Triploidization plays an important role in aquaculture and surrogate technologies. In this study, we induced triploidy in the matrinxã fish (Brycon amazonicus) using a heat-shock technique. Embryos at 2 min post fertilization (mpf) were heat shocked at 38°C, 40°C, or 42°C for 2 min. Untreated, intact embryos were used as a control. Survival rates during early development were monitored and ploidy status was confirmed using flow cytometry and nuclear diameter analysis of erythrocytes. The hatching rate reduced with heat-shock treatment, and heat-shock treatments at 42°C resulted in no hatching events. Optimal results were obtained at 40°C with 95% of larvae exhibiting triploidy. Therefore, we report that heat-shock treatments of embryos (2 mpf) at 40°C for 2 min is an effective way to induce triploid individuals in B. amazonicus.

Triploid and pentaploid breeding is of great importance in agricultural production, but it is not always easy to obtain double ploidy parents. However, in fishes, chromosome ploidy is diversiform, which may provide natural parental resources for triploid and pentaploid breeding. Both tetraploid and hexaploid exist in Schizothorax fishes, which were thought to belong to different subfamilies with tetraploid Percocypris fishes in morphology, but they are sister genera in molecule. Fortunately, the pentaploid hybrid fishes have been successfully obtained by hybridization of Schizothorax wangchiachii (♀, 2n = 6X = 148) × Percocypris pingi (♂, 2n = 4X = 98). To understand the genetic and morphological difference among the hybrid fishes and their parents, four methods were used in this study: morphology, karyotype, red blood cell (RBC) DNA content determination and inter-simple sequence repeat (ISSR). In morphology, the hybrid fishes were steady, and between their parents with no obvious preference. The chromosome numbers of P. pingi have been reported as 2n = 4X = 98. In this study, the karyotype of S. wangchiachii was 2n = 6X = 148 = 36m + 34sm + 12st + 66t, while that the hybrid fishes was 2n = 5X = 123 = 39m + 28sm + 5st + 51t. Similarly, the RBC DNA content of the hybrid fishes was intermediate among their parents. In ISSR, the within-group genetic diversity of hybrid fishes was higher than that of their parents. Moreover, the genetic distance of hybrid fishes between P. pingi and S.wangchiachii was closely related to that of their parental ploidy, suggesting that parental genetic material stably coexisted in the hybrid fishes. This is the first report to show a stable pentaploid F1 hybrids produced by hybridization of a hexaploid and a tetraploid in aquaculture.

In this study, polyploidy level was determined by flow cytometry analysis. The effect of polyploidy by colchicine treatment was examined on the growth parameters, malondealdehyde (MDA), as well as activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in response to different levels of salinity in Dunaliella salina. The results of algal growth indicated that 3 M NaCl was the optimal concentration of salt, since the highest enhancement in fresh and dry weight, chlorophyll and carotenoids, soluble sugar, glycerol, protein and starch content was observed in comparison to other concentrations. The amount of these metabolites declined in the concentrations under optimum salinity. The least and highest amounts of MDA were observed at 1 and 4 M NaCl respectively. Polyploidy in optimum concentration of salt, caused further increment of the above growth parameters. In relation to this, in most cases, treatment of 0.1% colchicine was most effective. The beneficial effects of polyploidy in non-optimal conditions were also found in some parameters such as biomass, chlorophyll, carotenoids, proteins and starch. Furthermore, the activity of antioxidant enzymes CAT, SOD and POD showed a positive significant correlation with salt stress and these were maximized at 4 M NaCl. Polyploidy (especially colchicine 0.1%) affected activity of these antioxidant enzymes in some concentrations of salt. Overall, our results suggest that the microalgae has significantly different responses to salt stress based on ploidy levels.

