RESUMEN
Pera is a neotropical genus that currently belongs to the family Peraceae. This circumscription resulted from an inclusion of the Rafflesiaceae between the old tribe Pereae and all other Euphorbiaceae, and wherein Pereae was elevated to family rank making Euphorbiaceae monophyletic again. These changes are necessary although Rafflesiaceae are holoparasitic with extremely reduced vegetative bodies and large flowers while Peraceae and Euphorbiaceae have well developed vegetative parts and reduced flowers. As the embryology of Peraceae was poorly known, and embryological processes are conservative, we studied the embryology of Pera glabrata, searching for similarities between Peraceae, Rafflesiaceae, and Euphorbiaceae that could support this grouping. Usual methods of light microscopy and scanning electron microscopy were utilised. The results show endothecium with reversed-T-shaped cells, prismatic crystals in the tapetum, and disintegrated aerenchymatous septum in the mature fruit as unique features for Peraceae and possibly apomorphies for the family. In addition to the unisexual flowers, porogamous fertilization is present and one ovule per carpel which may support the Peraceae-Rafflesiaceae-Euphorbiaceae clade. The comparative approach also suggests possible (syn-)apomorphies for linoids and phyllanthoids, only linoids, Rafflesiaceae, Euphorbiaceae, and Ixonanthaceae. The presence of a placental obturator found previously unknown in Peraceae emerged as a possible synapomorphy for the euphorbioids (including Ixonanthaceae, Linaceae, Phyllanthaceae, Picrodendraceae, Peraceae, Rafflesiaceae, and Euphorbiaceae), which appeared in a common ancestor of the group and has been lost in Rafflesiaceae.
Asunto(s)
Magnoliopsida/clasificación , Evolución Biológica , Clasificación , Euphorbiaceae/clasificación , Euphorbiaceae/citología , Euphorbiaceae/embriología , Euphorbiaceae/genética , Flores/clasificación , Flores/citología , Flores/embriología , Flores/genética , Magnoliopsida/citología , Magnoliopsida/embriología , Magnoliopsida/genética , Semillas/clasificación , Semillas/citología , Semillas/embriología , Semillas/genéticaRESUMEN
PREMISE OF THE STUDY: Phylogenetic and morphological studies have helped clarify the systematics of large and complex groups such as the tribe Crotoneae (Euphorbiaceae). However, very little is known about the diversity, structure, and function of anatomical features in this tribe. Crotoneae comprises the species-rich pantropical genus Croton and six small neotropical genera. Here we characterized the anatomy of leaf secretory structures in members of this tribe and explored their function and evolutionary significance. METHODS: Young and mature leaves of 26 species were studied using standard anatomical light microscopy techniques. Three sections of Croton and one representative of Brasiliocroton and Astraea were sampled. KEY RESULTS: We identified five types of secretory structures: laticifers, colleters, extrafloral nectaries, idioblasts, and secretory trichomes. Laticifers were present in all species studied except Croton alabamensis, which instead presented secretory parenchyma cells. Articulated laticifers are reported in Crotoneae for the first time. Colleters of the standard type were observed in the majority of the sampled taxa. Extrafloral nectaries were present in section Cleodora and in B. mamoninha, but absent in section Lamprocroton and Astraea lobata. Idioblasts were spread throughout the palisade and/or spongy parenchyma in most of the studied species. Secretory trichomes were restricted to Lamprocroton except for C. imbricatus. CONCLUSIONS: This study revealed a high diversity of secretory structures, including novel ones, in one of the largest clades of Euphorbiaceae. Our results are promising for investigations on the anatomical and ecophysiological bases of species diversification within Euphorbiaceae.
Asunto(s)
Biodiversidad , Evolución Biológica , Euphorbiaceae/anatomía & histología , Hojas de la Planta/anatomía & histología , Euphorbiaceae/citología , Filogenia , Hojas de la Planta/citología , Especificidad de la EspecieRESUMEN
Although much attention has been paid to the role of stabilizing selection, empirical analyses testing the role of developmental constraints in evolutionary stasis remain rare, particularly for plants. This topic is studied here with a focus on the evolution of a pollen ontogenetic feature, the last points of callose deposition (LPCD) pattern, involved in the determination of an adaptive morphological pollen character (aperture pattern). The LPCD pattern exhibits a low level of evolution in eudicots, as compared to the evolution observed in monocots. Stasis in this pattern might be explained by developmental constraints expressed during male meiosis (microsporogenesis) or by selective pressures expressed through the adaptive role of the aperture pattern. Here, we demonstrate that the LPCD pattern is conserved in Euphorbiaceae s.s. and that this conservatism is primarily due to selective pressures. A phylogenetic association was found between the putative removal of selective pressures on pollen morphology after the origin of inaperturate pollen, and the appearance of variation in microsporogenesis and in the resulting LPCD pattern, suggesting that stasis was due to these selective pressures. However, even in a neutral context, variation in microsporogenesis was biased. This should therefore favour the appearance of some developmental and morphological phenotypes rather than others.
