Alternative oxidase gene induced by nitric oxide is involved in the regulation of ROS and enhances the resistance of Pleurotus ostreatus to heat stress

Overexpression of the Potato StPYL20 Gene Enhances Drought Resistance and Root Development in Transgenic Plants

Drought is a primary limiting factor for potato growth. PYR/PYL/RCAR (referred to hereafter as PYL) proteins, as receptors for abscisic acid (ABA), play a crucial role in the plant response to drought stress. However, the underlying mechanisms of this control remain largely elusive in potatoes. In this study, a potato StPYL20 gene was identified through genome-wide investigation and transcriptome analysis under drought stress. Molecular feature analysis revealed that the StPYL20 gene exhibits the highest expression level in tubers, and is significantly up-regulated under ABA and drought stress conditions. The StPYL20 protein harbors a conserved domain exclusive to the PYL family. Further functional analysis showed that both transient and stable expressions of StPYL20 in tobacco enhanced the drought resistance of transgenic plants, resulting in increased plant height, leaf number, and fresh weight, and an improved root system. Compared to wild-type plants under drought conditions, transgenic tobacco with the StPYL20 gene exhibited lower levels of malondialdehyde (MDA), higher proline (Pro) accumulation, and increased antioxidant enzyme activity. Moreover, overexpression of the StPYL20 gene heightened the sensitivity of transgenic plants to ABA. Furthermore, StPYL20 up-regulated the expression of stress response and development-related genes in transgenic plants under drought stress. In conclusion, our findings indicated that StPYL20 enhances drought resistance and root development in transgenic plants, and plays a positive regulatory role in the potato's response to drought stress.

Overexpression of StCDPK13 in Potato Enhances Tolerance to Drought Stress

Calcium-dependent protein kinases (CDPKs), which are activated by transient changes in the Ca2+ concentration in plants, are important for various biological processes, such as growth, development, defense against biotic and abiotic stresses, and others. Mannitol is commonly used as an osmotic regulatory substance in culture medium or nutrient solutions to create water-deficit conditions. Here, we cloned the potato (Solanum tuberosum L.) StCDPK13 gene and generated stable transgenic StCDPK13-overexpression potato plants. To investigate the potential functions of StCDPK13 in response to drought stress, overexpression-transgenic (OE1, OE2, and OE7) and wild-type (WT) potato seedlings were cultured on MS solid media without or with mannitol, representing the control or drought stress, for 20 days; the elevated mannitol concentrations (150 and 200 mM) were the drought stress conditions. The StCDPK13 gene was consistently expressed in different tissues and was induced by drought stress in both OE and WT plants. The phenotypic traits and an analysis of physiological indicators revealed that the transgenic plants exhibited more tolerance to drought stress than the WT plants. The overexpression lines showed an increased plant height, number of leaves, dry shoot weight, root length, root number, root volume, number of root tips, fresh root weight, and dry root weight under drought stress. In addition, the activities of antioxidant enzymes (CAT, SOD, and POD) and the accumulation of proline and neutral sugars were significantly increased, whereas the levels of malondialdehyde (MDA) and reactive oxygen species (ROS), including hydrogen peroxide (H2O2) and O2•-, were significantly reduced in the OE lines compared to WT plants under drought stress. Moreover, the stomatal aperture of the leaves and the water loss rate in the leaves of the OE lines were significantly reduced under drought stress compared to the WT plants. In addition, the overexpression of StCDPK13 upregulated the expression levels of stress-related genes under drought stress. Collectively, these results indicate that the StCDPK13 gene plays a positive role in drought tolerance by reducing the stomatal aperture, promoting ROS scavenging, and alleviating oxidative damage under drought stress in potatoes.

