. Bot. 49(3): 233–26. Illus. 1962.—Chromosome counts are reported for individuals from 89 populations of Melampodium representing 26 species The genus is multibasic with x = 9, 10, 11, 12, 16 and 23. Chromosome numbers on a base of x = 10 characterize the section Melampodium while basic numbers of x = 23, 16, 12, 11 and 9 occur in the section Zarabellia. Melampodium camphoratum (n = 16) differs from all other species examined in having relatively small meiotic chromosomes. Only 6 of the 23 species are polyploid or have polyploid races. Melampodium leucanthum and M. cinereum have both diploid and tetraploid populations; the latter occur without any apparent morphological or geographical correlation and are probably autoploid in origin. A survey of the basic chromosome numbers known for other genera of the subtribe Melampodinae (12 of 22 genera) is presented. and it is suggested that x = 10 is the most probable basic number of the genus and subtribe.     

Population studies in Goodyera (Orchidaceae) with emphasis on the hybrid origin of G. Tesselata

Morphological, cytological, and paper Chromatographic studies of populations from northern Michigan and examination of herbarium specimens from throughout North America were used to clarify the relationships ofGoodyera oblongifolia, G. repens var.ophioides, andG. tesselata. A canonical analysis of morphological data from mixed populations of these three species depictsG. tesselata as intermediate betweenG. oblongifolia andG. repens var.ophioides. The latter two species are diploid (2n = 30) andG. tesselata is tetraploid (2n = 60). Triploids (2n = ca. 45) were found in two mixed-species populations in northern Michigan.Goodyera tesselata produces three phenolic compounds present inG. oblongifolia and five different compounds present inG. repens var.ophioides. The range ofG. tesselata is confined to glaciated territory (except for two stations) in northeastern North America where the postglacially produced ranges ofG. oblongifolia andG. repens var.ophioides overlap. However,G. tesselata is quite abundant in areas outside the region of sympatry of the other two species. Based on this evidence, it is postulated thatG. tesselata is an allotetraploid species which resulted from hybridization betweenG. oblongifolia andG. repens var.ophioides during early post-Pleistocene. The slightly earlier blooming season ofG. tesselata may have been selected for to provide a measure of reproductive isolation between the tetraploid and its parents and to adapt the new species to the rather short growing season of northeastern North America.     

Genetic Polymorphism and Evolution in Parthenogenetic Animals. II. Diploid and Polyploid SOLENOBIA TRIQUETRELLA (Lepidoptera: Psychidae)

Genic polymorphism at sixteen enzyme loci of four different chromosomal races of Solenobia triquetrella (bisexual, two diploid parthenogenetic races and tetraploid parthenogenetic) has been studied by starch gel electrophoresis. Isolated small diploid bisexual populations have rather uniform allele frequencies at all loci which we have studied. Diploid and tetraploid parthenogenetic individuals of this species are in general as heterozygous as bisexual ones. All parthenogenetic local populations are different from each other in the Alps. These parthenogenetic genotypes cannot be derived from a common ancestor through single mutations but rather bear evidence for a polyphyletic origin of parthenogenesis in Solenobia triquetrella. In the marginal distribution areas of the species in northern Europe single genotypes are spread over far larger areas than in the mountain regions of central Europe. This may be due to the old origin of parthenogenesis and polyploidy in northern Europe. No new parthenogenetic and polyploid strains have lately arisen in the regions outside of the Alps.     

Karyotaxonomische Untersuchungen anPotentilla taurica s.l. in Bulgarie

Several taxa considered by previous authors as intraspecific ofPotentilla taurica s.l. are considered as separate species. A diploid chromosome number 2n=14 and the characteristic chromosomes of karyotypes of 3 Balkan endemicsP. ni?i?i Adam.,P. emilipopii Nyarády andP. pirotensis (Borb.) Mark. are recorded.P. bornmuelleri Borb.,P. mollicrinis (Borb.) Stankov andP. astracanica Jacq. are widespread in South-eastern Europe. Of this groupP. mollicrinis is a diploid (2n=14),P. bornmuelleri is tetraploid and inP. astracanica a polyploid serie of 2x=14, 4x=28, 5x=35 and 6x=42 has been found. The karyotypes of all species are characterized by submetacentric chromosomes.     

