Polyploidy

The allohexaploid bread wheat genome consists of three closely related subgenomes (A, B, and D), but a clear understanding of their phylogenetic history has been lacking. We used genome assemblies of bread wheat and five diploid relatives to analyze genome-wide samples of gene trees, as well as to estimate evolutionary relatedness and divergence times. We show that the A and B genomes diverged from a common ancestor ~7 million years ago and that these genomes gave rise to the D genome through homoploid hybrid speciation 1 to 2 million years later. Our findings imply that the present-day bread wheat genome is a product of multiple rounds of hybrid speciation (homoploid and polyploid) and lay the foundation for a new framework for understanding the wheat genome as a multilevel phylogenetic mosaic.

Changes in polyploidization, chromatin supraorganization, and chromatin accessibility were investigated in hepatocytes collected from adult, nonobese diabetic (NOD) mice with increasing hyperglycemia and compared with adult normoglycemic controls and 56-week-old normoglycemic BALB/c mice. Our goal was to determine the changes in ploidy degrees and chromatin characteristics in mouse hepatocytes that are associated with insulin-dependent diabetes and to detect similarities in these aspects with those verified with aging, with greater accuracy than previous studies. Image analysis of Feulgen-stained nuclei revealed changes in ploidy degrees and chromatin supraorganization. Chromatin accessibility was assessed with micrococcal nuclease (MNase) digestion. Increased polyploidy was associated with increasing levels of glycemia, and this trend toward polyploidy was found even under normoglycemic conditions in NOD mice. Although high degrees of ploidy were also detected in aged BALB/c mice, the magnitude of polyploidy was not the same magnitude as that in the diabetic mice. While there was increased homogeneity of chromatin packaging with increasing polyploidy under conditions of severe hyperglycemia (and even under conditions of normoglycemia) in NOD mice, an inverse relationship was observed in aged BALB/c mice. Chromatin accessibility to MNase increased under severe hyperglycemia and advanced age, but it was much higher in the diabetic mice. In conclusion, although similarities in polyploidy were observed between the hepatocytes from increasingly hyperglycemic adult mice and those from normoglycemic aged mice, the relationship between chromatin remodeling and increases in ploidy degrees was not the same between the hepatocytes of these two groups. These findings demonstrate that strict similarities between diabetes and aging are not always true at the cellular level. This discordance is likely due to differences in the metabolic state of mouse hepatocytes during aging and diabetic conditions consequent to specificities in their gene regulatory programs.

Crocus sativus is a triploid sterile plant characterized by its long red stigmas, which produce and store significant quantities of the apocarotenoids crocetin and crocin, formed from the oxidative cleavage of zeaxanthin. Here, we investigate the accumulation and the molecular mechanisms that regulate the synthesis of these apocarotenoids during stigma development in C. sativus. We cloned the cDNAs for phytoene synthase, lycopene-b-cyclase, and bring hydroxylase from C. sativus. With the transition of yellow undeveloped to red fully developed stigmas, an accumulation of zeaxanthin was observed, accompanying the expression of CsPSY, phytoene desaturase, and CsLYCb, and the massive accumulation of CsBCH and CsZCD transcripts. We analyzed the expression of these two transcripts in relation to zeaxanthin and apocarotenoid accumulation in other Crocus species. We observed that only the relative levels of zeaxanthin in the stigma of each cultivar were correlated with the level of CsBCH transcripts. By contrast, the expression levels of CsZCD were not mirrored by changes in the apocarotenoid content, suggesting that the reaction catalyzed by the CsBCH enzyme could be the limiting step in the formation of saffron apocarotenoids in the stigma tissue. Phylogenetic analysis of the CsBCH intron sequences allowed us to determine the relationships among 19 Crocus species and to identify the closely related diploids of C. sativus. In addition, we examined the levels of the carotenoid and apocarotenoid biosynthetic genes in the triploid C. sativus and its closer relatives to determine whether the quantities of these specific mRNAs were additive or not in C. sativus. Transcript levels in saffron were clearly higher and nonadditive, suggesting that, in the triploid gene, regulatory interactions that produce novel effects on carotenoid biosynthesis genes are involved.

The first microsatellite primers were developed for Solanum centrale, a native Australian species used in the bush foods industry. Existing markers developed for other Solanum species were also amplified. Using an enrichment cloning protocol, seven novel markers were developed, and 48 existing markers from other Solanum species were tested, resulting in the characterization of a set of six highly polymorphic co-dominant loci for use in S. centrale. Microsatellite screening revealed polyploidy. Among the six highly polymorphic loci, allelic diversity ranged from 7 to 14. These markers will be useful for investigating genetic diversity and as a simple way of estimating ploidy of wild populations.