Analysis of the Respiratory Activity in the Antarctic Yeast Rhodotorula mucilaginosa M94C9 Reveals the Presence of Respiratory Supercomplexes and Alternative Elements

The respiratory activities of mitochondrial complexes I, II, and IV were analyzed in permeabilized Rhodotorula mucilaginosa cells and isolated mitochondria, and the kinetic parameters K0.5 and Vmax were obtained. No difference in substrate affinities were found between mitochondria and permeabilized cells. The activities of the components of the mitochondrial respiratory chain of the Antarctic yeast R. mucilaginosa M94C9 were identified by in-gel activity and SDS-PAGE. The mitochondria exhibited activity for the classical components of the electron transport chain (Complexes I, II, III, and IV), and supercomplexes were formed by a combination of the respiratory complexes I, III, and IV. Unfortunately, the activities of the monomeric and dimeric forms of the F1F0-ATP synthase were not revealed by the in-gel assay, but the two forms of the ATP synthase were visualized in the SDS-PAGE. Furthermore, two alternative pathways for the oxidation of cytosolic NADH were identified: the alternative NADH dehydrogenase and the glycerol-3-phosphate dehydrogenase. In addition, an NADPH dehydrogenase and a lactate cytochrome b2 dehydrogenase were found. The residual respiratory activity following cyanide addition suggests the presence of an alternative oxidase in cells.

Cobalt stress enhanced dendrobine-type total alkaloids biosynthesis of Trichoderma longibrachiatum UN32 through reactive oxygen species formation

Trichoderma longibrachiatum UN32 is a well-documented mutant strain known to produce dendrobine-type total alkaloids (DTTAs). It was serendipitously observed that the addition of Co2+ to the medium resulted in a notable enhancement in DTTAs production in the T. longibrachiatum UN32 strain, accompanied by an upregulating effect on the expression of antioxidase-related genes. Hence, the objective of the present work was to ascertain whether ROS (intracellular levels of hydrogen peroxide) induced by Co2+ treatment has a beneficial or detrimental impact on DTTAs biosynthesis. A comparison of the intracellular levels of hydrogen peroxide (H2O2) and DTTAs treated with CoCl2 and CH3COOH revealed that CoCl2 was the optimal inducer for investigating the relationship between ROS formation and DTTAs production. This was due to the observation that ROS formation was reduced by approximately 4% and DTTAs production was increased by 12.55% in comparison to the CH3COOH treatment. The physiological results revealed that the introduction of Co2+ resulted in the oxidative damage and activation of the expression of intracellular superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Furthermore, it was confirmed that ROS induced by Co2+ was beneficial to DTTAs production by adding exogenous ROS scavengers. The inclusion of all ROS scavengers, including vitamin C, tocopherol, melatonin, mannitol, and sesamol, resulted in a reduction in ROS accumulation and a concomitant decrease in DTTAs production. Specifically, the addition of melatonin at a concentration of 0.4 mg/L demonstrated significant effects, resulting in a 32.53% (P < 0.01) decrease in ROS accumulation and a 45.22% (P < 0.01) reduction in DTTAs production. Subsequently, the timelines of accumulation of intracellular H2O2 and DTTAs content indicated that ROS are also crucial for normal fermentation without CoCl2 addition. Specifically, the proper H2O2 dose for DTTAs accumulation is between 8.82 and 18.86 μmol/g. The present study offers the initial experimental evidence indicating that CoCl2 enhance DTTAs production during the culture of T. longibrachiatum UN32 via leading an increase in intracellular ROS, which is conductive to DTTAs production and can be inhibited by the ROS scavengers. Our results provide insights into the mechanistic study of DTTAs biosynthesis.

Genome-Wide Identification and Characterization of Alternative Oxidase (AOX) Genes in Foxtail Millet (Setaria italica): Insights into Their Abiotic Stress Response

