Theoretical and Experimental Plant Physiology最新文献

In flowering plants, reactive oxygen species (ROS) are actively involved in the regulation of sexual reproduction. Here we present the first evidence on the participation of ROS in sexual interactions in coniferous plants. In most gymnosperms, pollen hydrates and germinates in a pollination drop—a special type of ovular secretion. We studied the composition of this liquid for four conifer species from three families for the presence of ROS using the most sensitive method for detecting low concentrations of ROS—EPR (electron paramagnetic resonance) spectroscopy. ROS were present in pollination drops of all the plants studied, however, the composition of ROS was different: in Taxus, Pinus and Picea the main form was O^⋅₂⁻, in Thuja it was H₂O₂, reaching values comparable to stigma exudates of flowering plants. We tested the potential involvement of superoxide in the regulation of spruce pollen germination in vitro and found a strong stimulating effect on both total and bipolar germination efficiency. Thus, we found that conifers are characterized by the presence of ROS in the liquid intended for pollen germination, as well as in flowering plants. Hydrogen peroxide and superoxide radical, apparently represent a variety of ROS-based mechanisms for the regulation of pollen germination in vivo.

The leaves of Guzmania monostachia, a tank epiphytic bromeliad, present a functional division: the base performs water and nutrient uptake through absorbing trichomes, while the apex presents higher photosynthetic activity and nitrogen (N) assimilation. Drought conditions induce Crassulacean acid metabolism (CAM) in the apex portion, with N nutrition influencing this process. Ammonium (NH₄⁺) induces higher CAM activity, reducing greater water loss compared to nitrate (NO₃⁻). Aquaporins play a crucial role in regulating membrane permeability in leaf tissues under drought. This study aimed to evaluate how different N sources (NO₃⁻ and NH₄⁺) in combination with drought affect the diurnal gene expression of aquaporins along the leaf blade of G. monostachia. Detached leaves were immersed in 30% (w/v) polyethylene glycol 6000 solution containing NO₃⁻ or NH₄⁺ for 7 days. Leaf apexes and bases were harvested at dawn and dusk. At dawn, NH₄⁺ improved water conservation and upregulated the expression of five aquaporin genes in the apex compared to NO₃⁻, including GmNIP5;1. In the leaf base at dawn, GmNIP5;1 was the most upregulated gene by NH₄⁺, suggesting its involvement in NH₄⁺ transport to the apex, intensifying CAM and other aquaporin genes' expression under drought. At dusk, NH₄⁺ led to pronounced downregulation of TIPs and NIPs than NO₃⁻ in both leaf portions, possibly ensuring lower membrane permeability and higher water retention during drought. These results offer valuable insights for future studies on the functions of aquaporins in drought tolerance and nitrogen-use efficiency in plants.

Background

Climate changes have led to fluctuations in rainfall, reducing crop productivity during drought conditions. In addition to developing tolerant genotypes, plant growth-promoting microorganisms could be applied to maintain sustainable agriculture under environmental stresses.

Objective

Therefore, in this study the ability of the nematophagous fungus P. chlamydosporia to promote drought tolerance in soybean plants was assessed.

Results

Under water deficit conditions, the inoculated plants exhibited a one-day delay in reaching the same water potential as the noninoculated plants. Fungal colonization improved physiological parameters associated with drought tolerance, resulting in a 2- to 5-fold increase in water use efficiency (A/E). Moreover, the behavior of the inoculated drought-sensitive BR16 plants resembled that of the drought-tolerant parental Embrapa 48. The relative water content (RWC) increased from 15% to 26% in the leaves and roots of inoculated plants of both genotypes under water deficit. Consequently, the intrinsic efficiency of water use (A/gs) was 6.7-fold greater in the inoculated BR 16 plants under water deficit. The increase in drought tolerance may be related to the induction of root growth in inoculated plants, although this increase was not associated with hydraulic conductivity. Similarly, fungal inoculation led to increased concentrations of phenolics, which directly or indirectly contributed to drought tolerance. Reduced concentrations of proline and ABA confirmed that P. chlamydosporia alleviated water deficit stress. Conversely, the increases in spermine and spermidine concentrations may act as osmoprotectants, relieving the water deficit in the roots.

Conclusion

Thus, P. chlamydosporia inoculation may contribute to maintaining soybean productivity during periods of limited water availability.

