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Citrus fruits are highly susceptible to pathogenic fungal infections after harvesting, which causes serious economic losses. Therefore, it's necessary to develop new antifungal packaging. In this study, gamma-Decanolactone (DL) was successfully encapsulated in a polycaprolactone (PCL)/β-cyclodextrin (β-CD) composite system using electrostatic spinning technology. PCL/β-CD was compounded in different ratios, the ratio was screened through other indicators such as fiber morphologies and mechanical properties. Then, antifungal mats were prepared by adding different concentrations of DL to the PCL/β-CD solution. The results showed that when the mixture ratio of PCL/β-CD was 6:1 and loaded with 6 % DL, the antifungal felt had strong mechanical, significantly inhibiting the growth of three citrus pathogens (P. digitatum, P. italicum and G. candidum), released DL for up to 204 h and effectively reduced the morbidity rate of citrus fruits. Therefore, the antifungal pad prepared in this study has great potential in the field of citrus disease control., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Postharvest citrus fruit is susceptible to pathogenic infestation and quality reduction through wounds, leading to tremendous commercial losses. Herein, wound healing of citrus fruit was obviously at 25 °C for five days to form a barrier effective against the development of infectious diseases and water dissipation. Combined with the results of transcriptional and metabolic levels, wound healing activated the expression of CsKCS4, CsKCS11, CsCYP704B1, CsFAH1, CsGPAT3 and CsGPAT9 genes in suberin biosynthesis pathway, and CsPMEI7, CsCesA-D3, CsXTH2, CsXTH6, CsXTH22, CsXTH23, CsXTH24, CsC4H and CsCAD genes in cell wall metabolism pathway, leading to the accumulation of suberin monomers and cell wall components. The results of microscopic observations proved wound healing promoted suberin deposition and cell wall strengthening. Meanwhile, wound healing required the provision of energy and precursor substances by carbohydrate metabolism and amino acid metabolism. We provide new insights into the regulatory mechanism of wound healing on improving disease resistance and maintaining the quality of citrus fruit., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

The biocontrol effectiveness of Metschnikowia citriensis relies on its production of pulcherriminic acid (PA), which forms insoluble and stable pulcherrimin pigments by chelating iron ions, this inhibits pathogen growth by preventing their utilization of chelated Fe 3+ . In this study, ΔM. citriensis, which did not produce PA, was used as a control to examine changes in its biocontrol effectiveness by adding tryptophan to the medium. Tryptophan was shown to have no discernible impact on the growth and PA production of ΔM. citriensis; moreover, the PA synthesis-related genes PULs, Snf2, and leucyl-tRNA synthesis-related genes A3136 and A3022 were all down-regulated in ΔM. citriensis. The PA-free ΔM. citriensis eventually showed a much poorer inhibition zone against the pathogens in vitro, and a noticeably decreased control efficiency against postharvest diseases in citrus fruit. Tryptophan was added to the medium, which had no appreciable impact on inhibitory zone of ΔM. citriensis against pathogens in vitro, but enhanced its ability to control citrus postharvest diseases. Additionally, the control effects of culture broth of M. citriensis and ΔM. citriensis on postharvest diseases in citrus fruit were assessed. It was found that both culture broth of M. citriensis and ΔM. citriensis exhibited remarkable control effects against citrus postharvest diseases, with culture broth of M. citriensis which containing PA being more effective in controlling the disease. Last but not least, we extracted and dissolved pulcherrimin to obtain PA extracts, which were then injected to citrus fruits to assess the biocontrol effectiveness. The findings demonstrated that postharvest diseases of citrus fruit can be effectively controlled by PA extracts. This research suggested a new biological strategy for the management of citrus postharvest diseases., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Citrus fruit were easily infected by Penicillium digitatum, and caused green mold rapidly, resulting in enormous post-harvest losses. ε-poly-l-lysine (ε-PL) was generally regarded as a safe (GRAS) substance. Besides, it was proved to have a dual effect on harming fungi and triggering fruit defense responses. Fatty acid metabolism is closely related to fruit defense response. However, little is known about how ε-PL affected fatty acid metabolism in citrus fruit. Here, we found that ε-PL increased the expression of CsFATA, CsACSL, CsFAD2, CsFAD3, CsLOX2S, and CsHPL in fatty acid metabolism, decreasing oleic acid levels and enhancing linoleic and linolenic acid levels. Additionally, ε-PL enriched the activities of LOX and HPL during the oxidative decomposition of fatty acids, and activating C 9 aldehyde biosynthesis. Interestingly, ε-PL combined with (2E,4E)-nonadienal (C 9 aldehyde) would improve the inhibitory effect against Penicillium digitatum. And the combined bio-fungicide significantly delayed the citrus green mold compared to single concentrations of the individual components. These results suggested that ε-PL improved citrus fruit defense responses through fatty acid-mediated defense responses. Combined bio-fungicide consisting of ε-PL and (2E,4E)-nonadienal have an excellent prospect for controlling citrus green mold., (Copyright © 2023 Elsevier Inc. All rights reserved.)

