Alkaloids from leaves of Annona salzmannii and Annona vepretorum (Annonaceae)

Phytochemical investigation of the leaves of Annona salzmannii and Annona vepretorum (Annonaceae) led to the identification of seven aporphine alkaloids, anonaine, asimilobine, norcorydine, lanuginosine, liriodenine, lysicamine and oxonantenine, as well as, 1,3,6,6-tetramethyl-5,6,7,8-tetrahydro-isoquinolin-8-one and vomifoliol. Liriodenine, anonaine, asimilobine and norcorydine were found in A. salzmannii, while liriodenine, oxonantenine, lanuginosine, lysicamine, vomifoliol and 1,3,6,6-tetramethyl-5,6,7,8-tetrahydro-isoquinolin-8-one were found in A. vepretorum. All these compounds are being described for the first time in the leaves of A. salzmannii and A. vepretorum. This is the first report of 1,3,6,6-tetramethyl-5,6,7,8-tetrahydro-isoquinolin-8-one in the Annonaceae. The NMR data for oxonantenine, lanuginosine and lysicamine were reviewed.     

Chemical constituents from the bark of Annona salzmannii (Annonaceae)

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Highlights? Bark of Annona salzmannii yielded sesquiterpenes, steroids, and isoquinoline alkaloids. ? Isoquinoline alkaloids are the chemotaxonomic marker of the genus Annona. ? The NMR data for reticuline (12) were revised. ? Selin-11-en-4α-ol (3) is reported for the first time in the genus Annona.     

Isoquinoline alkaloids from the leaves of Annona leptopetala (Annonaceae)

The phytochemical investigation of the leaves of Annona leptopetala (R. E. Fr.) H. Rainer led to the characterization of tetrahydroprotoberberine corypalmine, and four aporphine (laurotetanine, anonaine, norannuradhapurine and nornuciferine) alkaloids. The structures were established after analysis of their NMR spectral data including 2D NMR experiments. This is the first report of laurotetanine and nornuciferine in A. leptopetala as well as norannuradhapurine in the genus Annona. The ¹³C NMR data of the natural alkaloid norannuradhapurine are reported here for the first time, and the NMR data for the compound corypalmine are reviewed.     

Cytogenotoxic effects of ethanolic extracts of Annona crassiflora (Annonaceae)

Infusions of the leaves and seeds of Annona crassiflora Mart. are commonly employed in the treatment of diarrhoea, snakebites, tumours and disorders of the hair and scalp. The aim of the present study was to investigate the cytotoxic and genotoxic properties of ethanolic extracts of A. crassiflora by evaluating their effects on germination, root elongation, chromosome structure and the cell division of Lactuca sativa (lettuce). The experiment followed a randomized design involving the treatment of L. sativa seeds with ethanolic extracts from leaves and seeds of A. crassiflora applied at ten concentrations (0.0125, 0.025, 0.05, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0, and 1.2 mg/L) and with five repetitions per treatment. Seeds of L. sativa exposed for 48 h to A. crassiflora leaf extract at concentrations ≥ 0.1 mg/L, or to seed extracts at concentrations ≥ 0.2 mg/L, showed germination percentages that were significantly (p < 0.05) lower than those of seeds exposed to aqueous ethanol control. Exposure of L. sativa seedlings to leaf (but not seed) extracts of A. crassiflora produced significant (p < 0.05) reductions in the mitotic indices of root meristem cells of lettuce and induced chromosome and nuclear abnormalities in the root cells. The presence of chromosome stickiness, bridges, fragments, laggard chromosomes and nuclear condensation were also observed. The cytogenetic effects observed suggest that folkloric medicines prepared with extracts of the leaves or seeds of A. crassiflora should be employed with caution.     

A new species of Annona (Annonaceae) from the northeastern Guayana Shield

Annona prevostiae, a new species from the northeastern margin of the Guayana Shield, is described and illustrated.     

Phylogenetics of Annona cherimola (Annonaceae) and some of its closest relatives

Annona cherimola is a woody perennial species in the Annonaceae family that produces edible fruits and has economic importance in several regions of the world with subtropical climates. Together with other 10‐12 species, A. cherimola belongs to the section Atta of the Annona genus with a center of origin in Central America and the Caribbean. Species of the section Atta produce soft skin ripe fruits with raised areoles bounded by recessed furrows. Annona cherimola is the only species of the section naturally found in the Andean region of South America. Currently, no information is available at the molecular level on the phylogenetic relationships of most of the species of Atta and closely related sections in Annona. In order to fill this gap, in this work a phylogenetic approach was performed using five coding and non‐coding plastid DNA regions, to determine the phylogenetic relationships between A. cherimola and other related species included in Atta and other sections of the genus. The results obtained support recent studies that demonstrated the likely Mesoamerican origin of A. cherimola based on biogeographical analysis with SSR markers, rather than the previously considered South American origin hypothesis. In addition, the species belonging to the Atta section did not show monophyly. Finally, A. cherimola and A. pruinosa seem to be phylogenetically close species and additional studies are needed to discern the relations between them.     

