Detailed cytomorphological investigations through male meiosis of polypetalous plants from the Kashmir Himalaya

Cytomorphological studies were made on 322 populations of 150 species/153 taxa belonging to 79 genera and 23 families of flowering plants. Out of these, 14 species were cytologically worked out for the first time on a worldwide basis along with B-chromosomes (0–1B) recorded for the first time in Agrimonia eupatoria. Similarly, 29 species were reported with varied chromosomal reports on a worldwide basis. The chromosome numbers ranged from 2n = 10 to 2n = 96 and posed high amount of intraspecific genetic diversity when seen in relation to other reports for the worked out species in light of previous chromosomal databases on India and world basis. The different levels of ploidy in these species/taxa vary from 2x to 12x with the overall polyploidy being 27.45 % and predominant in members belonging to the genera Ranunculus and Epilobium as well as families Ranunculaceae and Rosaceae. In the taxa showing anomalous meiotic behavior, cytomixis is found to be quite common and associated with various meiotic abnormalities in the meiocytes, which ultimately leads to pollen sterility and formation of variable sized pollen grains.     

Cytological evaluation of Apiaceae Lindl. from Western Himalayas

The present paper deals with cytological studies on 31 populations covering 17 species belonging to 10 genera of Apiaceae from Western Himalayas. The chromosome numbers in the two species as Chaerophyllum capnoides (n = 11) and Heracleum brunonis (n = 11), along with additional cytotypes for Pimpinella acuminata (n = 9) and Sium latijugum (n = 12) have been reported for the first time on world-wide basis. The genus Pleurospermum, although cytologically worked out earlier from outside India, its species densiflorum (n = 11) makes first representation of the genus from India. Besides, the chromosome number in Chaerophyllum aromaticum (n = 11) have been worked out for the first time from India. The course of meiosis varies from normal to abnormal in different populations of Chaerophyllum villosum, Pimpinella achilleifolia and Sium latijugum while abnormal meiotic course has been observed in all the studied populations of Chaerophyllum acuminatum, C. aromaticum, C. capnoides, Pimpinella acuminata, P. diversifolia, Pleurospermum densiflorum and Vicatia coniifolia. Such taxa are marked with meiotic abnormalities in the form of cytomixis, chromatin stickiness, formation of laggards and bridges resulting into abnormal microsporogenesis. The occurrence of structural heterozygosity has been recorded in the Chaerophyllum acuminatum and C. aromaticum. The effect of these abnormalities is clearly seen on the pollen size and fertility.     

Chromosome numbers in some cacti Of western North America—II

Documented chromosome numbers and meiotic behavior are recorded for an additional 30 taxa representing 25 species of Cactaceae of southwestern United States and northern Mexico. Diploid and polyploid taxa including two triploids were observed, all of which indicate the same base number,x = 11. Trisomism and inversions are reported for the first time in cacti.     

Chromosome number, male meiosis and pollen fertility in selected angiosperms of the cold deserts of Lahaul-Spiti and adjoining areas (Himachal Pradesh, India)

In this study the exact chromosome number, detailed meiotic behavior in pollen mother cells and pollen viability were investigated, which can contribute to a better understanding of the cytological evolution of the species growing in the cold deserts of Lahaul-Spiti (Himachal Pradesh, India). This study is the first such comprehensive attempt to explore the region chromosomally. Chromosome number, meiotic behavior and pollen fertility were analyzed in 301 accessions of 140 species of Polypetalae. Chromosome counts in 14 species are the first ever records, viz., Aquilegia pubiflora (n?=?7), Corydalis govaniana (n?=?8), C. thyrsiflora (n?=?8), Hedysarum astragaloides (n?=?7), H. microcalyx (n?=?7), Oxytropis thomsoni (n?=?8), Rhodiola tibetica (n?=?10), R. wallichianum (n?=?16), Rosularia alpestris (n?=?14), Epilobium chitralense (n?=?18), E. leiospermum (n?=?18), Heracleum brunonis (2n?=?33), H. thomsonii (n?=?11) and Pleurospermum govanianum (n?=?9). New intraspecific diploid or polyploid cytotypes have been recorded in 13 species. The species of these cold deserts are quite active in evolution, depicting heterogeneity in chromosome number involving polyploidy, 51 species (36.43%) and/or aneuploidy (37 species). Various meiotic abnormalities were observed in the majority of the species, causing pollen sterility and pollen grains of variable sizes. We are of the opinion that harsh climatic conditions have caused various meiotic abnormalities in the majority of the plants, which has affected the genetic constitution and viability of male gametes.     

