Study on the community structure and function of symbiotic bacteria from different growth and developmental stages of Hypsizygus marmoreus.

BACKGROUND: The symbiotic bacteria associated with edible fungi are valuable microbial resources worthy of in-depth exploration. It is important to analyze the community structure and succession of symbiotic bacteria in mushrooms. This can assist in the isolation of growth-promoting strains that have an essential relationship with the cultivation cycle as well as the agronomic traits and yields of fruiting bodies. RESULTS: In all of the samples from cultivation bags of Hypsizygus marmoreus, 34 bacterial phyla were detected. Firmicutes was the most abundant bacterial phylum (78.85%). The genus Serratia showed an exponential increase in abundance in samples collected from the cultivation bags in the mature period, reaching a peak abundance of 55.74% and the dominant symbiotic flora. The most predominant strain was Serratia odorifera HZSO-1, and its abundance increased with the amount of hyphae of H. marmoreus. Serratia odorifera HZSO-1 could reside in the hyphae of H. marmoreus, promote growth and development, shorten the fruiting cycle by 3-4 days, and further increase the fruiting body yield by 12%. CONCLUSIONS: This study is a pioneering demonstration of the community structure of the symbiotic microbiota and bacteria-mushroom interaction in the growth and development of edible fungi. This work lays a theoretical foundation to improve the industrial production of mushrooms with symbiotic bacteria as assisting agents.

S-type Anion Channels SLAC1 and SLAH3 Function as Essential Negative Regulators of Inward K+ Channels and Stomatal Opening in Arabidopsis.

Drought stress induces stomatal closure and inhibits stomatal opening simultaneously. However, the underlying molecular mechanism is still largely unknown. Here we show that S-type anion channels SLAC1 and SLAH3 mainly inhibit inward K+ (K+in) channel KAT1 by protein-protein interaction, and consequently prevent stomatal opening in Arabidopsis. Voltage-clamp results demonstrated that SLAC1 inhibited KAT1 dramatically, but did not inhibit KAT2. SLAH3 inhibited KAT1 to a weaker degree relative to SLAC1. Both the N terminus and the C terminuses of SLAC1 inhibited KAT1, but the inhibition by the N terminus was stronger. The C terminus was essential for the inhibition of KAT1 by SLAC1. Furthermore, drought stress strongly up-regulated the expression of SLAC1 and SLAH3 in Arabidopsis guard cells, and the over-expression of wild type and truncated SLAC1 dramatically impaired K+in currents of guard cells and light-induced stomatal opening. Additionally, the inhibition of KAT1 by SLAC1 and KC1 only partially overlapped, suggesting that SLAC1 and KC1 inhibited K+in channels using different molecular mechanisms. Taken together, we discovered a novel regulatory mechanism for stomatal movement, in which singling pathways for stomatal closure and opening are directly coupled together by protein-protein interaction between SLAC1/SLAH3 and KAT1 in Arabidopsis.

Cyclic nucleotide-gated channel 18 is an essential Ca2+ channel in pollen tube tips for pollen tube guidance to ovules in Arabidopsis.

In flowering plants, pollen tubes are guided into ovules by multiple attractants from female gametophytes to release paired sperm cells for double fertilization. It has been well-established that Ca(2+) gradients in the pollen tube tips are essential for pollen tube guidance and that plasma membrane Ca(2+) channels in pollen tube tips are core components that regulate Ca(2+) gradients by mediating and regulating external Ca(2+) influx. Therefore, Ca(2+) channels are the core components for pollen tube guidance. However, there is still no genetic evidence for the identification of the putative Ca(2+) channels essential for pollen tube guidance. Here, we report that the point mutations R491Q or R578K in cyclic nucleotide-gated channel 18 (CNGC18) resulted in abnormal Ca(2+) gradients and strong pollen tube guidance defects by impairing the activation of CNGC18 in Arabidopsis. The pollen tube guidance defects of cngc18-17 (R491Q) and of the transfer DNA (T-DNA) insertion mutant cngc18-1 (+/-) were completely rescued by CNGC18. Furthermore, domain-swapping experiments showed that CNGC18's transmembrane domains are indispensable for pollen tube guidance. Additionally, we found that, among eight Ca(2+) channels (including six CNGCs and two glutamate receptor-like channels), CNGC18 was the only one essential for pollen tube guidance. Thus, CNGC18 is the long-sought essential Ca(2+) channel for pollen tube guidance in Arabidopsis.