The gluten proteins from wheat, barley and rye are responsible both for celiac disease (CD) and for non-celiac gluten sensitivity, two pathologies affecting up to 6-8% of the human population worldwide. The wheat α-gliadin proteins contain three major CD immunogenic peptides: the p31-43, which induces the innate immune response; the 33-mer, formed by six overlapping copies of three highly stimulatory epitopes; and an additional DQ2.5-glia-α3 epitope which partially overlaps with the 33-mer. NGS and Sanger sequencing of α-gliadin genes from diploid and polyploid wheat provided six types of α-gliadins (named 1 to 6) with strong differences in their frequencies in diploid and polyploid wheat, and in the presence and abundance of these CD immunogenic peptides. Immunogenic variants of the p31-43 peptide were found in most of the α-gliadins. Variants of the DQ2.5-glia-α3 epitope were associated with specific types of α-gliadins. Remarkably, only Type 1 α-gliadins contained 33-mer epitopes...

Yeasts of the Saccharomyces sensu stricto species complex are able to convert sugar into ethanol and CO2 via fermentation. They have been used for thousands years by mankind for fermenting food and beverages. In the Neolithic times, fermentations were probably initiated by naturally occurring yeasts, and it is unknown when humans started to consciously add selected yeast to make beer,

This study was designed to assess the use of a computer-assisted system based on erythrocyte measurements as a possible alternative to flow cytometry for identifying triploid rainbow trout (Oncorhynchus mykiss). Blood smears were prepared from 26 triploid and 26 diploid specimens, as determined by flow cytometry after staining blood cells with propidium iodide. The cell and nucleus lengths of 10 erythrocytes were determined in each fish. This was followed by discriminatory analysis to distinguish between diploids and triploids based on their score profiles. Triploid trout showed significantly larger erythrocyte cell and nucleus measurements than their diploid counterparts (N 5 52; Po0.0001). Erythrocyte length correctly identified 100% of the fish specimens as diploid or triploid, while nucleus length was a less accurate predictor of the level of ploidy. Our findings validate the potential use of computer-assisted analysis for this purpose.

Preferential chromosome association at metaphase I has been analyzed and compared in autotetraploid cells obtained by colchicine treatment of hybrid diploid rye plants with different degrees of chromosomal divergence between homologs. The tendency to identical over homologous, but not identical, pairing preferences detected when homologous partners are contributed by less related parental lines indicates that chromosome differentiation may play an important role on preferential pairing behavior of polyploids. However, associations between more similar (identical) partners are not always favored, thus suggesting that additional factors must be considered. Other hypotheses for explaining pairing preferences in competitive situations are discussed. No clear relationship has been found between multivalent frequencies at metaphase I and chromosome differentiation between homologs or preferential pairing behavior. Therefore evolutionary divergences among related genomes should be carefull...

The study of species complexes is of particular interest to understand how evolutionary young species maintain genomic integrity. The Daphnia pulex complex has been intensively studied as it includes species that dominate freshwater environments in the Northern hemisphere and as it is the sole North American complex that shows transitions to obligate parthenogenesis. Past studies using mitochondrial markers have revealed the presence of 10 distinct lineages in the complex. This study is the first to examine genetic relationships among seven species of the complex at nuclear markers (nine microsatellite loci and one protein-coding gene). Clones belonging to the seven species of the Daphnia pulex complex were characterized at the mitochondrial NADH dehydrogenase (ND5) gene and at the Lactate dehydrogenase (LDH) locus. K-means, principal coordinate analyses and phylogenetic network analyses on the microsatellite data all separated European D. pulicaria, D. tenebrosa, North American D. pulex, D. pulicaria and their hybrids into distinct clusters. The hybrid cluster was composed of diploid and polyploid hybrids with D. pulex mitochondria and some clones with D. pulicaria mitochondria. By contrast, the phylogeny of the D. pulex complex using Rab4 was not well resolved but still showed clusters consisting mostly of D. pulex alleles and others of D. pulicaria alleles. Incomplete lineage sorting and hybridization may obscure genetic relationships at this locus. This study shows that hybridization and introgression have played an important role in the evolution of this complex.

Wheat was domesticated about 10,000 years ago and has since spread worldwide to become one of the major crops. Its adaptability to diverse environments and end uses is surprising given the diversity bottlenecks expected from recent domestication and polyploid speciation events. Wheat compensates for these bottlenecks by capturing part of the genetic diversity of its progenitors and by generating new diversity at a relatively fast pace. Frequent gene deletions and disruptions generated by a fast replacement rate of repetitive sequences are buffered by the polyploid nature of wheat, resulting in subtle dosage effects on which selection can operate.