A biosystematic study of Pacific Northwestern blue-eyed grasses (Sisyrinchium,Iridaceae)

Thirteen species of blue-eyed grasses had been described for the Pacific Northwest prior to this study. Contemporary taxonomic treatments vary; some authors recognize several of the taxa as valid species, others recognize only one highly variable, widely distributed species. Work has been directed to achieve an understanding of the biological integrity of all previously described species within the northwest. Living plants from natural populations were utilized in controlled artificial hybridization experiments, analysis of breeding systems, and cytological investigations. Hybrids of intraand interspecific crosses were examined for pollen fertility, and investigated cytologically for meiotic behavior. Eight genetically compatible groups are indicated from these experiments. Additional information gained from cytological analysis, breeding systems, ecology, distribution, and morphological studies substantiates the recognition of each genetically compatible group at the specific level, including the new species,S. hitchcockii, from southern Oregon. The following taxa are recognized for the Pacific Northwest: tetraploids (n = 16)S. bellum S. Wats.,S. halophilum Greene,S. septentrionale E. P. Bicknell; octoploids (n = 32)S. idahoense E. P. Bicknell (including the vars.segetum,macounii, andoccidentale), andS. hitchcockii D. Henderson; duodecaploids (n = 48)S. idahoense E. P. Bicknell var.idahoense, S. littorale Greene,S. montanum Greene, andS. sarmentosum Suksd. ex Greene.     

Chromosome observations on some eastern North American Eleocharis (Cyperaceae)

Chromosome numbers are reported forEleocharis obtusa var.ellipsoidalis (2n = 10),E. obtusa var.peasei (2n =10),E. engelmannii (2n =10),E. olivacea f.olivacea (2n = 20),E. olivacea f.reductiseta (2n = 20),E. flavescens (2n = 30),E. tenuis var.verrucosa (2n = 20),E. tenuis var.tenuis (2n = 24),E. tenuis var.pseudoptera (2n = 39), a possible hybrid betweenE. tenuis var.pseudoptera and var.tenuis (2n = ca. 34 & 68),E. intermedia (2n = 22),E. tuberculosa (2n = 30),E. smallii (2n = 36), andE. ambigens (2n = 46). Noticeable chromosome size differences inE. tenuis, E. smallii, andE. ambigens are consistent with size differences previously reported by other authors. Variable meiotic pairing configurations were observed inE. flavescens, E. intermedia, andE. tenuis. Chromosome data help verify taxonomic relationships of some taxa and indicate the need for further investigation of others.     

Cytological studies of Brassicaceae Burn. (Cruciferae Juss.) from Western Himalayas

Cytological studies have been carried out on 12 species of Brassicaceae Burn. on population basis from different geographical areas of Kashmir and Himachal Pradesh in the Western Himalayas. Variable chromosome reports for Barbaraea intermedia (n = 16), Cardamine loxostemonoides (n = 8), Nasturtium officinale (n = 8), Sisymbrium orientale (n = 14) on world-wide basis have been added to the previous reports of these species. The chromosome numbers in seven species as Barbaraea intermedia (n = 8), B. vulgaris (n = 8), Capsella bursa-pastoris (n = 8), Descuriania Sophia (n = 10), Rorippa islandica (n = 8), Sisymbrium strictum (n = 7) and Thlaspi alpestre (n = 7) have been worked out for the first time from India. The meiotic course in the populations of seven species such as Barbaraea intermedia, Capsella bursa-pastoris, Coronopus didymus, Descuriania sophia, Nasturtium officinale, Sisymbrium orientale and S. strictum varies from normal to abnormal while all the populations of two species Barbaraea vulgaris and Sisymbrium irio show abnormal meiotic course. Meiotic abnormalities are in the form of cytomixis, chromosomal stickiness, unoriented bivalents, inter-bivalent connections, formation of laggards and bridges, all resulting into abnormal microsporogenesis. Heterogenous sized fertile pollen grains and reduced reproductive potentialities have invariably been observed in all the meiotically abnormal populations. However, the meiotic course in all the populations of Cardamine loxostemonoides, Rorippa islandica and Thalspi alpestre is found to be normal with high pollen fertility.     