In fish, many factors can affect reproduction during in vitro fertilization, therefore determination of the factors that affect affecting gamete quality is needed. However, few studies have focused on gamete quality and the ploidy status. This study was conducted to elucidate whether oocyte storage can affect ploidy status, survival, and embryo viability in the characid species Astyanax altiparanae. Oocytes were stored in Dulbecco's phosphate-buffered saline (PBS) at 26°C, then aliquots were fertilized immediately after extrusion (control) and also after 60, 120, 180, and 240 min of storage. Fertilization and hatching rates were measured, and the developmental stages were analyzed at each stage before describing the main abnormalities. Ploidy status was analyzed by flow cytometry and blood smear. In the control group, 100% of the samples were diploid. After treatment for 60 min, 95.56 ± 4.44% samples were diploid and 4.44 ± 4.44% were triploid. After 120 min, 94.44 ± 9.62% of the samples was diploid and 5.56 ± 5.56% were triploid; 100% of the samples were diploid after 180 min and, after 240 min, there was no survival. In other treatments, the highest percentage of hatching was after 60 min (88.93 ± 5.15%; P = 0.015), and treatment with 180 min storage resulted in the highest percentage of abnormal larvae (95.76 ± 12.67%; P = 0.012). These results show that oocyte storage can affect ploidy status and may be an interesting parameter for analysis in studies on chromosome set manipulation and micromanipulation.

Soybean is a major crop cultivated in Brazil, and acetolactate synthase (ALS)-inhibiting herbicides are widely used to control weeds in this crop. The continuous use of these ALS-inhibiting herbicides has led to the evolution of herbicide-resistant weeds worldwide. Greater beggarticks is a polyploid species and one of the most troublesome weeds in soybean production since the discovery of ALS-resistant biotypes in 1996. To confirm and characterize the resistance of greater beggarticks to ALS inhibitors, whole-plant bioassays and enzyme experiments were conducted. To investigate the molecular basis of resistance in greater beggarticks the ALS gene was sequenced and compared between susceptible and resistant biotypes. Our results confirmed that greater beggarticks is resistant to ALS inhibitors and also indicated it possesses at least three isoforms of the ALS gene. Analysis of the nucleotide and deduced amino acid sequences among the isoforms and between the biotypes indicated that a single point mutation, G–T, in one ALS isoform from the resistant biotype resulted in an amino acid substitution, Trp574Leu. Two additional substitutions were observed, Phe116Leu and Phe149Ser, in a second isoform of the resistant biotype, which were not yet reported in any other herbicide-resistant ALS gene; thus, their role in conferring herbicide resistance is not yet ascertained. This is the first report of ALS mutations in an important, herbicide-resistant weed species from Brazil.

Johnsongrass is a common weed of corn in Chile, which is most often controlled by nicosulfuron, an acetohydroxyacid synthase (AHAS)-inhibiting herbicide. Recurrent nicosulfuron use has resulted in selection for resistant johnsongrass biotypes. We conducted studies to determine nicosulfuron resistance levels in two johnsongrass biotypes from Chile and to investigate if this resistance was target-site mediated. Whole-plant resistance to nicosulfuron was 33 and 46 times higher in resistant (R) than in susceptible (S) plants grown from seed and rhizomes, respectively. The nicosulfuron concentrations for 50% inhibition of AHAS enzyme activity in vitro were more than 11 times higher in R than in S plants. Sequencing analysis of the AHAS coding sequence revealed a Trp-574-Leu substitution in both R biotypes. This study shows that resistance to nicosulfuron in the two R biotypes is conferred by an altered target site. We also report the first consensus sequence of the johnsongrass AHAS gene corresponding to the known mutation sites conferring resistance to AHAS-inhibiting herbicides.

Momordica charantia L. (Cucurbitaceae) is a commonly cultivated functional food plant. In the present study, karyological variation among 34 accessions of M. charantia originating from the Indian subcontinent (Bangladesh, India and Pakistan) and Thailand was evaluated. Ploidy levels ranging from diploid (2n= 22) to hexaploid (2n= 66) were observed. Hexaploidy in M. charantia is reported herein for the first time. Chromosome length ranged from 0.8 to 2.9 μm. The hexaploid accessions had submetacentric and subtelocentric chromosomes. All accessions harboured median and submedian chromosomes. Only one hexaploid accession (TOT1140) had chromosomes with subterminal centromeres. There was considerable variation in chromosome length and chromosome arm ratio.

