Physiologia plantarum最新文献

Plastic film (mulch film) is widely used in saline and alkaline soils because it can effectively reduce salt stress damage. However, it results in the accumulation of microplastics (MPs) in the soil, which pose a threat to crop growth and production. This study investigates the effects of 50 mg l^-1 MPs and 100 mM sodium chloride (NaCl), individually or in combination, on the growth and physiological characteristics of maize (Zea mays) seedlings. The results demonstrated that compared to the control, MPs and NaCl single or combined stress reduced seedling biomass and water content, and the combined stress was more serious. Stress significantly reduced N and K contents in leaves, and Na content under combined stress was lower than under single NaCl stress. Compared to single stress, the combined stress further enhanced oxidative damage by increasing H₂O₂ and MDA content, a disrupted chloroplast structure, and reduced chlorophyll content, ultimately leading to a decline in chlorophyll fluorescence parameters and photosynthetic efficiency. Single MPs or NaCl stress led to the accumulation of proline, soluble proteins, and soluble sugars, while the combined stresses further increased the content of these osmotic substances in plants. Moreover, single or combined stress increased the activity of CAT, POD, SOD and the content of AsA and GsH. Collectively, NaCl and MPs single or combined stress exert notable toxic effects on maize seedling growth. Although the combined stress inhibited seedling growth more than the single stress, the combined stress of MPs and NaCl showed antagonistic effects. These findings underscore the importance of assessing the ecological risks posed by the combined effects of MPs and salt stresses on maize plants.

Methionine adenosyltransferase (MAT) is the only enzyme that synthesises S-adenosylmethionine (SAM) from ATP and methionine in organisms. While MAT has been extensively studied in plant development and responses to abiotic stress, its role in plant fertilization, particularly in pear pollen tube growth, has been scarcely researched. Here, we demonstrate that the homologous gene of AtMAT3 in pear, PbrMAT3, is positively involved in pear pollen tube elongation. PbrMAT3 is predominantly expressed in pear pollen. Transient knockdown of PbrMAT3 inhibits pollen tube growth. Ethionine, a toxic methionine analogue, suppressed pollen tube growth in control samples but had no inhibitory effect on PbrMAT3-knockdown pollen tubes, suggesting increased methionine accumulation in the latter. However, this accumulation is not responsible for the observed growth inhibition. PbrMAT3 interacts with a pectin lyase-like protein, PbrPLL1, both in vivo and in vitro. Transient knockdown of PbrPLL1 promotes pollen tube growth, suggesting its negative role in pear pollen tube elongation. Additionally, the pectate lyase activity of the pear pollen tube was increased when PbrMAT3 was knocked down. Thus, the inhibition of pollen tube growth due to PbrMAT3 knockdown is not caused by methionine accumulation but may be mediated by PbrPLL1. This study provides new insight into the relationship between S-adenosylmethionine synthesis and pollen tube growth.

Hydrogen peroxide (H₂O₂) displays significant and dual effects on seed germination and seedling development, depending on the application dosage. However, the definition of H₂O₂ thresholds and the mechanisms underlying the dual actions in Arabidopsis seed germination and seedling development are not yet clear. Here, we analyzed the Arabidopsis seed germination profiles in response to different concentrations of exogenous H₂O₂ and found that 2 mM functions as the key threshold, above this threshold, both seed germination and seedling establishment were gradually inhibited. By RNA-seq analysis and function verification, we identified pathways of abscisic acid (ABA) signalling, seed post-ripening, energy metabolism, ROS homeostasis, and cell wall loosening play positive roles in seed germination and seedling establishment downstream of the H₂O₂ signalling. Further physio-chemical approaches revealed that exogenous H₂O₂ affected the accumulation and distribution of O₂ ^•- and H₂O₂ in embryonic tissues by regulating the tissue-specific expression of SDH2-3, RHD2, and PRXs. Collectively, we found that germination rate and aerial growth were positively correlated with endogenous H₂O₂ content and root length was positively correlated with O₂ ^•- accumulation, demonstrating that different ROS signals played specific functions in different tissues and development processes. On the other hand, excessive H₂O₂ (10 mM) represses these two processes for radicle cell damage caused by oxidation stress. Finally, we put forward the mechanism model of the dual effects of exogenous H₂O₂ on seed germination and seedling establishment.

