A soil bacterium alters sex determination and rhizoid development in gametophytes of the fern Ceratopteris richardii

In many plants females invest more in reproduction than males. In organisms that exhibit environmental sex determination, individuals in low-quality environments or who are slow growing are expected to develop into males. The gametophytes of Ceratopteris richardii Brongn., a homosporous fern, may develop as males or hermaphrodites. Hermaphrodites secrete a pheromone called antheridiogen that induces undifferentiated spores to develop as males. Given that induction is not 100% in the presence of antheridiogen, it is hypothesized that resources may alter C. richardii gender decisions. An experiment was undertaken to determine (i) whether spore size predicts gender, (ii) whether spore size predicts gametophyte size, (iii) whether antheridiogen negatively affects the growth of C. richardii, and (iv) whether wild-type C. richardii and him1 mutants (genetic mutants disposed to male development regardless of antheridiogen presence) behave similarly in their response to antheridiogen. Spore size was not predictive of gender but was positively related to both male and hermaphrodite gametophyte size. Antheridiogen was found to slow the growth of male and hermaphrodite gametophytes of the wild type and male gametophytes of the him1 mutant. These results are supportive of the idea that gender may be determined indirectly through antheridiogen’s effect on gametophyte growth.

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Effects of variation in carbon, nitrogen, and phosphorus molarity and stoichiometry on sex determination in the fern Ceratopteris richardii

Botany ◽

10.1139/cjb-2015-0187 ◽

2016 ◽

Vol 94 (4) ◽

pp. 249-259 ◽

Cited By ~ 4

Author(s):

Taylor T. Goodnoe ◽

Jeffrey P. Hill ◽

Ken Aho

Keyword(s):

Sex Determination ◽

Normal Growth ◽

Early Response ◽

Sex Expression ◽

Dry Mass ◽

Phenotypic Trait ◽

Ceratopteris Richardii ◽

Nitrogen And Phosphorus ◽

Exogenous Glucose ◽

Nutrient Effects

Carbon (C), nitrogen (N), and phosphorous (P) are needed by all organisms for basic biological processes. When an individual macronutrient is not accessible, nutrient limitation occurs. The stochiometric balance between multiple nutrients and individual concentrations are both vital for normal growth and development. Labile sex expression in plants is a phenotypic trait predicted to be sensitive to local nutrient conditions because males and females differ in their nutritional demands. We applied concepts from ecological stoichiometry to assess the effects of variation in individual nutrient concentration and multiple macronutrient stoichiometry on sexual development in the fern Ceratopteris richardii Brongn. Manipulation of N, P, and organic and inorganic C was expected to yield variation in the ratio of males to females, consistent with environmental sex-determination theory. Our results suggest nutrient stoichiometry, not strictly concentration, influences sex determination at ambient CO2. However, an early response to population density preempted nutrient effects in elevated CO2 environments with exogenous glucose, in which C. richardii gametophytes presumably grow naturally. Although sex determination is not nutrient-dependent in the latter environment, C:N in the dry mass of meristic gametophytes is influenced by the external nutrient context, suggesting sex determination takes place before abiotic environmental factors subsequently influence plant nutrient uptake.

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Absolute and relative content of carbon and nitrogen differ by sex in Ceratopteris richardii gametophytes

Botany ◽

10.1139/cjb-2015-0254 ◽

2016 ◽

Vol 94 (5) ◽

pp. 405-410 ◽

Cited By ~ 1

Author(s):

Taylor T. Goodnoe ◽

Jeffrey P. Hill

Keyword(s):

