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1.
The present work includes detailed male meiotic studies on 46 species of grasses falling into 59 accessions from different localities of Parvati Valley in Kullu district of Himachal Pradesh in the altitudinal range of 1,100 to 2,750 m. All the species have been studied cytologically for the first time from the study area. The meiotic chromosome count of n = 14 for Calamagrostis emodensis is the first ever chromosome report. Three species, namely Agrostis alba (n = 21), Avena byzantina (n = 21) and Bromus inermis (n = 14) have been studied cytologically for the first time from India. New intraspecific diploid/polyploid cytotypes have been reported for Arthraxon serrulatus (2n = 4x = 32), Iseilema laxum (2n = 12x = 60), Digitaria albudens (2n = 8x = 72), Festuca kashmiriana (2n = 2x = 14) and Stipa orientalis (2n = 2x = 20). The existence of variable number of B-chromosomes (2n = 60 + 0-5B) has been reported for the first time in the 12x cytotype of Iseilema laxum. Secondary associations of chromosomes in the tetraploid cytotype of Cymbopogon martini (n = 20) indicated its secondary polyploid nature. As many as 18 species showed various meiotic anomalies such as the phenomenon of cytomixis involving inter PMC migration of chromatin material, chromatin stickiness, interbivalent connections, abnormal spindle activity, presence of bridges and laggards during anaphases and telophases and abnormal sporads. These meiotic abnormalities consequently yielded sterile and heterogeneous-sized fertile pollen grains. The polyploidy and aneuploidy have played an active role in the evolution of grasses.  相似文献   

2.
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.  相似文献   

3.
Detailed male meiosis, critical morphological observations and distribution pattern of diploid as well as tetraploid cytotypes of the Western Himalayan species, Bupleurum lanceolatum have been evaluated at present. A diploid (n = 8) cytotype is reported from Kashmir, whereas, both diploid (n = 8) and tetraploid (n = 16) cytotypes are available from two districts Kangra and Sirmaur of Himachal Pradesh. Out of these, the tetraploid cytotype makes new addition for the species on a worldwide basis. As per behavior, a tetraploid cytotype is characterized by abnormal meiosis leading to high pollen sterility and size variation of the pollen grains. Morphologically, tetraploids are noted to be luxuriant in comparison to the diploids.  相似文献   

4.
Silene vulgaris is an important ethnobotanical species, but so far no thorough meiotic analysis has been performed, despite its wide occurrence in temperate and alpine Himalayas, this prompted us to undertake present study. We investigated original meiotic chromosome number and effect of cytomixis on meiotic course, microsporogenesis and pollen grain size and fertility. The paper also summarizes the previously published chromosome counts in the species and cytogeography of 2x and 4x cytotypes in the Indian Himalayas and elsewhere. Meiocytes preparations were made through standard squashed technique in 1 % acetocarmine. Two ploidy levels have been determined during the cytomorphological surveys, diploid (2n = 2x = 24) and tetraploid (2n = 4x = 48). Most of the presently scored populations were found to be diploid (2n = 2x = 24). Morphologically 2x and 4x individuals were indistinguishable from each other. Meiosis was perfectly normal in 4x cytotype. However, some of the 2x plants showed the phenomenon of cytomixis and associated meiotic abnormalities. Consequent to cytomixis, hypo-, hyperploid and enucleated pollen mother cells (PMCs) were resulted. Such PMCs combined with other meiotic abnormalities yielded sterile and variable sized pollen grains. On the basis of overall information, it is clear that 2x cytotype is the most widely distributed cytotype in the Indian Himalayas as well as elsewhere. On the other hand, the 4x cytotype seems to be less frequently present in the Indian Himalayas and outside of India.  相似文献   

5.
The genus Saussurea comprises many species with highly medicinal, religious or other economical values. The chromosome number in the genus ranges from 2n = 24 to 108, based on x = 12, 13, 16, or 17, but the primary base number is still not clear. The present meiotic study cover 8 species (14 populations) of Saussurea from the Northwest Himalayas, and add new or varied cytotypes, as an attempt to solve the enigmatic cytogenetic variations in the genus. The chromosome numbers in Saussurea auriculata (n = 16) is new to the world, while S. costus (n = 17), S. jacea (n = 17) and S. roylei (n = 17) reveal the varied cytotypes at world level. Besides, S. taraxicifolia (n = 16) is a first ever report for Indian populations. The meiotic studies on different populations reveal a substantial amount of meiotic abnormalities in the form of chromosome stickiness, un-oriented bivalents, cytomixis, laggards, etc. leading to the meiocytes with less (aneuploidy) or more (polyploidy) chromosome numbers. These abnormalities may produce unreduced pollen grains and adversely affect pollen viability. The high number of these meiotic abnormalities may be responsible for the chromosome number variation in the genus.  相似文献   