Pinellia ternata (Thunb.) Breit is a member of the Araceae family and is globally distributed. The dry tuber has been used as a traditional Chinese medicine for over 2,000 years. With agricultural development, the harm of soft rot to P. ternata is an increasing problem. The lack of germplasm resources resistant to soft rot leads to less research on resistance mechanisms. In our study, we screened disease-resistant P. ternata P-1 and disease-susceptible P. ternata P-4 for the first time. Then, the infection of soft rot for 0, 24, and 48 hours was performed, and a de novo transcriptome analysis explored key genes associated with soft rot resistance. A total of 260,169 unigenes were identified and differentially expressed gene analysis was conducted. In total, 33 C3H-type ZFP genes were differentially expressed under Pectobacterium carotovorum infection. Transient expression of ZFP2-like (Cluster-5189.85444) resulted in a twofold increase at 24 hour post infection (hpi) and a threefold increase at 48 hpi in P-1 with soft rot infection, but no significant difference at P-4 enhanced the resistance of Nicotiana benthamiana to soft rot. Stable overexpression in P. ternata with a 2 ~ 11-fold increase in gene expression and reduced the lesion size from 6 mm to 2 ~ 4 mm at 24 hpi, demonstrating increased resistance to P. carotovorum. These findings indicated the ZFP2-like gene plays a pivotal role in soft rot resistance, enriches genetic data on disease resistance in P. ternata, and contributes to breed selection and improvement.

Salinity stress poses a significant threat to plant growth and agricultural productivity, affecting millions of hectares of land worldwide. The adverse effects of salt toxicity, primarily caused by high levels of sodium chloride in soil and water, disrupt essential physiological processes in plants, leading to reduced yields and degraded soil quality. The present study thoroughly investigated the potential involvement of hydrogen sulphide (H₂S) and nitric oxide (NO) in facilitating salt stress tolerance in cucumbers. In this investigation, NaHS (sodium hydrogen sulfide), which is the donor of H₂S, and SNP (sodium nitroprusside), which is the donor of NO, were used as treatments for cucumber seedlings exposed to salt stress. Additionally, L-NAME (N-nitro-L-arginine: 100 μM) and cPTIO (2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide), which are inhibitors and scavengers of NO respectively, were used to verify the involvement of NO in the presence of salinity. NaHS and SNP supplementation significantly boosted fresh weight, dry weight, plant height, and chlorophyll content, promoting growth under salt stress. These treatments raised endogenous H₂S and NO levels, upregulating antioxidative enzymes like SOD, CAT, APX, GR, GPX, and GSTs. This response reduced oxidative damages by lowering reactive oxygen species (ROS) and lipid peroxidation. The combined application of NaHS and SNP under salt stress offers a promising and cost-effective strategy to improve plant resilience to salinity, reduce oxidative stress, and ultimately enhance crop productivity. These findings provide important insights into the potential use of H₂S and NO donors for sustaining agricultural production in saline environments, addressing a critical global challenge for food security.

Legume leaves exhibit diverse compound forms, with various regulatory mechanisms underlying the development. The transcription factor-encoding KNOXI genes are required to promote leaflet initiation in most compound-leafed angiosperms. In non-IRLC (inverted repeat-lacking clade) legumes, KNOXI are expressed in compound leaf primordia but not in others (IRLC). Recent studies have highlighted LFY genes' role in regulating leaflet initiation across legumes. The LFY functions in leaf development are well understood in IRLC legumes but remain unclear in non-IRLC legumes. Soybean, a major crop belonging to non-IRLC legumes, has limited research on the trifoliate leaf morphogenesis. Here, we comprehensively analyzed soybean trifoliate leaf development and characterized two GmLFY gene copies, GmLFYa and GmLFYb, in compound leaf morphogenesis. Analyzing the loss-of-function mutants revealed that Gmlfya displayed a low frequency of simple-like leaves, while the Gmlfyb showed no visible phenotype. However, the Gmlfya Gmlfyb double mutant predominantly displayed simple-like leaves. Additionally, mutations in two genes also affect floral development: each single mutant exhibited slightly deformed floral organs, while double mutant produced inflorescence-like structures. The transformation from floral meristems to inflorescence-like structures is similar to lfy mutant in Arabidopsis but quite different from M. truncatula and L. japonicus. These findings suggest that the two GmLFY genes in soybean collaboratively regulate both compound leaf and flower morphogenesis. Our study not only creates foundational mutant materials for future research on leaf and flower development in soybean but also reinforces the role of LFY orthologs as master regulators in compound leaf morphogenesis across a broader range of legume taxa than previously recognized.