The genus Leontopodium (Pers.) R.Br. (Asteraceae, Compositae) is economically important for both pharmaceutical and horticultural purposes. This importance, however, has not led to a good understanding of species coherence and the delimitation of species. One fundamental aspect of a good understanding of a species is how many chromosomes it has and any possible indication of polyploidy. Here we present somatic chromosome numbers for 16 Leontopodium species, of which six are new for science. The results indicate basic chromosome numbers of x = 6, 8, 9 and 11, with x = 8 being most frequent among the species examined. While obviously including several distantly related lineages, the x = 8 species have distributions that are concentrated in the centre of diversity of the genus in southwest China. We identified two ‘species-pairs’ (Leontopodium dedekensii–L. sinense and L. souliei–L. calocephalum) in which the tetraploid species has more vigorous growth, but is confined geographically to the centre of diversity. The diploid species ascend to generally higher elevations and extend more towards the Tibetan Plateau. In contrast, our data also suggest range expansions in other polyploid species, such as the hexaploid Leontopodium ochroleucum extending into the mountains of Central Asia. Deviations from x = 8 are found at the edges of the wide Eurasian distribution of the genus. These may relate to subsequent range expansions into the Himalayas, northern Asia, the Far East, and a far disjunctive expansion to the mountains of Europe. This implies an increased ability of these species to colonise mountain floras and adapt to different environmental conditions. Thus, formation of higher ploidy levels in general might be significant for a successful radiation process.

Chromosome numbers were determined in 23 accessions representing 21 species hitherto belonging to Chirita (Gesneriaceae), a genus that has recently been remodelled and split into five different genera: Damrongia, Henckelia, Liebigia, Microchirita and Primulina. The previously monotypic Primulina tabacum was also investigated. Counts for 19 species were new, two were confirmatory and two gave different numbers from previously published counts. The results here, together with previously published cytological data for the erstwhile genus Chirita, were analysed in the light of the taxonomic revision of the genus and published phylogenetic data. Chirita was originally highly heterogeneous in chromosome numbers, including seven different somatic numbers, 2n = 8, 18, 20, 28, 32, 34 and 36. Among the five remodelled genera, Henckelia was found to be as equally heterogeneous as the erstwhile Chirita, Microchirita included only two chromosome numbers, 2n = 18 and 34, the three species of Damrongia were uniform with 2n = 18, while species belonging to the extended Primulina showed only one basic number, x = 18, with 15 samples being diploid, and one being tetraploid. In the light of recent phylogenetic studies, polyploid as well as dysploid changes appear to have shaped the genomes of the newly defined genera Henckelia, Microchirita and, to a lesser degree, Primulina.

The level of liver polyploidy was compared in three groups of humans: a young group aged 20–46, an older group aged 62–68 and the oldest group aged 70–79. The most important trend showed by the data was that there is a depletion of 2N and 4N cells, accompanied by an increase in 8N and 16N cells as a function of advancing age. There was a high degree of variability in the percentage of cells in each ploidy class from one individual to the next for all age groups. For this reason, polyploidy appears to be a less effective biomarker of aging in humans than it is in experimental animals.

The Dilatata group of Paspalum is a polyploid complex native to the grasslands of temperate South America. A pentaploid apomictic biotype of P. dilatatum is a widely recognized forage grass; however, the complex includes apomictic tetra- and hexaploids along with sexual allotetraploids (P. urvillei, P. dasypleurum, P. dilatatum ssp. flavescens, and biotypes Virasoro and Vacaria of P. dilatatum) which are suspected to be hybrids between different combinations of biotypes. Fifteen primer pairs for nuclear microsatellite loci were developed from a (CA)n-enriched genomic library. A single, low stutter, robust two-step PCR profile was used for all the primer pairs. Twelve primer pairs were analysed for their variability and transferability among all the sexual biotypes of the Dilatata group and the common apomictic pentaploid. Six primer pairs amplified more than one locus, and sequence and segregation evidence suggest that the additional bands correspond to homeologous loci. No close linkage was found among the 16 loci amplified in the tetraploids. One variable chloroplast microsatellite is also reported. All loci were successfully amplified from most members of the Dilatata group and variability was recorded for all the biotypes analysed. The set of loci reported here provide highly variable markers for intra-biotypic population studies, biotype-specific markers for the analysis of hybrid apomicts and a biotype-specific chloroplast marker.