Alternative oxidase (AOX) serves as a critical terminal oxidase within the plant respiratory pathway, playing a significant role in cellular responses to various stresses. Foxtail millet (Setaria italica), a crop extensively cultivated across Asia, is renowned for its remarkable tolerance to abiotic stresses and minimal requirement for fertilizer. In this study, we conducted a comprehensive genome-wide identification of AOX genes in foxtail millet genome, discovering a total of five SiAOX genes. Phylogenetic analysis categorized these SiAOX members into two subgroups. Prediction of cis-elements within the promoter regions, coupled with co-expression network analysis, intimated that SiAOX proteins are likely involved in the plant's adaptive response to abiotic stresses. Employing RNA sequencing (RNA-seq) and real-time quantitative PCR (RT-qPCR), we scrutinized the expression patterns of the SiAOX genes across a variety of tissues and under multiple abiotic stress conditions. Specifically, our analysis uncovered that SiAOX1, SiAOX2, SiAOX4, and SiAOX5 display distinct tissue-specific expression profiles. Furthermore, SiAOX2, SiAOX3, SiAOX4, and SiAOX5 exhibit responsive expression patterns under abiotic stress conditions, with significant differences in expression levels observed between the shoot and root tissues of foxtail millet seedlings. Haplotype analysis of SiAOX4 and SiAOX5 revealed that these genes are in linkage disequilibrium, with Hap_2 being the superior haplotype for both, potentially conferring enhanced cold stress tolerance in the cultivar group. These findings suggest that both SiAOX4 and SiAOX5 may be targeted for selection in future breeding programs aimed at improving foxtail millet's resilience to cold stress.

The Abscisic Acid Receptor Gene StPYL8-like from Solanum tuberosum Confers Tolerance to Drought Stress in Transgenic Plants

Pyrabactin resistance 1-like (PYL) proteins are abscisic acid (ABA) receptors that play a crucial role in the plant's response to adverse environmental conditions. However, as of yet, there is limited research on the role of PYL proteins in potato. In this study, a potato PYL gene, StPYL8-like, was identified through transcriptome analysis under drought stress. Molecular characterization revealed that the StPYL8-like protein possesses a highly conserved PYL family domain. Evolutionary analysis demonstrated that StPYL8-like protein clusters with various PYL proteins are involved in stress responses across different species. Functional assays showed that StPYL8-like robustly responds to different abiotic stresses, including drought and ABA treatment. Furthermore, the transient and stable expressions of StPYL8-like in tobacco enhanced their drought resistance, leading to increased plant height, leaf number, and fresh weight, as well as an improved root system. Transgenic tobacco carrying the StPYL8-like gene exhibited lower malondialdehyde (MDA) levels and higher proline accumulation and antioxidant enzyme activity compared to wild-type plants under drought conditions. Moreover, StPYL8-like upregulated the expression of stress-responsive genes (NtRD29A, NtLEA5, NtP5CS, NtPOD, NtSOD, and NtCAT) in transgenic plants subjected to drought stress. Collectively, these findings highlight the positive regulatory role of the StPYL8-like gene in enhancing potato plants' response to drought stress.

Nitric Oxide in Fungi: Production and Function

Nitric oxide (NO) is synthesized in all kingdoms of life, where it plays a role in the regulation of various physiological and developmental processes. In terms of endogenous NO biology, fungi have been less well researched than mammals, plants, and bacteria. In this review, we summarize and discuss the studies to date on intracellular NO biosynthesis and function in fungi. Two mechanisms for NO biosynthesis, NO synthase (NOS)-mediated arginine oxidation and nitrate- and nitrite-reductase-mediated nitrite reduction, are the most frequently reported. Furthermore, we summarize the multifaceted functions of NO in fungi as well as its role as a signaling molecule in fungal growth regulation, development, abiotic stress, virulence regulation, and metabolism. Finally, we present potential directions for future research on fungal NO biology.

Genome-wide analysis of bZIP gene family members in Pleurotus ostreatus, and potential roles of PobZIP3 in development and the heat stress response

