Cell Wall Degradation Research Articles

Transcriptional effects of carbon and nitrogen starvation on Ganoderma boninense, an oil palm phytopathogen.

Ganoderma boninense is a phytopathogen of oil palm, causing basal and upper stem rot diseases. The genome sequence was used as a reference to study gene expression during growth in a starved carbon (C) and nitrogen (N) environment with minimal sugar and sawdust as initial energy sources. This study was conducted to mimic possible limitations of the C-N nutrient sources during the growth of G. boninense in oil palm plantations. Genome sequencing of an isolate collected from a palm tree in West Malaysia generated an assembly of 67.12Mb encoding 19,851 predicted genes. Transcriptomic analysis from a time course experiment during growth in this starvation media identified differentially expressed genes (DEGs) that were found to be associated with 29 metabolic pathways. During the active growth phase, 26 DEGs wererelated to four pathways, including secondary metabolite biosynthesis, carbohydrate metabolism, glycan metabolism and mycotoxin biosynthesis. G. boninense genes involved in the carbohydrate metabolism pathway that contribute to the degradation of plant cell walls were up-regulated. Interestingly, several genes associated with the mycotoxin biosynthesis pathway were identified as playing a possible role in pathogen-host interaction. In addition, metabolomics analysis revealed six metabolites, maltose, xylobiose, glucooligosaccharide, glycylproline, dimethylfumaric acid and arabitol that were up-regulated on Day2 of the time course experiment. This study provides information on genes expressed by G. boninense in metabolic pathways that may play a role in the initial infection of the host.

Transcription factor LBD16 targets cell wall modification/ion transport genes in peach lateral root formation.

LATERAL ORGAN BOUNDARIES DOMAIN/ASYMMETRIC LEAVES2-LIKEs (LBDs/ASLs) are plant-specific transcription factors that function downstream of auxin-regulated lateral root (LR) formation. Our previous research found that PpLBD16 positively regulates peach (Prunus persica) LR formation. However, the downstream regulatory network and target genes of PpLBD16 are still largely unknown. Here, we constructed a PpLBD16 homologous overexpression line and a PpLBD16 silenced line. We found that overexpressing PpLBD16 promoted peach root initiation, while silencing PpLBD16 inhibited peach root formation. Through RNA sequencing (RNA-seq) analysis of roots from PpLBD16 overexpression and silenced lines, we discovered that genes positively regulated by PpLBD16 were closely related to cell wall synthesis and degradation, ion/substance transport, and ion binding and homeostasis. To further detect the binding motifs and potential target genes of PpLBD16, we performed DNA-affinity purification sequencing (DAP-seq) analysis in vitro. PpLBD16 preferentially bound to CCNGAAANNNNGG (MEME-1), [C/T]TTCT[C/T][T/C] (MEME-2), and GCGGCGG (ABR1) motifs. By combined analysis of RNA-seq and DAP-seq data, we screened candidate target genes for PpLBD16. We demonstrated that PpLBD16 bound and activated the cell wall modification-related genes EXPANSIN-B2 (PpEXPB2) and SUBTILISIN-LIKE PROTEASE 1.7 (PpSBT1.7), the ion transport-related gene CYCLIC NUCLEOTIDE-GATED ION CHANNEL 1 (PpCNGC1) and the polyphenol oxidase (PPO)-encoding gene PpPPO, thereby controlling peach root organogenesis and promoting LR formation. Moreover, our results displayed that PpLBD16 and its target genes are involved in peach LR primordia development. Overall, this work reveals the downstream regulatory network and target genes of PpLBD16, providing insights into the molecular network of LBD16-mediated LR development.