Plantago ovata is the cultivated and economically important species in the monotypic genus Plantago. P. ovata is a short-stemmed annual herb, 10–45 cm tall. The species is generally an in-breeder. The seed husk of this plant is commonly called Psyllium or Isabgol (in Hindi), which is a very effective laxative. Other usages of Isabgol are in ice cream making, cosmetics, printing and finishing. The intake of husk also reduces blood cholesterol levels. Isabgol is commercially very important as its export earns India foreign exchange worth INR 2.5 billion (US$1=44 INR). The plant is cultivated on a large scale in western India. In Gujarat, it is cultivated in about 144,000 ha of land, yielding 720 kg/ha. P. ovata has a narrow genetic base, and the lack of variability is on account of low chromosome number, small chromosome size, presence of high heterochromatin in the chromosomes, low chiasmata frequency and low recombination index. The genome size of the species is ∼500 Mb. Different breeding methods, namely selection, hybridization, induced mutations, polyploidy and tissue culture, have been used for genetic improvement of this plant. Except selections, which have led to isolation of a few varieties, the results of other methods have not been encouraging. P. ovata has about 200 wild allies, some of which are medicinally important. These wild species constitute a rich resource of important genes, which if transferred to cultivated species could revolutionize the production of Isabgol. The present paper highlights various aspects of genetic diversity, cultivation and utilization of this important medicinal plant, and suggests the prospects of genetic manipulation.

Polyploidization is often accompanied by increased cell size and conspicuous changes in secondary metabolism. Where vegetative plant organs are the source of secondary metabolites, as is the case with most medicinal plants, ploidy manipulations such as direct chromosome doubling or allopolyploidization provide a rapid means to realize enhanced production of phyto-pharmaceuticals. Supported with prospective examples, this article illustrates the potential of genomic and ploidy manipulation to enhance the resourcing of pharmaceuticals of plant origin and suggests some appropriate strategies for optimum utilization.

Oligoasthenoteratozoospermia (OAT) is defined by a combined low count < 20 × 106 sperm/ml, poor motility < 50 % forward progression or < 25 % rapid linear progression and abnormal morphology (5–8 % normal using Kruger strict criteria) and has been associated with increased levels of sperm aneuploidy. Here we report on the cytogenetic findings from three ‘spare’ embryos from a couple that were referred for ICSI because of OAT. The embryos were processed for sequential FISH in three hybridization rounds using probes for chromosomes 3, 7, 9, 13, 17, 18, 21, X and Y. Molecular cytogenetic analysis of nine chromosomes revealed that all three embryos were female polyploid. One of them was uniformly tetraploid for all chromosomes tested, while the remaining two embryos showed evidence of abnormal postzygotic segregation of chromosomes, causing the derivative blastomeres to have uneven chromosomal constitution. In one of them in particular, the non-disjoining chromosomes showed preferential segregation to the same pole, rather than randomly moving towards either pole, suggesting an abnormal spindle and causing the derivative blastomeres to have significantly uneven chromosomal constitutions. The possible scenarios leading to polyploidy and chromosomal imbalance through cytokinetic failure and subsequent abnormal centrosomal distribution are outlined.

Mitotic chromosome numbers and karyotypes of species in two sections of Lycium (Solanaceae) from the American continent were determined in 23 populations. Both species in the small South American section Schistocalyx were examined: Lycium ciliatum and three varieties of L. chilense had diploid (2n=24) as well as tetraploid (2n=48) populations. Lycium ameghinoi from the small American section Sclerocarpellum was diploid with 2n=24. The basic number x=12 for the genus was confirmed. The karyotypes of these taxa were highly symmetrical: the chromosomes were metacentric or submetacentric with the formula: 11 m + 1 sm. Microsatellites were present in chromosome pair no. 1 and were attached to the short arms. As in other Lycium taxa already investigated, karyotypic features suggest that morphological differentiation in the group has not been accompanied by karyotype divergence.