Chemical constituents from the leaves and branches of Annona coriacea Mart. (Annonaceae)

The phytochemical investigation of the leaves and branches of Annona coriacea Mart. (Annonaceae) led to the isolation and characterization of eight compounds: five isoquinoline-derived alkaloids, including pukateine (1), liriodenine (4), anonaine (5), obovanine (6), and norisocorydine (7); one terpene lactone known as loliolide (3); one benzoic acid derivative, 2-methoxybenzoic acid (2), and 3,4,5-trimethoxyphenol (8). All compounds, except liriodenine, are being described for the first time in the species A. coriacea, and their chemophenetics relationships were discussed. The structures were elucidated by extensive analyses of 1D and 2D NMR (COSY, HSQC, and HMBC) spectroscopy in combination with MS, and the data were compared with literature values. The NMR dataset of pukateine and obovanine was reviewed. Our results showed that A. coriacea is a typical species of the Annonaceae family and an important source of aporphine alkaloids with chemophenetic relationships with Xylopia, Duguetia, Guatteria, Artabotrys, and Goniothalamus genera.     

ent-Kaurane diterpenes from the stem bark of Annona vepretorum (Annonaceae) and cytotoxic evaluation

This work describes a novel ent-kaurane diterpene, ent-3β-hydroxy-kaur-16-en-19-al along with five known ent-kaurane diterpenes, ent-3β,19-dihydroxy-kaur-16-eno, ent-3β-hydroxy-kaur-16-eno, ent-3β-acetoxy-kaur-16-eno, ent-3β-hydroxy-kaurenoic acid and kaurenoic acid, as well as caryophyllene oxide, humulene epoxide II, β-sitosterol, stigmasterol and campesterol from the stem bark of Annona vepretorum Mart. (Annonaceae). Cytotoxic activities towards tumor B16-F10, HepG2, K562 and HL60 and non-tumor PBMC cell lines were evaluated for ent-kaurane diterpenes. Among them, ent-3β-hydroxy-kaur-16-en-19-al was the most active compound with higher cytotoxic effect over K562 cell line (IC₅₀ of 2.49 μg/mL) and lower over B16-F10 cell line (IC₅₀ of 21.02 μg/mL).     

Genetic diversity of Annona crassiflora (Annonaceae) in northern Minas Gerais State

Genetic diversity analyses of tropical tree species are relevant to landscape management, plant genetic resource inventory, and biological conservation of threatened species. Annona crassiflora is an endangered fruit tree native to the Cerrado biome that is threatened by reduction of natural populations and fruit extraction. We examined the intra- and interpopulational genetic diversity of this species in the northern region of Minas Gerais State. Seventy-two individuals from four natural populations were genotyped using RAPD markers. We found moderate genetic diversity among populations, with Shannon's I index varying between 0.31 and 0.44, and Nei's genetic diversity (H(E)) for the population set equal to 0.31. AMOVA indicated a greater genetic variation within (77.38%) rather than among populations (22.62%), tending towards isolation by distance (Mantel's r = 0.914; P = 0.089). Nei's genetic identity estimates among populations revealed a hierarchical pattern of genetic similarity of form [(CA1, CA2), MC], [(GM)], corroborating the high genetic differentiation between spatially isolated populations.     

The progamic phase of an early-divergent angiosperm, Annona cherimola (Annonaceae)

Background and Aims

Recent studies of reproductive biology in ancient angiosperm lineages are beginning to shed light on the early evolution of flowering plants, but comparative studies are restricted by fragmented and meagre species representation in these angiosperm clades. In the present study, the progamic phase, from pollination to fertilization, is characterized in Annona cherimola, which is a member of the Annonaceae, the largest extant family among early-divergent angiosperms. Beside interest due to its phylogenetic position, this species is also an ancient crop with a clear niche for expansion in subtropical climates.

Methods

The kinetics of the reproductive process was established following controlled pollinations and sequential fixation. Gynoecium anatomy, pollen tube pathway, embryo sac and early post-fertilization events were characterized histochemically.