Bukan abstrak, ini bagian dari BAB 1

Tumbuhan paku merupakan tumbuhan yang sangat mudah dijumpai disekitar kita. Sifatnya yang kosmopolit membuat tumbuhan ini dapat dijumpai diberbagai daerah meliputi ketinggian rendah (0-500 mdpl), ketinggian sedang (500-1000 mdpl), hingga tinggi ( > 1000 mdpl). Pteridophyta atau lazim juga disebut tumbuhan paku merupakan divisi tumbuhan yang memiliki kormus. Karena memiliki pembuluh (kormus) maka disebut pula cormophyta. Menurut Loveless (1989), tumbuhan paku tersebar diseluruh dunia, tetapi paling banyak tumbuh di daerah tropik yang lembab. Kurang lebih sebanyak 10000 jenis yang hidup diseluruh dunia. Pteridophyta dibagi menjadi menjadi beberapa kelas, psilopsida, lycopsida, sphenopsida, pteropsida (Moertolo, 2004).
Daerah penyebaran tumbuhan paku dipengaruhi oleh faktor lingkungan termasuk ketinggian tempat. Dalam usaha untuk membandingkan tingkat ploidi dan kaitannya dengan ketinggian, maka harus ditentukan spesies tumbuhan paku yang sering dijumpai didaerah tinggi, sedang, dan rendah. Kelompok Pteropsida  yang sering dijumpai adalah Pteris vittata, Pteris biaurita, dan Pteris ensiformis, jenis ini banyak tumbuh baik di pegunungan maupun di dataran rendah. Faktor lingkungan utama yang berpengaruh adalah suhu dan kelembapan, yang mempengaruhi tumbuhan paku pada perkembangan siklus hidup sejak germinasi spora sampai maturasi sporofit (Masahiro dan Iwatsuki,  dalam Setyawati, 2000).
Sering ditemukan adanya peristiwa poliploidi secara alami pada tumbuhan tingkat tinggi. Menurut Rodriguez (dalam Khotimah, 2002) poliploidi merupakan fenomena dimana individu memiliki lebih dari 2 genom. Peristiwa poliploidi merupakan akibat dari berbagai proses baik meiotik maupun somatik. Hal senada juga dinyatakan oleh Stace (Zubaidah, dalam Khotimah, 2002). Berdasarkan kajian literatur yang kami dapat, tumbuhan paku merupakan tumbuhan yang juga mengalami poliploidi secara alami di alam.
Kami menentukan suatu kota dimana ketinggiannya mencakup ketinggian 0 - > 1500 mdpl. Salah satu kota yang memenuhi kriteria tersebut adalah kota lumajang. Ketinggian daerah Lumajang sangat bervariasi, mulai dari 0-3676 mdpl. Jenis tanah di Lumajang, berdasarkan Peta Tanah Tinjau yang dikeluarkan Lembaga Penelitian Bogor 1966, terdiri dari alivial, regosol, andosol, mediteran, dan latosol. Secara umum keadaan pengairan di kota Lumajang cukup baik mengingat keadaan topografi yang bervariasi mulai datar sampai curam, hal tersebut menguntungkan dalam segi pengelolaan air (Anonim a, 2011).
Iklim dan curah hujan di Lumajang didasarkan sistem Schmidt dan Ferguson dimana terdapat 3 macam iklim, tipe iklim kering, agak basah, dan basah (Anonim a, 2011).
Berdasarkan paparan diatas kami melaksanakan penelitian dengan judul “Pengaruh Jenis Pteris dan Ketinggian Tempat terhadap Tingkat Ploidi Tumbuhan Paku di Daerah Lumajang”.

We present the clinical findings in a 21/2 year old girl with an unusual mosaic karyotype. Amniocentesis was performed at 35 weeks because of intrauterine growth retardation. The in situ cultures showed 47,XX,+15 in seven colonies, 69,XXX in four colonies, and in two colonies 46,XX was detected. Subcultures showed 69,XXX/47,XX,+15 with no normal cells. A small dysmorphic baby was born at term. Cytogenetic studies were performed on cord blood, amnion, and placental tissue immediately after birth and further studies on peripheral blood, bone marrow, muscle biopsy, and skin cultures at 11/2 years of age. FISH with two autosomal centromeric probes was performed on the peripheral blood sample. A normal cell line could not be seen in any postnatal tissue by either technique. The predominant cell line postnatally was 69,XXX. There were no cytogenetic polymorphisms and the parental origin of the different cell lines was not determined. Marked red cell macrocytosis of peripheral blood was noted on routine blood count. Bone marrow aspiration showed megaloblastic haemopoiesis without evidence of vitamin B12 or folate deficiency. At 21/2 years, the patient has significant developmental problems.

Individuals within a population of a sexually reproducing species will have some degree of heritable genomic variation caused by mutations, insertion/deletions (INDELS), inversions, duplications, and translocations. Such variation can be detected and screened using molecular, or genetic, markers. By defi nition, molecular markers are genetic loci that can be easily tracked and quantifi ed in a population and may be associated with a particular gene or trait of interest. This chapter will review the current major applications of molecular markers in plants.

