Environmental and Experimental Botany最新文献

Climate change, characterised by drought events and rising temperatures, exerts a significant threat to crop productivity and global food security. Halophytes, known for their resilience in harsh conditions, offer promising options for sustainable cultivation alternatives. Our study focused on Crithmum maritimum, commonly known as sea fennel, an edible halophyte with potential in the food and nutraceutical industries, to explore the impacts of drought and increased temperatures on its nutritional and antioxidant profiles. Different C. maritimum populations displayed high nutritional qualities, suitable for consumption despite appearing slight differences among localities. While both drought and increased temperatures affected plant growth and phytochemical profiles, their impact on nutritional value was minor. Surprisingly, drought induced an unexpected decline in phenolic content, challenging the assumption of increased antioxidants in response to water scarcity. Different rates of decrease in leaf production were observed among C. maritimum populations under drought, yet overall, they maintained similar levels, suggesting potential suitability for cultivation in environments with limited water availability. Diverse population-specific responses under climatic treatments revealed different alterations in amino acid and oxidative stress profiles, suggesting diverse adaptive strategies. These findings provide critical insights into C. maritimum adaptability to climate-driven changes, offering valuable information for future agricultural practices

The xerophyte Zygophyllum xanthoxylum can accumulate large amounts of Na⁺ in leaves for osmotic adjustment. HKT I is crucial for withdrawing Na⁺ from root xylem in salt-excluding species, however, its function in maintaining the characteristics of salt accumulation in Z. xanthoxylum remains unclear. Here, we found that ZxHKT1;1, a HKT I homolog in Z. xanthoxylum, is localized to the plasma membrane and functions as a Na⁺-selective transporter based on the heterologous expression analyses conducted in yeast and Xenopus laevis oocytes. The results of in situ PCR showed that ZxHKT1;1 was specifically expressed in the root stele. The over-expression of ZxHKT1;1 under the control of AtHKT1;1 native promoter significantly enhanced the retrieval of Na⁺ from root xylem and loading of K⁺ into xylem, thereby reducing Na⁺ accumulation and increasing K⁺ accumulation in shoots, and consequently, improving the salt tolerance of wild-type Arabidopsis or athkt1;1 mutant. Interestingly, the expression of ZxHKT1;1 was significantly down-regulated in roots of Z. xanthoxylum while up-regulated in roots of the ZxNHX1-silenced line under 50 mM NaCl, a salt condition that stimulates growth of Z. xanthoxylum. These results demonstrated that ZxHKT1;1 functions in maintaining the characteristics of salt accumulation in Z. xanthoxylum by modulating the retrieval of Na⁺ from root xylem, and this regulation is determined by its distinct expression patterns relying on the capacity of vacuolar Na⁺ compartmentation mediated by ZxNHX1 in leaves. Meanwhile, ZxHKT1;1 is involved in regulating K⁺ transport from roots to shoots in Z. xanthoxylum.

Previous studies have confirmed the stimulating effect of blue light on phenolic compound accumulation and emphasized that sufficient dose of blue light is essential for biosynthesis of B-dihydroxylated flavonoids with enhanced antioxidant properties (under UV-lacking conditions). This study investigates the importance of blue light and complex role of phenolic compounds in plant tolerance against acute photooxidative stress. Hordeum vulgare (L. Cv. Bojos) seedlings were acclimated to different light spectra (blue, green:red 1:1, and white composed of blue:green:red 1:1:1) at total irradiance 400 µmol.m⁻².s⁻¹. Subsequently, they were subjected to a 3-hour combined stress induced by high photosynthetically active (850–950 µmol.m⁻².s⁻¹) and UV-B (2.0–2.5 W.m⁻²) radiation. Content of flavonoids, expression of genes involved in their biosynthesis (phenylalanine ammonia-lyase, chalcone synthase, flavonoid 3′-hydroxylase), and antioxidant activity of plant extracts were significantly highest in plants acclimated to blue light. As an indicator of reactive oxygen species interaction with biomolecules, the content of lipid hydroperoxides was estimated. It was demonstrated that plants acclimated to blue light revealed significantly lower extent of lipid peroxidation compared to those acclimated to white or green:red light. Plants exposed to combined light-induced stress for 3 hours exhibited pronounced disruption of PSII function: F_V/F_M tended to decrease proportionally with decreasing amount of blue photons in the treatments. Additionally, stress exposure upregulated the expression of genes related to phenolic compounds but not genes encoding antioxidant enzymes. We confirmed higher resistance of plants acclimated to blue light and presume that phenolic compounds are significantly involved in protection during the acute phase of stress.

