Theoretical and Experimental Plant Physiology最新文献

Abstract

Since antiquity, plant life and complexity have aroused the curiosity of many scholars, including aspects of plant intelligence. While historically the topic of intelligence in plants in academia has been approached with scepticism, more recently this matter has gained evidence, especially in popular science literature. Based on a systematic literature review of scientific journals, this work had two objectives: (1) to describe the history and state-of-the-art of the research on plant intelligence; (2) to evaluate whether the academic literature has followed, in quantity and profile, the current profusion of the theme in popular science vehicles. The results showed that the academic production on the subject in scientific journals, although rich in arguments that account for intelligence in plants, is still not very expressive in comparison with the popular science boost in visibility. Such evidence indicates the persistence of academic resistance to the attribution of this trait to plants. Finally, we discuss implications of this trend for science and for human-nature relationships from a philosophical standpoint.

Higher education offers unique ways to provide students with knowledge of plant biology, as well as an engaging lens through which plants may be seen and appreciated. The tremendous volume of knowledge sometimes calls for introducing a different conceptual view to students who aim to become involved in plant research and related fields. It requires stepping back to consider the plant as a whole organism, connected to other organisms within an ecosystem and as a complex living form with its own plant-specific senses. Inspired by several bestselling books in this field, I launched a Plant Senses course. When using the Plant Senses tool to teach plant biology it is challenging to prevent students from over-interpreting and projecting animal features onto the plants, yet avoid an elitist zoocentric position that denies plant capacities we cannot observe with our animal perception. My course attempts to stimulate students to see the ecological importance of plants for much of life on this planet and to draw their attention to the economic value of plants to human societies. Here, I present the structure of the course and the topics covered. Further, I discuss the potential to spread this approach to other curricula and how these different fields may benefit from implementing such a course.

Motor cognition involves the process of planning and executing goal–directed movements and recognizing, anticipating, and interpreting others’ actions. Motor cognitive functions are generally associated with the presence of a brain and are ascribed only to humans and other animal species. A growing body of evidence suggests that aneural organisms, like climbing plants, exhibit behaviors driven by the intention to achieve goals, challenging our understanding of cognition. Here, we propose an inclusive perspective under motor cognition to explain climbing plants’ behavior. We will first review our empirical research based on kinematical analysis to understand movement in pea plants. Then, we situate this empirical research within the current theoretical debate aimed at extending the principles of cognition to aneural organisms. A novel comparative perspective that considers the perception–action cycle, involving transforming perceived environmental elements into intended movement patterns, is provided.

Phenotypic plasticity occurs when plants acclimatize to contrasting conditions. Herein, we test the hypothesis that seedlings of a light-demanding species have greater phenotypic plasticity compared to seedlings of a shade-tolerant species under high irradiance. Thus, we investigate the growth, anatomical, and leaf gas exchange responses of Citharexylum myrianthum, a light-demanding species, and Poecilanthe parviflora, a shade-tolerant species, under full light and 60% shading. Under full light, the seedlings of both species were shorter, showed lower photosynthetic rates and specific leaf area, and thicker palisade parenchyma. In the same conditions, C. myrianthum showed increased number of leaves, and P. parviflora reduced leaf area and increased number of stomata and allocation of phloem and cortical parenchyma. Lower photosynthetic rates may negatively affect biomass allocation and growth, although C. myrianthum seems to show a higher tolerance to irradiance since it produced more leaves. P. parviflora seems to optimize heat dissipation, reduce water loss, and improve the allocation of photoassimilate transport and storage, which could increase performance during establishment in field conditions. The plasticity index of both species was similar. Thus, generalizations about the species plasticity and ecological group to which they belong should be avoided. Species-related responses of growth, anatomical, and gas exchange parameters were found, indicating that generalizations about the performance of functional groups should also be avoided. These findings may contribute to the success of forest restoration projects.

It is suggestive that some plant features, like the absence of specialized sensory organs to detect various environmental stimuli and their sessile and autotrophic nature, may have influenced the historically limited interest in the comprehensive understanding of their capabilities. However, scientific evidence has progressively spurred changes in this scenario by revealing unexpected and astonishing capabilities of plants. The objective of this article is to explore significant scientific discoveries that have led to a complete reshaping of certain human perceptions of plant capabilities throughout history, as well as delve into the new findings that are currently remodeling our view of them in modern times. This is illustrated by outdated notions about their growth and sexual behavior that have been surpassed, as well as by current discoveries concerning plants' capacity to detect various environmental stimuli, even without specialized organs for such purposes. Following this trajectory of reshaping perceptions, we will delve into recent revelations about diverse mechanisms through which plants exchange specific and reliable information with the organisms they interact with. The article also discusses how certain discoveries made in the past few decades concerning memory and learning capacity contribute to dismantling the notion that plants operate solely through automated and linear behaviors triggered by stimuli. Furthermore, the article draws inferences about how these paradigm shifts in our understanding of plants impact on the resolution of longstanding gaps in comprehending biological phenomena, exemplified by somatic embryogenesis, as well as how they contribute to the advancement of new technologies for plant cultivation.

