Morphogenetic responses obtained from a variety of somatic explant tissues of data palm

Shoot tip, bud, leaf, stem and root explants from bearing trees, offshoots, seedlings, and asexual plantlets ofPhoenix dactylifera L. were cultured on modified Murashige and Skoog nutrient media containing 3 g/l activated charcoal, 100 mg/l 2,4-dichlorophenoxyacetic acid, 3 mg/l N ⁶-(Δ²-isopentyl)adenine to obtain callus. Differential morphogenetic responses were obtained from calli dependent on the explant type and parent source. Subcultured shoot tips and leafy lateral buds callus on nutrient media devoid of charcoal and supplemented with 0.1 mg/l α-naphthaleneacetic acid (NAA) produced adventitious plantlets. Subcultured leaf calli produced roots only. Root callus failed to exhibit any morphogenetic response upon subculturing. Undifferentiated non-leafy buds and stem tissues did not give rise to callus, regardless of the parent source. Generally, the best callus and embryogenetic responses from explants were obtained from seedling and plantlet parent sources. Similarly, organogenetic responses such as root formation and shoot development from shoot tips cultured on media containing 10 mg/l NAA were also related to the parent explant source. Mention of a trademark or proprietary product in the paper does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be available.     

Resource-related variables drive individual variation in flowering phenology and mediate population-level flowering responses to climate in an asynchronously reproducing palm

Many tropical plant species show wide intra-population variation in reproductive timing, resulting in the protracted presence of flowering and fruiting individuals. Various eco-evolutionary drivers have been proposed as ultimate causes for asynchronous phenology, yet little is known about the proximate factors that control reproductive onset among individuals or that influence the proportion of trees producing new inflorescences within a population. We employed a nine-year phenological record from 178 individuals of the hyperdominant, asynchronously flowering canopy palm, Oenocarpus bataua (Arecaceae)¸ to assess whether resource-related variables influence individual- and population-level flowering phenology. Among individuals, access to sunlight increased rates of inflorescence production, while the presence of resource sinks related to current investment in reproduction—developing infructescences—reduced the probability of producing new inflorescences. At the population level, climate anomalies induced by El Niño Southern Oscillation (ENSO) affected the proportion of the population producing inflorescences through time. Moreover, the effects of ENSO anomalies on flowering patterns depended on the prevalence of developing infructescences in the population, with stronger effects in periods of low developing-infructescence frequency. Taken together, these results suggest that resource-related variables can drive phenological differences among individuals and mediate population-level responses to larger-scale variables, such as climate anomalies. Consequently, a greater focus on the role of resource levels as endogenous cues for reproduction might help explain the frequent aseasonal phenological patterns observed among tropical plants, particularly those showing high intra-population asynchrony.     

Historical contingency in the evolution of primate color vision

Primates are unique among eutherian mammals for possessing three types of retinal cone. Curiously, catarrhines, platyrrhines, and strepsirhines share this anatomy to different extents, and no hypothesis has hitherto accounted for this variability. Here we propose that the historical biogeography of figs and arborescent palms accounts for the global variation in primate color vision. Specifically, we suggest that primates invaded Paleogene forests characterized by figs and palms, the fruits of which played a keystone function. Primates not only relied on such resources, but also provided high-quality seed dispersal. In turn, figs and palms lost or simply did not evolve conspicuous coloration, as this conferred little advantage for attracting mammals. We suggest that the abundance and coloration of figs and palms offered a selective advantage to foraging groups with mixed capabilities for chromatic distinction. Climatic cooling at the end of the Eocene and into the Neogene resulted in widespread regional extinction or decimation of palms and (probably) figs. In regions where figs and palms became scarce, we suggest primates evolved routine trichromatic vision in order to exploit proteinaceous young leaves as a replacement resource. A survey of the hue and biogeography of extant figs and palms provides some empirical support. Where these resources are infrequent, primates are routinely trichromatic and consume young leaves during seasonal periods of fruit dearth. These results imply a link between the differential evolution of primate color vision and climatic changes during the Eocene-Oligocene transition.     