Polygalacturonase inhibiting protein enhances cell wall strength of strawberry fruit for resistance to Botrytis cinerea infection

Polygalacturonase inhibitor protein (PGIP) plays an active role in resisting pathogens from degrading cell walls. Strawberry fruit quality is strongly affected by Botrytis cinerea (B. cinerea), so PGIP genes from heterologous species were cloned and analyzed to identify genes having good B.cinerea infection resistance. In this study, a PGIP gene from grape fruit was isolated and heterologously transiently expressed in strawberry fruit. The results revealed that VvPGIP (PGIPO) overexpression in strawberry fruit led to B. cinerea infection resistance, but RNA interference of VvPGIP (PGIPI) made fruit susceptible to B. cinerea infection. qPCR indicated that expression levels of FaPGIP was increased after transient expression of VvPGIP in PGIPO fruit for 48 h as compared to the control and that polygalacturonase enzyme (PG) was significantly down-regulated, whereas PGIPI fruit had the opposite effect, suggesting that VvPGIP may activate the FaPGIP expression levels, thereby reducing the disease incidence and index of strawberry fruits and improving the disease resistance of the fruits. VvPGIP also inhibited the decrease of total pectin and cellulose content. Transcriptome and metabolome results showed that PGIP is widely involved in photosynthesis, signal transduction, and secondary metabolism of fruits. In addition, many enzyme activities and defense reaction were also significantly enriched. Using Y2H and BiFC technology, we screened and verified the interaction protein of VvPGIP with Endo-1, 3-Beta-Glucanase (VvGLU) and pathogen-related protein 4 (VvPR-4) on the cell membrane. Taken together, PGIP as a key protein in plant defense response functions a key role in regulating the strength of cell walls and can inhibit the degradation of plant cell walls by pathogens.

Temporally-coordinated bivalent histone modifications of BCG1 enable fungal invasion and immune evasion

Bivalent histone modifications, including functionally opposite H3K4me3 and H3K27me3 marks simultaneously on the same nucleosome, control various cellular processes by fine-tuning the gene expression in eukaryotes. However, the role of bivalent histone modifications in fungal virulence remains elusive. By mapping the genome-wide landscape of H3K4me3 and H3K27me3 dynamic modifications in Fusarium graminearum (Fg) during invasion, we identify the infection-related bivalent chromatin-marked genes (BCGs). BCG1 gene, which encodes a secreted Fusarium-specific xylanase containing a G/Q-rich motif, displays the highest increase of bivalent modification during Fg infection. We report that the G/Q-rich motif of BCG1 is a stimulator of its xylanase activity and is essential for the full virulence of Fg. Intriguingly, this G/Q-rich motif is recognized by pattern-recognition receptors to trigger plant immunity. We discover that Fg employs H3K4me3 modification to induce BCG1 expression required for host cell wall degradation. After breaching the cell wall barrier, this active chromatin state is reset to bivalency by co-modifying with H3K27me3, which enables epigenetic silencing of BCG1 to escape from host immune surveillance. Collectively, our study highlights how fungal pathogens deploy bivalent epigenetic modification to achieve temporally-coordinated activation and suppression of a critical fungal gene, thereby facilitating successful infection and host immune evasion.

Exploring the Effects of Different 1-MCP Concentration Treatment on Chilling Injury of Postharvest Peach Fruit

Peach (Prunus persica (L.) Batsch) fruit are susceptible to chilling injury that is often manifested as browning of the internal flesh. As the ethylene antagonist, 1-methylcyclopropene (1-MCP) is an important contributor to resist chilling stress during peach (Prunus persica (L.) Batsch) storage at low temperatures, but the molecular mechanism of it is still elusive. The study examined in detail the effects of two concentrations (1 and 2 μL·L−1) of 1-MCP on alleviating chilling injury (CI) of postharvest peach fruit stored at 4 ± 0.5°C. The results showed that although all treatments relieved CI, treatment with 1 μL·L−1 more effectively alleviated CI symptoms of postharvest peach fruit than 2 μL·L−1. The internal browning (IB) and weight loss were significantly inhibited by 1 μL·L−1 1-MCP. Lower concentration of 1-MCP maintained normal softening by decreasing the gene expression of expansin (Exp) 1,3, polygalacturonase (PG) 3, and pectate lyase (PLY) 1, 2, 3 and increased the content of soluble sugar during the whole storage period. Meanwhile, the activities of polygalacturonase, pectinmethylesterase (PME), and endo-1,4-β-glucanase (EGase) were reduced by lower concentration of 1-MCP. Our results demonstrate that 1-MCP inhibited CI by suppressing the degradation of cell wall. This study provides a theoretical basis for revealing that 1-MCP alleviates chilling injury in peach fruit.

Genome evolution and transcriptome plasticity is associated with adaptation to monocot and dicot plants in Colletotrichum fungi.