The S-Type Anion Channel ZmSLAC1 Plays Essential Roles in Stomatal Closure by Mediating Nitrate Efflux in Maize.

Diverse stimuli induce stomatal closure by triggering the efflux of osmotic anions, which is mainly mediated by the main anion channel SLAC1 in plants, and the anion permeability and selectivity of SLAC1 channels from several plant species have been reported to be variable. However, the genetic identity as well as the anion permeability and selectivity of the main S-type anion channel ZmSLAC1 in maize are still unknown. In this study, we identified GRMZM2G106921 as the gene encoding ZmSLAC1 in maize, and the maize mutants zmslac1-1 and zmslac1-2 harboring a mutator (Mu) transposon in ZmSLAC1 exhibited strong insensitive phenotypes of stomatal closure in response to diverse stimuli. We further found that ZmSLAC1 functions as a nitrate-selective anion channel without obvious permeability to chloride, sulfate and malate, clearly different from SLAC1 channels of Arabidopsis thaliana, Brassica rapa ssp. chinensis and Solanum lycopersicum L. Further experimental data show that the expression of ZmSLAC1 successfully rescued the stomatal movement phenotypes of the Arabidopsis double mutant atslac1-3atslah3-2 by mainly restoring nitrate-carried anion channel currents of guard cells. Together, these findings demonstrate that ZmSLAC1 is involved in stomatal closure mainly by mediating the efflux of nitrate in maize.

Importance of a Laccase Gene (Lcc1) in the Development of Ganoderma tsugae.

In this study, a novel laccase gene (Lcc1) from Ganoderma tsugae was isolated and its functions were characterized in detail. The results showed that Lcc1 has the highest expression activity during mycelium development and fruit body maturation based on the analysis of Lcc1 RNA transcripts at different developmental stages of G. tsugae. To investigate the exact contribution of Lcc1 to mycelium and fruit body development in G. tsugae, Lcc1 transgenic strains were constructed by targeted gene replacement and over-expression approaches. The results showed that the lignin degradation rate in Lcc1 deletion mutant was much lower than the degradation efficiency of the wild-type (WT), over-expression and rescue strains. The lignin degradation activity of G. tsugae is dependent on Lcc1 and the deletion of Lcc1 exerted detrimental influences on the development of mycelium branch. Furthermore, the study uncovered that Lcc1 deletion mutants generated much shorter pale grey fruit bodies, suggesting that Lcc1 contributes directly to pigmentation and stipe elongation during fruit body development in G. tsugae. The information obtained in this study provides a novel and mechanistic insight into the specific role of Lcc1 during growth and development of G. tsugae.

Molecular analysis and biochemical characteristics of degenerated strains of Cordyceps militaris.

Cordyceps militaris has commercially been cultivated, but its degenerated subcultures have gradually resulted in the reduced production. In this study, the biological characteristics and DNA change of degenerated strains of C. militaris were analyzed in detail. The results showed that the degenerated strains exhibited the lower growth rate, and the deficiency in fruit body formation and pigment production. The degradation of strains was not attributable to DNA changes identified by RAPD and SRAP. Compared to normal strains, the biochemical indexes of degradation strains and normal strains showed that the carotenoid content of degradation strains was significantly lower, the activities of cellulase and amylase of degradation strains were slight lower, and the EPS content was lower, but the IPS was higher. All these results suggested that the degradation of C. militaris may be caused by the inhibition or in harmony of metabolite synthesis involved in the metabolic regulation, which should be further verified.

Protein kinase OsSAPK8 functions as an essential activator of S-type anion channel OsSLAC1, which is nitrate-selective in rice.

