Osmosensor-mediated control of Ca2+ spiking in pollen germination.

Higher plants survive terrestrial water deficiency and fluctuation by arresting cellular activities (dehydration) and resuscitating processes (rehydration). However, how plants monitor water availability during rehydration is unknown. Although increases in hypo-osmolarity-induced cytosolic Ca2+ concentration (HOSCA) have long been postulated to be the mechanism for sensing hypo-osmolarity in rehydration1,2, the molecular basis remains unknown. Because osmolarity triggers membrane tension and the osmosensing specificity of osmosensing channels can only be determined in vivo3-5, these channels have been classified as a subtype of mechanosensors. Here we identify bona fide cell surface hypo-osmosensors in Arabidopsis and find that pollen Ca2+ spiking is controlled directly by water through these hypo-osmosensors-that is, Ca2+ spiking is the second messenger for water status. We developed a functional expression screen in Escherichia coli for hypo-osmosensitive channels and identified OSCA2.1, a member of the hyperosmolarity-gated calcium-permeable channel (OSCA) family of proteins6. We screened single and high-order OSCA mutants, and observed that the osca2.1/osca2.2 double-knockout mutant was impaired in pollen germination and HOSCA. OSCA2.1 and OSCA2.2 function as hypo-osmosensitive Ca2+-permeable channels in planta and in HEK293 cells. Decreasing osmolarity of the medium enhanced pollen Ca2+ oscillations, which were mediated by OSCA2.1 and OSCA2.2 and required for germination. OSCA2.1 and OSCA2.2 convert extracellular water status into Ca2+ spiking in pollen and may serve as essential hypo-osmosensors for tracking rehydration in plants.

Cost-effective genomic prediction of critical economic traits in sturgeons through low-coverage sequencing.

Low-coverage whole-genome sequencing (LCS) offers a cost-effective alternative for sturgeon breeding, especially given the lack of SNP chips and the high costs associated with whole-genome sequencing. In this study, the efficiency of LCS for genotype imputation and genomic prediction was assessed in 643 sequenced Russian sturgeons (∼13.68×). The results showed that using BaseVar+STITCH at a sequencing depth of 2× with a sample size larger than 300 resulted in the highest genotyping accuracy. In addition, when the sequencing depth reached 0.5× and SNP density was reduced to 50 K through linkage disequilibrium pruning, the prediction accuracy was comparable to that of whole sequencing depth. Furthermore, an incremental feature selection method has the potential to improve prediction accuracy. This study suggests that the combination of LCS and imputation can be a cost-effective strategy, contributing to the genetic improvement of economic traits and promoting genetic gains in aquaculture species.

Yersinia ruckeri Infection and Enteric Redmouth Disease among Endangered Chinese Sturgeons, China, 2022.

During October 2022, enteric redmouth disease (ERM) affected Chinese sturgeons at a farm in Hubei, China, causing mass mortality. Affected fish exhibited characteristic red mouth and intestinal inflammation. Investigation led to isolation of a prominent bacterial strain, zhx1, from the internal organs and intestines of affected fish. Artificial infection experiments confirmed the role of zhx1 as the pathogen responsible for the deaths. The primary pathologic manifestations consisted of degeneration, necrosis, and inflammatory reactions, resulting in multiple organ dysfunction and death. Whole-genome sequencing of the bacteria identified zhx1 as Yersinia ruckeri, which possesses 135 drug-resistance genes and 443 virulence factor-related genes. Drug-susceptibility testing of zhx1 demonstrated high sensitivity to chloramphenicol and florfenicol but varying degrees of resistance to 18 other antimicrobial drugs. Identifying the pathogenic bacteria associated with ERM in Chinese sturgeons establishes a theoretical foundation for the effective prevention and control of this disease.

Mechanism of sturgeon intestinal inflammation induced by Yersinia ruckeri and the effect of florfenicol intervention.