CHROMOSOME NUMBERS IN BROMELIACEAE

Eighty-three chromosome counts are reported for 72 taxa of the Bromeliaceae. Fifty-eight of these counts are the first known chromosome number reports for their respective taxa. A model of chromosomal evolution in the Bromeliaceae (n = 25) is presented. The model is parsimonious and consistent with existing data on meiotic chromosome numbers within the family and in the closely related Velloziaceae (n = 9). Two hypothesized paleodiploids (n = 8 and n = 9) hybridized to form a tetraploid that in turn hybridized with the n = 8 lineage. The resultant n = 25 is the extant base number for the family. Two alternative hypotheses could explain the unique extant base number (n = 17) for Cryptanthus: 1) Cryptanthus represents the paleotetraploid level, i.e., prior to the second round of hybridization, or 2) the lower number represents the result of a more recent series of aneuploid reductions from n = 25. Given the existence of intergeneric hybrids involving Cryptanthus, aneuploid reduction is the more likely interpretation.     

Chromosomes in a hybrid zone of Israeli mole rars (Spalax, Radentia)

Chromosomal novelties and the level of meiotic and mitotic abnormalities were studied in a hybrid zone between two chromosomally differentiated Spalax cytotypes of 2n = 58 and 2n = 52. These cytotypes differ by five Rb fusions, four centromeric shifts accompanied by heterochromatin deletion, one paracentric inversion, and the Y-chromosome reorganization. Among 149 specimens studied, 82 were hybrids with 64 different karyotypes ranging in diploid numbers from 2n = 50 to 2n = 60. Nine hybrid specimens were mosaics for the chromosome numbers due to occurrence of cell lines with different Robertsonian chromosome arrangements, and six specimens possessed variable number of B-chromosomes. Mosaicism of B-chromosomes was found also in meiotic cells however chromatid breaks and abnormal chromosome pairing during meiosis occurred very rarely. All these results imply some local genomic instability resulting in the spontaneous process of reversible Rb fusions.     

Cytological studies of Angiosperms (174 species) from District Kangra,Himachal Pradesh (India)

During the present study, 360 populations of 174 species belonging to 82 genera and 23 families of dicots have been cytologically worked out from different localities of District Kangra (Himachal Pradesh) between 550 and 3,800 m altitude. As many as 10 species including Berberis ceratophylla (2n = 28), Caltha alba (2n = 32), Corydalis meifolia (2n = 16), C. thyrsiflora (2n = 16), Impatiens reidii (2n = 14), Indigofera hamiltonii (2n = 16), Potentilla thomsonii (2n = 14), Sedum trifidum (2n = 36), Stellaria semivestita (2n = 26) and Viola canescens (2n = 12) have been cytologically worked out for the first time at world level. New intraspecific diploid cytotypes have been recorded in 11 species while new intraspecific tetraploid cytotypes are noticed in 15 species. B-chromosomes have also been reported in 3 species viz. Anemone obtusiloba, Clematis grata and Ranunculus diffusus for the first time at world level. The species of the area are active state of evolution, depicting heterogeneity in chromosome numbers involving polyploidy (48 species, 28.18 %) as well as irregular meiotic behavior. The meiotic abnormalities have been witnessed in 69 species (39.65 %) showing different types of irregularities such as cytomixis, interbivalant connections, unoriented bivalents, chromatin stickiness, chromosomal laggards and bridges as well as abnormal microsprogenesis. All these meiotic abnormalities lead to reduced pollen fertility and formation of variable sized pollen grains in most of these species.     

