Comparative karyotype analysis in Haplopappus Cass. and Grindelia Willd. (Asteraceae) by double FISH with rRNA specific genes

The genera Grindelia Willd. and Haplopappus Cass. belong to the family Asteraceae - Astereae and are distributed in America and South America, respectively. Previous cytotaxonomic studies showed for South American species of Grindelia 2n=12 and for Haplopappus 2n=10 and 2n=12. Both Grindelia species (G. anethifolia, G. prunelloides), newly analyzed with molecular-cytological methods, exhibited symmetric karyotypes (AsI %=55.46 and 55.95) with metacentric chromosome sets (5m + 1m-sat) and 2n=12 chromosomes. The NOR was detected after fluorescence in situ hybridization (FISH) with 18/25S rDNA in the satellite chromosome 2. In contrast H. Happlopappus glutinosus, H. grindeloides and H. stolpii showed exclusively a higher asymmetric index (66.83%, 67.01% and 68.87%, respectively) with submetacentric chromosome sets (4sm + 1sm–sat). The sat-chromosomes 3 of H. glutinosus and H. grindelioides were both significantly different in their length from chromosomes 2 and 4. Furthermore in Grindelia the FISH with 5S rDNA could estimate signals in the short arms of chromosomes 3 or 4, that were not significantly differentiated in their length. Contrary to these findings in Grindelia, the position of 5S rDNA in Haplopappus was detected in the long arms of chromosome 1 (H. grindelioides and H. stolpii) and chromosome 2 (with two different loci) and chromosome 4 of H. glutinosus. The lengths of all measured chromosome arms with 5S rDNA were significantly different to those of the neighbours in the karyotypes. The two-color FISH of 5S and 18/25S rDNA had provided clear karyotypic markers for three (Haplopappus glutinosus) and two (H. grindelioides and H. stolpii) chromosomes. The number and position of rDNA signals were relatively highly conserved in the investigated five species without the double marked chromosome 2 of H. glutinosus, which shows an evolutionary dynamic of this 5S rRNA specific gene cluster. This investigation supports the assumption that the evolution of New World members of Grindelia and Haplopappus has not been accompanied by large karyotypic changes, but small chromosomal rearrangements have undoubtedly occurred (e.g. 5S rDNA localizations).     

Management tradeoffs between focal species and biodiversity: endemic plant conservation and solitary bee extinction

Conservation of rare species and ecosystem biodiversity should not lead to conflicts. However, situations may arise when the management of focal species places non-target species at risk. In the Willamette Valley of western Oregon, USA, eradication of a naturally hybridizing Grindelia integrifolia × Grindelia nana (Asteraceae) population from a wildlife refuge to preserve genetically “pure” populations of endemic G. integrifolia populations to the North, eliminated a dominant, late-summer, flowering plant from the plant community. While this decision undoubtedly arose from good intentions, the hybrid Grindelia was the sole pollen resource for the last known population (numbered in 100s prior to Grindelia removal) of an endemic solitary bee, Melissodes pullatella (Anthophoridae), a rare wetland butterfly, Lycaena xanthoides (Lycaenidae), and very likely additional pollinators. Approximately 15 years after the removal of Grindelia from the wildlife refuge, we found several small populations of M. pullatella (<20 individuals sighted) about 70 km to the south of the refuge in hybrid Grindelia-dominated remnant and restored wetlands. We present this case study to highlight the loss of local biodiversity that can accompany single species driven ecosystem management. We hope that land managers will consider not only the preservation of the formally recognized rare species in their conservation strategy but also the impacts of management practices on site biodiversity.     

