scholarly journals The Diversity and Dynamics of Sex Determination in Dioecious Plants

2021 ◽  
Vol 11 ◽  
Author(s):  
Ana Paula Leite Montalvão ◽  
Birgit Kersten ◽  
Matthias Fladung ◽  
Niels Andreas Müller
Keyword(s):  
Sex Determination ◽  
Classical Model ◽  
Genetic System ◽  
Sex Expression ◽  
Flowering Plants ◽  
Cytokinin Signaling ◽  
Dioecious Plants ◽  
Female Function ◽  
Unisexual Flowers ◽  
Evolution Of Dioecy

The diversity of inflorescences among flowering plants is captivating. Such charm is not only due to the variety of sizes, shapes, colors, and flowers displayed, but also to the range of reproductive systems. For instance, hermaphrodites occur abundantly throughout the plant kingdom with both stamens and carpels within the same flower. Nevertheless, 10% of flowering plants have separate unisexual flowers, either in different locations of the same individual (monoecy) or on different individuals (dioecy). Despite their rarity, dioecious plants provide an excellent opportunity to investigate the mechanisms involved in sex expression and the evolution of sex-determining regions (SDRs) and sex chromosomes. The SDRs and the evolution of dioecy have been studied in many species ranging from Ginkgo to important fruit crops. Some of these studies, for example in asparagus or kiwifruit, identified two sex-determining genes within the non-recombining SDR and may thus be consistent with the classical model for the evolution of dioecy from hermaphroditism via gynodioecy, that predicts two successive mutations, the first one affecting male and the second one female function, becoming linked in a region of suppressed recombination. On the other hand, aided by genome sequencing and gene editing, single factor sex determination has emerged in other species, such as persimmon or poplar. Despite the diversity of sex-determining mechanisms, a tentative comparative analysis of the known sex-determining genes and candidates in different species suggests that similar genes and pathways may be employed repeatedly for the evolution of dioecy. The cytokinin signaling pathway appears important for sex determination in several species regardless of the underlying genetic system. Additionally, tapetum-related genes often seem to act as male-promoting factors when sex is determined via two genes. We present a unified model that synthesizes the genetic networks of sex determination in monoecious and dioecious plants and will support the generation of hypothesis regarding candidate sex determinants in future studies.

scholarly journals Pleiotropic effects of sex-determining genes in the evolution of dioecy in two plant species

2019 ◽  
Vol 286 (1913) ◽  
pp. 20191805 ◽  
Author(s):  
Takashi Akagi ◽  
Deborah Charlesworth
Keyword(s):  
Theoretical Models ◽  
Ancestral State ◽  
Relative Importance ◽  
Sexual Antagonism ◽  
Dioecious Plant ◽  
Dioecious Species ◽  
Dioecious Plants ◽  
Sexual Dimorphisms ◽  
Evolution Of Dioecy ◽  
Plant Sex

One reason for studying sex chromosomes of flowering plants is that they have often evolved separate sexes recently, and the genomes of dioecious species may not yet have evolved adaptations to their changes from the ancestral state. An unstudied question concerns the relative importance of such adaptation, versus the effects of the mutations that led to separate sexes in the first place. Theoretical models for such an evolutionary change make the prediction that the mutations that created males must have sexually antagonistic effects, not only abolishing female functions, but also increasing male functions relative to the ancestral functional hermaphrodites. It is important to test this critical assumption. Moreover, the involvement of sexual antagonism also implies that plant sex-determining genes may directly cause some of the sexual dimorphisms observed in dioecious plants. Sex-determining genes are starting to be uncovered in plants, including species in the genera Diospyros and Actinidia (families Ebenaceae and Actinidiaceae, respectively). Here, we describe transgenic experiments in which the effects of the very different male-determining genes of these two dioecious species were studied in a non-dioecious plant, Nicotiana tabacum . The results indeed support the critical assumption outlined above.

