The fixed life pattern of plants is the most threatening factor that hinders the survival and reproduction rate of plants. Maximization of reproduction is determined by the survival rate of the ...organism. If part of a shoot apical meristem or root apical meristem is cut and planted in soil with appropriate nutrients and survival conditions, a cloned plant known as an ramet, may be developed. Therefore, the ability of plants to constantly produce meristems is essential for survival. In addition, meristem stem cells have enabled plants to evolve a wide variety of asexual reproductive systems. When a tree is pruned, at least one or more new meristems are formed in the surrounding area, and those meristems develop into new branches. In other cases, stem cells normally derived from meristems alone exhibit the potential for asexual reproduction through their seed-like roles. Alternatively, some plants can form somatic cells, which are important in various types of asexual reproduction. There are 125 species of plants in the genus of Kalanchoe, which are succulent plants, and most of these species are well known to reproduce asexually through somatic cells. When we cut the stem of a plant, a callus is formed at the end of the cut side. Plant callus is mainly used to develop new plant varieties in tissue culture research. Alternatively, the plant callus is also used as a material for asexual reproduction. Callus can also form if the plant is infected with bacteria such as Agrobacterium tumefaciens. Differentiated cells of a plant can reproduce asexually by acquiring the ability to function as stems through transdifferentiation. These characteristics play important roles in adapting to environmental changes and extending the lifespan of woody plants.
Rootless plants in the genus
are some of the fastest growing known plants on Earth.
have a reduced body plan, primarily multiplying through a budding type of asexual reproduction. Here, we generated ...draft reference genomes for
(Benth.) Hartog & Plas, which has the smallest genome size in the genus at 357 Mb and has a reduced set of predicted protein-coding genes at about 15,000. Comparison between multiple high-quality draft genome sequences from
clones confirmed loss of several hundred genes that are highly conserved among flowering plants, including genes involved in root developmental and light signaling pathways.
has also lost most of the conserved nucleotide-binding leucine-rich repeat (NLR) genes that are known to be involved in innate immunity, as well as those involved in terpene biosynthesis, while having a significant overrepresentation of genes in the sphingolipid pathways that may signify an alternative defense system. Diurnal expression analysis revealed that only 13% of
genes are expressed in a time-of-day (TOD) fashion, which is less than the typical ∼40% found in several model plants under the same condition. In contrast to the model plants
and rice, many of the pathways associated with multicellular and developmental processes are not under TOD control in
, where genes that cycle the conditions tested predominantly have carbon processing and chloroplast-related functions. The
genome and TOD expression data set thus provide insight into the interplay between a streamlined plant body plan and optimized growth.
Heterosis, or hybrid vigor, is exploited by breeders to produce elite high-yielding crop lines, but beneficial phenotypes are lost in subsequent generations owing to genetic segregation. Clonal ...propagation through seeds would enable self-propagation of F
hybrids. Here we report a strategy to enable clonal reproduction of F
rice hybrids through seeds. We fixed the heterozygosity of F
hybrid rice by multiplex CRISPR-Cas9 genome editing of the REC8, PAIR1 and OSD1 meiotic genes to produce clonal diploid gametes and tetraploid seeds. Next, we demonstrated that editing the MATRILINEAL (MTL) gene (involved in fertilization) could induce formation of haploid seeds in hybrid rice. Finally, we combined fixation of heterozygosity and haploid induction by simultaneous editing of all four genes (REC8, PAIR1, OSD1 and MTL) in hybrid rice and obtained plants that could propagate clonally through seeds. Application of our method may enable self-propagation of a broad range of elite F
hybrid crops.
Development in Aspergillus Krijgsheld, P.; Bleichrodt, R.; van Veluw, G.J. ...
Studies in mycology,
03/2013, Volume:
74, Issue:
1
Journal Article
Peer reviewed
Open access
The genus Aspergillus represents a diverse group of fungi that are among the most abundant fungi in the world. Germination of a spore can lead to a vegetative mycelium that colonizes a substrate. The ...hyphae within the mycelium are highly heterogeneous with respect to gene expression, growth, and secretion. Aspergilli can reproduce both asexually and sexually. To this end, conidiophores and ascocarps are produced that form conidia and ascospores, respectively. This review describes the molecular mechanisms underlying growth and development of Aspergillus.
The frequency of sex in fungi Nieuwenhuis, Bart P. S.; James, Timothy Y.
Philosophical transactions of the Royal Society of London. Series B. Biological sciences,
10/2016, Volume:
371, Issue:
1706
Journal Article
Peer reviewed
Open access
Fungi are a diverse group of organisms with a huge variation in reproductive strategy. While almost all species can reproduce sexually, many reproduce asexually most of the time. When sexual ...reproduction does occur, large variation exists in the amount of in- and out-breeding. While budding yeast is expected to outcross only once every 10 000 generations, other fungi are obligate outcrossers with well-mixed panmictic populations. In this review, we give an overview of the costs and benefits of sexual and asexual reproduction in fungi, and the mechanisms that evolved in fungi to reduce the costs of either mode. The proximate molecular mechanisms potentiating outcrossing and meiosis appear to be present in nearly all fungi, making them of little use for predicting outcrossing rates, but also suggesting the absence of true ancient asexual lineages. We review how population genetic methods can be used to estimate the frequency of sex in fungi and provide empirical data that support a mixed mode of reproduction in many species with rare to frequent sex in between rounds of mitotic reproduction. Finally, we highlight how these estimates might be affected by the fungus-specific mechanisms that evolved to reduce the costs of sexual and asexual reproduction.
