Cytotaxonomical analysis of <Emphasis Type="Italic">Momordica</Emphasis> L. (Cucurbitaceae) species of Indian occurrence

Somatic chromosome number and detailed karyotype analysis were carried out in six Indian Momordica species viz. M. balsamina, M. charantia, M. cochinchinensis, M. dioica, M. sahyadrica and M. cymbalaria (syn. Luffa cymbalaria; a taxon of controversial taxonomic identity). The somatic chromosome number 2n = 22 was reconfirmed in monoecious species (M. balsamina and M. charantia). Out of four dioecious species, the chromosome number was reconfirmed in M. cochinchinensis (2n = 28), M. dioica (2n = 28) and M. subangulata subsp. renigera (2n = 56), while in M. sahyadrica (2n = 28) somatic chromosome number was reported for the first time. A new chromosome number of 2n = 18 was reported in M. cymbalaria against its previous reports of 2n = 16, 22. The karyotype analysis of all the species revealed significant numerical and structural variations of chromosomes. It was possible to distinguish chromosomes of M. cymbalaria from other Momordica species and also between monoecious and dioecious taxa of the genus. Morphology and crossability among the dioecious species was also studied. Evidence from morphology, crossability, pollen viability and chromosome synapsis suggests a segmental allopolyploid origin for M. subangulata subsp. renigera. The taxonomic status of the controversial taxon M. cymbalaria was also discussed using morphological, karyological and crossability data.     

A phylogenetic analysis of Momordica (Cucurbitaceae) in India based on karyo-morphology,nuclear DNA content and rDNA ITS1–5.8S–ITS2 sequences

The infrageneric delimitation of Momordica, a medicinally important genus of Cucurbitaceae, is ill-defined until date. Momordica chromosomes are extremely small and are difficult to stain and visualize because of the dense cytoplasmic background. We have conducted karyomorphometric analysis by EMA method in five Indian Momordica species, and the nuclear genome sizes were estimated by flow cytometry for the first time. The somatic chromosome numbers ranged from 2n = 18 to 56 in the species. We have resolved previously disputed chromosome numbers in M. cymbalaria and M. dioica as 2n = 18 (lowest) and 2n = 56, respectively. Chromosome counts in the other species were re-confirmed as 2n = 22 in M. charantia, 2n = 28 in M. cochinchinensis and 2n = 56 in M. subangulata. The largest genome size was recorded in M. cymbalaria (3.74 pg 2C⁻¹), while the smallest size (0.72 pg 2C⁻¹) was detected in M. charantia var. charantia. The nuclear genome sizes were analysed in comparison to chromosome numbers and total chromosome lengths of the species. Karyomorphometric indices showed comparable symmetric karyotypes in the species except in M. cymbalaria having tendency towards asymmetry. The UPGMA phenogram and principle component analysis based on nuclear DNA contents and karyomorphometric parameters demonstrated interspecies differences, intraspecific distinction within M. charantia varieties and highlighted distinction of M. cymbalaria. This study was further supported by the rDNA ITS sequence-based phylogenetic analysis which revealed the monophyletic origin of the Indian members of Momordica and clarified the intraspecies relationship among the studied members. As a whole, the study brought out new insights on species diversification within the genus Momordica in India and would benefit further studies on biosystematics and plant breeding programmes.

     

Cytological Studies on Monnina

Three species of Monnina have been studied cytologically for the first time. The following chromosome numbers were found, M. brachystachya n = 9 and 2n = 18; M. dictyocarpa 2n = 40; M. rusbyi n = 10 and 2n = 20. Evolutionary trends in the genus are discussed.     