Sex Determination ◽

Nutrient Availability ◽

Abiotic Factors ◽

Sex Expression ◽

Dry Mass ◽

Ceratopteris Richardii ◽

Carbon And Nitrogen ◽

Individual Fitness ◽

Nutrient Effects ◽

Short Time

When habitats are heterogeneous regarding key abiotic factors, and individual organisms have no control over the environment in which they develop, labile sex expression can allow individuals to adjust their sex based on local environmental conditions, resulting in increased individual fitness. Sexual lability is found extensively in homosporous ferns, where sex expression is often regulated via the pheromone antheridiogen. Nutrient availability may provide additional signals for sex determination in fern gametophytes, particularly if nutrient demands required for sexual development differ by sex. The model fern Ceratopteris richardii Brongn. has a well-characterized antheridiogen response and short time to sexual maturity. Although tests for nutrient effects on sex determination have been conducted in this fern, tests for differences in nutrient demands by sex have not. Elemental analysis demonstrated that 14-day-old ameristic male and meristic female or hermaphrodite gametophytes of C. richardii differ significantly in their relative carbon and nitrogen masses, resulting in significantly dissimilar C:N ratios between the sexes. Average gametophyte dry mass in ameristic males was approximately half that of meristic plants of the same age, and contained less N than meristic gametophytes in both relative and absolute terms. Those characteristic differences in elemental composition imply that variation in nutrient availability could potentially influence sex expression in C. richardii gametophyte populations, rather than regulation of sex determination by the antheridiogen system alone.

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Genetic Interactions Among Sex-Determining Genes in the Fern Ceratopteris richardii

Genetics ◽

10.1093/genetics/142.3.973 ◽

1996 ◽

Vol 142 (3) ◽

pp. 973-985

Author(s):

James R Eberle ◽

Jo Ann Banks

Keyword(s):

Linkage Analysis ◽

Sex Determination ◽

Genetic Interactions ◽

Ceratopteris Richardii ◽

Male Development ◽

Sex Type

Abstract Haploid gametophytes of the fern Ceratopteris are either male or hermaphroditic. The determinant of sex type is the pheromone antheridiogen, which is secreted by the hermaphrodite and directs male development of young, sexually undetermined gametophytes. Three phenotypic classes of mutations that affect sex-determination were previously isolated and include the hermaphroditic (her), the transformer (tra) and feminization (fem) mutations. In the present study, linkage analysis and tests of epistasis among the different mutants have been performed to assess the possible interactions among these genes. The results indicate that sex determination in Ceratopteris involves at least seven interacting genes in addition to antheridiogen, the primary sex-determining signal. Two models describing how antheridiogen may influence the activity states of these genes and the sex of the gametophyte are discussed.

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Sex determination

AccessScience ◽

10.1036/1097-8542.617400 ◽

2015 ◽

Keyword(s):

Sex Determination

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Sex determination banned in India

Nature ◽

10.1038/379201e0 ◽

1996 ◽

Vol 379 (6562) ◽

pp. 201-201

Keyword(s):

Sex Determination

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Sex determination and Y chromosome constitutive heterochromatin

Current Research in Biochemistry and Molecular Biology ◽

10.33702/crbmb.2019.1.1.1 ◽

2019 ◽

Vol 1 (1) ◽

pp. 1-5

Author(s):

Abyt Ibraimov

Keyword(s):

Sex Determination ◽

Y Chromosome ◽

Constitutive Heterochromatin ◽

Sex Differentiation ◽

Secondary Sexual Characteristics ◽

Biological Meaning ◽

Heterochromatin Block ◽

Sexual Characteristics ◽

Open Question ◽

Efficient Elimination

In many animals, including us, the genetic sex is determined at fertilization by sex chromosomes. Seemingly, the sex determination (SD) in human and animals is determined by the amount of constitutive heterochromatin on Y chromosome via cell thermoregulation. It is assumed the medulla and cortex tissue cells in the undifferentiated embryonic gonads (UEG) differ in vulnerability to the increase of the intracellular temperature. If the amount of the Y chromosome constitutive heterochromatin is enough for efficient elimination of heat difference between the nucleus and cytoplasm in rapidly growing UEG cells the medulla tissue survives. Otherwise it doomed to degeneration and a cortex tissue will remain in the UEG. Regardless of whether our assumption is true or not, it remains an open question why on Y chromosome there is a large constitutive heterochromatin block? What is its biological meaning? Does it relate to sex determination, sex differentiation and development of secondary sexual characteristics? If so, what is its mechanism: chemical or physical? There is no scientifically sound answer to these questions.

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