THE FEMALE GAMETOPHYTE OF MACHAERANTHERA PATTERSONII (ASTER PATTERSONII) AND OF M. TANACETIFOLIA

The nucellus of Machaeranthera pattersonii (A. Gray) Greene (Aster pattersonii A. Gray) contains only one megaspore mother cell, and the female gametophyte develops from the chalazal megaspore of a row of four, thus conforming to the Polygonum type of development. These observations are contrary to the older work of Palm. Three nuclear divisions produce the typical eight nuclei with the egg apparatus, primary endosperm cell with two polar nuclei, and two antipodal cells, the micropylar one containing two nuclei. Usually no more antipodal cells are formed, although there is further nuclear division, apparently followed by nuclear fusion. The antipodal cells remain about the same size without forming an antipodal haustorium. Cell division accompanies the first division of the primary endosperm nucleus. The early stages of the embryo resemble those of other Compositae. Machaeranthera tanacetifolia (HBK) Nees also shows the Polygonum type of development of the female gametophyte. It is suggested that Palm may have been working on some species of Erigeron that had been wrongly identified, which would account for the difference in observations.     

Molecular cytogenetic studies of the “Xanthocephalum group” (Asteraceae)

Fourteen North American members of the “Xanthocephalum group” were studied by classical and molecular cytogenetics. Location and number of rDNA sites were determined by FISH. For the 5S rDNA, a probe was obtained from Prionopsis ciliata. Most species were diploid (2n?=?12), although Isocoma menziesii, Grindelia hirsutula, G. robusta, both varieties of G. stricta, and one population of G. camporum were tetraploid (2n?=?24). Diploid Grindelia and Prionopsis ciliata were 5m?+?1sm, tetraploids 10m?+?2sm, except G. hirsutula (8m?+?4sm), and Isocoma and Olivaea 6m?+?2sm and 3m?+?3sm, respectively. Most species had satellites on the short arms of m pairs: two in tetraploids and P. ciliata and one in diploids. Satellites were associated with two CMA⁺/DAPI^? bands in diploid species and four bands in tetraploids and in P. ciliata. rDNA loci (two in diploids to four in tetraploids) may be indicative of ploidy level. Grindelia tetraploids could have originated recently by autopolyploidy. Chromosome duplication was followed by modifications in the genome structure, resulting in higher heterochromatin amounts not associated with NORs. There is only one 5S site per basic genome in para or pericentromeric regions. Although not always large, chromosome variation has accompanied the evolutionary divergence of the taxa studied.     

Karyotypes,heterochromatin distribution and rDNA patterns in South American Grindelia (Asteraceae)

Grindelia is a genus with a complex evolutionary history with reticulate evolution. We studied the karyotype, fluorescent banding, and fluorescence in situ hybridization (FISH) using 18–5.8–26 S and 5 S ribosomal DNA probes to survey karyotypic diversity of South American Grindelia species. Chromosome basic numbers were x = 6 (with several ploidy levels: 2x, 4x, and 6x). All the Grindelia studied conserved the patterns of CG-rich heterochromatin and 18-5.8-26 S rDNA. The third m sat-chromosome pair was homeologous in Grindelia. Chromosome variation, although not always large, accompanied the evolutionary divergence of the taxa studied. The Grindelia studied formed two species groups: (1) G. globularifolia and G. pulchella var. pulchella, (2) G. buphthalmoides, G. cabrerae var. alatocarpa and var. cabrerae, G. chiloensis, G. orientalis, and G. prostrata. These groups do not show any morphological affinities and their phylogenetic relationships are not clearly resolved, suggesting that these groups have recently diverged.     