A comparison of chiasma frequency and distribution between sexes in three species of grasshoppers

Chiasma frequency and distribution have been compared in both sexes of the grasshoppers Chortoicetes terminifera (n=11+X) (Oedipodinae) Parapleurus alliaceus (n=11+X) (Oedipodinae) and Chrysochraon dispar (n=8+X) (Gomphocerinae). In the last two species, chiasmata in the males are terminally localised in all except the shortest bivalents. Strict chiasma localisation was not found in the females but chiasmata were rare near to the centromere. The sexes had different autosomal mean chiasma frequencies. Cell means were: C. terminifera Males 13.07, Females 13.02; P. alliaceus Males 12.32, Females 14.47; C. dispar Males 12.56, Females 13.57. Possible mechanisms affecting the distribution of chiasmata, and the significance of the intersex and interspecies difference, are discussed.     

Comparative chiasma analysis using a computerised optical digitiser

A new computerised technique has been devised for measuring the distribution of chiasmata along diplotene bivalents. The method involves the introduction into the field of view of the microscope, of a fine light spot which can be accurately manipulated along the chromosomes of each bivalent. The data recorded include (a) the positions of the chiasmata along the bivalent in terms of their relative distances from the centromere and (b) the individual bivalent and cellular chiasma frequencies. — The method has been applied to the analysis of chiasma distribution patterns in the two known species of the genus Caledia, C. species nova 1 and C. captiva and in two chromosomal races of the latter. Statistical tests indicate that within bivalents at least 40% of the comparative distribution patterns of chiasmata between races and species are significantly different. Similar comparisons between populations within races reveal only 18% significant differences. — The observed distribution patterns of chiasmata in this genus suggest that chiasma formation is sequential from centromere to telomere. — The variation in the frequency and distribution of chiasmata between races and species suggests that the interference distances between successive chiasmata are, at least partially, independent of chiasma frequency and position. — The interracial and interspecific differences in chromosome structure are correlated with changes in chiasma pattern.     

Cytogenetic studies in Cochlearia L. (Cruciferae). The origins of C. officinalis L. and C. micacea Marshall

Genome analysis has been used to investigate the evolutionary relationships of the tetraploid species in the genus Cochlearia. The results indicate that both C. officinalis L. (2n=24) and C. micacea Marshal (2n=26) are essentially autotetraploid in origin and that C. scotica Druce is simply a morphological variant of C. officinalis. The chromosomal relationships of the tetraploids to each other and to the diploids in the genus are discussed and the possible routes for the formation of all the species from a single, 2n=12, basic taxon are given. Evidence for the existence of a genic mechanism causing C. officinalis to form only bivalents is given and the mode of evolution of such a mechanism discussed.     

Cytogenetic Status of Meloidogyne (Hypsoperine) spartinae in Relation to Other Meloidogyne Species

Four populations of Meloidogyne spartinae from the coast of North and South Carolina were identical cytogenetically. Fourteen rod-shaped chromosomes were present in oogonia and spermatogonia, whereas seven bivalents were observed in oocytes and spermatocytes. There were no distinguishable sex chromosomes. Chromosome behavior was similar to that of other Meloidogyne species. A slight deviation in morphology of prometaphase bivalents was attributed to an increase in frequency of chiasmata that may be associated with the obligatorily amphimictic reproduction of this nematode. The anatomy of the oviduct-spermatotheca region and most cytogenetic features studied suggested that M. spartinae can be regarded as a root-knot nematode. Its position in the genus Meloidogyne or Hypsoperine can be decided by taxonomists. Its small chromosome number (n = 7) compared to the larger number (n = 13-19) of other Meloidogyne species suggests that, cytologically, M. spartinae stands closer to the ancestral form from which the prescent day root-knot nematodes have evolved.     