Colletotrichum fungi infect a wide diversity of monocot and dicot hosts, causing diseases on almost all economically important plants worldwide. Colletotrichum is also a suitable model for studying gene family evolution on a fine scale to uncover events in the genome associated with biological changes. Here we present the genome sequences of 30 Colletotrichum species covering the diversity within the genus. Evolutionary analyses revealed that the Colletotrichum ancestor diverged in the late Cretaceous in parallel with the diversification of flowering plants. We provide evidence of independent host jumps from dicots to monocots during the evolution of Colletotrichum, coinciding with a progressive shrinking of the plant cell wall degradative arsenal and expansions in lineage-specific gene families. Comparative transcriptomics of 4 species adapted to different hosts revealed similarity in gene content but high diversity in the modulation of their transcription profiles on different plant substrates. Combining genomics and transcriptomics, we identified a set of core genes such as specific transcription factors, putatively involved in plant cell wall degradation. These results indicate that the ancestral Colletotrichum were associated with dicot plants and certain branches progressively adapted to different monocot hosts, reshaping the gene content and its regulation.

Transcriptomic and sugar metabolic analysis reveals molecular mechanisms of peach gummosis in response to Neofusicoccum parvum infection.

Peach gummosis, a devastating disease caused by Neofusicoccum parvum, significantly shortens peach tree lifespan and reduces the yield of peach trees. Despite its impact, the molecular mechanism underlying this disease remains largely unexplored. In this study, we used RNA-seq, sugar metabolism measurements, and an integrated transcriptional and metabolomic analysis to uncover the molecular events driving peach gummosis. Our results revealed that N. parvum infection drastically altered the transcripts of cell wall degradation-related genes, the log2Fold change in the transcript level of Prupe.1G088900 encoding xyloglucan endotransglycosylase decreased 2.6-fold, while Prupe.6G075100 encoding expansin increased by 2.58-fold at 12 hpi under N. parvum stress. Additionally, sugar content analysis revealed an increase in maltose, sucrose, L-rhamnose, and inositol levels in the early stages of infection, while D-galactose, D-glucose, D-fructose consistently declined as gummosis progressed. Key genes related to cell wall degradation and starch degradation, as well as UDP-sugar biosynthesis, were significantly upregulated in response to N. parvum. These findings suggest that N. parvum manipulates cell wall degradation and UDP-sugar-related genes to invade peach shoot cells, ultimately triggering gum secretion. Furthermore, weighted gene co-expression network analysis (WGCNA) identified two transcription factors, ERF027 and bZIP9, as central regulators in the downregulated and upregulated modules, respectively. Overall, this study enhances our understanding of the physiological and molecular responses of peach trees to N. parvum infection and provide valuable insights into the mechanisms of peach defense against biotic stresses.

FACILE PRODUCTION OF 4-HYDROXYBENZOIC ACID FROM OIL PALM EMPTY FRUIT BUNCH CELL WALLS BY ALKALI DEGRADATION AT ROOM TEMPERATURE

Oil palm empty fruit bunches are biorefinery waste produced from the oil palm factory. Palm lignin is partially ended with p-hydroxybenzoylated structure, which is a promising resource to produce 4-hydroxybenzoic acid. Herein, 4-hydroxybenzoic acid is produced by the degradation of oil palm empty fruit bunch cell walls with sodium hydroxide solution at room temperature without lignin isolation. The 4-hydroxybenzoic acid was obtained as the only main monomeric product from the process. The yield of 4-hydroxybenzoic acid can reach 7.87% based on the amount of oil palm empty fruit lignin. The sodium hydroxide concentration is the most important factor that affects the 4-hydroxybenzoic acid production yield and selectivity. The possible 4-hydroxybenzoic acid production routes were proposed. And the production route is considered to be formed mainly by the cleavage of C-O bonds at the γ-hydroxyl position of the syringyl unit in oil palm empty fruit bunch lignin.

