Protoplasma最新文献

Calcium is a central signal regulating a plethora of cellular events. Specificity is brought about by spatio-temporal patterns, so-called signatures that are established by the activity of calcium channels residing in the membranes of different compartments. The role of two-pore calcium channels (TPC) for such signatures has been debated controversially, because evidence for localisation in both, the plasma membrane as well as in the tonoplast, has been proposed. Using a GFP fusion of the tobacco homologue NtTPC1A in the background of tobacco BY-2 cells, we show that this channel is localised at the tonoplast. This localisation depends on actin filaments, but not on microtubules, as shown by pharmacological interference. Since the construct is driven by the constitutive Cauliflower Mosaic Virus 35S promoter, we can also detect phenotypic differences, such as impaired auxin-dependent cell elongation, reduced intracellular calcium content (that can be rescued by supplementation of calcium), and partial resistance to gadolinium, inhibitors of calcium influx. We also monitored the response to harpin, an elicitor from the phytopathogenic bacterium Erwinia amylovora. Here, the overexpressor line shows a higher sensitivity indicating that NtTPC1Aparticipates in defence-related programmed cell death. The data are discussed with respect to a role of NtTPC1A for spatial calcium signatures, and the regulation of cell growth by actin and auxin.

Rupestrian fields are high-altitude environments with nutrient-poor soils, posing challenges for dioecious species like Baccharis platypoda DC. This study assessed leaf anatomy and chemical composition to explore variations related to environmental conditions and sex differences. Leaves from male and female individuals were collected in Serra do Cipó, Minas Gerais, Brazil. Anatomical and chemical analyses, including histochemical tests and chromatographic techniques, were performed to evaluate structural traits and compound profiles. Both sexes exhibited a uniseriate epidermis, dorsiventral mesophyll, and hypostomatic profile, with capitate glandular trichomes distributed on both surfaces, with abundant secretion observed predominantly on the abaxial side. Significant differences were observed between sexes in the thickness of the adaxial cuticle and epidermis, as well as in the proportions of palisade and spongy parenchyma. Histochemical tests detected various compounds in trichomes and secretions. Flavonoid content ranged from 5.95 to 7.50% relative to the dry weight of the crude extract, with higher values observed in female leaves. Chromatographic analyses annotated phenolic compounds, terpenes, and other less common classes. The findings highlight traits that may contribute to ecological success in nutrient-poor environments and reveal subtle sex-based anatomical and chemical differences. This study advances the understanding of the responses of dioecious species to challenging habitats and provides a basis for future ecological and biochemical research.

The dioecious species Ilex paraguariensis (yerba mate) holds significant economic and cultural value, yet key aspects of its reproductive development remain unresolved. This study combines histological, scanning electron microscopy (SEM), and cytogenetic analyses to elucidate floral ontogeny, microsporogenesis, and sexual differentiation in yerba mate. For both sexes, six arbitrary descriptive stages of floral development were established based on all available data. Our findings reveal that floral development follows a type I pattern, initiating as bisexual before diverging into unisexual flowers. In staminate flowers, functional androecium development coincides with early parenchymatization of the pistillode and suppression of megasporangial initiation-a potential adaptive strategy to minimise resource wastage. Cytogenetic analysis confirmed regular microsporogenesis, identified off-plate bivalents at higher frequencies than previously reported, and provided the first complete meiotic progression leading to gamete formation in this species. Besides, SEM revealed novel stephanocytic structures on pistillodes, interpreted as nectarostomata, suggesting a role in pollinator attraction. These findings challenge prior assumptions regarding nectary presence in yerba mate. In pistillate flowers, staminodes undergo abortion via tapetal degeneration and aberrant sporogenous tissue collapse before meiosis, aligning with previously defined categories of organ abortion. Sexual dimorphism emerges early and is governed by distinct mechanisms: constitutive pistillode sterility in males and selective microsporangial tissue abortion within the antherodes in females. This study advances the understanding of reproductive biology in a commercially important crop, providing key morphological and cytological insights that will guide future taxonomic, developmental, and evolutionary studies within Ilex.