The mechanism by which Y. ruckeri infection induces enteritis in Chinese sturgeon remains unclear, and the efficacy of drug prevention and control measures is not only poor but also plagued with numerous issues. We conducted transcriptomic and 16 S rRNA sequencing analyses to examine the differences in the intestinal tract of hybrid sturgeon before and after Y. ruckeri infection and florfenicol intervention. Our findings revealed that Y. ruckeri induced the expression of multiple inflammatory factors, including il1ß, il6, and various chemokines, as well as casp3, casp8, and multiple tumor necrosis factor family members, resulting in pathological injury to the body. Additionally, at the phylum level, the relative abundance of Firmicutes and Bacteroidota increased, while the abundance of Plesiomonas and Cetobacterium decreased at the genus level, altering the composition of the intestinal flora. Following florfenicol intervention, the expression of multiple apoptosis and inflammation-related genes was down-regulated, promoting tissue repair. However, the flora became further dysregulated, increasing the risk of infection. In conclusion, our analysis of the transcriptome and intestinal microbial composition demonstrated that Y. ruckeri induces intestinal pathological damage by triggering apoptosis and altering the composition of the intestinal microbiota. Florfenicol intervention can repair pathological damage, but it also exacerbates flora imbalance, leading to a higher risk of infection. These findings help elucidate the molecular mechanism of Y. ruckeri-induced enteritis in sturgeon and evaluate the therapeutic effect of drugs on intestinal inflammation in sturgeon.

Grazing exclusion had greater effects than nitrogen addition on soil and plant community in a desert steppe, Northwest of China.

BACKGROUND: The impacts of increasing nitrogen (N) deposition and overgrazing on terrestrial ecosystems have been continuously hot issues. Grazing exclusion, aimed at restoration of grassland ecosystem function and service, has been extensively applied, and considered a rapid and effective vegetation restoration method. However, the synthetic effects of exclosure and N deposition on plant and community characteristics have rarely been studied. Here, a 4-year field experiment of N addition and exclusion treatment had been conducted in the desert steppe dominated by Alhagi sparsifolia and Lycium ruthenicum in northwest of China, and the responses of soil characteristics, plant nutrition and plant community to the treatments had been analyzed. RESULTS: The grazing exclusion significantly increased total N concentration in the surface soil (0-20 cm), and increased plant height, coverage (P < 0.05) and aboveground biomass. Specifically, A. sparsifolia recovered faster both in individual and community levels than L. ruthenicum did after exclusion. There was no difference in response to N addition gradients between the two plants. CONCLUSIONS: Our findings suggest that it is exclusion rather than N addition that has greater impacts on soil properties and plant community in desert steppe. Present N deposition level has no effect on plant community of desert steppe based on short-term experimental treatments.

Bacterial community changes and their responses to nitrogen addition among different alpine grassland types at the eastern edge of Qinghai-Tibetan Plateau.

Soil microbes play a fundamental role in maintaining nutrient biogeochemical cycles. To understand the distribution of soil bacterial communities on grassland plateaus, high-throughput sequencing was used to compare bacterial communities in soils from swamp meadows (SM), alpine meadows (AM), alpine steppes (AS), and desert steppes (DS) at the eastern edge of the Qinghai-Tibetan Plateau (QTP) in China. We then compared response to nitrogen addition between SM and DS soils in microcosms. Bacterial α-diversity decreased from SM > AM > AS > DS. Variations in soil properties across grassland types was associated with different soil bacterial communities corresponding to bacterial species associated with nutrient cycles to those associated with degradation. Soil moisture, pH, and total phosphorus were the main drivers of these differences. Nitrogen addition decreased bacterial diversity but had inconsistent effects on soil bacterial communities in SM and DS, which may also indicate that different alpine grassland soil types have unique bacterial communities. Alpine grassland degradation significantly affects bacterial communities, and the response to nitrogen addition depends on the alpine grassland type. These results allow for better predictions of soil bacteria community-level responses to geochemical and environmental change in alpine areas.

