Polyploid specimens are usually characterized by greater exuberance: they reach larger sizes and/or have a larger number of some organs.
L. belongs to the section
. Based on morphological features, ...four subspecies of
have been already identified. On the other hand, it has two cytotypes: diploid and tetraploid. The main aim of our study was to distinguish morphological differences between the cytotypes of
, assuming that its phenotype differs significantly.
The nuclear DNA content was measured by flow cytometry in dry leaves from specimens originating from 13 populations of
. Several macrometric and micrometric traits of stems, spikelets and leaf blades were taken into account in the comparative analysis of two cytotypes.
In the case of cytotypes, specimens of tetraploids were larger than diploids. The conducted morphometric analysis of leaf cross-sections showed significant differences between the cytotypes.
The research has confirmed for the first time that in the case of
the principle of greater exuberance of polyploids is true. Differences between the cytotypes are statistically significant, however, they are not enough to make easy the distinction of cytotypes on the basis of the measurements themselves. Our findings favor the rule known in
taxonomy as a whole, i.e. that the ploidy level can be one of the main classification criteria.
The process of apophytism or spreading native species to human-made habitats is one of the main elements in the creation of plant cover in anthropogenic areas. Lately, an increase of anthropogenic ...localities with valuable flora has been observed. Apophytes are also members of the family Orchidaceae, especially from the genus
. The aim of the study was to (i) determine and compare the phenotypic variation of
(L.) Crantz plants in anthropogenic and natural habitats, (ii) compare the genome size of plants growing in natural and anthropogenic habitats. The results reported in this study may indicate that a habitat influences morphological characteristics of plant species.
Field studies were conducted on four native stands and four stands in anthropogenic areas of
in Poland in years 2011-2013. Biometrical analyses were performed on shoots and flowers. The flowers were characterised by 25 biometric features and measured using a Nikon SMZ 800 binocular, microscopic Moticam-1SP cameras and the MIPlus07 programme (Conbest Co.). The nuclear DNA content was determined in fresh and young leaves of
, collected from four natural and four anthropogenic populations.
We observed that in anthropogenic populations: (i) shoots were higher than shoots from natural populations, (ii) flowers differed significantly in terms of ten biometric features between habitats, (iii) the genome size of some population differed significantly between plants growing in natural and anthropogenic habitats.
According to some researchers, the presence of phenotypic variability and the occurrence of ecotypes are adaptation strategies of plants to environmental changes. In our opinion, in the case of the studied anthropogenic habitats (roadside) in which the
populations grew, we can talk about ecofen due to the often repeated set of characteristic features, i.e., high shoots, long inflorescence and long, broad leaves. We agree, however, that it is difficult to isolate a taxonomic unit for ecofen due to the lack of experimental research.
Rates of phenotypic evolution have changed throughout the history of life, producing variation in levels of morphological, functional, and ecological diversity among groups. Testing for the presence ...of these rate shifts is a key component of evaluating hypotheses about what causes them. In this paper, general predictions regarding changes in phenotypic diversity as a function of evolutionary history and rates are developed, and tests are derived to evaluate rate changes. Simulations show that these tests are more powerful than existing tests using standardized contrasts. The new approaches are distributed in an application called Brownie and in r8s.
Generating chromosome-level, haplotype-resolved assemblies of heterozygous genomes remains challenging. To address this, we developed gamete binning, a method based on single-cell sequencing of ...haploid gametes enabling separation of the whole-genome sequencing reads into haplotype-specific reads sets. After assembling the reads of each haplotype, the contigs are scaffolded to chromosome level using a genetic map derived from the gametes. We assemble the two genomes of a diploid apricot tree based on whole-genome sequencing of 445 individual pollen grains. The two haplotype assemblies (N50: 25.5 and 25.8 Mb) feature a haplotyping precision of greater than 99% and are accurately scaffolded to chromosome-level.