The basic leucine zipper (bZIP) transcription factor (TF) is widespread among eukaryotes and serves different roles in fungal processes including nutrient utilization, growth, stress responses and development. The oyster mushroom (Pleurotus ostreatus) is an important and widely cultivated edible mushroom worldwide; nevertheless, reports are lacking on the identification or function of bZIP gene family members in P. ostreatus. Herein, 11 bZIPs on 6 P. ostreatus chromosomes were systematically identified, which were classified into 3 types according to their protein sequences. Phylogenetic analysis of PobZIPs with other fungal bZIPs indicated that PobZIPs may have differentiated late. Cis-regulatory element analysis revealed that at least one type of stress-response-related element was present on each bZIP promoter. RNA-seq and RT-qPCR analyses revealed that bZIP expression patterns were altered under heat stress and different developmental stages. We combined results from GST-Pull-down, EMSA and yeast two-hybrid assays to screen a key heat stress-responsive candidate gene PobZIP3. PobZIP3 overexpression in P. ostreatus enhanced tolerance to high temperature and cultivation assays revealed that PobZIP3 positively regulates the development of P. ostreatus. RNA-seq analysis showed that PobZIP3 plays a role in glucose metabolism pathways, antioxidant enzyme activity and sexual reproduction. These results may support future functional studies of oyster mushroom bZIP TFs.

Function of Transcription Factors PoMYB12, PoMYB15, and PoMYB20 in Heat Stress and Growth of Pleurotus ostreatus

MYB transcription factors (TFs) have been extensively studied in plant abiotic stress responses and growth and development. However, the role of MYB TFs in the heat stress response and growth and development of Pleurotus ostreatus remains unclear. To investigate the function of PoMYB12, PoMYB15, and PoMYB20 TFs in P. ostreatus, mutant strains of PoMYB12, PoMYB15, and PoMYB20 were generated using RNA interference (RNAi) and overexpression (OE) techniques. The results indicated that the mycelia of OE-PoMYB12, OE-PoMYB20, and RNAi-PoMYB15 mutant strains exhibited positive effects under heat stress at 32 °C, 36 °C, and 40 °C. Compared to wild-type strains, the OE-PoMYB12, OE-PoMYB20, and RNAi-PoMYB15 mutant strains promoted the growth and development of P. ostreatus. These mutant strains also facilitated the recovery of growth and development of P. ostreatus after 24 h of 36 °C heat stress. In conclusion, the expression of PoMYB12 and PoMYB20 supports the mycelium's response to heat stress and enhances the growth and development of P. ostreatus, whereas PoMYB15 produces the opposite effect.

Transcriptome Analysis Revealed That Hydrogen Peroxide-Regulated Oxidative Phosphorylation Plays an Important Role in the Formation of Pleurotus ostreatus Cap Color

Pleurotus ostreatus is widely cultivated in China. H2O2, as a signaling molecule, can regulate the formation of cap color, but its regulatory pathway is still unclear, severely inhibiting the breeding of dark-colored strains. In this study, 614 DEGs specifically regulated by H2O2 were identified by RNA-seq analysis. GO-enrichment analysis shows that DEGs can be significantly enriched in multiple pathways related to ATP synthesis, mainly including proton-transporting ATP synthesis complex, coupling factor F(o), ATP biosynthetic process, nucleoside triphosphate metabolic processes, ATP metabolic process, purine nucleoside triphosphate biosynthetic and metabolic processes, and purine ribonuclease triphosphate biosynthetic metabolic processes. Further KEGG analysis revealed that 23 DEGs were involved in cap color formation through the oxidative phosphorylation pathway. They were enriched in Complexes I, III, IV, and V in the respiratory chain. Further addition of exogenous uncoupling agents and ATP synthase inhibitors clarifies the important role of ATP synthesis in color formation. In summary, H2O2 may upregulate the expression of complex-encoding genes in the respiratory chain and promote ATP synthesis, thereby affecting the formation of cap color. The results of this study lay the foundation for the breeding of dark-colored strains of P. ostreatus and provide a basis for the color-formation mechanism of edible fungi.