Diverse chromosome complements in the functional gametes of interspecific hybrids of MT- and A-karyotype Lycoris spp.

The karyotype and numeric changes in chromosomes among taxa of Lycoris (spider lilies) have been attributed to whole-arm rearrangements; however, the history of karyotype evolution of Lycoris is still ambiguous. In the natural habitat, one-third of Lycoris taxa are interspecific hybrids that are mainly sterile and extremely diverse in morphologies. Lycoris are geophytes with the reproductive stage initiated inside the bulbs during the storage period, which brings some inconveniences in collecting meiotic materials for studying chromosome pairing. The partial fertility of an artificial F1 interspecific hybrid between L. aurea (2n = 14) and L. radiata (2n = 22) provides an alternative option for tracing the meiotic process in F1 hybrids. The chromosome compositions of those functional gametes generated by the F1 hybrid could be recovered according to the chromosome complements of backcross progenies. We perform genomic in situ hybridization (GISH) analysis on somatic chromosomes of 34 BC1 plants (2n = 14–22) to reveal chromosomal divergences in number and composition of those functional gametes. GISH results also indicated a high homology between the MT- and A-genomes of Lycoris, reflecting on the partial fertility and frequently homoeologous recombination at meiosis of the F1 interspecific hybrids. The diverse chromosome complements and recombinant patterns presented in these functional gametes suggested that interspecific hybridization is an important force in driving diversification among Lycoris species. We suggest that the MT-karyotype genome may be the ancestral type in Lycoris, and some other chromosomal rearrangements in addition to centromeric fission may have played roles in the karyotype evolution of Lycoris.     

Cytology of five species of subfamily Papaveroideae from the Western Himalayas

During the present course, population-based meiotic studies were carried out on five species of subfamily Papaveroideae from selected localities of Kashmir and Himachal Pradesh in the Western Himalayas (India). Varied intraspecific chromosome counts were reported for the first time in Argemone mexicana and Meconopsis latifolia, both existing on 2n?=?2x?=?14. The x?=?7, confirmed for the first time from the newly found diploid cytotype, is suggested to be the primary chromosomal basic number for the Meconopsis. Furthermore, meiotic course was noted to be normal in Argemone ochroleuca, it varied from normal to abnormal in the populations of A. mexicana and Papaver dubium whereas it was invariably found to be abnormal in all the populations of Meconopsis aculeata and M. latifolia. These anomalous taxa were marked with meiotic abnormalities in the form of cytomixis, chromosomal stickiness, unoriented bivalents, formation of laggards and bridges resulting in abnormal microsporogenesis, and production of heterogeneous-sized fertile pollen grains along with reduced pollen fertility.     

TAXONOMIC SIGNIFICANCE OF CHROMOSOME OBSERVATIONS IN CARIBBEAN SPECIES OF LANTANA (VERBENACEAE)

Chromosome numbers and, in most cases, meiotic configurations are provided for 12 taxa and 5 morphological intermediates of Lantana collected in the Bahamas, Dominican Republic, Florida, the Lesser Antilles, Puerto Rico, and Texas. Reported for the first time are Lantana bahamensis, n = 11; L. microcephala, n = 12; L. leonardiorum, n = 11; L. odorata, n = 12; L. reticulata, n = 24; L. subcordata, n = 11; L. urticifolia, n = 11, 22. Numbers differing from previous reports were obtained for L. involucrata, n = 12, 24, and L. trifolia, n = 27. Triploids indicate the natural occurrence of hybridization between diploid and tetraploid taxa. Bivalents are formed regularly, except in the triploids and in morphologically intermediate tetraploids. These reports confirm that Lantana is based on at least two numbers, x = 11 and 12, and that the genus comprises polyploid complexes in each of these basic lines. The polyploids are weedier and more widely distributed than are the diploids. Chromosome numbers and configurations aid in the delimitation of diploid foundation species and in the recognition of naturalized hybrids.     