Is salinity the main ecological factor that influences foliar nutrient resorption of desert plants in a hyper-arid environment?

BACKGROUND: Soil salinity is a major abiotic constraint to plant growth and development in the arid and semi-arid regions of the world. However, the influence of soil salinity on the process of nutrient resorption is not well known. We measured the pools of both mature and senesced leaf nitrogen (N), phosphorus (P), potassium (K), and sodium (Na) of desert plants from two types of habitats with contrasting degrees of soil salinity in a hyper-arid environment of northwest China. RESULTS: N, P, K revealed strict resorption, whereas Na accumulated in senesced leaves. The resorption efficiencies of N, P, and K were positively correlated with each other but not with Na accumulation. The degree of leaf succulence drives both intra-and interspecific variation in leaf Na concentration rather than soil salinity. Both community- and species-level leaf nutrient resorption efficiencies (N, P, K) did not differ between the different habitats, suggesting that soil salinity played a weak role in influencing foliar nutrients resorption. CONCLUSIONS: Our results suggest that plants in hyper-arid saline environments exhibit strict salt ion regulation strategies to cope with drought and ion toxicity and meanwhile ensure the process of nutrient resorption is not affected by salinity.

Recyclable and mechanically tough nanocellulose reinforced natural rubber composite conductive elastomers for flexible multifunctional sensor.

The development of flexible wearable multifunctional electronics has gained great attention in the field of human motion monitoring. However, developing mechanically tough, highly stretchable, and recyclable composite conductive materials for application in multifunctional sensors remained great challenges. In this work, a mechanically tough, highly stretchable, and recyclable composite conductive elastomer with the dynamic physical-chemical dual-crosslinking network was fabricated by the combination of multiple hydrogen bonds and dynamic ester bonds. To prepare the proposed composite elastomers, the polyaniline-modified carboxylate cellulose nanocrystals (C-CNC@PANI) were used as both conductive filler to yield high conductivity of 15.08 mS/m, and mechanical reinforcement to construct the dynamic dual-crosslinking network with epoxidized natural rubber latex to realize the high mechanical strength (8.65 MPa) and toughness (29.57 MJ/m3). Meanwhile, the construction of dynamic dual-crosslinking network endowed the elastomer with satisfactory recyclability. Based on these features, the composite conductive elastomers were used as strain sensors, and electrode material for assembling flexible and recyclable self-powered sensors for monitoring human motions. Importantly, the composite conductive elastomers maintained reliable sensing and energy harvesting performance even after multiple recycling process. This study provides a new strategy for the preparation of recyclable, mechanically tough composite conductive materials for wearable sensors.

Fabrication of fully bio-based malleable thermoset derived from cellulose, furfural and plant oil for advanced capacitive sensor.

Fabrication of sustainable bio-based malleable thermosets (BMTs) with excellent mechanical properties and reprocessing ability for applications in electronic devices has attracted more and more attention but remains significant challenges. Herein, the BMTs with excellent mechanical robustness and reprocessing ability were fabricated via integrating with radical polymerization and Schiff-base chemistry, and employed as the flexible substrate to prepare the capacitive sensor. To prepare the BMTs, an elastic bio-copolymer derived from plant oil and 5-hydroxymethylfurfural was first synthesized, and then used to fabricate the dynamic crosslinked BMTs through Schiff-base chemistry with the amino-modified cellulose and polyether amine. The synergistic effect of rigid cellulose backbone and the construction of dynamic covalent crosslinking network not only achieved high tensile strength (8.61 MPa) and toughness (3.77 MJ/m3) but also endowed the BMTs with excellent reprocessing ability with high mechanical toughness recovery efficiency of 104.8 %. More importantly, the BMTs were used as substrates to fabricate the capacitive sensor through the CO2-laser irradiation technique. The resultant capacitive sensor displayed excellent and sensitive humidity sensing performance, which allowed it to be successfully applied in human health monitoring. This work paved a promising way for the preparation of mechanical robustness malleable bio-thermosets for electronic devices.