Transgenerational stress memory (TSM) in plants is a fascinating area of research, particularly when it comes to understanding how plants respond to drought stress. Therefore, our study explored the genetic architecture/causative alleles controlling transgenerational drought stress memoryin a diverse collection of 111 wheat accessions that enhanced seed germination parameters and antioxidant components in response to drought stress tolerance using a Genome-Wide Association Study (GWAS). This experiment was performed in two distinct stages. In the first stage, all wheat accessions were exposed to control and drought conditions following the primed acclimation technique. Two different groups of genotypes were recovered at this stage: the seeds of stressed plants (SP) and those of non-stressed plants (NP) and evaluated under drought treatment. Our study revealed a highly significant increase in root and shoot lengths by 42 % and 56 % for the seeds of stressed plants Similarly, a highly significant increase in superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase was detected for stressed plants by 55 %, 43 %, 44 %, and 63 % when compared to those of non-stressed wheatplants. Using GWAS mapping, a significant marker (Kukri_c53629_239) associated with APX_SP, DW_SP, and SOD_SP on chromosome 2 H was located inside the gene TraesCS2B02G192700 candidate is annotated as protein kinase activity that triggering various protective mechanisms, such as antioxidative enzymes under drought stress. Altogether, TSM is a cornerstone in the genetic research of drought stress tolerance, offering invaluable insights that can drive the development of drought-resilient crop varieties.

Pepper (Capsicum annuum L.) as often out-of-season vegetable is cultivated in greenhouse along with the large difference between night and day. To cope with repeated and frequent low temperature stress, pepper often adopt a memory response by remembering one past recurring stress, and enable survival of a harsher chilling stress that may arise later. Here, we wanted to determine how continuous and intermittent low temperature stress affect the priming and elimination of low temperature memory of pepper plants, as well as the response to subsequent stress and their capacity to remember low temperature information. The results showed that the continuous low temperature induced the priming of low temperature memory and improved cold resistance of pepper, and the storage of low temperature information in pepper plants could be maintained for at least 12 h, but not longer than 36 h. The results of rewarming for 3–5 d after 3 d of low temperature priming at 5 °C and then triggering low temperature stimulus for 1–2 d showed that rewarming for 3 d to trigger the stimulus again could still prime the low temperature memory, but the duration of low temperature memory was almost completely eliminated after rewarming for 5 d. Our study also unveiled that low temperature memory of pepper continued for 3–4 d under low temperature stress. Overall, these findings unraveled that the priming, elimination and maintenance of low temperature memory was associated with the duration of low temperature treatment and rewarming, and the low temperature memory in pepper was not enhanced with the extension of low temperature treatment, but the low temperature memory in pepper would be completely eliminated with the extension of rewarming.

Copper (Cu) and cadmium (Cd) are highly phytotoxic heavy metals that are widespread contaminants in soil. Plants are efficient at taking up heavy metals, which adversely impacts human health. Therefore, it is important to decrease the accumulation of Cu/Cd in plants to reduce human exposure from the food web. Here, we determined the function of a rapeseed (Brassica napus) Cu/Cd transporter, plant cadmium resistance protein 2.7 (BnPCR2.7), in enhancing Cu/Cd tolerance in seedlings and decreasing the accumulation of Cu/Cd in seeds. A subcellular localization analysis revealed that BnPCR2.7 is localized at the plasma membrane (PM). CRISPR/Cas9-mediated BnPCR2.7 knockout lines and knockdown lines had increased sensitivity to high Cu/Cd than wild-type (WT) plants. In contrast, overexpression of BnPCR2.7 enhanced the adaptation to high Cu/Cd than in WT. Additionally, the Cu/Cd content in the roots of overexpression lines was significantly lower than those of the WT, while the contents in the stems increased. A non-invasive micro-test technology (NMT) assay showed that overexpression plants promoted the efflux of Cu and Cd from the roots. A field trial of rapeseed grown in soil contaminated with Cu or Cd showed that overexpression plants grew and developed better than the WT with higher yields and less Cu/Cd that accumulated in the seeds, while knockout and knockdown lines were contrary to these results. Additionally, when grown in soils contaminated by both Cu and Cd, the content of these heavy metals decreased by 12–20 % and 20–30 %, respectively, in seeds of overexpression lines. Collectively, BnPCR2.7 may promotes resistance to Cu/Cd by efflux pathways. Significantly, it is a candidate genetic resource to increase the resistance to heavy metals and reduce the accumulation of Cu/Cd in rapeseed.