Fertility relationships ofGeranium (Geraniaceae): sectt.Ruberta,Anemonifolia, Lucida andUnguiculata

Cross-pollinations were carried out among 11 briefly described species ofGeranium. Eight species pairs produced hybrids, of which five had not been reported before. The close relationship ofG. purpureum, G. robertianum andG. rubescens (sect.Ruberta) was confirmed; they form a polyploid series (diploid, tetraploid and octoploid on base x = 16). ForG. canariense (sect.Anemonifolia), another octoploid on base x = 16, the results suggest greater affinity with the former section.G. maderense andG. palmatum of sect.Anemonifolia (2n = 68) are confirmed as closely related to each other.G. maderense produced hybrids withG. robertianum (2n = 64; sect.Ruberta) and withG. cataractarum (2n = 36; sect.Unguiculata). Meiosis in the latter hybrid suggests allopolyploidy between parents with 2n = 32 and 2n = 36. Whereas all these species clearly form a very close alliance,G. lucidum (sect.Lucida) andG. macrorrhizum andG. dalmaticum (both sect.Unguiculata), appear genetically more isolated from them. One plant ofG. macrorrhizum ×G. dalmaticum was raised. — In crosses where hybrids or non-germinating seeds resulted, the reciprocal cross in the majority of cases produced a greatly inferior result or none at all. This asymmetry of response could in some cases be explained by inability of pollentubes from short-styled parents to reach the ovary of a long-styled species and in others by a modification of Hogenboom's theory of incongruity, but neither explanation works for every case. In all our asymmetric results where the ploidy level differed the diploid was the successful female, not the tetraploid, as is usually the case. — Some variation in results from year to year could be attributed to weather conditions.Dedicated to Hofrat Univ.-Prof. DrK. H. Rechinger on the occasion of his 80th birthday.     

A new species of Psilostrophe (Compositae) from Mexico

Psilostrophe mexicana is described as new and compared with the closely related speciesP. gnaphalodes. Chromosome numbers forP. mexicana are reported asn = 32, a tetraploid number. This new species is the seventh and only polyploid species in the genus.     

国产毛茛科驴蹄草属两种植物的细胞学研究

为探讨国产毛茛科(Ranunculaceae)驴蹄草属(Caltha L.)植物的细胞学特征,对驴蹄草(C.palustris L.)3个居群和花葶驴蹄草(C.scaposa Hook.f.&Thoms.)5个居群进行了细胞学研究。驴蹄草贵州纳雍居群的染色体数目为2n=32(四倍体),两个云南中甸居群的染色体数目均为2n=64(八倍体)。花葶驴蹄草四川红原、康定、石渠居群的染色体数目均为2n=32(四倍体),该数目为首次报道;西藏林芝和云南德钦居群的染色体数目均为2n=64(八倍体)。驴蹄草的染色体比花葶驴蹄草大。这两种植物的32或64条染色体分别以4条或8条为单位大致能够排列为8组同源染色体,但同一组内的染色体经常具有明显的异形性(heteromorphy),不同居群的核型组成多少具有差异。同时,还分析了驴蹄草和花葶驴蹄草的不同倍性细胞型在我国的地理分布式样。     

The karyotype of Nothoscordum arenarium Herter (Gilliesioideae, Alliaceae): A populational and cytomolecular analysis