Biomimetic ultra-strong, ultra-tough, degradable cellulose-based composites for multi-stimuli responsive shape memory.

Fabrication of ultra-strong, ultra-tough, sustainable, and degradable bio-based composites is urgently needed but remains challenging. Here, a biomimetic sustainable, degradable, and multi-stimuli responsive cellulose/PCL/Fe3O4 composite with ultra-strong mechanical strength and ultra-high toughness was developed. To prepare the proposed composites, the soft poly(ε-caprolactone) (PCL) side chain was grafted onto the rigid cellulose backbone, then the cellulose graft copolymer (EC-g-PCL) reacted with rigid hexamethylenediamine modified Fe3O4 nanoparticle (Fe3O4-NH2) to construct the crosslinking network using MDI-50 as a crosslinker. Given by the construction of crosslinking network and the "hard" and "soft" interactive structure, the composites showed ultra-strong mechanical strength (25.7 MPa) and ultra-high toughness (107.0 MJ/m3), and the composite specimen could lift a weight of approximately 21,200 times its mass. The composites also exhibited rapid degradation ability with high degradation efficiency. In addition, the composites showed excellent thermal responsive shape memory property with a shape recovery ratio above 96 %. Most importantly, the Fe3O4 nanoparticles endowed the composites with photothermal conversion property, the composites exhibited superior NIR light-triggered shape memory capability. The EC-g-PCL/Fe3O4 composites with ultra-strong mechanical strength and ultra-high toughness have promising applications in heavy-lift, object transportation, and self-tightening knots.

Phylogenetic and Physiological Diversity of Cultivable Actinomycetes Isolated From Alpine Habitats on the Qinghai-Tibetan Plateau.

Actinomycetes in extreme alpine habitat have attracted much attention due to their unique physiological activities and functions. However, little is known about their ecological distribution and diversity. Here, we explored the phylogenetic relationship and physiological heterogeneity of cultivable actinomycetes from near-root soils of different plant communities in the Laohu Ditch (2200 - 4200 m) and Gaize County area (5018 - 5130 m) on the Qinghai-Tibetan Plateau. A total of 128 actinomycete isolates were obtained, 16S rDNA-sequenced and examined for antimicrobial activities and organic acid, H2S, diffusible pigments, various extracellular enzymes production. Seventy three isolates of the total seventy eight isolates from the Laohu Ditch, frequently isolated from 2200 to 4200 m, were closely related to Streptomyces spp. according to the 16S rDNA sequencing, while four isolates within the genus Nocardia spp. were found at 2200, 2800, and 3800 m. In addition, one potential novel isolate with 92% sequence similarity to its nearest match Micromonospora saelicesensis from the GenBank database, was obtained at 2200 m. From the Gaize County area, fifty Streptomyces isolates varied in diversity at different sites from 5018 to 5130 m. The investigation of phenotypic properties of 128 isolates showed that 94.5, 78.9, 68, 64.8, 53, 51.6, 50, 36.7, 31.2, and 22.7% of the total isolates produced catalase, lipase 2, urease, protease, H2S, lipase 3, amylase, lipase 1, diffusible pigment and organic acid, respectively. The antimicrobial assays of the total isolates revealed that 5, 28, 19, and 2 isolates from Streptomyces spp. exhibited antimicrobial activity against Escherichia coli, Staphylococcus aureus, Candida albicans, and Pseudomonas aeruginosa, respectively. This study intends to bring helpful insights in the exploitation and utilization of alpine actinomycetes for novel bioactive compounds discovery.

Molecular cloning, functional analysis and localization of a novel gene encoding polygalacturonase-inhibiting protein in Chorispora bungeana.