Allocation of resources to sex functions in flowering plants

1991 ◽  
Vol 332 (1262) ◽  
pp. 91-102 ◽  
Keyword(s):  
Resource Allocation ◽  
Natural Selection ◽  
Population Level ◽  
Theoretical Models ◽  
Flowering Plants ◽  
Allocation Of Resources ◽  
Biological Reality ◽  
Theoretical Predictions ◽  
Allocation Patterns ◽  
Unisexual Flowers

The study of allocation of resources offers the possibility of understanding the pressures of natural selection on reproductive functions. In allocation studies, theoretical predictions are generated and the assumptions as well as the predictions can be tested in the field. Here, we review some of the theoretical models, and discuss how much biological reality can be included in them, and what factors have been left out. We also review the empirical data that have been generated as tests of this body of theory. There are many problems associated with estimating reproductive resources, and also with testing how allocation of these resources affects reproductive and other components of fitness, and we assess how important these may be in allowing empirical results to be interpreted. Finally, we discuss the relevance of resource allocation patterns to the evolution of unisexual flowers, both at the level of individual plants (monoecy, andro- and gynomonoecy) and at the population level (dioecy).

REGULATION OF SEX EXPRESSION IN DESERT AND MEDITERRANEAN POPULATIONS OF AN ANDROMONOECIOUS PLANT (GAGEA CHLORANTHA, LILIACEAE)

1998 ◽  
Vol 46 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Lorne M. Wolfe
Keyword(s):  
Sex Ratio ◽  
Male Flower ◽  
Sex Expression ◽  
Male Reproduction ◽  
Rainfall Gradient ◽  
Hermaphrodite Flower ◽  
Mediterranean Populations ◽  
Female Function ◽  
The Difference ◽  
Male Flowers

This study examined issues related to the ecology of andromonoecy in Gagea chlorantha (Liliaceae), a perennial geophyte that grows in desert and Mediterranean-type habitats in Israel. Andromonoecy is a plant sexual system where individuals produce both male and hermaphrodite flowers and is thought to have evolved to optimize resource allocation to male and female function. Individuals of this species produced 1–6 flowers, and flower production was significantly correlated with the size of the storage organ (bulb). Three sexual phenotypes were found to exist: those that made only male flowers, plants that made only hermaphrodite flowers, and those that produced both flower types. Two lines of evidence suggest that hermaphroditic reproduction is more costly than male reproduction: (1) hermaphroditic flowers were heavier than male flowers in terms of dry biomass; (2) bulb size was greater on single-flower plants that were hermaphrodite compared to male. In addition, bulb size was greater on multiple-flowered plants that made a hermaphrodite flower as the last flower, compared to those that made a male flower. The floral sex ratio varied extensively along a latitudinal rainfall gradient within Israel. The five Mediterranean populations were male-biased. In contrast, the production of males in the three Negev desert populations was extremely rare, and approximately 94% of the flowers were hermaphrodite. The difference in sex ratio between the two habitat types is explained in terms of environmental unpredictability.

scholarly journals Sex Determination in Monoecious and Dioecious Plants.

1989 ◽  
pp. 737-744 ◽  
Author(s):  
E. E. Irish ◽  
T. Nelson
Keyword(s):  
Sex Determination ◽  
Dioecious Plants

Sex Determination in Monoecious and Dioecious Plants

1989 ◽  
Vol 1 (8) ◽  
pp. 737 ◽  
Author(s):  
Erin E. Irish ◽  
Timothy Nelson
Keyword(s):  
Sex Determination ◽  
Dioecious Plants

scholarly journals Cell death and cell protection genes determine the fate of pistils in maize

Development ◽  
1999 ◽  
Vol 126 (3) ◽  
pp. 435-441
Author(s):  
A. Calderon-Urrea ◽  
S.L. Dellaporta
Keyword(s):  
Cell Death ◽  
Sex Determination ◽  
Sexual Maturation ◽  
Temporal Pattern ◽  
Death Process ◽  
Cell Protection ◽  
Selective Elimination ◽  
Cell Death Process ◽  
A Cell ◽  
Unisexual Flowers

The formation of unisexual flowers in maize requires the selective elimination and sexual maturation of floral organs in an initially bisexual floral meristem. Elimination of pistil primordia occurs in the primary and secondary florets of the tassel spikelets, and in the secondary florets of ear spikelets. Ill-fated pistil cells undergo a cell death process associated with nuclear degeneration in a specific spatial-temporal pattern that begins in the subepidermis, eventually aborting the entire organ. The sex determination genes tasselseed1 and tasselseed2 are required for death of pistil cells. tasselseed1 is required for the accumulation of TASSELSEED2 mRNA in pistil cells. All pistil primordia express TASSELSEED2 RNA but functional pistils found in ear spikelets are protected from cell death by the action of the silkless1 gene. silkless1 blocks tasselseed-induced cell death in the pistil primordia of primary ear florets. A model is proposed for the control of pistil fate by the action of the ts1-ts2-sk1 pathway.

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