The genus Nothoscordum Kunth comprises approximately 20 species native to South America. Karyologically, the genus is remarkable for its large chromosomes and Robertsonian translocations. Variation in chromosome number has been recorded in a few polyploid species and it is unknown among diploids. This study presents the chromosome number and morphology of 53 individuals of seven populations of N. arenarium Herter (2n = 10). In addition, karyotype analyses after C-banding, staining with CMA and DAPI, and in situ hybridization with 5S and 45S rDNA probes were performed in six individuals from one population. All individuals exhibited 2n = 10 (6M + 4A), except for one tetraploid (2n = 20, 12M + 8A) and one triploid (2n = 15, 9M + 6A) plant. C-banding revealed the presence of CMA(+) /DAPI (-) heterochromatin in the short arm and in the proximal region of the long arm of all acrocentric chromosomes. The 45S rDNA sites co-localized with the CMA (+) regions of the acrocentrics short arms, while the 5S rDNA probe only hybridized with the subterminal region of a pair of metacentric chromosomes. A change in the pattern of CMA bands and rDNA sites was observed in only one individual bearing a reciprocal translocation involving the long arm of a metacentric and the long arm of an acrocentric chromosome. These data suggest that, despite isolated cases of polyploidy and translocation, the karyotype of N. arenarium is very stable and the karyotypic instability described for other species may be associated with their polyploid condition.     

CHROMOSOME NUMBERS IN PLATYSCHKUHRIA RYDBERG (COMPOSITAE) AND THEIR SYSTEMATIC SIGNIFICANCE

Diploid (2n = 12_II), tetraploid, pentaploid, and hexaploid level chromosome numbers are reported for Platyschkuhria Rydb. (Compositae). First reports of accessory chromosomes in the genus are also presented. Known polyploidy in Platyschkuhria is thus far restricted to P. integrifolia (Gray) Rydb. var. desertorum (M. E. Jones) Ellison from south-central Utah. Cytogenetic analysis, using methods and models of Jackson and Hauber (1982), suggests alloploid origins for the tetraploid levels. Diploid and polyploid populations correlate strongly with distinctively different edaphic situations, yet no consistent morphological features were identified that could justify taxonomic recognition of the polyploids.     

Construction and Characterization of Isogenic Series of Saccharomyces cerevisiae Polyploid Strains

Tetraploid cells of Saccharomyces cerevisiae are generated spontaneously in a homothallic MATa/MATα diploid population at low frequency (approximately 10⁻⁶ per cell) through the homozygosity of mating-type alleles by mitotic recombination followed by homothallic switching of the mating-type alleles. To isolate tetraploid clones more effectively, a selection method was developed that used a dye plate containing 40 mg each of eosin Y and amaranth in synthetic nutrient agar per liter. It was possible to isolate tetraploid clones on the dye plate at a frequency of 1 to 3% among the colonies colored dark red in contrast to the light red of the original diploid colonies. Isogenic series of haploid to tetraploid clones with homozygous or heterozygous genomic configurations were easily constructed with the tetraploid strains. No significant differences in specific growth rate or fermentative rate were observed corresponding to differences in ploidy, although the haploid clones showed a higher frequency of spontaneous respiratory-deficient cells than did the others. However, a significant increment in the fermentative rate in glucose nutrient medium was observed in the hybrid strains constructed with two independent homozygous cell lines. These observations strongly suggest that the polyploid strains favored by the brewing and baking industries perform well not because of the physical increment of the cellular volume by polyploidy but because of the genetic complexity or heterosis by heterozygosity of the genome in the hybrid polyploid cells.     

A new species of Erigeron (Asteraceae) and its relatives in southwestern Utah

A narrow endemic of southwestern Utah,Erigeron flagellaris A. Gray var.trilobatus Maguire ex Cronq., is given specific status asErigeron proselyticus Nesom. It is closely related to two other rare endemics of the Zion National Park area,Erigeron religiosus Cronq. andErigeron sionis Cronq., but it does not share a similarly close relationship with typicalE. flagellaris. Erigeron proselyticus is diploid;E. sionis is tetraploid and probably agamospermic; three diploid populations and several triploid populations ofE. religiosus are known, including a population of triploids from the site of a paratype collection of this species. Variation in these triploids suggests the possibility of hybridization withErigeron divergens Torr. & Gray, or with an unknown species no longer occurring sympatrically withE. religiosus.     

