scholarly journals Asexual thalli originated from sporophytic thalli via apomeiosis in the green seaweed Ulva

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Kensuke Ichihara ◽  
Tomokazu Yamazaki ◽  
Shinichi Miyamura ◽  
Masanori Hiraoka ◽  
Shigeyuki Kawano
Keyword(s):  
Mating Type ◽  
Asexual Reproduction ◽  
Ulva Prolifera ◽  
Transcriptomic Analysis ◽  
Reproductive Cell ◽  
Reproduction System ◽  
Green Seaweed ◽  
Asexual Populations ◽  
And Behavior

Abstract Apomixis is an asexual reproduction system without fertilization, which is an important proliferation strategy for plants and algae. Here, we report on the apomeiosis in the green seaweed Ulva prolifera, which has sexual and obligate asexual populations. Genomic PCR of mating type (MT)-locus genes revealed asexual thalli carrying both MT genomes. Observation of the chromosomes during the formation of each type of reproductive cell revealed that cells in asexual thalli performed apomeiosis without chromosome reduction. Moreover, genotyping revealed that laboratory-cultured sporophytic thalli produced not only each type of gametophyte but also diploid thalli carrying the mt− and mt+ genome (mt± thallus strains). The mt± thallus strain released diploid biflagellate zoids, with ultrastructure and behavior similar to mt+ gametes. Additionally, a transcriptomic analysis revealed that some meiosis-related genes (Mei2L and RAD1) were highly expressed in the quadriflagellate zoosporoids. Our results strongly suggest that asexual thalli originally evolved via apomeiosis in sporophytic thalli.

scholarly journals Population Genetic Structure of Tapesia acuformis in Washington State

2003 ◽  
Vol 93 (6) ◽  
pp. 650-656 ◽  
Author(s):  
G. W. Douhan ◽  
T. D. Murray ◽  
P. S. Dyer
Keyword(s):  
Genetic Structure ◽  
Mating Type ◽  
Asexual Reproduction ◽  
Permutation Test ◽  
Phylogenetic Analyses ◽  
Random Mating ◽  
Likelihood Ratio Statistic ◽  
Washington State ◽  
Homogeneous Population ◽  
Sexual And Asexual Reproduction

Eyespot of wheat is caused by Tapesia yallundae and T. acuformis. Historically, T. yallundae has been considered the more important causal agent of the disease in Washington state and consists of a large homogeneous population with a genetic structure consistent with both sexual and asexual reproduction. T. acuformis has increased significantly in Washington in the past 10 years and apothecia were found recently under natural field conditions, indicating that T. acuformis may have a more important role in eyespot of wheat than previously was thought. To determine the genetic structure of T. acuformis in Washington, 141 single conidial isolates were sampled from four subpopulations in the eastern wheat-growing region of the state. Isolates were scored for mating type and six amplified fragment length polymorphism markers. All markers segregated in a 1:1 ratio and were determined to be unlinked based on genetic analysis of 24 progeny from an in vitro cross. No significant differences in allele frequencies (0.127 < P < 0.809) were found among individual loci across the four subpopulations and over all loci based on contingency table analysis of the log-likelihood ratio statistic G2. Likewise, no overall differences between subpopulations were detected using the population differentiation statistic θ (θ = -0.004, P = 0.537). Random mating could not be rejected within each subpopulation or for the combined data using clone-corrected data sets based on (i) 1:1 ratio of mating-type, (ii) multilocus gametic disequilibrium analyses (index of association), (iii) phylogenetic analyses (parsimony tree length permutation test), and (iv) genotypic diversity analyses. T. acuformis has a genetic structure similar to that of sympatric populations of T. yallundae in Washington, with both sexual and asexual reproduction contributing to the structuring of this species.

scholarly journals Hox genes regulate asexual reproductive behavior and tissue segmentation in adult animals

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Christopher P. Arnold ◽  
Analí Migueles Lozano ◽  
Frederick G. Mann ◽  
Stephanie H. Nowotarski ◽  
Julianna O. Haug ◽  
...  
Keyword(s):  
Asexual Reproduction ◽  
Hox Genes ◽  
Adult Stage ◽  
Tissue Segmentation ◽  
Hox Gene ◽  
Downstream Effector ◽  
Effector Genes ◽  
And Behavior ◽  
Insight Into ◽  
Anterior Posterior

AbstractHox genes are highly conserved transcription factors renowned for their roles in the segmental patterning of the embryonic anterior-posterior (A/P) axis. We report functions for Hox genes in A/P tissue segmentation and transverse fission behavior underlying asexual reproduction in adult planarian flatworms, Schmidtea mediterranea. Silencing of each of the Hox family members identifies 5 Hox genes required for asexual reproduction. Among these, silencing of hox3 genes results in supernumerary fission segments, while silencing of post2b eliminates segmentation altogether. The opposing roles of hox3 and post2b in segmentation are paralleled in their respective regulation of fission behavior. Silencing of hox3 increases the frequency of fission behavior initiation while silencing of post2b eliminates fission behavior entirely. Furthermore, we identify a network of downstream effector genes mediating Hox gene functions, providing insight into their respective mechanisms of action. In particular, we resolve roles for post2b and effector genes in the functions of the marginal adhesive organ in fission behavior regulation. Collectively, our study establishes adult stage roles for Hox genes in the regulation of tissue segmentation and behavior associated with asexual reproduction.

