- SEX DETERMINATION

Sex determination and phenogenetic in Ecballium elaterium (L.) Richard. The sexual inflorescence type on the stem

The cucurbitous Ecballium elaterium (L. Richard) has attracted the studies in the zigote sex biology during years. (Galan, 1946, 1951, 1953, 1964 ; Mathar, 1949; Galan-Estella, 1989), specially due, to the easy morphological analysis that can be made for clarifying the phenotype- genotype relationship of this plant. It is well known the three main sexual allele combination influence in the plant sex (Galán, 1954 and Ayala, 1984). The works carried out in this angyosperm are quite simple because these plants are considered paradigmatic, in the sense that female plants have only female inflorescences with female flowers, androgyne plants have andropolygamous inflorescences with all kind of flowers and a specific flower sexual polarity distribution along the inflorescences (Marañón et al. submmited) and male plants have only male inflorescences. Thus, only three main sexual inflorescence types (S. I. T.) correspond to the five sexual genotype of sexual alleles found in plants. (Table 1). In spite of their rarity (2%-7%) the andropolygamous inflorescences have a great importance, not only by the existence of the hermaphrodite flowers, but by the different development of the androecium respect the gynoecium (Sánchez Anta, 1974 and Marañón et al., submmited) wich is a unique finding in the research on the zygotic sex of plants. The greater development of the gynoecium and the lesser of the androecium constitute conclusive macroscopic proof of the existence of a sexual substance wich according its concentration, governs the sex of Ecballium elaterium (Galán, 1971)
Other works found the curious distribution of these plants according the climatic gradient (Costich, 1995) at Earth, the physiological properties of the Ecballium elaterium juice in isolated rabbit hearts (Hasen et al., 1993) and the influence of steroidal hormones on flower sex expression (Kopcewicz, 1971), but the most promising studies will come from the knowledge of plant sex determination regarding the understanding of the biochemical events related with the genetic of the plants.
Following our research into the biology of the sex of this angiosperm, begun by Professor Galán we were promted to examine the existence of a sexual polarity respect the sexual inflorescence type (S.I.T.) on the stem of this androgyne cucurbitous. To check experimentally the sexual polarity of the inflorescences in the stem two variables were employed, the sexual inflorescence type (S.I.T) and the phylotactic number (P.N.) of the inflorescence on the stem. The relationship between S.I.T and P.N. is homologous to the relationship defined of the flower sex and the P.N. on the stem (Marañón et al. summited), but not analogous, because the different S.I.T are contingently related to another two characters of the same inflorescence: the number of flowers and the lenght of the peduncle of the inflorescence. These characters are easily observable in the inflorescences of the intersubspecific hybrid androgyne plants (a+ad genotype). A statystical formula will be included and the results obtained will be referred in such terms. So, the aim of the present work is the finding of a relation between the S.I.T and the P.N.. It will be necessary to study the stochastic distribution proccess of the inflorescence type on the stem of the Ecballium elaterium androgyne plants. This proccess can be analyzed during the stem development if the proccess is considered from the time point of view or along the stem if it is considered in spatial terms . We will only study the latter stochastic proccess.

Sex determination and phenogenetic in Ecballium elaterium (L.) Richard. Flower sexual polarity in inflorescences.

Floral biology and sex distribution along the inflorescences has been studied in Ecballium elaterium (L.) Richard, a cucurbitaceae that can be found in Nature in two subspecies: Dioecious (with male and female plants) and monoecious (with androgyne, or trimonoecious, plants). A statistical analysis has been carried out in a number of inflorescences corresponding to androgynous plants of the monoecious subspecie and the interspecific hybrid born as a result of the crossing of a dioecious plant with a monoecious one of the Mediterranean wild cucurbitaceae Ecballium elaterium (L.) Richard. An acropetal sexual "female --> male" distribution can be discerned in both studied subspecies (wild and interspecific hybrid), but it can be found some differences in the number of hermaphrodite flowers and their distribution along the inflorescence. These events let us to relate the genetic theory that explains the dioeciae and monoeciae in Ecballium elaterium with some processes in the development of the primary and secondary floral organs. It can be purposed some explanations that clarify, as possible, the three fields of research in sex determination: the identification of specific markers for stamens, carpels…(expression program); the analysis of induced signals (such as phytohormones), and finally, the knowledge of the regulatory genes of the sex determination. All of this could give an explanation of the morphogenetic processes that occurs in the sexual determination in Ecballium elaterium (L.) Richard.