6.
Despite the presence of intraspecific polyploidy (2x, 4x, 5x and 6x) in Agrimonia eupatoria, origin of these cytotypes has never been addressed adequately. The aim of the present study was to record the original chromosome counts and characterize chromosomal pairing during meiosis and microsporogenesis in the 5x cytotype, and discussing the hypothesis regarding the possible origin of polyploid cytotypes (4x, 5x and 6x) in the species. The geographical distribution pattern of cytotypes in the Indian Himalayas and elsewhere has also been analyzed. The present meiotic analysis revealed three chromosomes counts, the tetraploid (2n?=?4x?=?56), the pentaploid (2n?=?5x?=?70) and the hexaploid (2n?=?6x?=?84) cytotypes based on x?=?14. Meiotic course was perfectly normal in the 4x and 6x cytotypes resulting into high pollen fertility (94–100 %). Meiotic course in the imbalanced 5x cytotype has been found to be irregular characterized by the presence of high frequency of univalents at diakinesis and metaphase-I. Abnormal meiotic course contributed towards high pollen sterility (74–88 %). Even the apparently fertile/stained pollen grains were of irregular shape and of heterogeneous sizes. Meiotic behaviour of the 5x cytotype is like typical of allopolyploid. Individuals of 5x cytotype did not produce seeds and propagate vegetatively (root suckers) while 4x and 6x cytotypes exploited sexual (seeds) as well as vegetative means for propagation. Chromosomal pairing in pentaploid cytotype is like typical of an allopolyploid and we assume that it might have originated owing to natural inter-cytotype hybridization between 4x and 6x cytotypes in a mixed population. Analysis of geographical distribution pattern of cytotypes shows that Indian Himalayas represent the most cytotype-diverse region for A. eupatoria with the existence of all the four cytotypes (2x, 4x, 5x, 6x). This shows the dynamic nature of the species at chromosomal level in this part of the world.  相似文献   

7.
Tordyliopsis brunonis (Apiaceae) is cytologically investigated here for the first time from India. The chromosome count of 2n = 33, ascertained here, represents a new intraspecific triploid cytotype in the species, supplementing the earlier report of a diploid cytotype with 2n = 22 from Nepal Himalayas. The diploid chromosome count (n = 11) has also been found in some of the presently investigated individuals which showed perfectly normal meiosis with 100 % pollen fertility and normal seed set. However, the individuals with triploid chromosome count showed irregular meiotic behaviour and abnormal microsporogenesis resulting in high pollen sterility (56.26 %) and no seed set. The irregular meiotic behaviour in the triploid individuals is attributed to the occurrence of variable number of univalents (1–7) at diakinesis and metaphase-I. In the subsequent meiotic stages, these univalents lagged at anaphases and constituted micronuclei in sporads. The triploid plants were also observed for natural propagation and it was noticed that no seeds were set. These plants were noticed to propagate vegetatively by rootstocks. Chromosomal pairing in triploid cytotype is typical of an allopolyploid. Based on the characterization of chromosomal pairing during meiosis, we assumed that the triploid individuals are probably alloploid in nature. Hypotheses concerning the possible origin of allotriploid in T. brunonis are also discussed.  相似文献   

8.
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.  相似文献   

9.
The present paper deals with cytological studies on the population basis of 21 species belonging to 9 genera of tribe Paniceae of family Poaceae from cytologically unexplored area of Western Himalayas i.e. district Kangra of Himachal Pradesh for the assessment of genetic diversity of grass flora. On world-wide basis, the chromosome counts have been made for the first time for three species such as Brachiaria remota (n = 16), Digitaria granularis (n = 36) and Isachne albens (n = 5). Similarly, on India basis, altogether new records are made for two species such as Echinochloa cruspavonis (n = 27) and Paspalum distichum (2n = 50). A comparison of the different euploid cytotypes studied at present for Digitaria adscendens, D. setigera and Oplismenus compositus revealed significant variations in their morphology, depicting increase in some of the characters of polyploid cytotypes. The course of meiosis has been observed to be normal in all the studied populations with high pollen fertility except for two species such as Paspalum dilatatum and P. distichum marked with abnormal meiosis and reduced pollen fertility.  相似文献   