Asunto(s)
Euphorbiaceae/fisiología , Evolución Molecular , Glucanos/metabolismo , Polen/fisiología , Selección Genética , Adaptación Fisiológica , Evolución Biológica , Pared Celular/fisiología , Citocinesis , Euphorbiaceae/clasificación , Euphorbiaceae/citología , Gametogénesis en la Planta , Fenotipo , Filogenia , Polen/clasificación , Polen/citología , Especificidad de la EspecieRESUMEN
Roots of three mangroves, Acanthus ilicifolius, Ceriops tagal and Excoecaria agallocha, collected from forests of the Sundarbans of India were stained with trypan blue to observe arbuscular mycorrhizal colonization. Spores of arbuscular mycorrhizal fungi isolated from rhizospheric soil, collected together with the root samples, also were stained for testing the suitability of the dye as a fluorochrome. Confocal laser scanning microscopy images were constructed. A. ilicifolius and E. agallocha exhibited "Arum" type colonization with highly branched arbuscules, whereas C. tagal showed "Paris" type association with clumped and collapsed arbuscules. We demonstrated that trypan blue is a suitable fluorochrome for staining arbuscular mycorrhizal fungal spores, fungal hyphae, arbuscules and vesicles, which presumably have a considerable amount of surface chitin. It appears that as the integration of chitin into the fungal cell wall changes, its accessibility to trypan blue dye also changes.
Asunto(s)
Colorantes Fluorescentes , Magnoliopsida/microbiología , Micorrizas/citología , Raíces de Plantas/microbiología , Azul de Tripano , Acanthaceae/química , Acanthaceae/citología , Acanthaceae/microbiología , Euphorbiaceae/química , Euphorbiaceae/citología , Euphorbiaceae/microbiología , Magnoliopsida/química , Magnoliopsida/citología , Microscopía Confocal/instrumentación , Microscopía Confocal/métodos , Micorrizas/química , Rhizophoraceae/química , Rhizophoraceae/citología , Rhizophoraceae/microbiología , Esporas/química , Esporas/citologíaRESUMEN
Investigations on callus cultures of Securinega suffruticosa indicated that the cell line of S. suffruticosa callus was able to accumulate four known Securinega alkaloids with dextro rotation but not levo rotation as reported before: virosecurinine (1), viroallosecurinine (2), 14,15-dihydrovirosecurinine (3) and ent-phyllanthidine (4). Time course studies on the growth of callus cultures were carried out. The effects of different plant growth regulators, sucrose concentrations on callus growth and virosecurinine production were also reported.
Asunto(s)
Alcaloides/metabolismo , Euphorbiaceae/química , Euphorbiaceae/metabolismo , Alcaloides/análisis , Alcaloides/biosíntesis , Alcaloides/química , Azepinas/análisis , División Celular/fisiología , Línea Celular , Cromatografía Líquida de Alta Presión , Medios de Cultivo , Citocininas/farmacología , Euphorbiaceae/citología , Compuestos Heterocíclicos de 4 o más Anillos/análisis , Compuestos Heterocíclicos de Anillo en Puente , Ácidos Indolacéticos/farmacología , Lactonas/análisis , Espectroscopía de Resonancia Magnética , Piperidinas/análisis , Tallos de la Planta/citología , Tallos de la Planta/metabolismo , EstereoisomerismoRESUMEN
In Hevea, rubber synthesis is confined to the cytosol of the highly differentiated laticifer cells. Agronomic and biochemical studies showed that this process uses high amounts of sugars that are efficiently imported into the laticifer. A H(+)-sugar symport system located in the plasma membrane is involved in sugar uptake into laticifers. Laticifer protoplasts were prepared and used in electrophysiological and labeling experiments to test the capacity of this system to transport a variety of sugars such as oligosaccharides from the raffinose family, trace compounds in rubber. Translocation of sugars known to be transported with different efficiency across the plasma membrane of plant cells was also tested. A 1 mM sucrose affinity was found for the symport. All the sugars tested, except palatinose induce membrane depolarization indicating that they were actively absorbed by the laticifer network. This reveals the wide capacity of this peculiar sink for the uptake of sugars.