MAIN CONCLUSION: OsSAPK8 is an essential activator of OsSLAC1 by phosphorylation, and OsSLAC1 is a nitrate-selective anion channel. S-type anion channel AtSLAC1 and protein kinase AtOST1 have been well-characterized as two core components of ABA signaling cascade in Arabidopsis guard cells, and AtOST1 functions as a main upstream activator of AtSLAC1 for drought stress- and ABA-induced stomata closure. However, the identity of the ortholog of AtOST1 in rice, the main activator of OsSLAC1, is still unknown. Here, we report that protein kinase OsSAPK8 interacts with and activates OsSLAC1 mainly by phosphorylating serine 129 (S129) of OsSLAC1, and this phosphorylating site corresponds to the specific phosphorylating site serine 120 (S120) of AtSLAC1 for AtOST1. Additionally, we found that OsSLAC1 is a nitrate-selective anion channel without obvious permeability to chloride, malate, and sulfate, and the expression of OsSLAC1 in Arabidopsis slac1-3 (atslac1-3) mutant successfully rescued the hypersensitive phenotype of this mutant to drought stress. Together, this research suggests that OsSAPK8 is a counterpart of AtOST1 for the activation of OsSLAC1, which is a nitrate-selective anion channel.

The response of Serratia marcescens JG to environmental changes by quorum sensing system.

Many bacterial cells are known to regulate their cooperative behaviors and physiological processes through a molecular mechanism called quorum sensing. Quorum sensing in Serratia marcescens JG is mediated by the synthesis of autoinducer 2 (AI-2) which is a furanosyl borate diester. In this study, the response of quorum sensing in S. marcescens JG to environment changes such as the initial pH, carbon sources and boracic acid was investigated by a bioreporter and real-time PCR analysis. The results show that glucose can affect AI-2 synthesis to the greatest extent, and 2.0 % glucose can stimulate S. marcescens JG to produce more AI-2, with a 3.5-fold increase in activity compared with control culture. Furthermore, the response of quorum sensing to changes in glucose concentration was performed by changing the amount of luxS RNA transcripts. A maximum of luxS transcription appeared during the exponential growth phase when the glucose concentration was 20.0 g/L. AI-2 production was also slightly impacted by the low initial pH. It is significant for us that the addition of boracic acid at microdosage (0.1-0.2 g/L) can also induce AI-2 synthesis, which probably demonstrated the feasible fact that the 4,5-dihydroxy-2, 3-pentanedione cyclizes by the addition of borate and the loss of water, is hydrated and is converted to the final AI-2 in S. marcescens JG.

The dependence of quorum sensing in Serratia marcescens JG on the transcription of luxS gene.

Bacteria communicate with one another using chemical signal molecules. This phenomenon termed quorum sensing enables the bacteria to monitor the environment for other bacteria and to alter behavior on a population-wide scale in response to cell density. Serratia marcescens JG, a quorum sensing bacterium, can secrete a furanosyl borate diester autoinducer (AI-2) in the exponential phase of growth. In this study, to further investigate the regulation of AI-2 production in S. marcescens JG, the pfs and luxS promoter fusions to an operon luxCDABE reporter were constructed in a low-copy-number vector pBR322K, which allows an examination of transcription of the genes in the pathway for signal synthesis. The results show that the luxS expression is constitutive, and the transcription of luxS is tightly correlated with AI-2 production in S. marcescens JG because the peaks of AI-2 production and transcriptional level of luxS appear at the same time point. The close relation of the profiles of luxS transcription and AI-2 production was also confirmed with real-time PCR technology. These results support the hypothesis that the quorum sensing in S. marcescens JG is luxS dependent.

A new NAD(H)-dependent meso-2,3-butanediol dehydrogenase from an industrially potential strain Serratia marcescens H30.