10.
At present 14 species of Potentilla L. have been cytologically worked out from different geographical areas of Kashmir and Himachal Pradesh in the Western Himalayas. New chromosome numbers in nine species—Potentilla argyrophylla (n = 14), P. atrosanguinea (n = 7, 14), P. desertorum (n = 7), P. gerardiana (n = 14), P. indica (n = 14), P. micropetala (n = 14), P. nepalensis (n = 14), P. sibbaldia (n = 14) and P. thomsonii (n = 7)—have been reported on a worldwide basis for the first time. Additional chromosomal races of polyploid cytotypes for P. argyrophylla (n = 28) and P. desertorum (n = 14) along with a diploid cytotype for P. micropetala (n = 7) plus diploid cytotypes for the five species as P. fulgens (n = 7), P. gelida (n = 7), P. kleiniana (n = 7), P. sibbaldia (n = 7) and P. sundaica (n = 7) as well as a tetraploid cytotype for P. fruticosa (n = 14) all have been cytologically worked out from India for the first time. The course of meiosis varies from normal to abnormal in different populations of the majority of the species, such as P. argyrophylla, P. atrosanguinea, P. desertorum, P. fruticosa, P. fulgens, P. gelida, P. indica, P. nepalensis, P. sibbaldia and P. sundaica, except for normal meiosis observed in P. gerardiana, P. kleiniana, P. micropetala and P. thomsonii. The anomalous taxa are 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 heterogenous-sized fertile pollen grains along with reduced pollen fertility. All the taxa with normal meiotic courses show nearly one hundred percent pollen fertility.  相似文献   

11.
Campuloclinium macrocephalum DC. is a perennial herb widely distributed in the New World and introduced in South Africa, where it is commonly called “pompom weed”. This species is considered one of the most important weeds of Brazil and one of the problematic invasive plants of South Africa. The meiotic system can be studied to assess the ability of a weed to spread, but only few studies on C. macrocephalum have been realized. In this study, we examined the meiotic behavior and pollen fertility of 14 natural populations of C. macrocephalum from Argentina and Uruguay. Meiotic analysis revealed 2 triploid (2n = 3x = 30), 11 tetraploid (2n = 4x = 40) and 1 mixed population (2n = 2x = 20, 2n = 4x = 40). Both, triploid and tetraploid specimens showed a widely variable meiotic behavior with irregular chromosome pairing showing univalents, bivalents, trivalents (in triploids) and tetravalents (in tetraploids) at diacinesis of first meiotic division. Different abnormalities were observed, such as: laggard chromosomes, chromatin bridges, and out of plate chromosomes at metaphase I. During meiosis I (prophase), some cells showed the phenomenon of cytomixis or chromatin transfer between pollen mother cells. The meiotic indexes suggest that only four populations were normally fertile (over 90 % of fertile pollen), indicating meiotically stable plants. The remaining populations share variable pollen fertility, with triploids ranging from 46.64 to 54.83 % and tetraploids varying from 3.54 to 45.30 %. We suggest that polyploidy seems to be recurrent in C. macrocephalum, promoting partial sterility of pollen grains, generating large numbers of individuals by apomixis promoting invasion of crop fields. This study presents the meiotic behavior of this weed, these could be useful for future studies of biological control in areas with no natural enemies.  相似文献   

12.
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.  相似文献   

13.
Centaurium pulchellum is an annual herb native to Europe, but introduced in South America, where it is widely used in the preparation of digestive infusions and bitter drinks. In this species, a wide variation in the aperture pattern of pollen grains was reported and has been attributed to environmental factors or irregularities at meiosis. For this reason, cytological and palynological studies have been undertaken on two different populations. The pollen grain analysis showed that some types are more frequent within each population, but the most common forms were the typical 3-colporate and 4-colporate. The cytological analysis revealed that the analyzed populations of C. pulchellum have chromosome number 2n = 36. The presence of tetravalents at meiosis strongly suggests that these populations are autotetraploid based on x = 9. The meiotic behavior showed a significant percentage of irregularities in different phases: off-plate bivalents, precocious segregation, laggard chromosomes, bridges, and cytomixis. However these irregularities are not related to the variation in the aperture pattern of pollen grains. The heteromorphism in the pollen grains observed in C. pulchellum could be a normal condition to which the species is well adapted.  相似文献   