In the face of global climate change, several unprecedented challenges are currently faced by agriculture. To achieve food security, understanding the developmental program from seed formation and germination, through early seedling establishment until plant growth and crop yield, is required to increase agricultural production and ensure sustainability. Natural auxin, a heterogeneous group of aromatic carboxylic acids, is one of the most important plant hormones, mediating several endogenous developmental signals and exogenous environmental cues that profoundly affect virtually all plant growth and development processes. There must be a balance in endogenous auxin dynamics between synthesis, influx, efflux, degradation, receptor binding, and downstream signaling to modulate plants responses. While the genes and biochemical reactions for endogenous auxin metabolism are well understood, the involvement of auxin in plant central metabolism (e.g. photosynthesis and respiration) remains poorly known. Nevertheless, it is already known that endogenous auxin acts as the main epigenetic regulator responsible for mesophyll cell expansion and thus, indirectly, for photosynthesis. Furthermore, endogenous auxin response factors have been identified that mediate sugar and starch metabolism, as well as abiotic stress tolerance, indicating that auxin should be further explored as a key molecule to improve plant performance under normal and stressful conditions in crops. Here, we summarize recent advances in dissecting auxin metabolism, their importance on central metabolism, and discuss the functions of endogenous auxin in the overall control of plant growth. We further provide an overview of the pivotal role of endogenous auxin and how mutations in different auxin signaling modulate photosynthetic and respiratory processes, which is likely crucial for coordinating cellular responses.

Plants face harsher conditions with increasing elevation, including shorter growing seasons, lower temperatures, and reduced gas pressure. This often leads to increased leaf mass per area, suggesting greater limitation to photosynthesis due to decreased mesophyll conductance. However, some species maintain consistent photosynthetic rates at higher elevations, suggesting compensatory mechanisms. In the central Chile Andes, high-elevation habitats present cold temperatures with no soil moisture deficits, whereas low-elevations experience warm temperatures and summer droughts. Zonal plants adapt to these changes, whereas azonal plants grow near water sources and avoid drought. We assessed how elevation affects photosynthesis and its limitations in these plant-types, together with the role of leaf internal anatomy. This was done with gas exchange and chlorophyll fluorescence analyses, along with measurements of leaf inner structure, on zonal and azonal species growing at 2600 and 3550 m a.s.l. Results showed that whilst photosynthesis decreased with elevation in azonal plants, zonal plants showed no change, with mesophyll conductance being a primary limitation, influenced by chloroplast arrangement rather that cell wall thickness. This affects carbon acquisition in high-elevation plants due to low gas pressure and light availability.

Grape (Vitis vinifera L.), as an important deciduous perennial fruit tree, constantly confronts various abiotic stresses such as salinity and drought. The lateral organ boundaries domain (LBD) proteins are a class of plant-specific transcription factors that play pivotal roles in regulating plant growth and responding to abiotic stress. However, the biological function of the LBD transcription factor in grape remains poorly understood. Here, we cloned and characterized the VvLBD39 gene from grape, which contained a highly conserved LBD domain and localized to the cell nucleus. qRT-PCR analyses showed that the expression of VvLBD39 was downregulated upon exposure to NaCl, polyethylene glycol 6000 (PEG6000) and abscisic acid (ABA) treatments, respectively. Overexpression of VvLBD39 in grape calli and Arabidopsis resulted in hypersensitivity to PEG6000 and NaCl stress. Moreover, VvLBD39-overexpressing transgenic tobacco exhibited decreased tolerance to drought and salt stress, as well as insensitivity to exogenous ABA. After drought and salt stress treatments, the chlorophyll content, root length and antioxidant enzyme activity of the transgenic tobacco were lower than those of the wild-type (WT). Conversely, malonic dialdehyde (MDA) content, electronic conductivity, hydrogen peroxide (H₂O₂) content and superoxide anion (O₂^-) productivity were markedly elevated in the transgenic tobacco compared to the WT. Further investigations found that VvLBD39 had a negative impact on stomatal closure, ABA biosynthesis and ABA signaling under drought and salt treatments. In addition, the expression of genes related to reactive oxygen species (ROS) scavenging and stress response were significantly downregulated in VvLBD39 transgenic tobacco. Taken together, these results indicated that VvLBD39 functions as a negative regulator of salt and drought tolerance, making it a promising target for drought and salt resistance breeding.

Rice (Oryza sativa) has a higher tolerance to manganese (Mn) stress than other cereals. However, the regulatory mechanisms governing Mn tolerance in rice remain poorly understood. In this work, seedlings of the rice cultivar Nipponbare were treated with 1.0 mM MnCl₂ for 10 days before root samples were collected for transcriptome-wide N⁶-methyladenosine (m⁶A) methylation and metabolome profiling. In the presence of extra Mn, we identified 2050 significantly modified m⁶A peaks and 2549 differentially expressed genes (DEGs). These DEGs were linked to key signaling pathways such as MAPK signaling, calcium signaling, and peroxides. Among these, 282 DEGs showed differential m⁶A methylation peaks, including 29 transcription factors, indicating they might be key upstream regulators of the Mn toxicity response. Furthermore, metabolomic research indicated considerable metabolic alterations in rice roots under Mn stress, notably in purine metabolism, amino acid biosynthesis, and glycerophospholipid metabolic pathways. Almost half of the metabolites were lipids or lipid-like compounds, indicating a potential function in signal transduction and membrane biogenesis. The findings lead to a better understanding of regulatory networks in rice roots that aid in Mn stress tolerance.