The budC gene coding for a new meso-2,3-butanediol dehydrogenase (BDH) from Serratia marcescens H30 was cloned and expressed in Escherichia coli BL21(DE3), purified, and characterized for its properties. The recombinant BDH with a molecular weight of 27.4 kDa exhibited a reversible transformation between acetoin and 2,3-butanediol. In the presence of NADH, BDH could catalyze the reduction of diacetyl and (3R)-acetoin to (3S)-acetoin and meso-2,3-butanediol, respectively, while (3S)-acetoin as a substrate could be further transformed into (2S, 3S)-2,3-butanediol at pH 9.0. For diol oxidation reactions, (3R)-acetoin and (3S)-acetoin were obtained when meso-2,3-butanediol and (2S,3S)-2,3-butanediol were used as the substrates with BDH and NAD(+). (2R,3R)-2,3-butanediol was not a substrate for the BDH at all. The low K m value (4.1 mM) in meso-2,3-butanediol oxidation reaction and no activity for diacetyl, acetoin, and 2,3-butanediol as the substrates with NADP(+)/NADPH suggested that the budC gene product belongs to a NAD(H)-dependent meso-2,3-BDH. Maximum activities for diacetyl and (3S/3R)-acetoin reduction were observed at pH 8.0 and pH 5.0 while for meso-2,3-butanediol oxidation it was pH 8.0. However, the optimum temperature for oxidation and reduction reactions was about 40 °C. In addition, the BDH activity for meso-2,3-butanediol oxidation was enhanced in the presence of Fe(2+) and for diacetyl and (3S/3R)-acetoin reduction in the presence of Mg(2+) and Mn(2+), while several metal ions inhibited its activity, particularly Fe(3+) for reduction of diacetyl and acetoin. Sequence analysis showed that the BDH from S. marcescens H30 possessed two conserved sequences including the coenzyme binding motif (GxxxGxG) and the active-site motif (YxxxK), which are present in the short-chain dehydrogenase/reductase superfamily.

Cloning, expression and characterization of glycerol dehydrogenase involved in 2,3-butanediol formation in Serratia marcescens H30.

The meso-2,3-butanediol dehydrogenase (meso-BDH) from S. marcescens H30 is responsible for converting acetoin into 2,3-butanediol during sugar fermentation. Inactivation of the meso-BDH encoded by budC gene does not completely abolish 2,3-butanediol production, which suggests that another similar enzyme involved in 2,3-butanediol formation exists in S. marcescens H30. In the present study, a glycerol dehydrogenase (GDH) encoded by gldA gene from S. marcescens H30 was expressed in Escherichia coli BL21(DE3), purified and characterized for its properties. In vitro conversion indicated that the purified GDH could catalyze the interconversion of (3S)-acetoin/meso-2,3-butanediol and (3R)-acetoin/(2R,3R)-2,3-butanediol. (2S,3S)-2,3-Butanediol was not a substrate for the GDH at all. Kinetic parameters of the GDH enzyme showed lower K m value and higher catalytic efficiency for (3S/3R)-acetoin in comparison to those for (2R,3R)-2,3-butanediol and meso-2,3-butanediol, implying its physiological role in favor of 2,3-butanediol formation. Maximum activity for reduction of (3S/3R)-acetoin and oxidations of meso-2,3-butanediol and glycerol was observed at pH 8.0, while it was pH 7.0 for diacetyl reduction. The enzyme exhibited relative high thermotolerance with optimum temperature of 60 °C in the oxidation-reduction reactions. Over 60 % of maximum activity was retained at 70 °C. Additionally, the GDH activity was significantly enhanced for meso-2,3-BD oxidation in the presence of Fe(2+) and for (3S/3R)-acetoin reduction in the presence of Mn(2+), while several cations inhibited its activity, particularly Fe(2+) and Fe(3+) for (3S/3R)-acetoin reduction. The properties provided potential application for single configuration production of acetoin and 2,3-butanediol .

A novel breeding strategy for new strains of Hypsizygus marmoreus and Grifola frondosa based on ligninolytic enzymes.