14.
The mitotic chromosome numbers of 35 species belonging to 25 genera from East Azerbaijan Province of Iran and meiotic numbers of five species of Salicornia from different parts of Iran of family Chenopodiaceae are reported. Some of them are first reports and some are first counts from Iran. Based on a review of previously published reports, 145 species and 46 genera occurring in SW Asia have been cytologically studied either based on populations within or surrounding regions. The nomenclature and generic position of all these species are updated based on recent phylogenetic and taxonomic studies. The polyploidy percentage of 26.2 % is beyond the average known in flowering plants, which is surprising for dominant plants of saline and desert ecosystems. The polyploidy of annual plants is only 16 % and that of perennials 19 %, respectively. It was found that C4 plants represent lower polyploidy levels than C3 plants. This is correlated by the fact that large number of annuals in the area is C4 and secondly, polyploidy may constrain niche advantageous in C4 plants. However, presence of different cytotypes in the widespread species is advantageous as they can occupy different niches. The basic chromosome numbers in chenopods is x = 9 with few derived exceptions in Spinacia (x = 6), Camphorosma (x = 6) and some species of Petrosimonia (x = 8).  相似文献   

15.
Genus Helianthus comprises diploid and polyploid species. An autoallopolyploid origin has been proposed for hexaploid species but the genomic relationships remain unclear. Mitotic and meiotic studies in annual Helianthus annuus (2n = 2x = 34) and perennial Helianthus resinosus (2n = 6x = 102) as well as the F1 hybrids between both species were carried out. Chromosome counting confirmed the hybrid origin of the latter plants and their tetraploid condition. Bivalents in hybrids ranged from 12 to 28 ( $ \bar{x} $  = 20.8). Univalents, trivalents and quadrivalents were also observed. Meiotic products comprised dyads, triads and normal tetrads and pollen grains were heterogeneous in size. These observations suggest the occurrence of 2n pollen in addition to the expected n. Genomic in situ hybridization (GISH) of total H. annuus DNA on H. resinosus chromosomes rendered weak but uniform signals; similar hybridization pattern was observed using three other annual species. Hybridization with H. annuus probe performed on root tip cells of F1 H. annuus × H. resinosus hybrids revealed 17 chromosomes with a strong hybridization signal. GISH in hybrid meiocytes distinguished chromosomes from parental species and revealed autosyndetic pairing of H. resinosus chromosomes, allosyndetic pairing in bivalents, trivalents and quadrivalents, and the presence of univalents derived from parents, H. annuus and H. resinosus. Results obtained from classical and molecular cytogenetics do not support H. annuus as a direct ancestor of H. resinosus. The occurrence of allosyndetic pairing and the relatively high fertility of the F1 hybrids point to the possibility that useful genes could be transferred from H. resinosus to cultivate sunflower, although the effective rate of recombination has not been evaluated. GISH method proved effective to recognize parental chromosomes in H. annuus × H. resinosus progeny.  相似文献   

16.
Abstract

In the present study 16 populations belonging to 13 species of the genus Vernonia Schreb. were examined cytologically. In total, six different chromosome numbers, which represent three basic numbers: x = 10, x = 16 and x = 17, were found. These results include the first chromosome number reports for the following four species: V. lanifera Cristóbal & Dematt. (2n = 2x = 32), V. membranacea Gardner (2n = 2x = 34), V. salzmannii DC. (2n = 2x = 20) and V. scabrifoliata Hieron. (2n = 2x = 128). Besides, a new chromosome number was found in V. saltensis Hieron. (2n = 2x = 32), for which only tetraploid populations have been previously recorded. The data obtained in this work, along with the information available from the literature, show that the genus Vernonia in South America is heterogeneous with basic chromosome numbers that range between x = 9 and x = 19. These numbers suggest that a combination of polyploidy and aneuploidy has played an important role in the evolution of the genus.  相似文献   

17.
The genus Eigenmannia (Teleostei: Gymnotiformes), a widely distributed fish genus from the Neotropical region, presents very complex morphological patterns and many taxonomic problems. It is suggested that this genus harbors a species complex that is hard to differentiate using only morphological characteristics. As a result, many species of Eigenmannia may be currently gathered under a common name. With the objective of providing new tools for species characterization in this group, an analysis of the polymorphism of DNA inter-simple sequence repeats (ISSR), obtained by single primer amplification reaction (SPAR), combined with karyotype identification, was carried out in specimens sampled from populations of the Upper Paraná, São Francisco and Amazon river basins (Brazil). Specific ISSR patterns generated by primers (AAGC)4 and (GGAC)4 were found to characterize the ten cytotypes analyzed, even though the cytotypes 2n = 38 and 2n = 38 XX:XY, from the Upper Paraná basin, share some ISSR amplification patterns. The geographical distribution of all Eigenmannia specimens sampled was inferred, showing the cytotype 2n = 31/2n = 32 as the most frequent and largely distributed in the Upper Paraná basin. The cytotype 2n = 34 was reported for the first time in the genus Eigenmania, restricted to the São Francisco basin. Polymorphic ISSR patterns were also detected for each cytotype. Considering our results and the data reported previously in the literature, it is suggested that many of the forms of Eigenmannia herein analyzed might be regarded as different species. This work reinforces the importance of employing diverse approaches, such as molecular and cytogenetic characterization, to address taxonomic and evolutionary issues.  相似文献   