Polygalacturonase-inhibiting proteins (PGIPs) are plant defense proteins. To date, no spatial distribution of PGIPs and interaction between PGIPs and nitric oxide (NO) in plant were described. Here, we first reported the full-length cDNA sequence of PGIP of Chorispora bungeana (CbPGIP1). Notably, immunofluorescence localization showed that the CbPGIP was evenly distributed in leaves but it was mainly localized in epidermis and vascular bundle in stems and roots. Further studies indicated that CbPGIP had higher abundance in roots than in stems and leaves. Conversely, the bulk PGIP of C. bungeana showed a higher activity in leaves than in stems and roots. In addition, quantitative real-time polymerase chain reaction demonstrated that CbPGIP1 expression was induced by Stemphylium solani, salicylic acid (SA), 4, -4 degrees C and NO. This is a first report attempting to predict if NO can induce the PGIP expression. Taken together, these findings showed that the gene was spatially regulated and NO and SA might take part in CbPGIP1 expression induced by biotic and abiotic stresses. This study highlighted the potential importance of CbPGIP1 and NO in plant resistance.

A new potyvirus first isolated and identified from Angelica sinensis.

A filamentous virus was isolated in Angelica sinensis (Angelica sinensis (Oliv.) Diels) which shows mosaic symptoms on leaves in Minxian, Gansu province, China. According to morphology and molecular biology properties, this virus, which has a flexuous rod-shaped particle about 750 nm in length and 12 nm in width, was assigned to the genus Potyvirus, family Potyviridae. Its coat protein (CP) shows high similarity with six other potyviruses by analysis of peptide mass fingerprinting (PMF). The 919 bp nucleotides of 3' terminal covering partial CP gene and 3'-untranslated region was amplified by RT-PCR using degenerate primers which were designed according to the result of PMF. In sequence comparisons and phylogenetic analysis, the new isolate was found to be closely related to Japanese hornwort mosaic virus (JHMV), Konjak mosaic virus (KoMV), and Zantedeschia mosaic virus (ZaMV). The most closely related virus is JHMV03 (AB251346), with 96.59% aa and 87.60% nt identity to the isolate. All results suggest the presence of a new member of potyvirus, tentatively named Dang Gui strain of Japanese hornwort mosaic virus (JHMV-DG*). In our research the antiserum against the CP of JHMV-DG had also been prepared. To our knowledge, it is the first time that a potyvirus has been isolated and identified in Angelica sinensis.

Comparative transcriptome analysis reveals expression signatures of albino Russian sturgeon, Acipenseriformes gueldenstaedtii.

Albinism is a genetically inherited condition that is caused by a series of genetic abnormalities leading to a reduction in melanin production. Russian sturgeon is one of the most valuable freshwater fish species worldwide, and albino individuals have been found in fish farms. Due to its complicated genome and scarce genome-wide genetic resources, the underlying molecular basis of albinism in Russian sturgeon is unknown. In the present study, we first generated transcriptome profile of Acipenser gueldenstaedtii using pooled tissues, which provided reliable reference sequences for future molecular genetic studies. A total of 369,441 contigs were assembled, corresponding to 32,965 unique genes. A comparative analysis of the transcripts from the skin of albino and wildtype individuals was conducted afterwards. A total of 785 unique genes were differentially expressed, including the upregulation of 385 genes and the downregulation of 400 genes in albino individuals. The expression pattern of 16 selected differentially expressed genes was validated using qRT-PCR. Additional annotation, GO enrichment analysis and gene pathway analysis indicated that the melanogenesis pathway may be interrupted in albinism. Eight potential causative genes that were highly likely to be responsible for sturgeon albinism were identified, including Dct, Tyrp1b, Slc45a2, Ctns, Pmela, Pmelb, Cd63, and Bloc1s3, which were found to be significantly down-regulated in albino Russian sturgeon. Moreover, a sliding window analysis of the ratio of nonsynonymous to synonymous nucleotide substitution rates (Ka/Ks) ratios indicated that seven out of the eight genes underwent positive selection during evolution. Our results provide a valuable basis for understanding the molecular mechanism of albinism in fish species and will facilitate future genetic selection and breeding of sturgeon with market-favored traits in aquaculture.