scholarly journals Genomic structure and evolution of the mating type locus in the green seaweed Ulva partita

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Tomokazu Yamazaki ◽  
Kensuke Ichihara ◽  
Ryogo Suzuki ◽  
Kenshiro Oshima ◽  
Shinichi Miyamura ◽  
...  
Keyword(s):  
Mating Type ◽  
Genomic Structure ◽  
Type Locus ◽  
Mating Type Locus ◽  
Green Seaweed

scholarly journals Validation of mating type-related markers in Ulva prolifera (Ulvophyceae, Chlorophyta) and their detection during various reproductive modes

2022 ◽  
Vol 62 ◽  
pp. 102611
Author(s):  
Qianchun Liu ◽  
Chunhui Wu ◽  
Weifeng Xie ◽  
Jin Zhao ◽  
Peng Jiang
Keyword(s):  
Mating Type ◽  
Ulva Prolifera ◽  
Reproductive Modes

scholarly journals Simulation of Karyotype Evolution and Biodiversity in Asexual and Sexual Reproduction

2018 ◽  
Author(s):  
Andrew Y. Ying ◽  
Christine J. Ye ◽  
Hui Jiang ◽  
Steven D. Horne ◽  
Batoul Y. Abdallah ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Genome Integrity ◽  
Main Function ◽  
Sexual And Asexual Reproduction ◽  
Gene Level ◽  
Genome Level ◽  
Asexual Populations ◽  
Deleterious Genes

AbstractWhether sexual reproduction increases biodiversity remains controversial. Traditionally, sex within a species has been thought to increase genetic diversity, inferring an acceleration of macro-evolution, promoting biodiversity. Recently, it was suggested that the main function of sex is to maintain genome integrity, rather than increase genetic diversity or purify deleterious genes within populations, as the karyotype encodes/safeguards the genomic blueprint. As such, the contribution of sex to biodiversity needs to be re-examined. Since many simulation studies focus only on gene-level selection, it is important to investigate how sexual and asexual reproduction differentially impact patterns of genome-level evolution and biodiversity. Based on the key difference between sexual and asexual reproduction, that sexual individuals are required to mate with a partner of the same genome for successful reproduction, we have performed a simulation to illustrate how such differences impact genome-mediated biodiversity. Asexual populations displayed high genome-level diversity whereas sexual populations evidenced low genome-level diversity. Further analysis demonstrated that the requirement of finding a partner possessing a compatible genome prevents new sexual species from emerging, which may explain why geographic isolation can promote speciation: by increasing mating and survival-domination opportunities. This study challenges the traditional concepts of speciation and the function of sex.

scholarly journals Variability in Virulence Among Asexual Progenies of Phytophthora infestans

2003 ◽  
Vol 93 (3) ◽  
pp. 293-304 ◽  
Author(s):  
F. M. Abu-El Samen ◽  
G. A. Secor ◽  
N. C. Gudmestad
Keyword(s):  
Phytophthora Infestans ◽  
Mating Type ◽  
Asexual Reproduction ◽  
Banding Pattern ◽  
Major Gene ◽  
Dna Fingerprints ◽  
Continuous Change ◽  
Genetic Changes ◽  
Different Levels ◽  
Late Blight Of Potato

One hundred two single zoospore isolates of Phytophthora infestans, derived asexually from four parental isolates of US-8 genotype and one isolate of US-1 genotype, were characterized for their virulence phenotypes to determine changes in virulence during asexual reproduction. Potato differentials, each containing a major gene for resistance to P. infestans (R1 to R11), were used to characterize the virulence patterns. Isolates were also characterized for mating type, glucose-6-phosphate isomerase (Gpi) banding pattern, and DNA fingerprints using probe RG57 to determine any genotypic changes in the single zoospore isolates. A subset of these single zoospore isolates was tested for response to mefenoxam to determine any shifts in sensitivity. Results showed that single zoospore isolates derived from parent PI-1 (US-8, 11 isolates) were identical to their parental virulence. Isolates derived from parent PI-191 (US-8, 29 isolates) showed some differences in virulence, mainly toward R8 and R9. Isolates derived from parent PI-126 (US-8, 14 isolates) demonstrated a higher level of virulence diversity. Isolates derived from parents PI-52 (US-1, 28 isolates) and PI-105 (US-8, 20 isolates) showed the highest level of virulence variability among the single zoospore isolates. Mating type, Gpi banding pattern, and DNA fingerprints for the single zoospore isolates were, in most cases, identical to the parental isolates. Single zoospore isolates showed different levels of sensitivity to mefenoxam. Virulence and other genetic changes during asexual reproduction are likely to play a major role in changing the race structure of P. infestans populations. This continuous change in the race structure is a serious problem and now poses a new challenge for utilization of race-specific resistance to manage late blight of potato.

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