Role of gum Arabic combined with cinnamic acid coating on quality and cell wall degradation enzymes of mango fruits at low temperature

Mango exhibits a short shelf life when kept under ambient conditions. Therefore, this study was carried out to assess the synergistic effect of gum Arabic (GA) and cinnamic acid (CA) coatings on mango fruits stored for 28 days at 12 ± 1 °C. The treatments included GA 10 and 20 % sole and its formulation with CA 0.2 % while the uncoated fruits were used as control. The results revealed that GA + CA coatings exhibited reduced weight loss, flesh firmness, delayed respiratory peak, retained soluble solids content (SSC), titratable acidity (TA) and skin colour, retarded spoilage, and decreased electrolyte leakage of fruit as compared to uncoated fruit during storage. Among all, the coating GA 20 % + CA 0.2 % maintained higher firmness (16.6 N), SSC (20.1 %), TA (0.71 %), total flavonoid content (152 mg/kg) and total carotenoids content (45.1 mg/kg) and retained the higher sensory quality of mango fruit at the end of storage. Additionally, the GA 20 % + CA 0.2 % coating suppressed activities of polygalacturonase (PG), cellulase (CL) and pectin methyl esterase (PME) in stored mango fruits.

Evaluation of antifungal activity against Corynespora cassiicola by bacteria isolated from soil in the root zone of cucumber plants

Abstract. Duy LQ. 2023. Evaluation of antifungal activity against Corynespora cassiicola by bacteria isolated from soil in the root zone of cucumber plants. Biodiversitas 24: 6584-6591. Target leaf spot caused by Corynespora cassiicola poses a major disease threat to cucumber cultivation worldwide. Reliance on chemical fungicides has raised resistance to environmental and health concerns. As cucumber production expands globally, sustainable solutions are needed. Plant Growth-Promoting Rhizobacteria (PGPR) show promise but remain underexplored against C. cassiicola in cucumber. This study aimed to assess the potency of rhizobacteria in antagonistic activity against C. cassiicola, causing cucumber target leaf spots under in vitro conditions. The present study isolated bacterial strains from cucumber soil rhizosphere and screened for antifungal activity against C. cassiicola using dual culture assays. Using quantitative assays, selected antagonistic strains were further assessed for key biocontrol traits, including ?-1,3-glucanase, chitinase, and siderophore production. Cell-free supernatants were tested for direct fungal growth inhibition using the environmental toxicity. Isolated PGPR strains showed robust C. cassiicola inhibition from 39.8% to 62.6% growth reduction. Most antagonistic isolates produced ?-1,3-glucanase, chitinase, and siderophores and suppressed pathogen growth via metabolites in their supernatants. These results demonstrate multiple biocontrol mechanisms, including enzymatic degradation of fungal cell walls, iron competition through siderophores, and antimicrobial compound secretion. Bacillus siamensis strain TV16 exhibited the strongest overall antagonism against C. cassiicola. These findings reveal the biocontrol potential of PGPR for managing cucumber-target leaf-spot disease, offering a sustainable alternative to chemical pesticides. With further optimization and field testing, PGPR-based biopesticides can be integrated into cucumber production to improve crop health while reducing fungicide reliance.

Metatranscriptomics sheds light on the links between the functional traits of fungal guilds and ecological processes in forest soil ecosystems.

Soil fungi belonging to different functional guilds, such as saprotrophs, pathogens, and mycorrhizal symbionts, play key roles in forest ecosystems. To date, no study has compared the actual gene expression of these guilds in different forest soils. We used metatranscriptomics to study the competition for organic resources by these fungal groups in boreal, temperate, and Mediterranean forest soils. Using a dedicated mRNA annotation pipeline combined with the JGI MycoCosm database, we compared the transcripts of these three fungal guilds, targeting enzymes involved in C- and N mobilization from plant and microbial cell walls. Genes encoding enzymes involved in the degradation of plant cell walls were expressed at a higher level in saprotrophic fungi than in ectomycorrhizal and pathogenic fungi. However, ectomycorrhizal and saprotrophic fungi showed similarly high expression levels of genes encoding enzymes involved in fungal cell wall degradation. Transcripts for N-related transporters were more highly expressed in ectomycorrhizal fungi than in other groups. We showed that ectomycorrhizal and saprotrophic fungi compete for N in soil organic matter, suggesting that their interactions could decelerate C cycling. Metatranscriptomics provides a unique tool to test controversial ecological hypotheses and to better understand the underlying ecological processes involved in soil functioning and carbon stabilization.