Cardiac performance and heart gene network provide dynamic responses of bay scallop Argopecten irradians irradians exposure to marine heatwaves

The increased frequency of marine heat waves (MHWs) caused by global climate change is predicted to threaten the survival of economic bivalves, therefore having severely adverse effects on local ecological communities and aquaculture production. However, the study of scallops facing MHWs is still scarce, particularly in the scallop Argopecten irradians irradians, which has a significant share of "blue foods" in northern China. In the present study, bay scallop heart was selected to detect its cardiac performance, oxidative impairment and dynamic molecular responses, accompanied by assessing survival variations of individuals in the simulated scenario of MWHs (32 °C) with different time points (0 h, 6 h, 12 h, 24 h, 3 d, 6 d and 10 d). Notably, cardiac indices heart rate (HR), heart amplitude (HA), rate-amplitude product (RAP) and antioxidant enzyme activities superoxide dismutase (SOD) and catalase (CAT) all peaked at 24 h but sharply dropped on 3 d, coinciding with mortality. Transcriptome analysis revealed that the heart actively defended against heat stress at the acute stage (<24 h) via energy supply, misfolded proteins correction and enhanced signal transduction, whereas regulation of the defense response and apoptotic process combined with twice transcription initiation were the dominant responses at the chronic stage (3-10 d). In particular, HSP70 (heat shock protein 70), HSP90 and CALR (calreticulin) in the endoplasmic reticulum were identified as the hub genes (top 5 %) in the HR-associated module via WGCNA (weighted gene co-expression network analysis) trait-module analysis, followed by characterization of their family members and diverse expression patterns under heat exposure. Furthermore, RNAi-mediated knockdown of CALR expression (after 24 h) significantly weakened the thermotolerance of scallops, as evidenced by a drop of 1.31 °C in ABT (Arrhenius break temperature) between the siRNA-injected group and the control group. Our findings elucidated the dynamic molecular responses at the transcriptome level and verified the cardiac functions of CALR in bay scallops confronted with stimulated MHWs.

Salicylic Acid Treatment Alleviates the Heat Stress Response by Reducing the Intracellular ROS Level and Increasing the Cytosolic Trehalose Content in Pleurotus ostreatus

Pleurotus ostreatus is usually cultivated in horticultural facilities that lack environmental control systems and often suffer heat stress (HS). Salicylic acid (SA) is recognized as a plant defense-related hormone. Here, SA treatment (200 μM) induced fungal resistance to HS of P. ostreatus, with decreased malondialdehyde (MDA) content and HSP expression. Further analysis showed that SA treatment in P. ostreatus increased the cytosolic trehalose content and reduced the intracellular reactive oxygen species (ROS) level. Moreover, H₂O₂ could restore the MDA content and HSP expression of P. ostreatus treated with SA under HS. In addition, trehalose (25 mM) or CaCl₂ (5 mM) treatment induced fungal resistance to HS, and CaCl₂ treatment increased the cytosolic trehalose content of P. ostreatus under HS. However, inhibiting Ca²⁺ levels using Ca²⁺ inhibitors or mutants reversed the trehalose content induced by SA in P. ostreatus under HS. In addition, inhibiting trehalose biosynthesis using Tps-silenced strains reversed the MDA content and HSP expression of P. ostreatus treated with SA under HS. Taken together, these results indicate that SA treatment alleviates the HS response of P. ostreatus by reducing the intracellular ROS level and increasing the cytosolic trehalose content. IMPORTANCE Heat stress (HS) is a crucial environmental challenge for edible fungi. Salicylic acid (SA), a plant defense-related hormone, plays key roles in plant responses to biotic and abiotic stresses. In this study, we found that SA treatment increased the cytosolic trehalose content and induced fungal resistance to HS in P. ostreatus. Further analysis showed that SA can alleviate the HS of P. ostreatus by reducing the intracellular ROS level and increasing the cytosolic trehalose content. Our results help to understand the mechanism underlying the responses of P. ostreatus to HS. In addition, this research provides new insights for the cultivation of P. ostreatus.

milR20 negatively regulates the development of fruit bodies in Pleurotus cornucopiae