Polyploidy, which arises through complex genetic and ecological processes, is an important mode of plant speciation. This review provides an overview of recent advances in understanding why plant polyploid species are so ubiquitous and diverse. We consider how the modern framework for understanding genetic mechanisms of speciation could be used to study allopolyploid speciation that occurs through hybrid genome doubling, that is, whole genome doubling of interspecific F1 hybrids by the union of male and female unreduced gametes. We outline genetic and ecological mechanisms that may have positive or negative impacts on the process of allopolyploid speciation through hybrid genome doubling. We also discuss the current status of studies on the underlying genetic mechanisms focusing on the wheat (Triticum and Aegilops) hybrid-specific reproductive phenomena that are well known but deserve renewed attention from an evolutionary viewpoint.

Cyprininae is the largest subfamily (>1300 species) of the family Cyprinidae and contains more polyploid species (􏰀400) than any other group of fishes. We examined the phylogenetic relationships of the Cyprininae based on extensive taxon, geographical, and genomic sampling of the taxa, using both mitochondrial and nuclear genes to address the phylogenetic challenges posed by polyploidy. Four datasets were analyzed in this study: two mitochondrial gene datasets (465 and 791 taxa, 5604 bp), a mitogenome dataset (85 taxa, 14,771 bp), and a cloned nuclear RAG1 dataset (97 taxa, 1497 bp). Based on resulting trees, the subfamily Cyprininae was subdivided into 11 tribes: Probarbini (new; Probarbus + Catlocarpio), Labeonini Bleeker, 1859 (Labeo & allies), Torini Karaman, 1971 (Tor, Labeobarbus & allies), Smiliogastrini Bleeker, 1863 (Puntius, Enteromius & allies), Poropuntiini (Poropuntius & allies), Cyprinini Rafinesque, 1815 (Cyprinus & allies), Acrossocheilini (new; Acrossocheilus & allies), Spinibarbini (new; Spinibarbus), Schizothoracini McClelland, 1842 (Schizothorax & allies), Schizopygopsini Mirza, 1991 (Schizopygopsis & allies), and Barbini Bleeker, 1859 (Barbus & allies). Phylogenetic relationships within each tribe were dis- cussed. Two or three distinct RAG1 lineages were identified for each of the following tribes Torini, Cyprinini, Spinibarbini, and Barbini, indicating their hybrid origin. The hexaploid African Labeobarbus & allies and Western Asian Capoeta are likely derived from two independent hybridization events between their respective maternal tetraploid ancestors and Cyprinion.

effects of whole genome duplications on the balance of genomic networks. See also the sister articles focusing on plants by Ashman et al. and Madlung and Wendel in this themed issue. Polyploidy is the heritable condition of possessing more than 2 complete sets of chromosomes . This condition can arise as a result of genome duplication(s) within a species (autopolyploidy), or from hybridization of 2 different species (allopolyploidy). A polyploidization event causes a dramatic change in the genome structure and cell organization. It imposes several major challenges on cell cycle processes (e.g. mitoses, meiosis), cell physiology (e.g. metabolism, growth, stoichiometry), regulation of gene expression and genome stability. This 'genome shock' of combining two, either similar or diverged, genomes can lead to a bottleneck of instability . For polyploidy to become stable, genomic reorganizations may occur. Part of the genome reorganization involves a process called 'diploidization'. This is the gradual conversion of polyploidy to diploidy through genetic changes that differentiate duplicated genes and chromosomes, and the loss of many, or most, of the duplicated genes.

† Background Biological invasions are a major ecological and socio-economic problem in many parts of the world. Despite an explosion of research in recent decades, much remains to be understood about why some species become invasive whereas others do not. Recently, polyploidy (whole genome duplication) has been proposed as an important determinant of invasiveness in plants. Genome duplication has played a major role in plant evolution and can drastically alter a plant's genetic make-up, morphology, physiology and ecology within only one or a few generations. This may allow some polyploids to succeed in strongly fluctuating environments and/or effectively colonize new habitats and, thus, increase their potential to be invasive. † Scope We synthesize current knowledge on the importance of polyploidy for the invasion (i.e. spread) of introduced plants. We first aim to elucidate general mechanisms that are involved in the success of polyploid plants and translate this to that of plant invaders. Secondly, we provide an overview of ploidal levels in selected invasive alien plants and explain how ploidy might have contributed to their success. † Conclusions Polyploidy can be an important factor in species invasion success through a combination of (1) 'pre-adaptation', whereby polyploid lineages are predisposed to conditions in the new range and, therefore, have higher survival rates and fitness in the earliest establishment phase; and (2) the possibility for subsequent adaptation due to a larger genetic diversity that may assist the 'evolution of invasiveness'. Alternatively, polyploidization may play an important role by (3) restoring sexual reproduction following hybridization or, conversely, (4) asexual reproduction in the absence of suitable mates. We, therefore, encourage invasion biologists to incorporate assessments of ploidy in their studies of invasive alien species.