Combined volatile compounds and non-targeted metabolomics analysis reveals variation in flavour characteristics, metabolic profiles and bioactivity of mulberry leaves after Monascus purpureus fermentation.

Mulberry leaves (MLs) are widely used in food because of their nutritional and functional characteristics. However, plant cell walls and natural bitterness influence nutrient release and the flavor properties of MLs. Liquid-state fermentation using Monascus purpureus (LFMP) is a common processing method used to improve food properties. The present study used headspace solid-phase micro extraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and non-targeted metabolomics to examine changes in volatile and non-volatile metabolites in MLs. The transformation mechanism of LFMP was investigated by microscopic observation and dynamic analysis of enzyme activity, and changes in the biological activity of MLs were analyzed. LFMP significantly increased total phenolics, total flavonoids, free amino acids and soluble sugars in MLs, at the same time as decreasing phytic acid levels. In total, 92 volatile organic compounds (VOCs) were identified and quantified. VOCs such as (2R,3R)-(-)-2,3-butanediol, terpineol and eugenol showed some improvement in the flavour characteristics of MLs. By using non-targeted metabolomics, 124 unique metabolites in total were examined. LFMP altered the metabolic profile of MLs, mainly in plant secondary metabolism, lipid metabolism and amino acid metabolism. Microscopic observation and dynamic analysis of enzyme activity indicated that LFMP promoted cell wall degradation and biotransformation of MLs. In addition, LFMP significantly increased the angiotensin I-converting enzyme and α-glucosidase inhibitory activity of MLs. LFMP altered the flavour characteristics, metabolite profile and biological activity of MLs. These findings will provide ideas for the processing of MLs into functional foods. In addition, they also provide useful information for biochemical studies of fermented MLs. © 2023 Society of Chemical Industry.

Assessment of cell wall degrading enzymes by molecular docking and dynamics simulations: Effects of novel infrared treatment

Cell wall-degrading enzymes' activities under infrared treatment are vital for peeling; it is critical to elucidate the mechanisms of the novel infrared peeling in relation to its impact on cell wall-degrading enzymes. In this study, the activities, and gene expressions of eight degrading enzymes closely related to pectin, cellulose and hemicellulose were determined. The most influential enzyme was selected from them, and then the mechanism of its changes was revealed by molecular dynamics simulation and molecular docking. The results demonstrated that infrared had the most significant effect on β-glucosidase among the tested enzymes (increased activity and up-regulated gene expression of 195.65 % and 7.08, respectively). It is suggested infrared crucially promotes cell wall degradation by affecting β-glucosidase. After infrared treatment, β-glucosidase's structure moderately transformed to a more open one and became flexible, increasing the affinity between β-glucosidase and substrate (increasing 75 % H-bonds and shortening 15.89 % average length), thereby improving β-glucosidase's activity. It contributed to cell wall degradation. The conclusion is that the effect of infrared on the activity, gene expression and molecular structure of β-glucosidase causes damage to the peel, thus broadening the applicability of the new infrared dry-peeling technique, which has the potential to replace traditional wet-peeling methods.

Effects of Near-Freezing Temperature Combined with Jujube Polysaccharides Treatment on Proteomic Analysis of 'Diaogan' Apricot (Prunus armeniaca L.).

This study involved the extraction of polysaccharides from jujube for application in apricot storage. Although near-freezing temperature (NFT) storage is commonly employed for preserving fresh fruit, its effectiveness is somewhat limited. Incorporating jujube polysaccharides was proposed to augment the preservative effect on apricots. Our findings demonstrated that the combined use of NFT and jujube polysaccharides can maintain fruit color, and effectively inhibit decay. Additionally, Tandem Mass Tag (TMT) quantitative proteomic technology was utilized to analyze protein variations in 'Diaogan' apricots during storage. This dual approach not only markedly lowered the activity of polyphenol cell wall-degrading enzymes (p < 0.05) but also revealed 1054 differentially expressed proteins (DEPs), which are related to sugar and energy metabolism, stress response and defense, lipid metabolism, and cell wall degradation. The changes in DEPs indicated that the combined use of NFT and jujube polysaccharides could accelerate the conversion of malic acid to oxaloacetic acid and regulate antioxidant ability, potentially extending the storage lifespan of apricot fruit.