A novel breeding strategy for new strains of Hypsizygus marmoreus and Grifola frondosa using ligninolytic enzymes as markers was evaluated with the detection and analysis of activities and composition of 15 edible fungi. The results showed that the activity and composition of ligninolytic enzyme system varied in response to changes of fungal strains. By analyzing the growth rate of mycelia and their ability to produce ligninolytic enzymes, H. marmoreus and P. geesteranus, G. frondosa and P. sajor-caju were screened for further study. Three colonies of 26 regenerated colonies of H. marmoreus and P. geesteranus protoplast fusion and one colony of 48 regenerated colonies of G. frondosa and P. sajor-caju were selected respectively. At the same time, these four strains were identified using RAPD and ISSR molecular markers. The results showed that the strains HM5G1 and PS7F1 are new strains and have low similarity to parental strains H. marmoreus and G. frondosa. These results are supported by the results of antagonism tests. These two fusants were significantly higher in their ligninolytic enzyme activity than H. marmoreus and G. frondosa. The growth rates of strains HM5G1and PS7F1 were also noticeably higher than those of H. marmoreus and G. frondosa, by 1.36 and 1.5 times respectively. The biological efficiency of the strain HM5G1 was 11.5% higher than that of the parental strain H. marmoreus. This work suggests that it is an efficient way of breeding new strains to use the decolorization of ligninolytic enzymes as a preliminary screening marker.

Metabolomics-Based Analysis on the Effect and Metabolic Response of Mycelia by Sawdust Addition from Hypsizygus marmoreus.

The composition of culture substrate is an important environmental factor that affects the growth and metabolism of Hypsizygus marmoreus, and sawdust is commonly used as the substrate for cultivating mushrooms. However, the influences of sawdust on metabolic level of H. marmoreus in mycelial growth is little reported. In this study, the effect of sawdust addition on mycelial growth rate, morphological characteristics and nutrient content of H. marmoreus was explored, and the metabolic response was analyzed based on LC-MS/MS. The results showed the mycelial growth rates and the number of mycelial clamp connections in sawdust medium A and sawdust medium B were significantly higher than that of the basic medium (Control). The mycelial morphology in sawdust medium A was denser, with higher edge trimness and stronger aerial mycelia. The contents of crude fiber, crude protein and polysaccharide of the mycelia from sawdust medium A increased by 85.15%, 90.65% and 92.61%, respectively, compared to that in the basic medium. A total of 551 metabolites were identified and obtained. The differential accumulated metabolites (DAMs) were mainly amino acids, lipids compounds and carbohydrates. It was speculated that the addition of sawdust played a vital role in promoting the cell division and, thus, the formation of clamp connections in H. marmoreus mycelia. Regarding amino acids, the metabolism of glycine, serine and ABC transporters was active with the increase in sawdust, thereby increasing the protein content. And some valuable bioactive molecules were found, such as docosahexaenoic acid (DHA). This study will lay the foundation for further research on the substance transformation and quality improvement of cultivation substrate for mushrooms.

Evaluation of Physicochemical Properties and Prebiotics Function of a Bioactive Pleurotus eryngii Aqueous Extract Powder Obtained by Spray Drying.

A bioactive Pleurotus eryngii aqueous extract powder (SPAE) was obtained by spray drying and its performance in terms of physicochemical properties, in vitro digestion, inflammatory factors, and modulation of the intestinal microbiota was explored. The results indicated that the SPAE exhibited a more uniform particle size distribution than P. eryngii polysaccharide (PEP). Meanwhile, a typical absorption peak observed at 843 cm-1 in the SPAE FTIR spectra indicated the existence of α-glycosidic bonds. SPAE exhibited higher antioxidant abilities and superior resistance to digestion in vitro. In addition, SPAE supplementation to mice significantly reduced the release of factors that promote inflammation, enhanced the secretion of anti-inflammatory factors, and sustained maximum production of short-chain fatty acids (SCFAs). Additionally, it significantly enhanced the relative abundance of SCFAs-producing Akkermansia and reduced the abundance of Ruminococcus and Clostridiides in intestines of mice. These results show the potential of SPAE as a novel material with prebiotic effects for the food and pharmaceutical industries.

A chromosome-scale genome and proteome draft of Tremella fuciformis.

