First evidence of late-acting self-incompatibility in the Aristolochiaceae.

Most Aristolochiaceae species studied so far are from temperate regions, bearing self-compatible protogynous trap flowers. Although self-incompatibility has been suggested for tropical species, the causes of self-sterility in this family remain unknown. To fill this gap, we studied the pollination of the tropical Aristolochia esperanzae, including the physical and physiological anti-selfing mechanisms. Floral visitors trapped inside flowers were collected to determine the pollinators. Protogyny was characterized by observing the temporal expression of sexual phases and stigmatic receptivity tests. The breeding system was investigated using hand-pollination treatments. Pollen tube growth was observed using epifluorescence to identify the self-incompatibility mechanism. Flies were the most frequent visitors found inside A. esperanzae trap flowers, with individuals from the family Ulidiidae being potential pollinators since they carried pollen. The characteristic flower odour and presence of larvae indicate that A. esperanzae deceives flies through oviposition-site mimicry. Although this species showed incomplete protogyny, stigmatic receptivity decreased during the male phase, avoiding self-pollination. Fruits developed only after cross- and open pollination, indicating that the population is non-autonomous, non-apomictic, and self-sterile. This occurred through a delay in the growth of geitonogamous pollen tubes to the ovary and lower ovule penetration, indicating a late-acting self-incompatibility mechanism. Our findings expand the number of families in which late-acting self-incompatibility has been reported, demonstrating that it is more widespread than previously thought, especially when considering less-studied tropical species among the basal angiosperms.

Investigating the longstanding mystery of stigma length differences between morphs of distylous plants.

Longer stigmas in short-styled morphs of distylous plants have been considered an adaptive characteristic that increases intermorph pollen deposition. The greater pollen deposition in short-styled stigmas may be a by-product of their longer length, making deposition effectiveness comparison between morphs unfeasible. Thus, investigating which morph has the relatively most efficient stigma (i.e., pollen deposition per unit length) can boost our understanding of the adaptive significance of longer stigmas. Here, we compared pollen deposition between morphs relative to stigma length and assessed whether short-styled stigmas are more, less, or equally effective in receiving pollen grains per unit length. We reviewed the literature to characterize the extent of sigma length differences between morphs using the two most speciose distylous genera as model systems: Palicourea and Psychotria (Rubiaceae). Then, we conducted a between-morph comparison of raw and relative pollen depositions in a Palicourea rigida population. We confirmed that short-styled stigmas were longer than long-styled stigmas in both Palicourea (194.31% longer) and Psychotria (52.59% longer) flowers. Furthermore, in the focal Pal. rigida, although short-styled stigmas were 268.04% longer and received 97.04% more pollen grains than long-styled stigmas, the relative pollen deposition had a reverse pattern, with short-styled stigmas being two-times less efficient in receiving pollen. Our results indicate that the longer length of the short-styled stigmas may have a compensatory effect, increasing the chances of pollen grains reaching the stigma and probably maintaining disassortative intermorph pollination in distylous plants.

Incomplete resupination during floral development leads to pollination failure in a slipper orchid.

In many families, plants undergo floral resupination by twisting through approximately 180° during floral development so that the flower is effectively positioned upside down. In most orchids, resupination results in the median petal (i.e., the labellum) becoming lowermost, which plays a crucial role in pollination by serving as a landing platform or as a trapping device, or both. Incomplete resupination is predicted to lead to reduced pollination, although tests of this assumption are still lacking. We investigated the effect of resupination using Phragmipedium vittatum, a rare lady's slipper orchid whose specialized labellum forms a trapping device. First, we surveyed the natural occurrence of incomplete resupination. Then we manipulated flowers into non- (≈0°), half- (≈90°), and fully resupinate (≈180°) positions to test the effect of orientation on pollen smear removal and deposition by pollinators (female hoverflies). We found that ca. 10% of flowers in the natural population were not fully resupinate, being either non- (upward, 0-60°) or half-resupinate (sideward, 60-120°). The change in orientation prevented the effectiveness of pollination by hoverflies since no pollen smear removal or deposition were found in flowers from non- and half-resupinate treatments. Although these flowers still attracted hoverflies, they were not trapped effectively. As this orchid is incapable of autonomous self-pollination, flowers that do not resupinate fail to set fruits. These results highlight the importance of correct floral orientation provided by resupination to ensure pollination in orchids and other resupinate flowers.

MULTIFOCAL FIXED DRUG ERUPTION MIMICKING ACQUIRED DERMAL MELANOCYTOSIS.

Fixed drug eruptions (FDEs) are adverse drug reactions manifesting in the skin after exposure to a certain drug. The lesions can manifest as single or multiple eruptions followed by a post-inflammatory hyperpigmentation. The condition is very common among the young adult population and can be located on different parts of the body: the trunk, extremities, face, lips, etc. We report a case of a multifocal FDE following oral intake of Loratadine, Cetirizine dihydrochloride, Ibuprofen and/or Acetylsalicylic acid. Patch testing was recommended but later on declined by the patient. However, a small punch biopsy confirmed the diagnosis of multifocal fixed drug eruption. The lesions are often misdiagnosed or mistaken for other skin conditions. Differential diagnosis with an acquired dermal melanocytosis or other cutaneous eruptions could be done. Therefore, a brief review of the above-mentioned medications in the pathogenesis of the condition will be discussed.

Host plant intraspecific variation determines gall traits.

Galls display a multiplicity of traits, including colours, which are driven by pigment accumulation. Their conspicuousness has attracted researchers' attention and several hypotheses have been raised. However, plants themselves vary intra-specifically, including in their pigment concentrations. As galls are a result of host tissue development, colours may be a by-product of the host's own traits, being more conspicuous simply because the sites where galls develop already have the predisposition to accumulate more pigment. Here, we call this the host variation hypothesis. We test this hypothesis using the system of galls induced by Palaeomystella oligophaga on Macairea radula host plant. Using spectrophotometry, we calculated the Anthocyanin Reflectance Index (ARI) of gall projections, which are responsible for their characteristic colours. We tested the influence of occupant identity (galling insect or any natural enemy), gall volume, parenchyma thickness, height from the ground, ARI of leaf, ARI of gall surface and ARI of the respective stem. We corroborated the host variation hypothesis since the anthocyanin content in stems and in galls' projections were positively related. Moreover, anthocyanin in galls' projections was positively related to anthocyanin in the gall surface and negatively related to gall volume and parenchyma thickness. This shows that, besides the host specificities, galls' own traits may also be responsible for pigment accumulation, influencing their colours. In this study, using colour as an example, we show that although galls tend to be considered complex expressions of galling insects' stimuli, their traits may be simply influenced by previous and specific attributes of the host organs.