Taxonomic and functional assembly cues enrich the endophytic tobacco microbiota across epiphytic compartments.

The plant microbiome plays a critical role in plant growth, development, and health, with endophytes being recognized as essential members due to their close interactions with host plants. However, knowledge gaps remain in understanding the mechanisms driving the colonization and establishment of endophytic communities. To address this issue, we investigated the microbiota of tobacco roots and leaves, including both epiphytic and endophytic microorganisms. We found that Actinobacteria and Alphaproteobacteria were significantly enriched in the root endosphere. Additionally, we identified higher abundances of functional traits involved in antibiotic synthesis, plant cell wall degradation, iron metabolism, secretion systems, and nicotine degradation enzymes in the endosphere. We further studied metagenome-assembled genomes from the rhizosphere and root endosphere, revealing a greater diversity of secondary metabolites in bacteria within the root endosphere. Together, this study provides insights into the taxonomic and functional assembly cues that may contribute to shaping the endophytic plant microbiota.IMPORTANCEThe presence of diverse microorganisms within plant tissues under natural conditions is a well-established fact. However, due to the plant immune system's barrier and the unique microhabitat of the plant interior, it remains unclear what specific characteristics bacteria require to successfully colonize and thrive in the plant endosphere. Recognizing the significance of unraveling these functional features, our study focused on investigating the enriched traits in the endophytic microbiota compared to the epiphytes. Through our research, we have successfully identified the taxonomic and functional assembly cues that drive the enrichment of the endophytic microbiota across the epiphytic compartments. These findings shed new light on the intricate mechanisms of endophyte colonization, thereby deepening our understanding of plant-microbe interactions and paving the way for further advancements in microbiome manipulation.

Histological and biophysical changes of cassava roots during retting, a key step of fufu processing.

Retting is a key step of cassava processing into widely consumed foods (fufu, chikwangue, miondo and bobolo) in sub-Saharan Africa. For some populations, retting ability is a major quality criterion that drives the adoption of new cassava varieties. Despite this importance, the physiological basis associated with this process remains poorly understood, and should lead to improved screening tools for breeding. Eight cassava varieties contrasting in retting ability properties were used in the present study. Roots and soaking water were sampled during retting and characterized at both histological and biochemical levels. Histological data highlighted the degradation of root cell wall during retting. The average pH of soaking water decreased from 5.94 to 4.31 and the average simple sugars decreased from 0.18 to 0 g L-1, whereas the organic acids increased up to 5.61 g L-1. In roots tissue, simple sugars and organic acid contents decreased from 22.9 to 0 g kg-1 and from 80 to 0 g kg-1, respectively. The total pectin content of roots among varieties at harvest was similar, and decreased during the retting process. Overall, there was a negative correlation between total pectins content and root softening, although this did not reach statistical significance. Major histological and biochemical changes occurred during cassava root retting, with some of them associated with the process. Retting affected starch pasting properties more than starch content. Although this process is characterized by root softening and degradation of cell wall structure, the present study strongly suggested that pectin is not the only cell wall component involved in these changes. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Mutation of mltG increases peptidoglycan fragment release, cell size, and antibiotic susceptibility in Neisseria gonorrhoeae.

Neisseria gonorrhoeae is unusual in that the bacteria release larger amounts of cell wall material as they grow as compared to related bacteria, and the released cell wall fragments induce inflammation that leads to tissue damage in infected people. The study of MltG revealed the importance of this enzyme for controlling cell wall growth, cell wall fragment production, and bacterial cell size and suggests a role for MltG in a cell wall synthesis and degradation complex. The increased antibiotic sensitivities of mltG mutants suggest that an antimicrobial drug inhibiting MltG would be useful in combination therapy to restore the sensitivity of the bacteria to cell wall targeting antibiotics to which the bacteria are currently resistant.

Biocontrol of Peach Gummosis by Bacillus velezensis KTA01 and Its Antifungal Mechanism.