Understanding the physiological aspects associated with the response of Coffea arabica seeds to drying is crucial for enhancing their production. We assessed the physiological quality and expression of the 1-Cys-PRX protein in coffee seeds subjected to drying and storage. Seeds of Coffea arabica L. were dried to water contents of 40, 20, and 10% and stored for 60, 120, and 180 days. The physiological quality of the seeds was evaluated through germination, emergence percentage, and speed index (IVE) tests. The expression of the 1-Cys-PRX protein was also analyzed using Western blotting. Greater PRX protein expression was detected in the coffee seeds dried with 20 and 10% water throughout storage, while no protein expression was detected in the seeds with 46% water (control treatment) or in the seeds with 40% water after 60 days of storage. The physiological quality of Coffea arabica seeds is influenced by water content and the storage period. A greater expression of peroxiredoxin protein was detected in coffee seeds dried with 20% and 10% water. There was a reduction in seed vigor when the plants were dry, particularly at 20% and 10% water contents.

Plant root growth and development undergo significant alterations as an adaptation to environmental stressful conditions. Remodeling of roots exposed to salinity is coordinated by complex interactions among various signaling pathways involving phytohormones, nitric oxide (NO), and reactive oxygen species (ROS). Polyamines (PAs), small, cationic amine molecules with diverse roles in plant growth and stress responses, are also known to influence root morphology. Studies reported that treatment of sunflower seedlings with PA biosynthesis inhibitors [DFMA (DL-α-difluoromethylarginine) or DFMO (DL-α-difluoromethylornithine)], promotes extension growth of primary roots both in the absence or presence of NaCl. This work explores the possible role of PAs and their crosstalk with auxin signaling in the modeling of the root morphology in etiolated sunflower seedlings. We observed that inhibition of root growth by salinity is possibly governed by a disruption of the polar localization of PIN1 (auxin efflux protein) leading to IAA deficiency in the root apex. Application of PA inhibitors (DFMA or DFMO), in contrast, brings about an enhancement in IAA accumulation in the root apices of seedlings relative to control (−NaCl), albeit to a lesser degree in seedlings also exposed simultaneously to 120 mM NaCl. These alterations in IAA accumulation coincide with changes in primary root extension previously reported in sunflower seedlings in response to treatment with PA inhibitors, both in the absence or presence of NaCl. We found that the enhancement in root extension observed in seedlings subjected to a combined treatment of PA biosynthesis inhibitors and NaCl possibly involves the maintenance of polar distribution of PIN1 in the root cells which, in turn, may be responsible for the restoration of IAA distribution in the root apex to further support the observed extension growth of primary root. On the other hand, the role of nitric oxide and hydrogen peroxide in the observed PA inhibitor-triggered response on root extension remains uncertain at present. Therefore, a possible role of PAs and their crosstalk with auxin is evident in root architecture remodeling in sunflower seedlings exposed to salinity.

DNA methylation balance plays an important regulatory role in drought response and tolerance and also in the control of tomato fruit ripening, and its study may help to understand how fleshy fruits respond to drought. This work aimed to investigate how drought affects the expression profile of genes related to DNA methylation balance during tomato fruit ripening. Micro-Tom tomato plants were subjected to irrigated control (C) and two water deficit intensities (T1 and T2) treatments and analyzed for leaf gas exchange rates, leaf water potential (Ψ_w) and expression of genes encoding DNA methylases/demethylases during the mature green (MG), breaker (BR) and red ripe (RR) stages of fruit ripening. Water deficit promoted a significant reduction in the values of Ψ_w, photosynthetic rate (A), transpiration (E), stomatal conductance (gs), regardless of its applied intensity. In silico analysis of RNA-Seq data showed that CHROMOMETHYLASE 2 (SlCMT2) and DEMETER-LIKE 2 (SlDML2) were those, among all tomato DNA methylases/demethylases genes, that showed dramatic and opposite changes in expression during fruit ripening. Water deficit positively regulated the expression of SlCMT2 in the MG stage and SlDML2 in BR, with no significant variations in expression for these genes in the other stages of fruit ripening. These results show that genes related to DNA methylation balance have their expression further increased by water deficit in the fruit ripening stages in which they act, suggesting that drought enhances, but does not disrupt, the intrinsically programmed DNA methylation dynamics necessary for ripening progression.