In this study, we first reported a high-quality chromosome-scale genome of Tremella fuciformis using Pacbio HiFi sequencing combining Hi-C technology. According to 21.6 Gb PacBio HiFi reads and 18.1 Gb Hi-C valid reads, we drafted a T. fuciformis genome of 27.38 Mb assigned to 10 chromosomes, with the contig N50 of 2.28 Mb, GC content of 56.51 %, BUSCOs completeness of 93.1 % and consensus quality value of 33.7. The following annotation of genomic components predicted 5,171 repeat sequences, 283 RNAs, and 10,150 protein-coding genes. Next, the intracellular proteins at three differential life stages of T. fuciformis (conidium, hyphal and fruiting body) were identified by the shot-gun proteomics. 6,823 canonical proteins (68.1 % of predicted proteome) have been identified with protein FDR cut-off of 0.01, establishing the first proteome draft of predicted protein-coding genes of T. fuciformis. Finally, 24 T. fuciformis polysaccharides (TPS) biosynthesis-related genes in mycelia were identified by comparative transcriptomics and proteomics, which may be more active than in conidium and revealed the TPS biosynthesis process in mycelia. This present study elucidated T. fuciformis genome composition and organization, drafted its associated proteome, and provided a genome-view of TPS biosynthesis, which will be a powerful platform for biological and genetic studies in T. fuciformis.

Analysis and modification of central carbon metabolism in Hypsizygus marmoreus for improving mycelial growth performance and fruiting body yield.

Hypsizygus marmoreus is one of the main industrially cultivated varieties of edible fungi, with a delicious taste and high nutritional value. However, the long harvest period of 130-150 days greatly limits its large-scale expansion. This study aimed to investigate the effects of central carbon metabolism (CCM) on the mycelial growth performance and fruiting body formation of H. marmoreus. Nine edible fungi with different harvest periods were collected and used to evaluate their intracellular carbon metabolic differences in the CCM, which revealed that the imbalanced distribution of intracellular carbon metabolic levels in the CCM of H. marmoreus might be one of the key factors resulting in a slow mycelial growth rate and a long harvest period. Further analysis by three strategies, including metabolomics, adaptation of different carbon sources, and chemical interference, confirmed that low carbon flux into the pentose phosphate pathway (PPP) limited the supply of raw materials, reduced power, and thus influenced the mycelial growth of H. marmoreus. Furthermore, four transformants with increased expression levels of glucose-6-phosphate dehydrogenase (G6PDH), a key rate-limiting enzyme in the PPP of H. marmoreus, were developed and showed more extracellular soluble protein secretion and higher sugar assimilation rates, as well as improved mycelial growth rates in bottle substrate mixtures. Finally, cultivation experiments indicated that the maturation periods of the fruiting body with ~4-5 days in advance and the maximum fruiting body yield of 574.8 g per bag with an increase of 7.4% were achieved by improving the G6PDH expression level of the PPP in H. marmoreus. This study showed that CCM played an important role in the mycelial growth and development of H. marmoreus, which provided new insights for future advancements in cultivating and breeding edible fungi.

The Promoting Mechanism of the Sterile Fermentation Filtrate of Serratia odorifera on Hypsizygus marmoreus by Means of Metabolomics Analysis.

Hypsizygus marmoreus has become one of the most popular edible mushrooms due to its high nutritional and economic value. Previous researchers found that Serratia odorifera could promote the growth of H. marmoreus by producing and secreting some of its inducers. However, the specific mechanism of action was still unclear. In this study, we found that the exogenous addition of sterile fermentation filtrate (HZSO-1), quorum sensing (QS) signaling molecules, 3-oxo-C6-HSL, cyclo(Pro-Leu), and cyclo(Tyr-Leu) could significantly promote the growth of H. marmoreus, increase the number of clamp junctions, and the diameter of mycelium (p < 0.05). In addition, non-targeted metabolomic analysis revealed that 706 metabolites were detected in the treated group. Of these, 307 metabolites were significantly different (p < 0.05). Compared with the control, 54 and 86 metabolites were significantly increased and decreased in the HZSO-1 group, respectively (p < 0.05). We speculate that the sterile fermentation filtrate of S. odorifera could mediate the carbohydrate and amino acid metabolism of H. marmoreus by influencing the pentose phosphate pathway (PPP) to increase the energy supply for the growth and development of the mycelium. The above results will further reveal the growth-promoting mechanism of S. odorifera on H. marmoreus.

Transcriptome Analysis Reveals the Function of a G-Protein α Subunit Gene in the Growth and Development of Pleurotus eryngii.