RESURRECTION OF THE GENUS ENDOLEPIS AND CLARIFICATION OF ATRIPLEX PHYLLOSTEGIA (CHENOPODIACEAE)

The genus Endolepis was first described by Torrey in 1860 with E. suckleyi (E. dioica [Nutt.] Standley) as the only species, noting that it differed from species of Atriplex by the presence of perianth parts in the female flowers. Later, Standley described two additional species: E. covillei and E. monilifera. H. M. Hall and Clements merged Endolepis with Atriplex because they thought that the presence of perianth parts in female flowers was variable in Atriplex phyllostegia. It is now clear that this observation was erroneous; A. phyllostegia never has perianth parts in its female flowers. The plants that they examined that had female flowers with perianth parts were specimens of Endolepis covillei; only those with female flowers devoid of perianth parts were specimens of Atriplex phyllostegia. These two taxa differ by several other major attributes including differences in leaf shape, leaf anatomy, fruiting-bract size and shape, fruiting-bract appendages, and flowering habit, and therefore justify taxonomic separation. Also, because the presence of perianth parts in bracteolate female flowers is a rare attribute in the tribe Atripliceae, consistently absent in Atriplex, but always present in Endolepis, the retention of the genus Endolepis, separate from Atriplex, is deemed warranted. We propose that the genus Endolepis comprise two species, E. dioica and E. covillei. The species named E. monilifera by Standley is based on a specimen of Atriplex serenana Nels.     

Revision of the western Palaearctic Mesoleptus (Hymenoptera: Ichneumonidae)

The western Palaearctic species of the genus Mesoleptus Gravenhorst 1829 are redescribed and keys are given for their identification. Also a key for the identification of the three stilpnine genera (Atractodes, Mesoleptus, and Stilpnus) is given and the biology of the genus is discussed shortly. The following species are described as new: Mesoleptus hispanicus n. sp., M. sawoniewiczi n. sp. and M. tunisiensis n. sp. The male of Mesoleptus tobiasi Jonaitis is described for the first time. New combinations is M. incessor (Haliday). New synonyms number 143 and 34 lectotypes are chosen.     

Cytology of ten South American Libellulidae,with cytophylogenetic considerations on the genera Orthemis Hagen and Erythrodiplax Brauer (Odonata,Anisoptera)

Notes on karyotypic morphology are given for ten South American species of the dragonfly family Libellulidae that were either cytologically little known or not studied previously, viz. Dasythemis venosa (Burm.) (Brasil, n=13), Orthemis ferruginea (Fab.) (Peru, n=12), Micrathyria laevigata Calv. (Brasil, n=13), Erythrodiplax cleopatra Ris (Peru, n=13), E. connata connata (Burm.) (Chile, n=12). E. media Borror (Brasil, n=11), E. melanorubra Borror (Venezuela, n=13), Dythemis velox Hag. (Peru, n=13), Macrothemis declivata Calv. (Brasil, n=12) and M. imitans imitans Karsch (Brasil, n=13). A pair (bivalent) of m-chromosomes is present in all species. Orthemis is the only genus in the family with n=12 or a derivative of it, met with in all species. This number is considered primary rather than secondary. As seen from pronounced variations in cytogenetic structure of its members, the genus appears genetically unstable, while the low recombination indices in all species may serve a need for biological stability.The cytophylogenetic history of the connata group of Erythrodiplax is discussed.     

A cytological study ofPelargonium sect.Eumorpha (Geraniaceae)

The chromosome numbers of seven species ofPelargonium sect.Eumorpha have been determined from material of known wild origin, and karyotypic comparisons have been made. Within the section there is variation in basic chromosome number (x = 4, 8, 9, 11), variation in chromosome size, and two species have polyploid races. The three species with chromosome numbers based on x = 11 have the smallest chromosomes (1.0–1.5 µm); chromosomes are larger (1.0–3.0 µm) in the other species.P. elongatum has the lowest chromosome number in the genus (2n = 8).P. alchemilloides is exceptional in that it has four cytotypes, 2n = 16, 18, 34 and 36, and the form with 2n = 36 has large chromosomes (2.0–5.0 µm). Evidence from a synthesized hybrid suggests thatP. alchemilloides with 2n = 16 may be of polyploid origin. The three species based on x = 11 appear to be more closely related to species from other sections ofPelargonium that have the same basic chromosome number and small chromosome size, rather than to other species of sect.Eumorpha.     

