The current plant two-sex model makes the assumption that there are only two sexual reproductive states: male and female. However, the application of this model to the plant alternation of generations requires the subtle redefinition of several common terms related to sexual reproduction, which also seems to obscure aspects of one or the other plant generation: For instance, the homosporous sporophytic plant is treated as being “asexual,” and the gametophytes of angiosperms treated like mere gametes. In contrast, the proposal is made that the sporophytes of homosporous plants are indeed sexual reproductive organisms, as are the gametophytes of heterosporous plants. This view requires the expansion of the number of sexual reproductive states we accept for plants, therefore a three-sex model for homosporous plants and a four-sex model for heterosporous plants are described and then contrasted with the current two-sex model. These new models allow the use of sexual reproductive terms in a manner largely similar to that seen in animals, and may better accommodate the plant alternation of generations life cycle than does the current plant two-sex model. These new three-sex and four-sex models may also help stimulate new lines of research, and examples of how they might alter our view of the flower, and may lead to new perspectives in terms of sexual determination, are presented. Thus it is suggested that plants have more than merely two sexual reproductive states, and that recognition of this may promote our study and understanding of plants.

Ferns and lycophytes, now known as monilophytes, have received scant molecular attention in comparison to angiosperms. The advent of high-throughput technologies allowed an advance towards a greater knowledge of their elusive genomes. In this work, proteomic analyses of heart-shaped gametophytes of two ferns were performed: the apomictic species Dryopteris affinis ssp. affinis and its sexual relative Dryopteris oreades. In total, a set of 218 proteins shared by these two gametophytes were analyzed using the STRING database, and the proteome associated with metabolism, genetic information processing, and responses to abiotic stress is discussed. Specifi-cally, we report proteins involved in the metabolism of carbohydrates, lipids, and nucleotides, the biosynthesis of amino acids, and secondary compounds, energy, oxido-reduction, transcrip-tion, translation, protein folding, sorting and degradation, and responses to abiotic stress. Look-ing at the interactome of this set of proteins, it represents a total network composed of 218 nodes and 1,792 interactions, obtained mostly from databases and textmining. The interactions among the identified proteins of the ferns D. affinis and D. oreades, together with the description of their biological functions, might contribute to a better understanding of the function and develop-ment of ferns as well as to fill knowledge gaps in plant evolution.

Ferns and fern-allies, now known as Monylophytes, have received scant molecular attention, in relation to angiosperm group. The advent of high-throughput technologies allows to advance towards a greater knowledge of their elusive genome. In this work, samples of apogamous and sexual heart-shaped gametophytes from two ferns: the apomictic species Dryopteris affinis ssp. af-finisand its sexual relative Dryopteris oreades were extracted and identified. In total, a set of 218 proteins shared by these gametophytes were analysed by using the STRING database, and the proteome associated to metabolism, genetic information processing and responses to abitotic stress is discussed. Specifically, there are reported proteins involved in metabolism of carbohy-drates and lipids, biosynthesis of amino acids, metabolism of nucleotides, energy, and secondary compounds, oxido-reduction, transcription, translation, folding, sorting, and degradation, and response to abiotic stress. Some homologs of proteins found are MACCI-BOU (MAB1), MOSAIC DEATH 1 (MOD1), MAINTENANCE OF PHOTOSYSTEM II UNDER HIGH LIGHT 2 (MPH2), TRANSPARENT TESTA 5 (TT5), ALBINO OR GLASSY YELLOW 1 (AGY1), LEUCYL AMINOPEP-TIDASE 1 and 3 (LAP1 and LAP3), or LOW EXPRESSION OF OSMOTICALLY RESPONSIVE GENES 1 (LOS1). The interactome of the set of proteins was also studied, being the most common interac-tions database and textmining. All these data about the interactions that exist between the stud-ied proteins of the ferns D. affinis and D. oreades, together with the description of their biological function, might contribute to better understand the functioning and development of ferns as well as to fulfil gaps of knowledge in plant evolution.