GROWTH INDUCTION IN CULTURES OF HAPLOPAPPUS GRACILIS. II. THE BEHAVIOR OF THE NUCLEUS

Mitra , J., and F. C. Steward . (Cornell U., Ithaca, New York.) Growth induction in cultures of Haplopappus gracilis. II. The behavior of the nucleus. Amer. Jour. Bot. 48(5): 358–368. Illus. 1961.—Cells of Haplopappus, which have been stimulated to grow under the influence of coconut milk and such synergists as naphthalene or 2,4-dichlorophenoxy acetic acid, can be cultivated as free cells, as small cell clusters, or as peripheral cells on a cultured colony or mass. Such cells display forms and cell lineages, the general pattern of which is reminiscent of those that may occur in early embryogeny. To this extent, Haplopappus resembles what has previously been observed in the growth of free cells of carrot. The form of the normal chromosome of Haplopappus (2n = 4) is described with respect to root tip cells. The range of effects which may be observed in the nuclei of the cultured cell is also described. Such variations as the following were encountered: (1) multinucleate giant cells which may divide by internal segmentation; (2) polyploidy, giving rise to highly polyploid nuclei up to, and even in excess of, 64 chromosomes; (3) somatic pairing; (4) haploidy; (5) pseudochiasmata, with the evident implication of somatic “crossing-over”; (6) chromosome breaks, reunions and bridges, such as are commonly associated with effects of radiation and with chemical mutagens. Attention is drawn to the usefulness of this material for the further experimental investigation of the biochemical basis for the cytological events which are here described, and, if the variant cells may be cloned, of the relationship between the aberrant nuclear cytology and the ability of the cells or colonies to differentiate or to undergo morphogenesis.     

DISTRIBUTION ECOLOGY OF HAPLOPAPPUS AND CHRYSOTHAMNUS IN THE MOJAVE DESERT. I. NICHE POSITION AND NICHE SHIFTS ON NORTH-FACING GRANITIC SLOPES

The close systematic affinities between the composite genera Haplopappus and Chrysothamnus, including different points of contact with “intergeneric” hybrids, are reviewed. The Mohave Desert has several shrubby representatives of each genus, and at census sites from the east-central New York Mountains to buttes at the extreme western end of the desert, north-facing granitic slopes at the foothills of mountain ranges support four Haplopappus species (H. cuneatus. H. laricifolius, H. linearifolias and H. cooperi) and one Chrysothamnus (C. teretifolius). These five species occupy “distributional niches” represented as ranges and areas of dominance on the habitat plane of slope angle and proportion of rocks in the substrate. Central desert sites have four species (excluding C. teretifolius); peripheral desert sites always include C. teretifolius rather than H. laricifolius and support two to four species depending on the size and isolation of the suitable habitat area. Species may occupy different positions on the habitat gradient depending on species number at the site, moisture availability, and in particular competition from other species. C. teretifolius appears to be favored when population turnover rates are high, either in disturbed sites or on natural islands of habitat.     

Two new species of Grindelia (Astereae,Asteraceae) from Uruguay

Taxonomic revision of South American species ofGrindelia Willd. has revealed two new species from Uruguay:G. rupestris, an erect subshurb with crowded obovate denticulate leaves, subsessile heads, and pappus composed of numerous awns, andG. linearifolia, a prostrate shrublet with small entire linear leaves. Both species are described and illustrated. A key for the UruguayanGrindelia species is provided.     

Comparative embryology of threeGentianaceae species from the Central Caucasus and the European Alps

A comparative investigation was carried out on the ovule and seed development of three mountain species ofGentianaceae, the perennial speciesGentiana pyrenaica, and the two short-lived monocarpic speciesGentianella caucasea andG. germanica. In all three species most embryological characters conform to those generally found in the family of theGentianaceae. In some features, however,G. pyrenaica and the twoGentianella species differ from each other. InG. pyrenaica the ovule is anatropous, the integument 8–10 layered and the three reduced antipodals degenerate soon after fertilization. In contrast,G. caucasea andG. germanica form a hemitropous ovule, a 4–5 layered integument and up to 16 antipodal cells by secondary multiplication. All three species exhibit differences in synchronization between embryogenesis and endosperm development. Functional relations between the antipodal structure and the dynamics of seed development of the investigated species are postulated.     