Key Results

A plesiomorphic gynoecium with a semi-open carpel shows a continuous secretory papillar surface along the carpel margins, which run from the stigma down to the obturator in the ovary. The pollen grains germinate in the stigma and compete in the stigma-style interface to reach the narrow secretory area that lines the margins of the semi-open stylar canal and is able to host just one to three pollen tubes. The embryo sac has eight nuclei and is well provisioned with large starch grains that are used during early cellular endosperm development.

Conclusions

A plesiomorphic simple gynoecium hosts a simple pollen–pistil interaction, based on a support–control system of pollen tube growth. Support is provided through basipetal secretory activity in the cells that line the pollen tube pathway. Spatial constraints, favouring pollen tube competition, are mediated by a dramatic reduction in the secretory surface available for pollen tube growth at the stigma–style interface. This extramural pollen tube competition contrasts with the intrastylar competition predominant in more recently derived lineages of angiosperms.Key words: Annona cherimola, Annonaceae, embryo sac, endosperm, Magnoliid, ovule, pollen–pistil interaction, pollen tube     

The coexistence of bicellular and tricellular pollen in Annona cherimola (Annonaceae): Implications for pollen evolution

Most angiosperms release bicellular pollen. However, in about one-third of extant angiosperms, the second pollen mitosis occurs before anthesis such that pollen is tricellular upon release. The shift from bicellular to tricellular development has occurred several times independently, but its causes are largely unknown. In this work, we observed the coexistence of both kinds of pollen at anther dehiscence in Annona cherimola, a species that belongs to the basal angiosperm family Annonaceae. Examination of pollen cell number during anther development showed that this coexistence was due to a late mitosis starting shortly before pollen shedding. Both types of pollen germinated equally well over the course of development. Because variable proportions of bicellular and tricellular pollen were observed at different sampling times, we tested the role of temperature by performing field and growth chamber experiments, which showed that higher temperatures near anthesis advanced the time of pollen mitosis II. The results show that selection could favor the production of tricellular pollen under certain environmental circumstances that prime rapid pollen germination and provide evidence of a system in which developmental variation persists, but that can be modified by external factors such as temperature.     

Differential effects of weather,plant phenology and predators on the seasonal variation of aphids on cabbage

The aphids Lipaphis erysimi pseudobrassicae (Davis) and Myzus persicae (Sulzer) pose serious threats to the production of cruciferous crops in the tropics. Understanding their population dynamics is important for developing integrated pest management programmes to minimize their damage to crops. This study investigated the effects of climatic factors, natural enemies and plant age on the population dynamics of these pests. The population density of aphids and their natural enemies in 20 cabbage plants, and weather conditions were monitored for five cropping seasons from 2019 to 2021 in two agroecological zones of Ghana (Coastal Savannah and Deciduous Forest zones). The highest population density of L. e pseudobrassicae was recorded in January (dry season) in both agroecological zones, while the highest population density for M. persicae occurred in September (minor rainy season) and August (dry spell) in the Coastal Savannah and Deciduous Forest zones, respectively. The highest aphid densities were noted to occur during periods with low relative humidity and low rainfall. The population density of L. e. pseudobrassicae was significantly negatively related to plant age, air temperature and relative humidity, and positively related to syrphids (Paragus borbonicus) and spiders in the Coastal Savannah zone, while in the Deciduous Forest zone, it was significantly positively related to coccinellids. On the other hand, M. persicae population density was significantly positively related to syrphids and coccinellids in the Deciduous Forest zone. Rainfall negatively affected syrphids in the Coastal Savannah zone, while air temperature positively affected syrphids and negatively affected spiders in the Deciduous Forest zone. Coccinellids had a significant positive relationship with relative humidity in the Deciduous Forest zone. This study provides important insights into the key factors that regulate aphid population densities on cabbage and will support development of timely interventions to manage these pests.     

Influence of seasonal variation to the population growth and ecophysiology of Typha domingensis (Typhaceae)

Journal of Plant Research - Precipitation is an important climatic element that defines the hydrological regime, and its seasonal variation produces annual dry and wet periods in some areas. This...     

Characterization and cross‐species amplification of microsatellite markers in cherimoya (Annona cherimola Mill., Annonaceae)

Fifteen polymorphic microsatellites were developed using a CT/AG‐enriched genomic library of cherimoya cv. Fino de Jete and screened on 23 genotypes from different geographical areas. This is the first set of microsatellites developed in Annonaceae. Fourteen of the microsatellites detected a single locus and only one detected two loci. The number of alleles in the single locus microsatellites ranged from two to six and the observed and expected heterozygosity ranged from 0.17 to 0.61 and from 0.12 to 0.76, respectively. Most of the simple sequence repeats were transferable to other species in the family.     