The growth of 'Kyoho' (Vitis × labruscana Bailey × V. vinifera L.) grapevines grafted on colchicine-induced autotetraploids of two grape rootstocks, 'Riparia Gloire de Montpellier' ('Gloire', V. riparia Michx.), and 'Couderc 3309' ('3309', V. riparia × V. rupestris), was compared with the original diploids. Micro-propagated rootstock and 'Kyoho' grapevines were grafted in vitro and rooted. During the rooting and acclimating stage, 'Kyoho' grapevines grafted on tetraploids had much shorter shoots and internodes than those grafted on the counterpart diploids. In the nursery period in pots, 'Kyoho' grapevines grafted on each tetraploid rootstock also showed weaker growth than those grafted on the corresponding diploid rootstock. After planting in the vineyard, lateral shoot growth after primary shoot-tipping, the trunk cross-sectional area and pruned cane weight of 'Kyoho' grapevines grafted on each tetraploid rootstock were also smaller than those grafted on the corresponding diploid rootstock. The berries of 'Kyoho' grapevines grafted on tetraploids showed much deeper skin coloration than those of vines grafted on diploid rootstocks.

We look at the utility of flow cytometry in large- and small-scale population surveys of amphibians, work done to that point, and the implications for conservation projects ranging from the discovery of cryptic species to hybrid zones and toxicological impacts.

A 24-month-old female with severe physical and mental retardation is described. Peripheral lymphocytes demonstrated tetraploid/diploid mosaicism. That this does not represent an artifact in vitro was supported by the finding of buccal mucosal cells with two Barr bodies and tetraploid/diploid mosaicism in fibroblasts and bone marrow cells.

Using data gathered over a 4-year period from a large population of the A. laterale-jeffersonianum complex from Haliburton, Ontario, I examined four areas of reproductive ecology that may contribute to ecological partitioning: (1) fluctuating sex, hybrid, and ploidy ratios; (2) differential migratory response by triploid and tetraploid genomotypes; (3) ontogenetic differences among triploid and tetraploid genomotypes; and (4) genotypic differences within unisexual genomotypes. For each case I was able to reject a null hypothesis ascribing ecological equivalency to those biotypes involved. The most germane ecological differences among unisexuals were imbedded in the broad syndrome of delays in larval development, metamorphosis, and sexual maturity displayed by tetraploids. These findings parallel those reported in a large body of literature generated from laboratory studies of polyploid salamanders. Using these corresponding data, I conducted a broad review of potential developmental, physiological, and biotypic causes and consequences of the observed delays. The results indicated that several effects of polyploidy and hybridity directly influence community ecology and contribute to stable coexistence of bisexuals and unisexuals. Based on these findings, a strategic model summarizing interaction in these communities was constructed, from which testable hypotheses may be derived for future research. The findings of this study confirmed the ontological status of the biotypic distinctions (genomotype versus genotype) advanced here.

As a field naturalist, my doctoral research in plant ecology has focused on the biodiversity of open Mediterranean environments, conducted in parallel with a professional activity in a design office. This knowledge of botany, extended to the entire western Mediterranean, has subsequently allowed me to write chapters of books (monographs, identification keys, synonymic indexes, catalogs) on the flora of France and North Africa, then of the Middle East.
In collaboration with various European teams and Maghreb researchers, I started work on new lines of research (integrative systematics, biogeography and phylogeny). I diversified biological models (molluscs) and assimilated new methods (biochemistry, molecular genetics). Various endemic species have served as integrative models that we are studying at all levels, from in situ inventory and conservation, to the phylogenetic and paleo-ecological origins of endemism, works done in the context of several Ph.D. I participated and/or co-directed.
Within the research unit AMAP, I collaborated with Tela Botanica on the Pl@ntNet project (https://plantnet.org/) which continues through the Floris'Tic project (http://floristic.org/), with activities dedicated to the flora of North Africa and the Middle East. I refocused my research on descriptive botany and biodiversity cataloguing, through collaborative networking and the use of computerised information storage and taxonomic identification tools on the Mediterranean flora. I now focus on describing the unknown biodiversity in the Mediterranean hotspot, combining classical (morphological) and modern (molecular) approaches.
My research project is to continue the momentum that I initiated over the last dozen years. This project deals with biogeography, taxonomy and conservation in the service of knowledge, protection and promotion of biodiversity in the Mediterranean, particularly in the countries of the southern and eastern shores. It aims in the medium and long term to participate in the filling of the taxonomic deficit in areas of biodiversity hotspots but coldspots of knowledge, such as the Maghreb and the Mediterranean Middle East. The objective is the reappropriation, by the Maghrebian and Middle Eastern scientific corps, of a long and rich history of the biodiversity knowledge, partially interrupted for half a century, and whose historical collections of Montpellier (MPU), Paris (P), Geneva (G) or Barcelona (B) herbaria are its precious memory. The project draws its regional coherence through a natural biogeographic convergence and integrates all the disciplines from the biodiversity inventory to the decision support tools.
The project is structured around three objectives: 1) Improvement and capitalization of fundamental knowledge on Mediterranean botany in the Maghreb and the Middle East; 2) Training and assistance, in southern countries, of field teams, mixing professionals and amateurs; 3) Production of practical identification tools, classical or modern, adapted to the needs of botanists and ecologists.