Variation among tripsacum populations of Mexico and Guatemala

Seven species of the genusTripsacum, one with a well marked subspecies, are indigenous to Mexico and Guatemala. Two diploids,T. zopilotense andT. maizar, are restricted to western and southwestern Mexico. The typical diploid form of a third species,T. latifolium, occurs in south central and eastern Guatemala; atypical tetraploid forms of this species are found in western Mexico. Four tetraploids,T. dactyloides, T. dactyloides ssp.hispidum, T. lanceolatum, andT. pilosum, have ranges extending from northwestern Mexico southeastward into Guatemala. The seventh species is the highly sterile tetraploid,T. laxum, of doubtful occurrence in the wild. It is readily propagated vegetatively and has been widely distributed in Latin America and the West Indies as a forage plant. Field studies of the range of variation in 80 Mexican and Guatemalan populations included an evaluation of 16 definitive morphological characteristics from an average of approximately six individuals of each population. Seventy-three of the 80 populations were allopatric, and of these, 50 were classed as typical, 13 as atypical, and ten as intermediates. Thirty-nine of the 50 populations classed as typical were tetraploid, and 11 were diploid. Of the 23 atypical and intermediate populations, 17 were tetraploid and six were diploid. Fifty-eight tetraploid populations, which included typical, atypical, and intermediate forms ofT. dactyloides, T. dactyloides ssp.hispidum, T. lanceolatum, T. pilosum, andT. latifolium, comprised an inclusive intergrading series having different combinations of characteristics distinguishing the two very dissimilar diploids,T. mizar andT. zopilotense. This series was interpreted as support for the hypothesis of Randolph & Hernández (1950), that the tetraploid populations originated as alloploid derivatives of these or closely related diploid species. The occurrence in some of the tetraploid populations of characteristics not seen in either of the putative parental species was noted, and the possibility that other taxa also might have been involved in their origin is under investigation. In addition to the 73 allopatric populations included in this survey there were seven sympatric and mixed associations of diploid and tetraploid taxa. Among these were hybrids with various combinations of the characteristics differentiating taxa of the associated populations. These hybrids effectively obscured differences between taxa, thus creating a syngameon complex from which genetic recombinants were observed to have spread into recently disturbed habitats of neighboring areas. From such direct evidence, and the existing interrelationships among allopatric and sympatric populations, it was concluded that the origin of the Mexican and Guatemalan tetraploidTripsacum species and various atypical and intermediate variants, has involved, and is continuing to involve, alloploid recombinants of diploid species and syngameon complexes, of which those encountered in this survey are examples.     

Untersuchungen zur Karyologie und Mikrosporogenese vonPelargonium sect.Pelargonium (Geraniaceae)

The chromosome numbers of the 24 species of sect.Pelargonium were determined from field collected and cultivated plants of known localities in S. Africa. Twelve species are diploid (2n = 22), eight tetraploid (2n = 44), one hexaploid (2n = 66), and three octoploid (2n = 88). The chromosome numbers correlate well with the proposed subdivision of sect.Pelargonium. Its chromosomes are relatively small (1.0–1.5 µm) in comparison to most of the other sections, and its diploid karyotype is considered to be primitive. The occurrence of the basic number x = 11 in this section, in other sections of the genus, and in related genera (Monsonia, Sarcocaulon) leads to the conclusion that x = 11 probably is basic for the whole genus. — The pollen meiosis, microsporogenesis and pollen fertility of the diploid species is normal, with the exception of one, possibly young taxon from the Greyton Nature Reserve. The tetraploid species could be of autoploid origin, the higher polyploids exhibit a mixed auto-alloploid nature. — The 20 diploid and tetraploid species have a relatively small distribution range, most of them occur in the SW. Cape Province of South Africa. This area may therefore be considered as the centre of origin of the genus. Three of the four high polyploid species occupy rather large areas.

Untersuchungen zur Karyologie und Mikrosporogenese der GattungPelargonium, 1.     

Revision of the genus philactis (Compositae)

Philactis (Compositae-Heliantheae) is a genus of three species, all of limited distribution. A revision is presented, based upon herbarium specimens and field work. Cytological data are from bud material fixed in the field, and from root tips of seedlings. The basic chromosome number appears to be 14.P. nelsonii andP. liebmannii are tetraploid (2n = 56), andP. zinnioides is hexaploid (2n = 84).