| dc.description.abstract | Malpighiaceae comprises about 1,300 tropical species, distributed in 78 genera. The
family is proven monophyletic. However, many of its intrafamilial relationships have not
been elucidated, so its lineages are treated as informal clades. Embryological data,
especially on the development of anthers in the family, are available in the literature for
only six species. Of these, only Stigmaphyllon bonariense (Hook. & Arn.) C.E. Anderson
and S. jatrophifolium A. Juss. have detailed descriptions of anther development, but both
belong to derived lineages of Malpighiaceae. Embryological data are taxonomically
promising when examined from a phylogenetic perspective and could, for example, assist
in circumscribing genera and subfamilies in Malpighiaceae. In this context, the objective
was to describe the development of anthers, as well as the microsporogenesis and
microgametogenesis of species of basal lineages of Malpighiaceae and, by comparing
them to the data available in the literature for Malpighiaceae and other phylogenetically
close families, to raise possible plesiomorphic embryological characters for the family.
For this, we selected floral buds at different stages of the development of Galphimia
gracilis Bartl. and Verrucularia glaucophylla Juss. (galphimioid clade), Byrsonima
dealbata Griseb. and Byrsonima intermedia A.Juss. (byrsonimoid clade) and Pterandra
pyroidea A.Juss. (acmantheroid clade). The samples were usually processed for light
microscopy, and histochemical tests were performed. The anthers of the five species
showed very similar developmental patterns, fitting into the basic type of development.
However, the number of medium layers was variable: three in P. pyroidea and two in the
other species. The five species share the secretory tapetum with binucleated cells, the
simultaneous cytokinesis of microsporocytes; microspore tetrahedral tetrads; pollen
grains dispersed in bicellular form. In species of derived lineages, the basic type of anther
development is also observed. However, in Stigmaphyllon, the tapetum cells are
multinucleated, and the tissue can be secretory type in S. jatrophifolium, non-syncytial
invasive in S. bonariense and syncytial invasive in S. periplocaefolium f. intermediate
Nied. The anthers of the species analyzed in this work still share, with other families of
Malpighiales, the basic type of development, the secretory tapetum with binucleated cells,
and the bicellular pollen grains at the time of dispersal. Based on this data, it is possible
to infer that the basic anther developmental type, the secretory tapetum with binucleated
cells, and the dispersed grains with two cells are plesiomorphic states in Malpighiaceae.
However, knowledge about the development of Malpighiaceae anthers should be
expanded, and more species should be studied to corroborate the observed trends. | |
