Epidermal and subepidermal changes during the formation of hairy galls induced by Eriophyidae on Avicennia schaueriana leaves.

Leaf-galling Eriophyidae (Acarina) may promote simple or complex alterations in the organs of their host plants, such as an increase in indumentum density or the reorganization of epidermis and ground system tissue patterns. To test if hairy galls of Eriophyidae on Avicennia schaueriana (Acanthaceae) are related to complex changes, leaf galls in distinct developmental phases were compared to non-galled leaves using anatomical, histochemical, and histometric analyses. Quantitative comparisons of preferential gall induction sites and gall area according to distinct leaf portions were made to evaluate if the impacts of gall formation can be related to the distinct potentialities of leaf microsites.

Megagametophyte development and female sterility in Maytenus obtusifolia Mart. (Celastraceae).

Reproduction in flowering plants is closely related to the megagametophyte, since the megagametophyte is involved in pollen tube reception and contains the two female gametes-egg cell and central cell. Previous conventional light microscopy methods have shown that female sterility in perfect flowers of Maytenus obtusifolia is associated with the occurrence of sterile ovules whose megagametophytes have hypertrophied synergids. Here, using transmission electron microscopy and cytochemical methods, we compare the megagametophytes in fertile and sterile ovules from perfect and pistillate flowers, and investigate the cellular events that result in the degradation of the megagametophyte cells from sterile ovules.

Pollen grain development and male sterility in the perfect flowers of Maytenus obtusifolia Mart. (Celastraceae).

Perfect flowers of Maytenus obtusifolia have partial sterility of pollen grains, resulting in collapsed and developed free microspores. However, the cellular events resulting in partial male sterility have not been determined. In pistillate flowers of this species, male sterility is related to the premature programmed cell death (PCD) in tapetum and sporogenic cells.