18.
Inter- and intraspecific genomic variability of 18 isolates of Veronaea botryosa originating from clinical and environmental sources was studied using amplified fragment length polymorphism (AFLP). The species was originally described from the environment, but several severe cases of disseminated infection in apparently healthy individuals have been reported worldwide. All tested strains of V. botryosa, identified on the basis of sequencing and phenotypic and physiological criteria prior to our study, were confirmed by AFLP analysis, yielding a clear separation of V. botryosa as a rather homogeneous group from related species. In vitro antifungal susceptibility testing resulted in MIC90s across all strains in increasing order posaconazole (0.25 μg/ml), itraconazole (1 μg/ml), voriconazole (4 μg/ml), terbinafine (4 μg/ml), caspofungin (8 μg/ml), anidulafungin (8 μg/ml), isavuconazole (16 μg/ml), amphotericin B (16 μg/ml), and fluconazole (32 μg/ml). Overall, the isolates showed a uniform pattern of low MICs of itraconazole and posaconazole, but high MICs for remaining agents. The echinocandins (caspofungin and anidulafungin) had no activity against V. botryosa. There was no statistically significant difference between susceptibilities of environmental (n = 11) and clinical (n = 7) isolates of V. botryosa (P > 0.05).  相似文献   

19.
The present study is part of our research project on cytomorphology of gamopetalous flora of Kashmir Himalaya, a zone with rich biodiversity. Out of 134 species of Gamopetalae meiotically investigated, chromosome numbers for 30 accessions belonging to 17 species and six families are new or varied reports. Euphrasia paucifolia (n = 22), Lactuca decipiens (n = 8), Saussurea albescens (n = 17), Saussurea roylei (n = 16), Saussurea taraxacifolia (n = 16) and Veronica deltigera (n = 8) are first cytological reports for these species. Anaphalis nepalensis (n = 28), Codonopsis rotundifolia (n = 16) and Hieracium vulgatum (n = 27) are new euploid chromosome reports for these species suggesting potential speciation through chromosomal evolution. Besides, Androsace mucronifolia (n = 10), A. sempervivoides (n = 10), Cicerbita lessertiana (n = 8), Dracocephalum nutans (n = 5), Erigeron patentisquama (n = 9), Galium pauciflorum (n = 11), Onopordum acanthium (n = 17) and Xanthium spinosum (n = 8) are the first chromosome reports to Indian accessions of the species. Out of the 17 species, 9 species (52.9 %) viz. A. nepalensis, C. lessertiana, C. rotundifolia, D. nutans, E. patentisquama, Euphrasia paucifolia, L. decipiens, O. acanthium and V. deltigera show abnormal meiosis/microsporogenesis of one or other type, thereby leading to pollen anomalies.  相似文献   

20.
Ixeridium dentatum (I. dentatum; family Compositae) forms a complex species through intraspecific differentiation. In this study, intraspecific taxa of I. dentatum were analyzed by counting chromosome numbers, sequencing internal transcribed spacer (ITS), and detecting amplified fragment length polymorphisms (AFLP) to explore phylogenetic relationships within I. dentatum. Analysis of ploidy levels showed that I. dentatum subsp. kitayamense and subsp. nipponicum were diploid (2n = 2x = 14), I. dentatum subsp. kimuranum was tetraploid (2n = 4x = 28), and other intraspecific taxa of I. dentatum were triploid (2n = 3x = 21). The ITS sequences contained only 13 variable sites (2.7 %) among intraspecific taxa, suggesting that the I. dentatum complex originated by autoploidy. Our AFLP-based analysis separated these taxa into five groups: (1) I. dentatum subsp. kimuranum and subsp. kitayamense; (2) subsp. nipponicum and var. albiflorum; (3) two types of subsp. dentatum and f. atropurpureum; (4) f. amplifolium; (5) subsp. ozense and new taxa, which were discovered in this study. The identified clusters significantly differed from morphological classifications. For example, morphologically similar variety and forms of I. dentatum subsp. nipponicum were separated into different groups. Taken together with the ploidy data, this study proposes a possible evolutionary history generating the current taxonomic combinations of the I. dentatum complex. The proposed model suggests that diverse taxa recently emerged during migration to lowlands.  相似文献   

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