incompatibilities through non-Mendelian mechanisms, fostering polyploid genome reorganization in association with the establishment of new lineages. See also sister article focusing on animals by Collares-Pereira et al., in this themed issue.

Polyploidy, hybridization and variation in mating systems are central issues for a deeper understanding of animal evolution. The Iberian species Squalius alburnoides represents an example combining all three phenomena. Previous studies showed that S. alburnoides populations are mainly composed of triploid and diploid hybrid forms (mainly females), and that the tetraploid forms are rare or absent. Both populations from the Douro drainage reveal a distinct scenario: tetraploid individuals represent 85.6-97.5% of the population, with no sex ratio bias observed. Based on the flow cytometry measurements of blood and spermatozoa cells, microsatellite loci and experimental crosses, we describe here, for the first time, two symmetric allotetraploid populations (CCAA) that resumed normal meiosis after undergoing intermediate processes of non-sexual reproduction to give rise to a new sexually reproducing polyploid species. Prezygotic (habitat selection and assortative mating) and postzygotic mechanisms (nonviable embryos) are responsible for the reproductive isolation from other forms of the S. alburnoides complex (e.g. CA, CAA). This example illustrates how hybrid polyploid complexes may lead to speciation.

Invitro screening of antimicrobial activities of some heterocystous cyanobacteria from agricultural fields in the Pattukkottai, Thanjavur District were studied. The collected cyanobacterial supernatants, ethanolic extract from biomass of 80 strains of cyanobacteria were isolated and screened against five bacteria and five fungi. Ethanolic extracts and culture supernatants of 10 strains of cyanobacteria significant antimicrobial effect. According to these results, it is concluded that strains of Anabaena species, seem to be more potential for producing antimicrobial substances than other strains. This is interesting in that the traditional method of treating a microbial infection was by administering a decoction of the cyanobacteria, whereas according to our results a bacterium is better than fungi; hence this may be more beneficial.

The Brassicaceae, including Arabidopsis thaliana and Brassica crops, is unmatched among plants in its wealth of genomic and functional molecular data and has long served as a model for understanding gene, genome, and trait evolution. However, genome information from a phylogenetic outgroup that is essential for inferring directionality of evolutionary change has been lacking. We therefore sequenced the genome of the spider flower (Tarenaya hassleriana) from the Brassicaceae sister family, the Cleomaceae. By comparative analysis of the two lineages, we show that genome evolution following ancient polyploidy and gene duplication events affect reproductively important traits. We found an ancient genome triplication in Tarenaya (Th-a) that is independent of the Brassicaceae-specific duplication (At-a) and nested Brassica (Br-a) triplication. To showcase the potential of sister lineage genome analysis, we investigated the state of floral developmental genes and show Brassica retains twice as many floral MADS (for MINICHROMOSOME MAINTENANCE1, AGAMOUS, DEFICIENS and SERUM RESPONSE FACTOR) genes as Tarenaya that likely contribute to morphological diversity in Brassica. We also performed synteny analysis of gene families that confer self-incompatibility in Brassicaceae and found that the critical SERINE RECEPTOR KINASE receptor gene is derived from a lineage-specific tandem duplication. The T. hassleriana genome will facilitate future research toward elucidating the evolutionary history of Brassicaceae genomes.

The domestication of wheat was instrumental in spawning the civilization of humankind, and it occurred through genetic mutations that gave rise to types with non-fragile rachises, soft glumes, and free-threshing seed. Wild emmer (Triticum turgidum ssp. dicoccoides), the tetraploid AB-genome progenitor of domesticated wheat has genes that confer tenacious glumes (Tg) that underwent genetic mutations to give rise to free-threshing wheat. Here, we evaluated disomic substitution lines involving chromosomes 2A and 2B of wild emmer accessions substituted for homologous chromosomes in tetraploid and hexaploid backgrounds. The results suggested that both chromosomes 2A and 2B of wild emmer possess genes that inhibit threshability. A population of recombinant inbred lines derived from the tetraploid durum wheat variety Langdon crossed with a Langdon -T. turgidum ssp. dicoccoides accession PI 481521 chromosome 2B disomic substitution line was used to develop a genetic linkage map of 2B, evaluate the genetics of threshability, and map the gene derived from PI 481521 that inhibited threshability. A 2BS linkage map comprised of 58 markers was developed, and markers delineated the gene to a 2.3 cM interval. Comparative analysis with maps containing the tenacious glume gene Tg-D1 on chromosome arm 2DS from Aegilops tauschii, the D genome progenitor of hexaploid wheat, revealed that the gene inhibiting threshability in wild emmer was homoeologous to Tg-D1 and therefore designated Tg-B1. Comparative analysis with rice and Brachypodium distachyon indicated a high level of divergence and poorly conserved colinearity, particularly near the Tg-B1 locus. These results provide a foundation for further studies involving Tg-B1, which, together with Tg-D1, had profound influences on wheat domestication.