The tricarboxylic acid (TCA) cycle is an important metabolic pathway to underpin stomatal movements, given that respiration is thought to be the main energy source for guard cell (GC) metabolism. However, it is still unclear how the metabolic fluxes throughout the TCA cycle and associated pathways are regulated in GCs. Here we used a ¹³C-positional isotopomer approach and performed a multi-species/cell-types analysis based on previous ¹³C-labelling studies carried out using Arabidopsis rosettes, maize leaves, Arabidopsis source and sink leaves, and isolated GCs from Arabidopsis and tobacco. We aimed to compare flux modes through the TCA cycle and associated pathways in GCs and leaves, which are mostly composed by mesophyll cells (MCs). Mesophyll cells showed high ¹³C-enrichment into alanine and aspartate following provision of ¹³CO₂, whilst GCs and sink MCs showed high ¹³C-incorporation into glutamate/glutamine following provision of ¹³C-sucrose. Only GCs showed high ¹³C-enrichment in the carbon 1 atom of glutamine, which is derived from phosphoenolpyruvate carboxylase (PEPc)-mediated CO₂ assimilation. The PEPc-mediated ¹³C-incorporation into malate was similar between GCs and MCs, but GCs had higher ¹³C-enrichment and accumulation of fumarate than MCs. The metabolic fluxes throughout the TCA cycle of illuminated GCs resemble those of sink MCs, but with different contribution from PEPc, glycolysis and the TCA cycle to glutamate/glutamine synthesis. We further demonstrate that transamination reactions catalysed by alanine and aspartate amino transferases may support non-cyclic TCA flux modes in illuminated MCs.

Abstract

Proline is an amino acid acting as an osmoprotector in plants, as it reduces osmotic potential and enhances plant water uptake, especially under drought. Aluminum (Al) toxicity causes inhibition of root growth and low leaf hydration with negative consequences for photosynthetic performance. Thus, plants under Al toxicity could benefit from proline accumulation. Here we investigated whether proline is induced by Al in Pinus sylvestris, an Al-tolerant woody species. Proline and abscisic acid (ABA) concentration, gas exchange rates, stomatal conductance (gs), relative needle water content (RWC), stem water potential (Ψw), biometric data and plant biomass were evaluated in plants grown in nutrient solution with 0, 250, 500, and 1000 μM Al for 42 days. Plant growth, gas exchange rates, RWC and ABA were the same between the four treatments, as expected for an Al-tolerant species. The maintenance of needle hydration throughout the study provides a plausible explanation for the similar gas exchange values observed between Al-treated and untreated plants. Over the course of 7 to 14 days, plants exposed to Al showed a decrease in midday stem water potential (Ψmd), and an increase in proline concentration. Subsequently, both parameters exhibited similar values between treatments until the end of the study. These findings suggest proline may play a role in osmotic adjustment in P. sylvestris exposed to Al.

Modulation of melatonin signaling pathway occurs either by direct interaction with calmodulin (CaM) or through regulation of intracellular Ca²⁺ concentration. Intracellular CaM and CaM-dependent phosphodiesterase (PDE) activity are also possibly modulated by melatonin in vitro through melatonin-CaM interaction. Melatonin acts as a CaM antagonist and modulates CaM-dependent protein phosphorylation, thereby rhythmically regulating cellular functions. Melatonin also acts as a nitric oxide synthase (NOS) inhibitor by interfering with CaM binding to NOS peptide, thereby inhibiting NO biosynthesis. CaM also inhibits the effects of melatonin on cyclic GMP biosynthesis. Melatonin can cause increase in reactive oxygen species (ROS) generation through CaM–mediated activation of phospholipase A₂ (PLA₂). Thus, the prooxidant action of melatonin is mediated through CaM. Melatonin can directly scavenge ROS species and regulate the activities of various antioxidant enzymes though interaction with CaM. Melatonin causes microtubule depolymerization, thereby affecting cytoskeleton organization in the cells. CaM also inhibits tubulin polymerization. Melatonin is known to regulate photoperiodism and circadian rhythmicity in plants. Both salt stress and melatonin seem to modulate seedling growth by inhibiting CaM-mediated calcium signaling. Upregulation of genes encoding CaM-like protein, calcium-binding protein, calcium-dependent phosphodiesterase and CBL (calcineurin B-like proteins)-interacting protein kinase indicates possible calcium-mediated melatonin signaling in plants.

This study evaluated gene expression and activity of key enzymes associated with L-ascorbic acid metabolism during the development of acerola. Acerola cv. Flor-branca shows a double sigmoid growth curve reaching physiological maturity at 17 days after anthesis (DAA) and is fully ripe at 21 DAA. Thus, fruits were analyzed at 15, 17, 19, 21 and 23 DAA. Total L-ascorbic acid (T-AsA) concentration declined 60% from immature green (15 DAA) to the fully ripe stage (21 DAA), with a relative increase in the content of the reduced form L-ascorbic acid (AsA). Regarding AsA biosynthesis, L-GalLDH activity increased during fruit development from 15 to 19 DAA. Oxidative enzyme activity patterns differed during ripening, APX was initially higher and decreased, while ascorbate oxidase (AO) activity was initially lower and then increased until 21 DAA. The activity patterns of recycling enzymes monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) were similar and increased during fruit development. The genes associated with AsA biosynthesis (GalLDH, GMP and GME) showed similar expression profiles during fruit maturation (after 17 DAA) and may be related to the increase in L-GalLDH activity. The profile of genes linked to AsA degradation showed that AO isoform 2 is mainly involved in oxidation during fruit development. The high concentration of T-AsA in immature acerola seems related to cellular intake from phloem due to the high expression of the l-ascorbic acid transporter NAT3 gene. The data observed here gives an insight into the key points of regulation of AsA metabolism during acerola development that enables further fresh market and industrial uses, besides genetic manipulation efforts.

Graphical abstract