The mechanism underlying the development of fruit bodies in edible mushroom is a widely studied topic. In this study, the role of milRNAs in the development of fruit bodies of Pleurotus cornucopiae was studied by comparative analyses of the mRNAs and milRNAs at different stages of development. The genes that play a crucial role in the expression and function of milRNAs were identified and subsequently expressed and silenced at different stages of development. The total number of differentially expressed genes (DEGs) and differentially expressed milRNAs (DEMs) at different stages of development was determined to be 7,934 and 20, respectively. Comparison of the DEGs and DEMs across the different development stages revealed that DEMs and its target DEGs involved in the mitogen-activated protein kinase (MAPK) signaling pathway, protein processing in endoplasmic reticulum, endocytosis, aminoacyl-tRNA biosynthesis, RNA transport, and other metabolism pathways, which may play important roles in the development of the fruit bodies of P. cornucopiae. The function of milR20, which targeted pheromone A receptor g8971 and was involved in the MAPK signaling pathway, was further verified by overexpression and silencing in P. cornucopiae. The results demonstrated that the overexpression of milR20 reduced the growth rate of mycelia and prolonged the development of the fruit bodies, while milR20 silencing had an opposite effect. These findings indicated that milR20 plays a negative role in the development of P. cornucopiae. This study provides novel insights into the molecular mechanism underlying the development of fruit bodies in P. cornucopiae.

Genome-wide identification of AOX family genes in Moso bamboo and functional analysis of PeAOX1b_2 in drought and salinity stress tolerance

Five PeAOX genes from Moso bamboo genome were identified. PeAOX1b_2-OE improved tolerance to drought and salinity stress in Arabidopsis, indicating it is involved in positive regulation of abiotic stress response. Mitochondrial alternative oxidase (AOX), the important respiratory terminal oxidase in organisms, catalyzes the energy wasteful cyanide (CN)-resistant respiration, which can improve abiotic stresses tolerance and is considered as one of the functional markers for plant resistance breeding. Here, a total of five putative AOX genes (PeAOXs) were identified and characterized in a monocotyledonous woody grass Moso bamboo (Phyllostachys edulis). Phylogenetic analysis revealed that PeAOXs belonged to AOX1 subfamily, and were named PeAOX1a_1, PeAOX1a_2, PeAOX1b_1, PeAOX1b_2 and PeAOX1c, respectively. Evolutionary and divergence patterns analysis revealed that the PeAOX, OsAOX, and BdAOX families experienced positive purifying selection and may have undergone a large-scale duplication event roughly 1.35-155.90 million years ago. Additionally, the organ-specific expression analysis showed that 80% of PeAOX members were mainly expressed in leaf. Promoter sequence analysis of PeAOXs revealed cis-acting regulatory elements (CAREs) responding to abiotic stress. Most PeAOX genes were significantly upregulated after methyl jasmonate (MeJA) and abscisic acid (ABA) treatment. Moreover, under salinity and drought stresses, the ectopic overexpression of PeAOX1b_2 in Arabidopsis enhanced seed germination and seedling establishment, increased the total respiratory rate and the proportion of AOX respiratory pathway in leaf, and enhanced antioxidant ability, suggesting that PeAOX1b_2 is crucial for abiotic stress resistance in Moso bamboo.

Nitric oxide mediated alleviation of abiotic challenges in plants

Agriculture and ecosystem are negatively influenced by the abiotic stresses which create solemn pressures on plants as they are sessile in nature leading to excessive losses in economy. For maintenance of sustainable agriculture and to fulfil the cumulative call of food for rapidly growing population worldwide, it becomes crucial to protects the crop plants from climate fluctuations. Plants fight back against these challenges by generation of redox molecules comprising reactive oxygen species (ROS) and reactive nitrogen species (RNS) and cause modulation at cellular, physiological and molecular levels. Nitric oxide (NO) deliver tolerance to several biotic and abiotic stresses in plants by acting as signalling molecule or free radicals. It is also intricated in several developmental processes in plants using different mechanisms. Supplementation of exogenous NO reduce toxicity of abiotic stresses and provide resistance. In this review article, we summarize the recent research studies (five years) depicting the functional role of NO in alleviation of abiotic stresses such as drought, cold, heat, heavy metals and flooding. Moreover, by investigating studies found that among heavy metals works associated with Hg, Pb, and Cr is limited comparatively. Additionally, role of NO in abiotic stress resistance such as cold, freezing and heat stress less/poorly investigated. Consequently, further emphasis should be diverted towards how NO can facilitate protection against these stresses. In recent studies mostly beneficial role of NO against abiotic challenges have been elucidated by observing physiological/biochemical parameters but relatively inadequate research done at the transcripts level or gene regulation subsequently researchers should include it in future. Lastly, brief outline and an evaluative discussion on the present information and future prospective provided. Altogether, these inclusive experimental agendas could facilitate in future to produce climate tolerant plants. This will help to confront the constant fluctuations in the environment and to reduce the challenges in way of agriculture productivity and global food demands.