A CYTOGENETIC ANALYSIS OF CERTAIN POLYPLOIDS IN GRINDELIA (COMPOSITAE)

Two diploid taxa, Grindelia procera and G. camporum, and 3 tetraploid ones, G. camporum, G. hirsutula, and G. stricta, have been studied to ascertain their interrelationships. Meiosis in diploid parental strains was regular, the common chromosome configuration being 5 rod bivalents and 1 ring bivalent. The average chiasmata frequency per chromosome was 0.60. Pollen fertility was about 90% in all strains examined. Diploid interspecific hybrids had normal meiosis with an average chiasmata frequency of 0.56 per chromosome. No heterozygosity for inversions or interchanges was detected, and pollen fertility was above 85%. Meiosis in parental tetraploid strains was characterized by the presence of quadrivalents in addition to a complementary number of bivalents. The average chiasmata frequency per chromosome was 0.59 and pollen fertility was generally about 80%. Tetraploid interspecific hybrids also had quadrivalents, normal meiosis, and high pollen fertility. Close genetic relationships between the diploids and between the tetraploids are indicated, and geographical, ecological, and seasonal barriers to gene exchange exist. Attempts to obtain hybrids between diploids and tetraploids were successful in a few cases. The hybrids were tetraploid and had normal meiosis and fertility similar to parental and F₁ tetraploids. Their origin was by the union of unreduced gametes of the diploid female parent and normal pollen from the tetraploid parent. On the basis of chromosome homology, normal meiosis, plus high fertility exhibited in the diploid, tetraploid, and diploid X tetraploid interspecific hybrids, these species of Grindelia are considered to be a part of an autopolyploid complex. Gene exchange between diploids and diploids, tetraploids and tetraploids, and diploids and tetraploids is possible. Tetraploid G. camporum may have originated by hybridization between G. procera and diploid G. camporum with subsequent doubling of chromosomes and selection for the combined characteristics of the diploids.     

Reclassification of North American Haplopappus (Compositae: Astereae) completed: Rayjacksonia gen. nov.

Rayjacksonia R. L. Hartman & M. A. Lane, gen. nov. (Compositae: Astereae), is named to accommodate the “phyllocephalus complex,” formerly of Haplopappus Cass. sect. Blepharodon DC. The new combinations are R. phyllocephalus (DC.) R. L. Hartman & M. A. Lane, R. annua (Rydb.) R. L. Hartman & M. A. Lane, and R. aurea (A. Gray) R. L. Hartman & M. A. Lane. This transfer completes the reclassification of the North American species of Haplopappus sensu Hall, leaving that genus exclusively South American. Rayjacksonia has a base chromosome number of x = 6. Furthermore, it shares abruptly ampliate disk corollas, deltate disk style-branch appendages, and corolla epidermal cell type, among other features, with Grindelia, Isocoma, Olivaea, Prionopsis, Stephanodoria, and Xanthocephalum. Phylogenetic analyses of morphological and chloroplast DNA restriction site data, taken together, demonstrate that these genera are closely related but distinct.     

CHROMOSOME RELATIONSHIPS OF DIPLOID SPECIES OF GRINDELIA (COMPOSITAE) FROM COLORADO,NEW MEXICO,AND ADJACENT AREAS

Previous studies of chromosome relationships of Grindelia species recognized three basic genomes designated Oxylepis, Hallii, and Havardii. Differences are based on different end arrangements of the chromosomes resulting from reciprocal translocations. This report will review and give additional information about the genomes and interrelationships of 17 species. All of the species are diploids (2n = 12) and show six bivalents at meiosis. Species in this study that have the Oxylepis genome are G. oxylepis var. eligulata, G. fastigiata, G. inornata, G. revoluta, and G. squarrosa. Species that have the Havardii genome included G. havardii, G. grandiflora, G. lanceolata, G. littoralis, and G. texana. The Hallii genome is present in G. camporum var. davyi and G. procera. Hybrids of species with the same genome have six bivalents at meiosis. Hybrids between species with the Oxylepis genome and those having the Havardii genome have four bivalents and one quadrivalent at meiosis. Likewise for Oxylepis x Hallii hybrids. A new genome is presented for G. subalpina which would explain the configurations of two bivalents and two quadrivalents observed in G. subalpina x G. havardii and G. subalpina x G. fastigiata hybrids. This is designated the Subalpina genome. Species tested but with genomes as yet undetermined are G. acutifolia, G. arizonica, G. nana, and G. scabra.     