New chromosome numbers, meiotic behaviour and pollen fertility in American taxa of Lupinus (Leguminosae): contributions to taxonomic and evolutionary studies

Original chromosome determinations are presented for 20 American Lupinus taxa, including, for the first time, unifoliolate species, together with first data on meiotic behaviour and pollen fertility for some South American species. Most of the Brazilian multifoliolate L. lanatus, L. rubriflorus, L. multiflorus, L. paranensis, L. bracteolaris and L. reitzii and unifoliolate L. crotalarioides, L. guaraniticus and L. velutinus accessions analysed presented regular chromosome pairing. Meiotic indexes and estimations of pollen viability were higher than 90% for all species and accessions analysed, reflecting the generally regular meiotic behaviour of these plants. Chromosome numbers were determined for the first time for the eastern South‐American species L. guaraniticus, L. crotalarioides, L. paranensis, L. paraguariensis and L. velutinus (n = 18 or 2n = 36) and for the Andean L. ballianus, L. eanophyllus, L. huaronensis, L. semperflorens, plus another eight taxa (2n = 48) from Peru and Bolivia, and L. bandelierae (2n = 36) from Bolivia. Chromosome numbers were confirmed for L. lanatus, L. rubriflorus (2n = 36), L. bracteolaris (2n = 34) and L. microphyllus (2n = 48). In the three accessions of the North American unifoliolate species, L. cumulicola and L. villosus, a chromosome number (2n = 52) previously unknown among American taxa was found. The results of the study, plus published data, support the suggestions that south‐eastern South American species are a group cytologically differentiated from the Andean as well as from most other American ones, and that the Brazilian and the North American unifoliolate Lupinus had independent origins. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society, 2006, 150 , 229–240.     

Chromosome numbers in Heterotheca,including Chrysopsis (Compositae: Astereae), with Phylogenetic interpretations

A summation of both previously reported and original data on chromosome numbers is presented for species ofHeterotheca sens. lat. Chromosome numbers are listed for 24 taxa, including 20 different species. Chromosome numbers for the genus aren = 4, 5, 9, 12, and 18. The most common and possibly basic number for the genus isn = 9, with then = 18 taxa considered to be tetraploids, and those withn = 4 and 5 as probable aneuploid derivatives ; alternativelyn = 4 and 5 could be considered the basic numbers withn = 9 the result of polyploidy. Several nomenclatural changes have been made including the following new combinations:Heterotheca bolanderi (Gray) Harms,H. fastigiata (Greene) Harms, andH. villosa var.hispida (Hook.) Harms.     

Chromosome numbers and taxonomic notes in the genus Nama (Hydrophyllaceae)

Chromosome numbers are reported for 48 collections representing 15 species and three varieties ofNama. Counts for 10 taxa are initial reports, all being diploid withn = 7. Diploid counts forN. jamaicense (n = 7), previously known only as tetraploid, are also reported. Comments on the taxonomic relationships of selected taxa are included.     

Chromosome number variation and polyploidy in the genus Echinocereus (Cactaceae)

Analyses of meiotic and mitotic chromosomes were undertaken in 16 taxa of Echinocereus belonging to 12 species and all seven taxonomic sections (sensu Taylor). Chromosome numbers are reported for the first time for eight taxa, and previously published chromosome counts are confirmed for the remaining eight. Both diploid and polyploid counts were obtained. Eleven (69%) of the taxa surveyed were diploid (2n = 22); the five varieties of E. engelmannii were polyploid (2n = 44). Overall, chromosome counts are available for 23 of the 48 proposed species (sensu Taylor). Of these, 19 (82%) are diploid, and four (18%) are polyploid. Polyploid cytotypes are most common in the primitive sections, e.g., sections Erecti and Triglochidiatus, which suggests that polyploidy is probably a derived condition in Echinocereus. Polyploid taxa range from medium to high latitudes and elevations relative to the overall distribution of the genus. Polyploidy, hybridization, and cryptic chromosomal rearrangements are thought to be the major causes of the speciation events of the genus.     