Rac/Rop proteins, a kind of unique small GTPases in plants, play crucial roles in plant growth and development and in response to abiotic and biotic stresses. However, it is poorly understood whether cotton Rac/Rop protein genes are involved in mediating cotton resistance to Verticillium dahliae. Here, we focused on the function and mechanism of cotton Rac/Rop gene GhRac9 in the defense response to Verticillium dahliae infection. The expression level of GhRac9 peaked at 24 h after V. dahliae infection and remained consistently elevated from 24 to 48 h upon SA treatment. Furthermore, silencing GhRac9 using VIGS (Virus-induced gene silence) method attenuated cotton defense response to V. dahliae by reducing ROS (Reactive Oxygen Species) burst, peroxidase activity and lignin content in cotton plants. On the contrary, heterologous overexpression of GhRac9 enhanced Arabidopsis resistance to V. dahliae and significantly increased ROS production in Arabidopsis plants. Furthemore, transient overexpressing of GhRac9 significantly enhanced ROS burst and POD activity in cotton plants. In addition, GhRac9 positively regulated the expression levels of the genes related to SA signaling pathway in cotton plants. In conclusion, GhRac9 functioned as a positive regulator in the cotton defense response to V. dahliae, which provided important insights for breeding new cotton varieties resistant to V. dahliae.

Plant architecture and subsequent productivity are determined by the shoot apical dominance, which is disturbed by the deficiency of boron, one of the essential trace elements for plant growth and reproduction. However, the mechanism by which B controls shoot apical dominance or axillary bud outgrows under B deficiency is still unclear. This work aimed to investigate the mechanistic basis of this process, with focus on the interaction between B and polar auxin transport. Adopting an all-buds phenotyping methodology and employing several complementary approaches, we found that boron deficiency inhibited plant growth and changed the shoot architecture, resulting in the outgrowth of axillary buds at nodes 1-3. This was related to the auxin accumulation in shoot apical parts buds under B deficiency. Applying N-1-naphthylphthalamic acid to inhibit auxin transport from the shoot apex promoted the outgrowth of axillary buds in boron-sufficient (+B) plants. In decapitated plants, the application of exogenous auxin to the shoot apex only inhibited the outgrowth of axillary buds in +B plants. At higher auxin doses, the toxic effect of IAA was observed in the lower part of the shoot, which was more severe in +B plants than in B-deprived (-B) plants. Furthermore, the expression of PsPIN3 was significantly downregulated under -B conditions. These results indicate that B deficiency inhibits PAT from the apical bud through the main stem to the lower parts, leading to an increase of auxin level in the apical bud, which inhibits the growth of apical buds while stimulating the outgrowth of axillary buds.

Plants defend against chewing herbivores by up-regulating jasmonic acid (JA) signaling, which activates downstream signaling cascades and produces numerous secondary metabolites that act as defense molecules against the herbivores. Although secondary metabolism always remains a focus of research, primary metabolism is also reported to be realigned upon herbivory. However, JA signaling-mediated modulation of primary metabolites and their metabolic pathways in plants are mostly unexplored. Here, we applied gas chromatography-mass spectrometry-based untargeted metabolomics aided with computational statistical frameworks on wild type Arabidopsis, mutants of active JA receptor (i.e., CORONATINE-INSENSITIVE 1, COI1-1) and downstream transcription factor (i.e., MYC2) to navigate the JA signaling-mediated primary metabolism alterations during herbivory. Pathway and metabolite's chemical class enrichment analysis revealed JA signaling is crucial for constitutive as well as herbivore-induced primary metabolism and topology of their interaction networks. JA signaling majorly modulated alterations of sugars, amino acids and related metabolites. Herbivory-mediated sugar depletion and induction of methionine for aliphatic glucosinolates are also dependent on JA signaling. Taken together, our results demonstrate trails of JA signaling-mediated primary metabolic alterations associated with herbivory.

Investigating the effects of drought stress and subsequent recovery on the structure and function of chloroplasts is essential to understanding how plants adapt to environmental stressors. We investigated Ctenanthe setosa (Roscoe) Eichler, an ornamental plant that can tolerate prolonged drought periods (40 and 49 days of water withdrawal). Conventional biochemical, biophysical, physiological and (ultra)structural methods combined for the first time in a higher plant with in vivo small-angle neutron scattering (SANS) were used to characterize the alterations induced by drought stress and subsequent recovery. Upon drought stress, no significant changes occurred in the chloroplast ultrastructure, chlorophyll content, 77K fluorescence emission spectra and maximal quantum efficiency of PSII (Qy dark), but the actual quantum efficiency of PSII (Qy light) decreased, the amounts of PSI-LHCII complexes and PSII monomers declined, and that of PSII supercomplexes increased. Thickness of the leaf and of the adaxial hypodermis, chloroplast length and granum repeat distance (RD) values decreased upon drought stress, as shown by light microscopy and SANS, respectively. Because of the very slight (nm-range) changes in RD values, the large biological variability (significant differences in RD values among the leaves and studied leaf regions) and the invasive sampling required for this method, transmission electron microscopy (TEM) hardly showed significant differences. On the other side, in situ SANS analyses provided a unique insight in vivo into the fast structural recovery of the granum structure of drought-stressed leaves, which happened already 18 h after re-watering, while functional and biochemical recovery took place on a longer time scale.