Early inflorescence and floral development in Cocos nucifera L. (Arecaceae: Arecoideae)

Palms are generally characterized by a large structure with a massive crown that creates difficulties in anatomical studies. The flowering behaviour of palm species may be a useful indicator of phylogenetic relationships and therefore evolutionary events. This paper presents a detailed histological study of reproductive development in coconut (Cocos nucifera L.), from initiation up to maturation of staminate and pistillate flowers. Reproductive development in coconut consists of a sequence of individual events that span more than two years. Floral morphogenesis is the longest event, taking about one year, while sex determination is a rapid process that occurs within one month. The inflorescence consists of different ultimate floral structural components. Pistillate flowers are borne in floral triads that are flanked by two functional staminate flowers. The staminate flowers are born in floral diads towards the base of the rachilla followed by solitary flowers in the middle to top of the rachilla. Three primary phases were identified in reproductive development, namely, transition of axillary bud into inflorescence bud, formation of floral buds, and sexualisation of individual flower buds. All developmental events with respect to stage or time of occurrence were determined.     

Unusual stilbenoids and a stilbenolignan from seeds of Syagrus romanzoffiana

Stilbenoids, syagrusins A-B (1-2), and a stilbenolignan, 5-hydroxyaiphanol (3), along with three known phenylpropanoids (4-6), were isolated from seeds of Syagrus romanzoffiana. Compounds 1 and 2 possess unusual 1,4,4a,9a-tetrahydrofluoren-9-one and bicyclo[3.3.0]octanedione skeletons, respectively, whereas compound 3 is a stilbenolignan belonging to a very rare structural class of plant secondary metabolites. Their structures were elucidated by spectroscopic analyses. Compounds 1-3 exhibited moderate inhibitory activity against α-glucosidase with IC₅₀ values of 16.9 μM (1), 23.7 μM (2) and 12.8 μM (3), respectively.     

Litter‐trapping plants: filter‐feeders of the plant kingdom

Litter‐trapping plants have specialized growth habits and morphologies that enable them to capture falling leaf litter and other debris, which the plants use for nutrition after the litter has decayed. Litter is trapped via rosettes of leaves, specially modified leaves and/or upward‐growing roots (so‐called ‘root baskets’). Litter‐trappers, both epiphytic and terrestrial, are found throughout the tropics, with only a few extra‐tropical species, and they have evolved in many plant families. The trapped litter mass is a source of nutrients for litter‐trapping plants, as well as food and housing for commensal organisms. Despite their unique mode of life, litter‐trapping plants are not well documented, and many questions remain about their distribution, physiology and evolution.–© 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 554–586.     

Taxonomy and conservation: A case study from Chamaedorea alternans

BACKGROUND AND AIMS: The establishment of justified recommendations in conservation biology requires robust taxonomic treatments for the group(s) being considered. Controversial or poorly developed taxonomies can have a negative impact on conservation assessments. One example of a taxonomically difficult and controversial species complex that is important in conservation involves two species of Mexican palms, Chamaedorea tepejilote and C. alternans. The goal of this study was to investigate whether C. alternans and C. tepejilote are genetically distinct within the Los Tuxtlas region of Veracruz. METHODS: Individuals corresponding to the morphology of C. alternans and C. tepejilote were collected from sympatric and allopatric regions within the Los Tuxtlas Biological Station. Eighty-eight samples were genotyped using amplified fragment length polymorphism (AFLP) markers. Cluster and ordination analyses were used to investigate patterns of differentiation. KEY RESULTS: UPGMA and PCO analyses of AFLP profiles recovered two divergent clusters corresponding to morphologically defined C. tepejilote and C. alternans. No intermediate genotypes were observed and five of the 45 loci were fixed for either the presence or absence between the species. The patterns of divergence observed do not identify a role for sympatric speciation. CONCLUSIONS: The observed patterns of differentiation support the recognition of C. alternans as distinct from C. tepejilote. A suite of vegetative and reproductive morphological features can be used to help distinguish these taxa in the field, but they can be difficult to differentiate from preserved material. Previous treatments of the variation found within the complex (C. alternans and C. tepejilote) as intraspecific variance is unjustified. Given that the Los Tuxtlas region has suffered from historical and ongoing deforestation and that Chamaedorea includes numerous endangered taxa, retaining conservation status for C. alternans serves to help safeguard individuals of the species as well as a region and larger taxonomic group all under considerable threat from human activities.