Pleurotus eryngii is a commercially important edible fungus with high nutritional and economic value. However, few functional studies have examined key genes affecting the growth and development of P. eryngii. In this study, transformed strains, including over-expression (PeGNAI-OE) and RNA interference (PeGNAI-RNAi) lines, were constructed to elucidate the role of GNAI in P. eryngii growth. GNAI expression was found to affect the mycelial growth and the number of clamp connections. Moreover, the transformed strains were shown to have higher endogenous cAMP levels, thus affecting amylase and laccase activity. Fruiting experiments showed that GNAI expression revealed the formation of P. eryngii primordia and the number of buttons, while transcription analysis identified GNAI gene involvement in the growth and development of P. eryngii. Seven downstream genes regulated by GNAI were differentially expressed in PeGNAI-OE and PeGNAI-RNAi compared to wild type (WT). These genes may be related to mycelial growth and enzyme activity. They were involved in the MAPK signaling pathway, inositol phosphate metabolism, ascorbate, aldarate metabolism, and starch and sucrose metabolism. In summary, GNAI performs different physiological functions in regulating the growth and development of P. eryngii. Importantly, the molecular mechanisms of GNAI regulatory function are relatively complex and need further study.

A TFIIIA-type zinc finger protein confers multiple abiotic stress tolerances in transgenic rice (Oryza sativa L.).

The TFIIIA-type zinc finger transcription factors are involved in plant development and abiotic stress responses. Most TFIIIA-type zinc finger proteins are transcription repressors due to existence of an EAR-motif in their amino acid sequences. In this work, we found that ZFP182, a TFIIIA-type zinc finger protein, forms a homodimer in the nucleus and exhibits trans-activation activity in yeast cells. The deletion analysis indicated that a Leu-rich region at C-terminus is required for the trans-activation. Overexpression of ZFP182 significantly enhanced multiple abiotic stress tolerances, including salt, cold and drought tolerances in transgenic rice. Overexpression of ZFP182 promotes accumulation of compatible osmolytes, such as free proline and soluble sugars, in transgenic rice. ZFP182 activates the expression of OsP5CS encoding pyrroline-5-carboxylate synthetase and OsLEA3 under stress conditions, while OsDREB1A and OsDREB1B were regulated by ZFP182 under both normal and stress conditions. Interestingly, site-directed mutagenesis assay showed that DRE-like elements in ZFP182 promoter are involved in dehydration-induced expression of ZFP182. The yeast two-hybrid assay revealed that ZFP182 interacted with several ribosomal proteins including ZIURP1, an ubiquitin fused to ribosomal protein L40. The in vivo and in vitro interactions of ZFP182 and ZIURP1 were further confirmed by bimolecular fluorescence complementation and His pull-down assays. Our studies provide new clues in the understanding of the mechanisms for TFIIIA-type zinc finger transcription factor mediated stress tolerance and a candidate gene for improving stress tolerance in crops.

Effects of Drying Methods on the Physicochemical Aspects and Volatile Compounds of Lyophyllum decastes.

In this study, fresh Lyophyllum decastes was dried using hot air drying (HAD), hot air combined with vacuum drying (HAVD), and vacuum freeze drying (VFD). Additionally, the quality and volatile compounds were analyzed. VFD achieved the best color retention, the highest rehydration capacity, and the slightest damaged tissue structure; however, it recorded the longest drying time and the highest energy consumption. HAD was the most energy-efficient of the three methods. Furthermore, the products with more hardness and elasticity were obtained by HAD and HAVD-this finding was convenient for transportation. In addition, GC-IMS demonstrated that the flavor components had significantly changed after drying. A total of 57 volatile flavor compounds was identified, and the aldehyde, alcohol, and ketone compounds were the primary ingredient of the L. decastes flavor component, whereby the relative content of the HAD sample was apparently higher than HAVD and VFD. Taken together, VFD was better at preserving the color and shape of fresh L. decastes, but HAD was more appropriate for drying L. decastes because of the lower energy consumption, and was more economical. Meanwhile, HAD could be used to produce a more intense aroma.