Bemerkungen zur Karyologie und Systematik einiger Sippen der Gattung Vicia L

Continuing the earlier investigations of Vicia species, karyologically not examined hithero, the following taxa of th genus have been described:

• 1 Chromosome numbers reported for the first time–V. Meyeri Boiss. (2n = 14), V. pubescens (DC.) Link (2n = 14), V. graminea SM (2n = 14), V. ramuliflora (MAXIM .) OHWI (2n = 28), V. semiglabra RUPR . ex BOISS . ssp. caucasica (EKVTIM .) RADZHI (2n = 10), V. semenovii (RGL . et HERD .) FEDTSCH . (2n = 12), V. costata LDB (2n = 12), V. hajastana GROSSH . (2n = 10).
• 2 Re-investigations – V. tenuissima (M. BIEB .) SCHINZ et THELL . (2n = 14), V. benghalensis L. (2n = 14), V. lathyroides L. (2n = 12).

Brief cytological and systematical remarks are given for all the species mentioned above. Discrepancies in the literature are especially discussed (V. benghalensis, V. peregrina, V. lathyroides). Our data support the uniformity of the subgen. Ervum in regard to chromosome number (2n = 14) and primitivity of the karyotype. The finding of an advanced karyotype with 10 chromosomes (V. semiglabra) within the subgen. Cracca has been recorded for the first time. In this group a new polyploid taxon (V. ramuliflora) has been found too. The known polyploid representatives of the genus are summarized, all of which belong to perennial species of the subgen. Cracca. Most of the taxa are characterized by obviously distinct karyotypes, that is partly ture for chromosome sizes too (conspicuously long: V. hajastana, V peregrina; conspicuously shrt: V. ramuliflora, V. lathyrodies). This striking karyological differentiation seems to refer not only to the Old world species but also to the New world ones, of which V. graminea (and a strain named „V. selloi”︁) has been examined for the first time. In general the chromosome number and structure (besides the traditional morphological characters) have been proved as extremely valuable for taxonomical considerations within the genus. This is a common situation in many other plant groups too. We therefore think of further cytotaxonomical studies as especially suitable for explaning the evolution and the evolutionary mechanisms within the genus.     

A new species of freshwater turbellarian from Africa,predatory on mosquitoes: Mesostoma zariae n. sp. (Typhloplanoida)

A new species of the genus Mesostoma Ehrenberg 1935, M. zariae n.sp. is described and its relationship discussed. The new species belongs to the M. lingua species-group and is characterised by the presence of two kinds of prostate secretions and a pear-shaped penis papilla. It occurs in small standing or slowly running waters at Zaria, Nigeria. It has previously been proven (Mead 1978) that this species is predatory on the aquatic stages of mosquitoes.     

Molecular identification and genetic diversity among six Begomovirus isolates affecting cultivation of cucurbitaceous crops in Uttar Pradesh,India

Begomoviruses cause a number of serious diseases of cultivated crops and are considered as the major constraint for the cultivation of several crops all over the world. During a survey in the years 2007 and 2008, the typical symptoms of Begomovirus (yellow mosaic and yellow vein) were observed on six cucurbitaceous crops, viz. bitter gourd (Momordica charantia L.), pointed gourd (Trichosanthes dioica), pumpkin (Cucurbita pepo), pumpkin (Cucurbita maxima), sponge gourd (Luffa cylindrica) and ridged gourd (Luffa acutangula) being cultivated in northern India. Begomovirus infection was suspected due to significant infestation of whiteflies (Bemisia tabaci, the known vector of Begomoviruses) on these species. The presence of Begomovirus was detected from the total DNA extracted from six infected leaf samples of these species by polymerase chain reaction using the specific primers of a well-characterised Begomovirus. The ～800 bp amplicons of these isolates were cloned, sequenced and the data obtained were compared with each other and with sequence database available in GenBank for best sequence identities and phylogenetic relationships. Based on highest 97–99% sequence identities and closest phylogenetic relationships, four representative Begomovirus species were identified as Ageratum enation virus (from T. dioica), Squash leaf curl China virus (from C. maxima), Tomato leaf curl New Delhi virus (from M. charantia, L. cylindrica and L. acutangula) and Tomato leaf curl Palampur virus (from C. pepo). These results suggested the existence of a high genetic diversity among Begomoviruses infecting cucurbitaceous crops.     