The crop species within the genus Brassica have highly replicated genomes. Three base 'diploid' species, Brassica oleracea , B. nigra and B. rapa , are likely ancient polyploids, and three derived allopolyploid species, B. carinata , B. juncea and B. napus , are created from the interspecific hybridization of these base genomes. The base Brassica genome is thought to have hexaploid ancestry, and both recent and ancient polyploidization events have been proposed to generate a large number of genome rearrangements and novel genetic variation for important traits. Here, we revisit and refine these hypotheses. We have examined the B. oleracea linkage map using the Arabidopsis thaliana genome sequence as a template and suggest that there is strong evidence for genome replication and rearrangement within the base Brassicas, but less evidence for genome triplication. We show that novel phenotypic variation within the base Brassicas can be achieved by replication of a single gene, BrFLC , that acts additively to influence flowering time. Within the derived allopolyploids, intergenomic heterozygosity is associated with higher seed yields. Some studies have reported that de novo genomic variation occurs within derived polyploid genomes, whereas other studies have not detected these changes. We discuss reasons for these different findings. Large trans-locations and tetrasomic inheritance can explain some but not all genomic changes within the polyploids. Transpositions and other small-scale sequence changes probably also have contributed to genomic novelty. Our results have shown that the Brassica genomes are remarkably plastic, and that polyploidy generates novel genetic variation through gene duplication, intergenomic heterozygosity and perhaps epigenetic change.

Here we report that the Drosophila citron gene encodes an essential effector kinase of Pbl-RhoA signalling in vivo. Drosophila citron is expressed in proliferating tissues but is downregulated in differentiating tissues. We find that Citron can bind RhoA and that localisation of Citron to the contractile ring is dependent on the cytokinesis-specific Pbl-RhoA signalling. Phenotypic analysis of mutants showed that citron is required for cytokinesis in every tissue examined, with mutant cells exhibiting multinucleate and hyperploid phenotypes. Strong genetic interactions were observed between citron and pbl alleles and constructs. Vertebrate studies implicate at least two Rho effector kinases, Citron and Rok, in cytokinesis. By contrast, we failed to find evidence for a role for the Drosophila ortholog of Rok in cell division. We conclude that Citron plays an essential, non-redundant role in the Rho signalling pathway during Drosophila cytokinesis.

The data on chromosome numbers (somatic and basic) characteristic to species and subspecies of earthworms (Lumbricidae) of Georgia (Caucasus region) are summarized. Four values of basic chromosome number (11, 15, 17, 18) while 6 values of somatic number (22, 30, 34, 36, 72, 108) are registered in 19 species and subspecies studied. The diploid karyotypes dominate over polyploid karyotypes. It is supposed that the modal numbers, somatic 2n=36 and basic n=18, are evolutionarily initial on the basis of which the formation of the main part of species and subspecies of earthworms have proceeded in Georgia. Polyploidy did not represent the main evolutionary mechanism of the origin of species in Georgia (and the whole Caucasus).

Polyploid genomes evolve and follow a series of dynamic transfigurations along with adaptation and speciation. The initial formation of a new polyploid individual within a diploid population usually involves a triploid bridge, a two-step mechanism of cell fusions between ubiquitous (reduced) and rare (unreduced) gametes. The primary fusion event creates an intermediate triploid individual with unbalanced genome sets, a situation of genomic-shock characterized by gene expression dysregulation, high dosage sensitivity, disturbed cell divisions, and physiological and reproductive attributes drastically altered. This near-sterile neotriploid must produce (even) eupolyploids through secondary fusion events to restore genome steadiness, meiotic balance, and fertility required for the demographic establishment of a nascent lineage. Natural conditions locate several difficulties to polyploid establishment, including the production of highly unbalanced and rarely unreduced (euploid) gametes, frequency-dependent disadvantages (minority cytotype exclusion), severe fitness loss, and ecological competition with diploid parents. Persistence and adaptation of neopolyploids depend upon genetic and phenotypic novelty coupled to joint selective forces that preserve shock-induced genomic changes (subgenome homeolog partitioning) and drive meiotic (reproductive) stabilization and ecological diversification. Thus, polyploid establishment through the triploid bridge is a feasible but not ubiquitous process that requires a number of low-probability events and singular circumstances. Yet, frequencies of polyploids suggest that polyploid establishment is a pervasive process. To explain this disparity, and supported in experimental evidence, I propose that situations like hybridization and ploidy-state transitions associated to genomic shock and substantial developmental alterations can transiently activate apomixis as a mechanism to halt genomic instability and cancel factors restraining neopolyploid's sexual fertility, particularly in triploids. Apomixis –as a temporal alternative to sex– skip meiosis and syngamy, and thus can freeze genomic attributes, avoid unbalanced chromosomal segregation and increase the formation of unreduced euploid gametes, elude frequency-dependent reproductive disadvantages by parthenogenetic development of the embryo and permissive development of endosperm during seed formation, and increase the effective population size of the neopolyploid lineage favoring the formation rate of eupolyploids compared to aneuploids. The subsequent action of genome resilience mechanisms that alleviate transcriptomic shock and selection upon gene interactions might restore a stable
meiosis and sexual fertility within few generations, as observed in synthetic polyploids. Alternatively, provided that resilience mechanisms fail, the neopolyploid might retain apomixis and hold genomically and transcriptionally altered states for many generations.