Contributions of climate,plant phenology and natural enemies to the seasonal variation of aphids on cabbage

Brevicoryne brassicae (L), Lipaphis erysimi (Kalt) and Myzus persicae (Sultzer) (Homoptera: Aphididae) form the aphid complex that causes great losses in Brassicaceae in tropical and subtropical regions. Knowledge of their population dynamics is important for the development of integrated pest management programmes. This study aimed to investigate the effects of cabbage phenology, climatic factors and natural enemies populations on the dynamics of these organisms, and the factors regulating their predators’ occurrence. The densities of aphids and their natural enemies and the climate were monitored for two years in 16 cabbage crops. The highest densities of the aphids occurred during periods of relative humidity (RH) drop, a condition that affects them positively. Regarding the predators, the factors affecting their abundance varied but RH was positively related to most of them. This study provides relevant insights into the factors that regulate the aphids in cabbage and for the decision‐making process of control of these severe pests.     

Influence of physiological phenology on the seasonal pattern of ecosystem respiration in deciduous forests

Understanding the environmental and biotic drivers of respiration at the ecosystem level is a prerequisite to further improve scenarios of the global carbon cycle. In this study we investigated the relevance of physiological phenology, defined as seasonal changes in plant physiological properties, for explaining the temporal dynamics of ecosystem respiration (R_ECO) in deciduous forests. Previous studies showed that empirical R_ECO models can be substantially improved by considering the biotic dependency of R_ECO on the short‐term productivity (e.g., daily gross primary production, GPP) in addition to the well‐known environmental controls of temperature and water availability. Here, we use a model‐data integration approach to investigate the added value of physiological phenology, represented by the first temporal derivative of GPP, or alternatively of the fraction of absorbed photosynthetically active radiation, for modeling R_ECO at 19 deciduous broadleaved forests in the FLUXNET La Thuile database. The new data‐oriented semiempirical model leads to an 8% decrease in root mean square error (RMSE) and a 6% increase in the modeling efficiency (EF) of modeled R_ECO when compared to a version of the model that does not consider the physiological phenology. The reduction of the model‐observation bias occurred mainly at the monthly time scale, and in spring and summer, while a smaller reduction was observed at the annual time scale. The proposed approach did not improve the model performance at several sites, and we identified as potential causes the plant canopy heterogeneity and the use of air temperature as a driver of ecosystem respiration instead of soil temperature. However, in the majority of sites the model‐error remained unchanged regardless of the driving temperature. Overall, our results point toward the potential for improving current approaches for modeling R_ECO in deciduous forests by including the phenological cycle of the canopy.     

Pollen--stigma Interactions: Development and Cytochemistry of Stigma Papillae and their Secretions in Annona squamosa L. (Annonaceae)

The development and cytochemical features of the stigma andstyle have been investigated in Sugar apple, Annona squamosaL., using light and electron microscopy. The pistil is a syncarpwith an open stylar canal. Papillae of epidermal origin lineboth the surface of the stigma and the inner face of the stylarcanal. The papillae contain organelles characteristic of secretorycells with a highly thickened cellulosic wall. The wall is multi-layered,the zones differing in their microfibrillar stacking and orientation.The stigma is of the ‘wet’ type and the surfaceexudate is heterogeneous in microscopic appearance and reactscytochemically for proteins, carbohydrates and lipids. The surfacecuticle undergoes dissolution prior to anthesis. A secretionalso appears in the thickened middle lamella of the sub-epidermalcell layer which reacts cytochemically for pectinaceous acidicpolysaccharides. Esterase activity of papillae is indicative of the receptiveareas, and it is also related to the onset of receptivity. Acidphosphatase activity is intense in the sub-epidermal cell layerswhich probably reflects their secretory activity. Pollinationtriggers a copious flow of secretion onto the stigma surfacewhich engulfs the pollen grains. It appears that most of theacidic polysaccharides of this secretion come from the middlelamella of the sub-epidermal cell layer. Compatible pollen tubes have no apparent barriers to overcomeon their route to the embryo sac and the inherent protogynousdichogamy seems to control the acceptance or rejection of compatiblepollen. Annona squamosa L., sugar apple, stigma, style, secretions     

Pollen development in Annona cherimola Mill. (Annonaceae). Implications for the evolution of aggregated pollen

Background  

In most flowering plants, pollen is dispersed as monads. However, aggregated pollen shedding in groups of four or more pollen grains has arisen independently several times during angiosperm evolution. The reasons behind this phenomenon are largely unknown. In this study, we followed pollen development in Annona cherimola, a basal angiosperm species that releases pollen in groups of four, to investigate how pollen ontogeny may explain the rise and establishment of this character. We followed pollen development using immunolocalization and cytochemical characterization of changes occurring from anther differentiation to pollen dehiscence.