Our knowledge of cytological data published on members of the family Gesneriaceae is summarized and critically evaluated in the light of current taxonomic treatments and phylogenetic hypotheses. There are about 1000 published chromosome counts, covering 56% of the genera but only 18% of the species. In particular the New World tribes Beslerieae and Napeantheae and the Old World tribe Didymocarpeae are underexplored at generic level. In Gesneriaceae chromosome data are a valuable source of taxonomic characters. From our current knowledge of the phylogenetic relationships in the family we know that basic chromosome numbers in the New World subfamily Gesnerioideae appear to be rather conserved, but that a more complex pattern of genome evolution seems to be present among the Old World tribes. Both polyploidy and dysploid changes have played a significant role in the evolution of the family. However, the number of species for which both cytological and molecular data are available is at present too low to reach firm conclusions on ancestral basic chromosome numbers, particularly for the Old World group. To facilitate wider access to cytological data on the Gesneriaceae, a website has been developed (http://www.rbge.org.uk/rbge/web/search/index.jsp), which is introduced in this paper.

The development of techniques for production of gynogenetic, androgenetic, polyploid, and monosex progenies in common carp (Cyprinus carpio L.) is described from a chronological perspective. Gynogenetic progenies were obtained either by suppression of the second meiotic division in eggs (meiotic gynogenesis) or by suppression of the first mitotic division in haploid embryos (mitotic gynogenesis). As a rule, gynogenetic progenies of common carp were all-female, revealing female homogamety (females—XX, males—XY) in this species. Induced gynogenesis results in increased homozygosity; the rate of increase depends on the type of gynogenesis. Inbreeding coefficient (F) for one generation of meiotic gynogenesis in common carp is about 0.6, while diploids obtained by mitotic gynogenesis are homozygous for all genes (F = 1.0). Mitotic gynogenesis was used for production of clones in common carp. In androgenetic progenies of common carp, YY males were identified, that after crossing with normal females (XX) produced all-male progenies. Triploids of common carp are characterized by a significant reduction in gonad development (especially ovaries). However, the reduction in gonad development did not result in an increase of somatic growth rate of fish. The procedure for androgen treatment to induce phenotypic sex reversal in genotypic females (XX) was elaborated. All-female progenies of common carp were produced on a large scale by crossing normal females (XX) with hormonally sex-reversed males (XX). Rearing of all-female progenies in conditions when fish normally reach sexual maturity before reaching of market size increased production yield by 7–8%. In a few cases distant hybridization resulted in polyploidy of fish without application of any physical treatment. The ability of hybrid females between crucian carp (Carassius auratus) and common carp to produce diploid (with unreduced chromosome number) gametes resulted in opportunities to produce triploid and tetraploid hybrid progenies.

Examination of morphology, ploidy and interfertility in the two subspecies of the Old World Senecio flavus (Decne.) Sch. Bip. (Compositae) and the closely related New World S. mohavensis A. Gray does not support the subspecific taxonomy of S. flavus. On the basis of our results S. flavus subsp. breviflorus Kadereit is transferred to S. mohavensis as a new subspecies: S. mohavensis subsp. breviflorus (Kadereit) M. Coleman comb. nov. The new subspecies has a distribution that includes Arabia, the Middle East, Sinai, Iran, Afghanistan, Djibouti, and the Thar Desert of Pakistan. The type subspecies of S. mohavensis occurs in the Mojave and Sonoran deserts of North America, providing an unusual disjunct distribution at the species level. Separation from S. flavus is based upon differences in morphology and chromosome number. Senecio flavus is diploid (2n = 20), while both subspecies of S. mohavensis are tetraploid (2n = 40). Further support for the new taxonomic treatment is provided by the results of controlled crosses. No artificial hybrids have been generated from crosses made between the previously recognized subspecies of S. flavus, while crosses between the newly recognized subspecies of S. mohavensis have produced fertile hybrids. The fertility of the hybrids is significantly lower than the parental taxa (P<0.001), indicating partial genetic divergence since isolation. Previous studies of isozyme and cpDNA variation in all three taxa also support the new treatment. The similarity of the S. mohavensis subspecies suggests a relatively recent separation, although the amount of genetic divergence does not support a post-Colombian introduction. Given that land bridges to North America via Beringia and the North Atlantic last existed in the Oligocene, long-distance dispersal seems the most likely explanation. Natural dispersal to rather than from the New World is supported, but whether this took place in an easterly or westerly direction is unclear. The evolution of S. mohavensis remains equivocal.