Hybridization and evolution in Picradeniopsis (Compositae)

The predominantly allopatric species of the genusPicradeniopsis, P. oppositifolia andP. woodhousei, are distinct in morphological, in phenolic and terpeniod chemical, and in cytological aspects (n = 24 andn = 12, respectively). In an area of sympatry in northeastern New Mexico, interbreeding occurs frequently with the production of morphologically intermediate hybrids. Morphological and phenolic chemical data from 191 plants in 40 isolated parental populations and from 91 plants in four hybrid populations are of limited value in determining the nature of this hybridization, but meiotic configurations of 12_II and 12_I and low pollen viabilities of 1–11% in the hybrids indicate that they are all of the F₁ generation (with one possible backcross). The absence of observed introgression, and therefore the absence of gene flow between the two taxa, strengthens the case for taxonomic recognition of two species in the genus. Comparisons of the morphology, phenolic and terpenoid chemistry, and cytology of parents and F₁ hybrids suggest that the tetraploid,P. oppositifolia, has arisen by allopolyploidy from a cross betweenP. woodhousei and an unknown diploid species. An extrapolated morphological and chemical reconstruction of this putative diploid parent is advanced.     

Chromosome number and secondary chromosomal associations in wild populations of Geranium pratense L. from the cold deserts of Lahaul-Spiti (India)

In this work we studied the meiotic chromosome number and details of secondary chromosomal associations recorded for the first time in Geranium pratense L. from the alpine environments in the cold deserts of Lahaul-Spiti (India). All the presently studied individuals of the species existed at 4x level (x = 14). The present chromosome count of n = 28 in the species adds a new cytotype to the already existing diploid chromosome count of 2n = 28 from the Eastern Himalayas and outside of India. Out of the six accessions scored presently four showed normal meiotic course. However, two accessions investigated from Mud, 3800 m and Koksar, 3140 m depicted abnormal meiotic course due to the presence of multivalents and univalents, and secondary associations of bivalents/chromosomes. The secondary chromosomal associations in the species existed among bivalents/chromosomes were noticed in the PMCs at prophase-I (diakinesis) and persisted till the separation of sister chromatids at M-II. The variation in the number of bivalents/chromosomes involved in the secondary associations at M-I (2–8) and A-I/M-II (2–12) has also been recorded. The occurrence of such secondary associations of bivalents/chromosomes in G. pratense which existed at 4x level indicated the secondary polyploid nature of the species.     

Meiotic configuration and chromosome number in some Iranian species of Elymus L. and Agropyron Gaertner (Poaceae: Triticeae)

Chromosome numbers and analyses of meiotic metaphase I are reported for the following taxa: Agropyron cristatum subsp. incanum (2n= 42), A. cristatum subsp. pecttnatum (2n=28 – 33), Elymus elongatus subsp. ponticus (2n= 69, 70), E. hispidus var. hispidus (2n= 41 43), var. podperae (2n= 42) and var. villosus (2n= 41, 42), E. libanoticus (2n= 14), E. pertenuis (2n= 28, 28+1B), E. repens (2n= 42), E. transhyrcanus (2n= 40–42), E. hispidus var. villosus x E. cf. repens (2n= 42). Chromosome numbers only are reported for the following taxa: E. gentri (2n= 41, 42), E. nodosus subsp. dorudicus (2n= 28), and E. elongatiformis (2n= 56, 57). The haploid genomic constitution SP is reported for Elymus pertenuis. Variable chromosome numbers (2n= 28–32) were observed in the meiotic metaphase I within single anthers of Agropyron cristatum subsp. pectinatum, and the supernumerary chromosomes in this taxon are assumed to have originated from crosses with hexaploids. Partial elimination of these supernumerary chromosomes probably occurs during archesporial mitotic divisions or at an early stage in the meiotic cycle. A hybrid, morphologically intermediate between E. hispidus and E. repens, was obtained from a seed of E. hispidus collected in the field. The meiotic metaphase I configuration in this E. hispidus hybrid suggests that the pollen parent may itself be a hybrid or hybrid derivative of E. repens x E. hispidus.