Peach tree gummosis is a botanical anomaly distinguished by the secretion of dark-brown gum from the shoots of peach trees, and Botryosphaeria dothidea has been identified as one of the fungal species responsible for its occurrence. In South Korea, approximately 80% of gummosis cases are linked to infections caused by B. dothidea. In this study, we isolated microbes from the soil surrounding peach trees exhibiting antifungal activity against B. dothidea. Subsequently, we identified several bacterial strains as potential candidates for a biocontrol agent. Among them, Bacillus velezensis KTA01 displayed the most robust antifungal activity and was therefore selected for further analysis. To investigate the antifungal mechanism of B. velezensis KTA01, we performed tests to assess cell wall degradation and siderophore production. Additionally, we conducted reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis based on whole-genome sequencing to confirm the presence of genes responsible for the biosynthesis of lipopeptide compounds, a well-known characteristic of Bacillus spp., and to compare gene expression levels. Moreover, we extracted lipopeptide compounds using methanol and subjected them to both antifungal activity testing and high-performance liquid chromatography (HPLC) analysis. The experimental findings presented in this study unequivocally demonstrate the promising potential of B. velezensis KTA01 as a biocontrol agent against B. dothidea KACC45481, the pathogen responsible for causing peach tree gummosis.

Response of Abscission Zone of Blue Honeysuckle (Lonicera caerulea L.) Fruit to GA3 and 2,4-D Spray Application

The nutritional value of blue honeysuckle (Lonicera caerulea L.) fruit is abundant; however, its production faces challenges due to a short harvesting period and fruit drop issues. In this study, the effects and potential mechanisms of two different plant growth regulators, GA3 (Gibberellins acid) and 2,4-D (2,4-Dichlorophenoxyacetic acid), on blue honeysuckle fruit abscission and abscission layer formation were investigated. The main cultivated variety of blue honeysuckle, ‘Berel’, was used as the experimental material. GA3 and 2,4-D were sprayed on the plants from the veraison. The anatomical structure of the fruit abscission zone (FAZ) was observed after treatment. Key enzymes involved in cell wall degradation, pectinase, cellulase, polygalacturonase, and pectin methylesterase, were analyzed for their activities. Furthermore, the gene expression levels of cell wall detachment-related genes CX1, CX2, PL20, PE, and key genes for gibberellin and ethylene synthesis GA2OX1, GA1, ACO, and ACO3 were examined. The results indicated that the application of GA3 and 2,4-D could delay the formation of the abscission layer. In the FAZ treated with GA3 and 2,4-D at 5 DAT, the activity of key enzymes involved in cell wall degradation decreased, the expression of genes related to cell wall degradation enzymes and key genes for ethylene synthesis was inhibited, and the drop of fruit reduced. In conclusion, exogenous application of GA3 and 2,4-D suppresses the abscission of ‘Berel’ blue honeysuckle fruit, likely through the inhibition of cell wall degradation and abscission layer formation.

Morin Treatment Delays the Ripening and Senescence of Postharvest Mango Fruits.

A 0.005% and 0.01% morin treatment was applied to treat mango fruits stored under ambient conditions (25 ± 1 °C) with 85-90% relative humidity, and the effects on quality indexes, enzyme activity related to antioxidation and cell wall degradation, and gene expressions involved in ripening and senescence were explored. The results indicate that a 0.01% morin application effectively delayed fruit softening and yellowing and sustained the nutritional quality. After 12 days of storage, the contents of soluble sugar and carotenoid in the treatment groups were 68.54 mg/g and 11.20 mg/100 g, respectively, lower than those in control, while the vitamin C content in the treatment groups was 0.58 mg/g, higher than that in control. Moreover, a morin application successively enhanced the activity of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), but reduced the activity of polygalacturonase (PG) and pectin lyase (PL). Finally, real-time PCR and correlation analysis suggested that morin downregulated the ethylene biosynthesis (ACS and, ACO) and signal transduction (ETR1, ERS1, EIN2, and ERF1) genes, which is positively associated with softening enzymes (LOX, EXP, βGal, and EG), carotenoid synthesis enzymes (PSY and, LCYB), sucrose phosphate synthase (SPS), and uncoupling protein (UCP) gene expressions. Therefore, a 0.01% morin treatment might efficiently retard mango fruit ripening and senescence to sustain external and nutritional quality through ethylene-related pathways, which indicates its preservation application.