THE USE OF A NEW CLEARING TECHNIQUE FOR THE STUDY OF EARLY OVULE DEVELOPMENT,MEGASPOROGENESIS, AND MEGAGAMETOGENESIS IN FIVE SPECIES OF CORNUS L.

The application of a new clearing technique proved successful for the study of ovule development, megasporogenesis, and megagametogenesis in Cornus asperifolia Michaux., C. stricta Lam., C. amomum Miller, C. florida L., and C. alternifolia L. These were the first studies of embryological features in C. asperifolia and C. stricta. Consistent features for both species include: slightly crassinucellate nucelli, megaspore mother cells, and equal dyads with the upper member obliquely aligned to the parietal cell. Alignment of nucelli of the 4-nucleate megagametophyte is not the same for both species. More than one mature 8-nucleate megagametophyte per nucellus was recorded for C. asperifolia. Embryological features not revealed in previous investigations of the other three species include: equal dyad cells for C. alternifolia and C. amomum, although disintegration of defunct megaspores is variable for both species; vacuole formation at the micropylar end at the 2-nucleate stage of C. amomum; a 4-nucleate stage in C. amomum and C. alternifolia with different alignments of nuclei; synergids that disintegrate rapidly in both species although antipodal shapes vary for each; and fusion of polar nuclei at varying locations within different species. A prominent hypostase is formed in all five species. Because of embryological features, it is recommended that C. forida be separated from the genus Cornus.     

Maxillary palps can mediate taste rejection of plant allelochemicals by caterpillars

All caterpillars possess a pair of maxillary palps that “drum” the surface of foods during feeding. These chemosensory organs contain over 65% of a caterpillar's taste receptor cells, but their functional significance remains largely unknown. We examined their role in rejection of plant allelochemicals, using the tobacco hornworm (Manduca sexta) as a model insect and an extract from a plant species (Grindeliaglutinosa) as a model stimulus. We selected this system because hornworms reject foods containing Grindelia extract, and because preliminary studies indicated that their maxillary palps respond to this extract. We hypothesized that Grindelia extract elicits rejection through stimulating: (1) olfactory receptor cells, (2) taste receptor cells, (3) oral mechanoreceptors, and/or (4) a postingestive response mechanism. Our results were consistent only with hypothesis 2: caterpillars approached Grindelia-treated diets without apparent hesitation, but rejected it within 6 s of initiating biting; Grindelia-treated solutions stimulated taste receptor cells in the maxillary palp, but not the other gustatory chemosensilla; and ablating the maxillary palps eliminated rejection of Grindelia-treated diets. Our results demonstrate that taste receptor cells in the maxillary palps mediate rejection of Grindelia extract, and provide the first direct evidence for a role of maxillary palps in rejection of plant allelochemicals. Accepted: 25 January 1998     

Two new species of Haplopappus (Astereae, Asteraceae) from Mendoza, Argentina

A review of the Argentinean specimens ofHaplopappus Cass. has revealed two new species from Mendoza province, both of the sectionHaplopappus:H. boelkei, unique by its caespitose habit and long petiolate leaves, andH. mendocinus, related toH. macrocephalus (Less.) DC.,H. ochagavianus Phil. andH. tiltilensis Phil.     

A new species of Grindelia (Asteraceae, Astereae) from the Meseta del Somuncura (Patagonia), Argentina

Grindelia coronensis, a new species from the Meseta del Somuncura, Prov. Río Negro, Argentina, is described and illustrated. It is similar toG. chiloensis (Cornel.) Cabrera but it is readily distinguished by its leaves which are conspicuosly differentiated into a obovate blade and a long petiole.     