RNA viruses are the only known RNA-protein (RNP) entities capable of autonomous replication (albeit within a permissive host environment). A 33.5 kilobase (kb) nidovirus has been considered close to ...the upper size limit for such entities; conversely, the minimal cellular DNA genome is in the 100-300 kb range. This large difference presents a daunting gap for the transition from primordial RNP to contemporary DNA-RNP-based life. Whether or not RNA viruses represent transitional steps towards DNA-based life, studies of larger RNA viruses advance our understanding of the size constraints on RNP entities and the role of genome size in virus adaptation. For example, emergence of the largest previously known RNA genomes (20-34 kb in positive-stranded nidoviruses, including coronaviruses) is associated with the acquisition of a proofreading exoribonuclease (ExoN) encoded in the open reading frame 1b (ORF1b) in a monophyletic subset of nidoviruses. However, apparent constraints on the size of ORF1b, which encodes this and other key replicative enzymes, have been hypothesized to limit further expansion of these viral RNA genomes. Here, we characterize a novel nidovirus (planarian secretory cell nidovirus; PSCNV) whose disproportionately large ORF1b-like region including unannotated domains, and overall 41.1-kb genome, substantially extend the presumed limits on RNA genome size. This genome encodes a predicted 13,556-aa polyprotein in an unconventional single ORF, yet retains canonical nidoviral genome organization and expression, as well as key replicative domains. These domains may include functionally relevant substitutions rarely or never before observed in highly conserved sites of RdRp, NiRAN, ExoN and 3CLpro. Our evolutionary analysis suggests that PSCNV diverged early from multi-ORF nidoviruses, and acquired additional genes, including those typical of large DNA viruses or hosts, e.g. Ankyrin and Fibronectin type II, which might modulate virus-host interactions. PSCNV's greatly expanded genome, proteomic complexity, and unique features-impressive in themselves-attest to the likelihood of still-larger RNA genomes awaiting discovery.
Genome evolution is usually viewed through the lens of growth in size and complexity over time, exemplified by plants and animals. In contrast, genome reduction is associated with a narrowing of ...ecological potential, such as in parasites and endosymbionts. But, can nuclear genome reduction also occur in, and potentially underpin a major radiation of free-living eukaryotes? An intriguing example of this phenomenon is provided by the red algae (Rhodophyta) that have lost many conserved pathways such as for flagellar motility, macroautophagy regulation, and phytochrome based light sensing. This anciently diverged, species-rich, and ecologically important algal lineage has undergone at least two rounds of large-scale genome reduction during its >1 billion-year evolutionary history. Here, using recent analyses of genome data, we review knowledge about the evolutionary trajectory of red algal nuclear and organelle gene inventories and plastid encoded autocatalytic introns. We compare and contrast Rhodophyta genome evolution to Viridiplantae (green algae and plants), both of which are members of the Archaeplastida, and highlight their divergent paths. We also discuss evidence for the speculative hypothesis that reduction in red algal plastid genome size through endosymbiotic gene transfer is counteracted by ongoing selection for compact nuclear genomes in red algae. Finally, we describe how the spliceosomal intron splicing apparatus provides an example of "evolution in action" in Rhodophyta and how the overall constraints on genome size in this lineage has left significant imprints on this key step in RNA maturation. Our review reveals the red algae to be an exciting, yet under-studied model that offers numerous novel insights as well as many unanswered questions that remain to be explored using modern genomic, genetic, and biochemical methods. The fact that a speciose lineage of free-living eukaryotes has spread throughout many aquatic habitats after having lost about 25% of its primordial gene inventory challenges us to elucidate the mechanisms underlying this remarkable feat.
The complete genome of a new rhabdovirus infecting papaya (Carica papaya L.) in Ecuador, named papaya virus E, was sequenced and characterized. The negative-sense single-stranded RNA genome consists ...of 13,469 nucleotides with six canonical open reading frames (ORFs) and two accessory short ORFs predicted between ORFs corresponding to P3 (movement protein) and M (matrix protein). Phylogenetic analyses using amino acid sequences from the nucleocapsid, glycoprotein and polymerase, grouped the virus with members of the genus Cytorhabdovirus, with rice stripe mosaic virus, yerba mate chlorosis-associated virus and Colocasia bobone disease-associated virus as closest relatives. The 3' leader and 5' trailer sequences were 144 and 167 nt long, respectively, containing partially complementary motifs. The motif 3'-AUUCUUUUUG-5', conserved across rhabdoviruses, was identified in all but one intergenic regions; whereas the motif 3'-ACAAAAACACA-5' was found in three intergenic junctions. This is the first complete genome sequence of a cytorhabdovirus infecting papaya. The virus was prevalent in commercial plantings of Los Ríos, the most important papaya producing province of Ecuador. Recently, the genome sequence of bean-associated cytorhabdovirus was reported. The genome is 97% identical to that of papaya virus E, indicating that both should be considered strains of the same virus.
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