Inhibition of glutathione synthesis decreases chilling tolerance in Chorispora bungeana callus.

The possible roles of reduced glutathione (GSH) in chilling tolerance were studied in callus generated from a representative alpine plant, Chorispora bungeana Fisch. & C.A. Mey (C. bungeana). The callus grew well under low-temperature and chilling treatment led only to slight injury, as indicated by a low level of ion leakage (IL). Malondialdehyde measurements also were not elevated, however GSH was. Exogenously application of l-buthionine-(S R)-sulfoximine (BSO), an inhibitor of gamma-glutamylcysteine synthetase (gamma-ECS), arrested the GSH accumulation induced by chilling and resulted in a significant decrease in cell growth and an increase in IL and malondialdehyde. These results implied that C. bungeana is a plant with a strong low-temperature tolerance mechanism, and the tolerance of C. bungeana may be associated with GSH accumulation. Under chilling treatment, the proportion of unsaturated fatty acid in the plasma membrane (PM) increased significantly in callus of C. bungeana mainly due to increases in C18:2 and C18:3, the membrane fluidity (indicated by DPH fluorescent polarization) however was maintained. High PM H(+)-ATPase activities were also induced by chilling. Exogenously application of BSO blocked the effects of chilling treatments on the changes of fatty acids and PM H(+)-ATPase activities, reducing the PM membrane fluidity. On the other hand, simultaneous application of GSH and BSO to callus under chilling treatments reversed the effects of BSO on the changes of fatty acids, PM fluidity and PM H(+)-ATPase activities. These results suggested that GSH induced by low-temperature treatments may confer chilling tolerance to C. bungeana, probably by increasing unsaturated fatty acid compositions and maintaining PM fluidity and high enzymatic activity.

NADPH oxidase-dependent hydrogen peroxide production, induced by salinity stress, may be involved in the regulation of total calcium in roots of wheat.

Hydrogen peroxide (H(2)O(2)) is often generated by cells and tissues under environmental stress. In this work, we provide evidence that plasma membrane (PM) NADPH oxidase-dependent H(2)O(2) production might act as an intermediate step in the NaCl-induced elevation of calcium (Ca) in roots of wheat. Remarkable increases in the content of total Ca were observed not only in roots exposed to NaCl but also in roots of seedlings exposed to exogenous H(2)O(2). In roots, H(2)O(2) production increased upon exposure to salt stress. PM vesicles were isolated from roots, and NADPH oxidase activity was determined by measuring superoxide anion (O(2)(-)) production. NADPH oxidase-dependent O(2)(-) production was 11.6nmolmg(-1)proteinmin(-1) in control vesicles, but 19.6nmol after NaCl treatment (24h), indicating that salt stress resulted in the activation of the PM NADPH oxidase. Furthermore, the NaCl-induced increase in total Ca was partially abolished by the addition of 150U/mL catalase (CAT), a H(2)O(2) scavenger, and also by 10microM diphenylane iodonium (DPI), a NADPH oxidase inhibitor. This data suggest that NADPH oxidase-dependent H(2)O(2) production might be involved in the modulation of the Ca content in wheat roots. In conclusion, our results show that salinity stress increases the total Ca content of wheat roots, which is partly due to PM NADPH oxidase-dependent H(2)O(2) generation.

Nutrient resorption or accumulation of desert plants with contrasting sodium regulation strategies.

Desert plants are thought to rely more heavily on nutrient resorption due to the infertile soil. However, little is known regarding the phylogenetic effects on this traits, specifically for halophytes. Here we determined contents of nitrogen (N), phosphorus (P), potassium (K), sodium (Na), calcium (Ca) and magnesium (Mg) in 36 desert plants in a hyper-arid environment. The patterns of resorption or accumulation of the six elements were compared among plant groups with diverse leaf Na regulation strategies: i.e., euhalophytes (Eu), secretohalophytes (Se), pseudohalophytes (Ps) and glycophytes (Gl). Overall, N, P, K presented strict resorption across all groups, but no more efficient than global estimations. Ca and Mg tended to be resorbed less or accumulated during leaf senescence. Significant phylogenetic signal of both leaf Na content and plant group implies the pivotal role of Na regulation in the adaptation of plants to desert environment. Resorption proficiency, rather than resorption efficiency, is more phylogenetically conservative and more relevant to leaf functional traits.