The Brazilian Cerrado stands as the most biodiverse neotropical savanna, supporting a vast array of endemic species uniquely adapted to its challenging environment. These species have evolved under strong selective pressures imposed by recurrent natural disturbances, including pronounced seasonal drought, intense herbivory, and frequent fire events. Consequently, Cerrado species have evolved diverse morpho-anatomical adaptations to persist in this fire-prone ecosystem. Resprouting capacity -whether from belowground or aboveground buds-represents a key functional trait for post-disturbance regeneration. While thick bark has long been recognized as the primary mechanism protecting aerial meristematic tissues, emerging research reveals finer-scale adaptations that complement bark defenses. This study investigates the protective features of aerial buds in two herbaceous Chamaecrista species (Fabaceae) to the Brazilian Cerrado. We employed a multi-technique anatomical approach combining light microscopy, histochemical analysis, fluorescence microscopy, and scanning electron microscopy (SEM). Our results revealed the presence of secretory structures, such as colleters and extrafloral nectaries, which develop at distinct temporal stages, indicating different phases of bud protection throughout plant development. Additionally, structures such as hairy leaf primordia with phenolic compound accumulation, stipules, and accessory buds were observed, reinforcing both structural and chemical investments in the protection of aerial buds. These structures confer high resilience to intense UV radiation and herbivory, providing the species with greater resistance and the ability to withstand various environmental disturbances. These findings demonstrate that herbaceous Cerrado species employ sophisticated, multi-layered strategies for aerial bud protection, comparable in complexity to woody species. The discovery of such refined adaptive mechanisms in herbaceous and subshrub growth forms challenges the traditional woody-centered paradigm of Cerrado resilience research.

This study examined the influence of exogenous gamma-aminobutyric acid (GABA) on drought tolerance in faba bean (Vicia faba) under 15% PEG-induced drought stress conditions. Faba bean plants were subjected to treatments with varying GABA concentrations (0.5, 1, and 2 mM) to evaluate physiological, biochemical, and molecular responses to drought stress. The results indicated that a concentration of 0.5 mM GABA significantly enhanced the photosynthetic rate, stomatal conductance, and chlorophyll content, while also markedly improving relative water content (RWC). At this concentration, GABA treatment mitigated oxidative damage, evidenced by reduced levels of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂), and increased antioxidant enzyme activities (catalase, superoxide dismutase, and ascorbate peroxidase). Furthermore, GABA supplementation influenced the accumulation of proline and soluble sugars, thereby facilitating osmotic regulation and stress adaptation. Gene expression analysis revealed that GABA modulated key drought-responsive genes, notably enhancing the expression of those associated with antioxidant defenses (VfCAT, VfSOD, VfAPX), water transport (VfPIP), and osmoprotection (VfP5CDH), particularly in leaf and root tissues, with differential effects observed across GABA concentrations. Interestingly, higher concentrations of GABA (1 and 2 mM) yielded reduced or inconsistent outcomes, suggesting the existence of an optimal concentration threshold for stress mitigation. Collectively, these findings underscore the potential of GABA as a beneficial agent for enhancing drought resilience in faba bean, providing a promising strategy to improve crop tolerance to water scarcity.

Adult males of Podisus nigrispinus Dallas (Heteroptera: Pentatomidae) produce pheromones in their dorsal-abdominal glands, which are located internally between abdominal tergites III and IV. These pheromones attract adult individuals making them useful for biological control and as bait for capture. This article presents a morphological description of the dorsal-abdominal glands in male P. nigrispinus using light microscopy, as well as scanning and transmission electron microscopy. The glands consist of a pair of coiled tubular secretory structures, each opening in an enlarged reservoir. The glandular epithelium is composed of three cell layers: a basal layer of flattened cells, a middle layer of both columnar secretory cells and narrowed interstitial cells, and an apical layer of duct cells. The duct cells enclose a glandular reservoir lined with a cuticle, into which the secretory cells release their products through a sinuous intracellular duct. Each glandular reservoir opens outward through a pair of ostioles in the dorsal tergite, controlled by a tegumental valve. Cytoplasmic characteristics suggest that the secretory product is likely synthesized through fatty acid metabolism, similar to the sex pheromones produced by other insects.