We compared the decomposition, topology, and properties of 58 natural woody crown networks (WCN) from Cerrado and Caatinga vegetation with the same number of WCN built randomly at different sizes, from 10 to 248 nodes (the branching regions). The random distribution of nodes did not wrack the intrinsic relationships between WCN properties and created woody crowns similar to those found in Caatinga with relatively safe hydraulics to face severe water and other stresses. Nevertheless, growing by random node addition is an inflexible, unintentional procedure incapable of creating WCN-like Cerrado trees. These Cerrado trees showed WCN with less laterality and basitony, potentially achieving higher maximum crown height, but inherently had a riskier hydraulic architecture with lower navigability between nodes. Hence, random node distribution is unsuitable for building WCN in environments with mild stresses where trees typically attain considerable height. A sense of node numerosity (abundance), location of node insertion (rectilinear or lateral), node relative position (near or far from the initial node) along the woody axis, and anticipation behavior are essential to construct a suitable and adaptable WCN in each changing environment. Besides remarkable structural plasticity, the cognition-related features could be accomplished by some constitutional random traits of WCN, constructing safe hydraulic architecture even by haphazard node addition, and modulating the WCN decomposition and topology within limits through a blueprint project.

The ongoing post-normal times face two intertwining imperatives: sustainability and digital technology. Interestingly, the languages that address these imperatives are increasingly making use of concepts historically associated to or confined to the biological sciences, in particular botany and plant physiology. We address this phenomenon by applying two distinct but interacting conceptual frameworks. First, that of language ecology, i.e., the study of interactions between any given language and its environment. Language has an anticipatory nature, since it is an essential part of how we organise memory and past experience, therefore helping us to understand the present and to project the future. This paper surveys five biological concepts: autopoiesis, ecosystem, exaptation, regeneration, seed. By using an academic search engine, we assessed how often they have been used in academic publications related to biology/botany as compared to other fields. We found that their meanings are being expanded by their use in the sustainability and/or digital technology realms. Motivations for these uses include biomimetics, biophilia and/or, more simply, manipulation of words with the intention to create specific public or private rhetoric. Second, we examined this linguistic pattern as a symptom of ontological expansion, i.e., the integration and dialogue between technical innovation, philosophy and biology creating space for the emergence of new domains of experience and meanings that did not exist before. This research indicates that botany—and plant physiology in particular—can be an important source of inspiration for futures studies.

Although iron (Fe) is abundant in most agricultural soils, its bioavailability to plants is limited. The Fe deficiency can cause significant changes in plant metabolites, impacting the plant’s life cycle. In this context, selenium (Se) has been shown promising effects against Fe deficiency. However, there are few studies addressing the role of Se against the deleterious effects of Fe deficiency, mainly with the soybean crop. Hence, this study aimed to evaluate the effects of Se on dry mass, Fe concentration in the roots and shoots, as well as the photosynthetic performance and primary metabolism in soybean plants subjected to Fe deficiency. The experimental design used was completely randomized with 4 treatments: 1) absence of Fe without Se; 2) absence of Fe with Se; 3) sufficiency of Fe without Se (control); and 4) sufficiency of Fe with Se. Our results demonstrated that Fe deficiency combined with the absence of Se significantly reduced shoot and root dry mass, as well as Fe concentration in plants. Additionally, Fe deficiency had a detrimental impact on photosynthetic traits, whereas Se-treated plants exhibited a higher net CO₂ assimilation rate and improved carboxylation efficiency and photochemical characteristics. Moreover, Fe deficiency negatively influenced primary metabolism, leading to the altered accumulation of sucrose and amino acids, and reduced protein concentration and ammonia. In contrast, Se-treated plants showed lower accumulation of sucrose and maintenance of protein concentration. These findings highlight the potential of Se as a valuable intervention to mitigate Fe deficiency in soybean crops.

SPEECHLESS (SPCH), MUTE and FAMA drive stomatal development in Arabidopsis. They do so in association with SCREAM/INDUCER OF CBF EXPRESSION (SCRM/ICE) proteins. Orthologous proteins have also been reported for other plants, including now for Vitis, suggesting that a similar process occurs during stomata formation also in other plants. However, the details of this process likely vary because the Vitis protein sequences are most similar to those of dicots other than Arabidopsis. We recently reported a 2nd type of ICE protein in angiosperms, VrICE4L, with unique sequences in its putative protein-interacting bHLH and ACTL domains. This brings up the question whether this second ICE protein is also involved in stomatal formation. Overexpression of any one of the Vitis riparia SPCH, MUTE, FAMA or ICE proteins was found to affect stomata numbers in tobacco leaves. Localization, bimolecular fluorescence complementation (BiFC) and pull-down experiments pointed that VrSPCH, VrMUTE and VrFAMA can interact with both types of ICE proteins present in angiosperms, represented by VrICE1 and VrICE4. Taken together, these findings suggest that stomatal development in Vitis involves SPCH/ICE, MUTE/ICE and FAMA/ICE complexes with functions that are less similar to those in Arabidopsis than to those in other dicots.