The chiasmatic systems in populations of two spiny leaf beetles (Coleoptera,Chrysomelidae)

The number and distribution of chiasmata per cell at diakinesis has been analyzed in four populations ofDicladispa testacea (L.) and in two ofPolyconia caroli Lepr. both having 2n=16 and a 7+Xy_p male melotic formula. Most bivalents were unichiasmate and the distal chiasma position was the one most frequently encountered. One population ofDicladispa testacea could be distinguished from the remaining ones by the total number of chiasmata per cell. This intraspecific difference is discussed in relation with the degree of isolation between the four populations and other geographical characteristics.     

ON THE LIFE CYCLE,CYTOLOGY AND TAXONOMY OF CLADOPHORA CALLICOMA FROM INDIA

The present investigation deals with the cultural observations on the morphology, reproduction, life cycle, cytology and taxonomy of a freshwater Cladophora, C. callicoma (L.) Kütz, from India. There is a regular isomorphic alternation of generations between quadriflagellate zoospore-producing diploid plants and biflagellate isogamete-producing haploid plants, coupled with heterothallism in the latter. Chromosome numbers of n = 12 and 2n = 24 were determined respectively for gametophytes and sporophytes. Twelve bivalents were counted in meiosis where chiasmata varied from one to three. In light of above observations, the affinity of C. callicoma with C. glomerata, to which the former has often been assigned, has been discussed. It is proposed that the C. glomerata complex, which consists of intraspecific polyploid races, might have two distinct lines of evolution with regard to life cycle; one with forms having higher ploidy levels and lacking an alternation of generations, and the other with forms having low ploidy levels and alternation of generations.     

Chromosome association and pollen fertility of parental and interspecific hybrids of Lycopersicon esculentum X L. hirsutum and L. pennellii

Cytological studies were carried out on two wild species (L. hirsutum and L. pennellii) and the cultivated species (L. esculentum) of tomato and their F1 hybrids. Both parents and hybrids show a diploid chromosome number of 2n=24. The meiotic behaviour of the cultivated species showed a high degree of chromosome homology resulting in a high level of chiasmata frequency per bivalent. In contrast, the two wild species showed a slight increase in uniyalent frequency and a decrease in bivalent formation and chiasmata frequency. The meiotic behaviour of the hybrids showed a high level of univalents and low levels of bivalents as well as trivalents. Highly significant decreases in chiasmata frequency and increases in meiotic abnormalities, especially in the L. esculentum X L. pennellii hybrid, also were detected. The high meiotic irregularity and low chiasmata frequency recorded in the second hybrid indicated the disharmony and difference between its parental genomes and also served to predict its sterility. With regard to degree of pairing recorded in the hybrids, there is a possibility that sterility in such cases may refer to genetic factors in addition to the previously mentioned reasons. Pollen fertility showed no great difference between L. esculentum and L. hirsutum and their F1 hybrid, but a significant decrease was recorded in the L. esculentum X L. pennellii hybrid, which was clearly associated with high meiotic irregularity, low chiasmata frequency and chromosome association.     

凤仙花近缘种间核型分析与叶表皮微形态研究

为探究凤仙花近缘种植物的细胞学和微形态学方面的亲缘关系,该文选取荔波凤仙花(Impatiens liboensis)及近缘种赤水凤仙花(I.chishuiensis)和管茎凤仙花(I.tubulosa)的根尖和叶表皮为实验材料,采用体细胞染色体常规压片法和叶表皮光学显微镜观察法对凤仙花近缘种植物进行染色体及叶表皮特征研...