Seasonal variation in resource allocation of extractable compounds in Asclepias,Chrysothamnus and Grindelia

The yields of whole plant hexane and methanol soluble extractables from Asclepias speciosa; Chrysothamnus itnauseosus subsp, consimilis and Grindelia squarrosa were examined throughout the growing season. The yields of non-polar extractables remained relatively constant during the growing season with increases in late summer or early fall according to the species. Each of the three taxa showed a similar pattern with the methanol soluble fraction reaching a maximum in June. However, a second maximum was observed in Asclepias and Grindelia in August. Protein content was examined in Asclepias and Grindelia and was found to decline throughout the growing season. Individual components of the hexane extract of Asclepias were examined and several components were found to vary seasonally. Principal components analysis of the nonpolar components revealed that the components with high intercorrelations were members of five chemical biosynthetic classes: alkanes, fatty acids, pentacyclic triterpenoids and tetracyclic sterols. Canonical variate analysis grouped the samples by date of sample from May to September-October.     

Notes on the bryophytes of the schistose valleys of western Crete,including Asterella africana new to Greece,and an assessment of the conservation status of Rhamphidium purpuratum and Jungermannia handelii

Atrichum laoshanense Y.-J.Yi &; S.He, a new species of Polytrichaceae from Laoshan mountain in Shandong Province, eastern China, is described and illustrated. The new species resembles, and is related to A. angustatum (Brid.) Bruch &; Schimp., but differs in the presence of stellately papillose median leaf cells, multicellular laminal teeth with well-defined outgrowths of pedestal cells on the distal dorsal lamina, and papillose stem epidermal cells. An updated key to species of Atrichum in China is presented.     

CHROMOSOME NUMBERS IN SOUTH AMERICAN HAPLOPAPPUS CASS. (COMPOSITAE)

Chromosome counts are reported for 33 species from all four sections of the genus Haplopappus in South America. These include first reports for 28 species and two putative hybrids. All chromosome numbers reported herein are 2n = 5_II, with the exception of H. prunelloides with 2_n = 6_II. Unlike the North American species, the morphological diversity of South American taxa is not concomitant with chromosomal variation.     

DEVELOPMENT OF THE OVULE AND FEMALE GAMETOPHYTE IN EUSTACHYS PETRAEA AND E. GLAUCA (POACEAE)

The unilocular pistil in Eustachys contains a single ovule with lateral placentation. In E. petraea and E. glauca, the mature ovule is bitegmic, tenuinucellate, and amphitropous with the endostomic micropyle oriented toward the base of the locule. A single hypodermal archesporial cell enlarges to form the megasporocyte. The chalazal dyad member is larger than the micropylar one, and meiosis II is nonsynchronized. Two-thirds of the tetrads are linear and one-third T-shaped. The chalazal megaspore is functional. Initially ovoid, the two-nucleate female gametophyte becomes curved as it enlarges. The four-nucleate stage becomes wider at its extremities and constricted in the center. Synchronous mitotic divisions establish the eight-nucleate stage with four nuclei at each pole separated by a large central vacuole. In E. petraea, the maturation sequence begins with antipodal differentiation, followed by differentiation of the egg apparatus, migration of the polar nuclei to the center, and division of the antipodals to produce twelve cells. The sequence in E. glauca begins with migration of the polar nuclei followed by differentiation of the antipodals, egg apparatus, and antipodal replication to six cells. The polar nuclei fuse to form a secondary nucleus appressed to the egg cell in E. glauca and separated from it by a vacuole in E. petraea. T-tests for length measurements for various stages of development indicate that the functional megaspore and two-nucleate female gametophyte are significantly larger in E. glauca than in E. petraea. There is no significant difference in gametophyte length at the four-nucleate stage, and at the eight-nucleate stage, length in E. petraea surpasses that in E. glauca. This gap widens significantly at the mature stage. Nuclear volumes are significantly greater in E. glauca than in E. petraea in the functional megaspore and two-nucleate stage, but the volumes are similar at the four-nucleate stage. Consideration of the differences in structural complexity between the sporophyte and gametophyte generations leads to the conclusion that the female gametophytes of these species are more distinctive than are the sporophytes.