This article is part of the themed issue ‘Weird sex: the underappreciated diversity of sexual reproduction’.
Fine-tuning quantitative traits for continuous subtle phenotypes is highly advantageous. We engineer the highly conserved upstream open reading frame (uORF) of FvebZIPs1.1 in strawberry (Fragaria ...vesca), using base editor A3A-PBE. Seven novel alleles are generated. Sugar content of the homozygous T1 mutant lines is 33.9-83.6% higher than that of the wild-type. We also recover a series of transgene-free mutants with 35 novel genotypes containing a continuum of sugar content. All the novel genotypes could be immediately fixed in subsequent generations by asexual reproduction. Genome editing coupled with asexual reproduction offers tremendous opportunities for quantitative trait improvement.
A variety of plants in diverse taxa can reproduce asexually via vegetative propagation, in which clonal propagules with a new meristem(s) are generated directly from vegetative organs. A basal land ...plant, Marchantia polymorpha, develops clonal propagules, gemmae, on the gametophyte thallus from the basal epidermis of a specialized receptacle, the gemma cup. Here we report an R2R3-MYB transcription factor, designated GEMMA CUP-ASSOCIATED MYB1 (GCAM1), which is an essential regulator of gemma cup development in M. polymorpha. Targeted disruption of GCAM1 conferred a complete loss of gemma cup formation and gemma generation. Ectopic overexpression of GCAM1 resulted in formation of cell clumps, suggesting a function of GCAM1 in suppression of cell differentiation. Although gemma cups are a characteristic gametophyte organ for vegetative reproduction in a taxonomically restricted group of liverwort species, phylogenetic and interspecific complementation analyses support the orthologous relationship of GCAM1 to regulatory factors of axillary meristem formation, e.g., Arabidopsis REGULATOR OF AXILLARY MERISTEMS and tomato Blind, in angiosperm sporophytes. The present findings in M. polymorpha suggest an ancient acquisition of a transcriptional regulator for production of asexual propagules in the gametophyte and the use of the regulatory factor for diverse developmental programs, including axillary meristem formation, during land plant evolution.
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•The gemma cup is a specialized organ that produces clonal progenies in M. polymorpha•An R2R3-MYB, GCAM1, is an essential regulator of gemma cup formation•Ectopic overexpression of GCAM1 promotes proliferation of undifferentiated cells•GCAM1 is an ortholog of regulators of axillary meristem formation in angiosperms
The gemma cup is a specialized organ that produces clonal progenies, gemmae, in the liverwort Marchantia polymorpha. Yasui et al. identify an R2R3-MYB transcription factor, GCAM1, as an essential regulator of gemma cup formation. GCAM1 is an ortholog of regulatory factors of axillary meristem formation in angiosperms.
Abstract Centrioles are the core constituent of centrosomes, microtubule-organizing centers involved in directing mitotic spindle assembly and chromosome segregation in animal cells. In sexually ...reproducing species, centrioles degenerate during oogenesis and female meiosis is usually acentrosomal. Centrioles are retained during male meiosis and, in most species, are reintroduced with the sperm during fertilization, restoring centriole numbers in embryos. In contrast, the presence, origin, and function of centrioles in parthenogenetic species is unknown. We found that centrioles are maternally inherited in two species of asexual parthenogenetic nematodes and identified two different strategies for maternal inheritance evolved in the two species. In Rhabditophanes diutinus , centrioles organize the poles of the meiotic spindle and are inherited by both the polar body and embryo. In Disploscapter pachys , the two pairs of centrioles remain close together and are inherited by the embryo only. Our results suggest that maternally-inherited centrioles organize the embryonic spindle poles and act as a symmetry-breaking cue to induce embryo polarization. Thus, in these parthenogenetic nematodes, centrioles are maternally-inherited and functionally replace their sperm-inherited counterparts in sexually reproducing species.
The rarity of parthenogenetic species is typically attributed to the reduced genetic variability that accompanies the absence of sex, yet natural parthenogens can be surprisingly successful. ...Ecological success is often proposed to derive from hybridization through enhanced genetic diversity from repetitive origins or enhanced phenotypic breadth from heterosis. Here, we tested and rejected both hypotheses in a classic parthenogen, the diploid grasshopper
. Genetic data revealed a single hybrid mating origin at least 0.25 million years ago, and comparative analyses of 14 physiological and life history traits showed no evidence for altered fitness relative to its sexual progenitors. Our findings imply that the rarity of parthenogenesis is due to constraints on origin rather than to rapid extinction.
Asexual reproduction is ancestral in prokaryotes; the switch to sexuality in eukaryotes is one of the major transitions in the history of life. The study of the maintenance of sex in eukaryotes has ...raised considerable interest for decades and is still one of evolutionary biology's most prominent question. The observation that many asexual species are of hybrid origin have led some to propose that asexuality in hybrids results from sexual processes being disturbed because of incompatibilities between the two parental species' genomes. However, in some cases, failure to produce asexual F1s in the lab may indicate that this mechanism is not the only road to asexuality in hybrid species. Here, we present a mathematical model and propose an alternative, adaptive route for the evolution of asexuality from previously sexual hybrids. Under some reproductive alterations, we show that asexuality can evolve to rescue hybrids' reproduction. Importantly, we highlight that when incompatibilities only affect the fusion of sperm and egg's genomes, the two traits that characterize asexuality, namely unreduced meiosis and the initiation of embryogenesis without the incorporation of the sperm's pronucleus, can evolve separately, greatly facilitating the overall evolutionary route. Taken together, our results provide an alternative, potentially complementary explanation for the link between asexuality and hybridization.
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