Phylogenetic diversity of culturable bacteria from alpine permafrost in the Tianshan Mountains, northwestern China.

Microbes have been discovered in permafrost sediments for nearly a century. However, microbiological analyses of alpine permafrost are very scarce. This study is a first attempt to describe the phylogenetic diversity of a culturable bacterial community isolated from alpine permafrost in the Tianshan Mountains in northwestern China. Aerobic 2.5-6.0x10(5) CFU/gdw (CFU per 1 gram of dry weight) on modified PYGV medium were recovered from alpine permafrost samples at 4 degrees C; among these, 91 bacterial isolates with different morphotypes were characterized by phenotypic properties, such as morphology, colony pigmentation, Gram staining, endospore formation and temperature range of growth. The isolates were further categorized based on amplified rDNA restriction analysis (ARDRA), and 51 representative isolates possessing distinct ARDRA patterns selected for subsequent 16S rDNA sequencing and phylogenetic analysis. The phylogenetic trees placed the 51 isolates in four major groups: the high-G+C Gram-positives, the low-G+C Gram-positives, Proteobacteria and the Cytophaga-Flavobacterium-Bacteroides (CFB) phylum. The most abundant and diverse isolates were members of Gram-positive bacteria, particularly the Arthrobacter as a dominant group in alpine permafrost culturable populations. Results of the Jukes-Cantor evolutionary distance matrix suggested that the vast majority of the isolates were different strains of known species, and three may represent new species within the genus Chryseobacterium of the CFB phylum. From this study, it is proposed that alpine permafrost sediments in the Tianshan Mountains provide a specific ecological niche for prolonging survival of diverse microbial lineages.

Molecular cloning and characterization of a novel MAP kinase gene in Chorispora bungeana.

Chorispora bungeana Fisch. and C.A. Mey (Chorispora bungeana) is a rare alpine subnival plant species that is highly capable of resisting freezing environment. Since it is a stress-tolerant plant, we investigated the participation of mitogen-activated protein kinases (MAPKs) as possible mediators of abiotic stresses. We have isolated from Chorispora bungeana a new MAPK cDNA CbMAPK3 which encodes a 369 amino-acid protein with moderate to high nucleotide sequence similarity to previously reported plant MAPK genes. CbMAPK3 contains all 11 of the MAPK conserved subdomains and the phosphorylation motif TEY. The transcripts of CbMAPK3 were detected and no tissue-specific expression were observed in both roots and leaves, The transcripts of CbMAPK3 accumulated highly and rapidly when Chorispora bungeana treated with cold (4 and -4 degrees C), ABA and salinity stress. These results indicate that the CbMAPK3 may play an important role in response to environmental stresses.

Effect of lanthanum ions (La3+) on ferritin-regulated antioxidant process under PEG stress.

The physiological effects of lanthanum(III) ions on the ferritin-regulated antioxidant process were studied in wheat (Triticum aestivum L.) seedlings under polyethylene glycol (PEG) stress. Treatment with 0.1 mM La3+ resulted in increased levels of chlorophyll, carotenoid, proline, ascorbate, and reduced glutathione. The activities of superoxide dismutase, catalase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, glutathione reductase, and peroxidase were also increased after La3+ treatment. Treatment with La3+ seems to enhance the capacity of the reactive oxygen species scavenging system, affect the Fe2+ and Fe3+ electron-transfer process in ferritin, and restrain the formation of hydroxyl radical (OH.), alleviating the oxidative damage induced by PEG stress.