Random Amplified Polymorphic DNA (RAPD) and Inter-Simple Sequence Repeat (ISSR) analyses were used to evaluate genetic variability and relationships of Greek Aegilops species. Thirty-eight accessions of seven Greek Aegilops species [Ae. triuncialis (genome UC), Ae. neglecta (UM), Ae. biuncialis (UM), Ae. caudata (C), Ae. comosa (M), Ae. geniculata (MU) and Ae. umbellulata (U)] as well as Triticum accessions were studied. Nineteen RAPD and ten ISSR primers yielded 344 and 170 polymorphic bands, respectively, that were used for the construction of dendrograms. Regardless of the similarity coefficient and marker type used, UPGMA placed 38 Aegilops accessions into one branch while the other branch consisted of wheat species. Within the Aegilops cluster, subgroups were identified that included species that shared the same genome or belonged to the same botanical section. Within the Triticum cluster, two robust subgroups were formed, one including diploid wheat and another including polyploid wheat. In conclusion, results showed that there is genetic diversity in the Greek Aegilops species studied, and clustering based on genetic similarities was in agreement with botanical classifications.

•The micro-evolutionary mechanisms that drive large-scale radiations are not completely understood, partly because of a shortage of population-level studies aimed at identifying putative causes of rapid evolutionary change. The Dianthus broteri complex, representing the largest polyploid series known to date for any species in the genus (2×, 4×, 6× and 12× cytotypes), belongs to a lineage that was recently found to have diversified at unusually rapid rates.•We used a combination of genome sequencing (internal transcribed spacer (ITS), plus chloroplast DNA (cpDNA) regions trnH-psbA, psbA-trnK and trnK-matK) and amplified fragment length polymorphism (AFLP) fingerprinting in 25 populations to infer the evolutionary history of extant polyploid races.•The haplotype, ribotype and AFLP reconstructions showed a star-shaped arrangement suggesting a pattern of radiative evolution. The major, widespread haplotype occurred at all ploidy levels, whereas 20 minor haplotypes were restricted to single populations and cytotypes. In addition, AFLP analyses retrieved well-supported cytogeographic groups: six clades were clearly differentiated in terms of ploidy level and geography. Molecular data indicate that gene flow among different cytotypes is rare or nonexistent.•Our study supports a scenario of rapid diversification in carnations in which autopolyploidy and allopolyploidy, in interaction with geography and/or isolation, have played prominent roles.The micro-evolutionary mechanisms that drive large-scale radiations are not completely understood, partly because of a shortage of population-level studies aimed at identifying putative causes of rapid evolutionary change. The Dianthus broteri complex, representing the largest polyploid series known to date for any species in the genus (2×, 4×, 6× and 12× cytotypes), belongs to a lineage that was recently found to have diversified at unusually rapid rates.We used a combination of genome sequencing (internal transcribed spacer (ITS), plus chloroplast DNA (cpDNA) regions trnH-psbA, psbA-trnK and trnK-matK) and amplified fragment length polymorphism (AFLP) fingerprinting in 25 populations to infer the evolutionary history of extant polyploid races.The haplotype, ribotype and AFLP reconstructions showed a star-shaped arrangement suggesting a pattern of radiative evolution. The major, widespread haplotype occurred at all ploidy levels, whereas 20 minor haplotypes were restricted to single populations and cytotypes. In addition, AFLP analyses retrieved well-supported cytogeographic groups: six clades were clearly differentiated in terms of ploidy level and geography. Molecular data indicate that gene flow among different cytotypes is rare or nonexistent.Our study supports a scenario of rapid diversification in carnations in which autopolyploidy and allopolyploidy, in interaction with geography and/or isolation, have played prominent roles.