Mnsod1 promotes the development of Pleurotus ostreatus and enhances the tolerance of mycelia to heat stress

Background

Superoxide dismutases (SODs, EC 1.15.1.1) are defense proteins that can be used as sweepers to clear reactive oxygen species (ROS). They have been widely studied in the plant. Intensive research demonstrates that SOD plays an essential role in plants. However, in Pleurotus ostreatus, the function and regulatory pathway of SOD in the growth and development and the abiotic stress response have not been clear.

Results

In this study, three MnSOD-encoding genes of the P. ostreatus CCMSSC00389 strain were cloned and identified. Mnsod1, Mnsod2, and Mnsod3 were interrupted by 3, 7, and 2 introns, and encoded proteins of 204, 220, and 344 amino acids, respectively. By comparing the relative expression of three MnSOD-encoding genes in mycelia, the results showed that the gene with the highest primary expression was Mnsod1. Subsequently, the function of P. ostreatus Mnsod1 was explored by overexpression (OE) and RNA interference (RNAi). The results showed that during the growth and development of P. ostreatus, MnSOD1 protein increased gradually from mycelia to the fruiting body, but decreased in spores. The change of Mnsod1 transcription level was not consistent with the changing trend of MnSOD1 protein. Further studies showed that during primordia formation, the expression of Mnsod1 gradually increased, reaching a peak at 48 h, and the transcription level was 2.05-folds compared to control. H₂O₂ content progressively accumulated during the formation of primordia, and its change trend was similar to that of Mnsod1 transcription. OE-Mnsod1-1 and OE-Mnsod1-21 strains accelerated the formation of primordia. The results suggested that Mnsod1 may participate in the formation rate of P. ostreatus primordium by regulating the signal molecule H₂O₂. In addition, OE-Mnsod1-1 and OE-Mnsod1-21 strains shortened the mycelial recovery time after heat stress and improved the tolerance of the strains to 2.5 mM and 5 mM H₂O₂, which showed that Mnsod1 was involved in the response of P. ostreatus mycelium to heat stress.

Conclusions

This study indicates that Mnsod1 plays an active role in the formation of P. ostreatus primordia and the response to abiotic stress.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12934-022-01878-2.

Comparative Transcriptome Analysis Provides Insights Into the Mechanism by Which 2,4-Dichlorophenoxyacetic Acid Improves Thermotolerance in Lentinula edodes

As the widest cultivated edible mushroom worldwide, Lentinula edodes suffers serious yield and quality losses from heat stress during growth and development, and in our previous study, exogenous 2,4-Dichlorophenoxyacetic acid (2,4-D) was found to improve the thermotolerance of L. edodes strain YS3357, but the molecular mechanism remains unclear. Here, we explored the potential protective mechanism of exogenous 2,4-D against heat stress by transcriptome analysis. 2,4-D possible improve the thermotolerance of L. edodes through regulating antioxidant genes, transcription factors, energy-provision system, membrane fluidity, and cell wall remodeling. Furthermore, 2,4-D was also found to regulate the saturation levels of fatty acids and ATP content in L. edodes mycelium under heat stress. This study proposed a regulatory network of 2,4-D in regulating L. edodes response to heat stress, providing a theoretical basis for improving L. edodes thermotolerance, and facilitating the understanding of the molecular mechanism of exogenous hormones in alleviating abiotic stress damage to macrofungi.