As the most productive fruit in the world, there is a lack of research on disease resistance mechanisms in citrus. WRKY transcription factors are mediators of disease resistance in plants. In this research, CsWRKY23, which could respond to exogenous salicylic acid (SA) was identified. As a variant WRKY, the transient overexpression of CsWRKY23 in citrus peel enhanced the resistance to Penicillium digitatum. The potential targets of CsWRKY23 were identified by using DNA affinity purification sequencing (DAP-seq). In combination with RNA sequencing (RNA-seq) data, 48 direct target genes of CsWRKY23 were identified. In addition, five genes for EMSA and dual-luciferase report system analysis were selected and the results showed that CsWRKY23 activate CsAAE12, CsRbohD, CsSARD1, CsWRKY22 and CsIQM6 expressions. Further analysis revealed that CsWRKY23 contributed to SA synthesis pathway, reactive oxygen species (ROS) accumulation, and cell wall strengthening. This study presented a possible regulatory network for disease resistance involving the CsWRKY23., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Segment drying is a common internal physiological disorder in citrus fruit, and vesicles get granulated or collapsed. This study aimed to probe whether and how the phenylpropanoid metabolism changes in vesicles during collapse of blood orange (Citrus sinensis cv. Tarocco). Vesicle collapse led to a decrease in the content of nutrients and flavonoids, while an increase in lignin content. This disorder was further associated with the increasing enzyme activities and gene expression levels of both the general phenylpropanoid pathway and branch pathway of lignin synthesis, while decreasing enzyme activities and gene expression levels of branch pathway of flavonoids synthesis. Targeted metabolomics analysis of 14 metabolites of the lignin pathway revealed that lignin precursors were accumulated in collapsed vesicles. We provide solid evidence that phenylpropanoid metabolism could be activated, and, intriguingly, metabolic flux may be shuttled to lignin precursors synthesis rather than flavonoids synthesis in vesicles during collapse of blood orange., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Biological antagonists are a series of microbes that can control pathogens to reduce the incidence of disease or reduce symptoms. Herein, four varieties of citrus fruit were selected to perform an amplicon sequencing on their epiphytic microbiota to get a systematic understanding of them. Co-occurrence network, Venn, and LefSe analysis were performed to filter to 24 genera which represent the universality, specificity, and correlation among samples. Functional analysis hinted that the genes related to chitinase, which most of these 24 bacteria carry, might lead to a disease-suppressive phenotype. 115 strains of epiphytic bacteria were isolated, and the bacterial synthetic community was constructed by 8 strains. The in vivo test results indicated they were able to reduce pathogen development for a longer time than separate inoculation. Collectively, this study showed the disease control potential provided by native epiphytic bacteria of fruit and give a new strategy to sustainable agriculture., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The aim of this work was to study the capability and mechanism of enhancing the yield of pulcherriminic acid (PA) produced by Metschnikowia citriensis FL01 with the help of tryptophan for the control of postharvest diseases on citrus caused by Penicillium italicum, Geotrichum citri-aurantii and Penicillium digitatum. The adding of 10 mmol/L tryptophan to the growth medium resulted in the widest pulcherrimin pigment zone produced by M. citriensis FL01. The adding of tryptophan to the growth medium upregulated A3136 and A3022 gene expression (responsible for leucyl-tRNA biosynthesis from leucine), downregulated A1350 gene expression (responsible for the biosynthesis of leucine to branched-chain fatty acids), and decreased the content of intracellular leucine in M. citriensis FL01, speculating that the addition of tryptophan in the growth medium induced leucine conversion toward leucyl-tRNA in M. citriensis FL01. Moreover, the adding of tryptophan to the growth medium upregulated PULs (responsible PA biosynthesis) and Snf2 (transcriptional regulator) gene expression and promoted intracellular, extracellular or total PA production by M. citriensis FL01 in liquid medium. In addition, the addition of tryptophan in the growth medium showed no effect on the growth of M. citriensis FL01 itself in liquid medium, while the population dynamics in citrus fruit wounds of M. citriensis FL01 with the addition of tryptophan in the growth medium were increased compared with those of M. citriensis FL01. What's more, M. citriensis FL01 with the addition of tryptophan in the growth medium completely inhibited the growth of pathogens in vitro. The disease incidences and lesion diameters of blue mold, sour rot and green mold on citrus fruit were lower in group which treated with M. citriensis FL01 containing tryptophan in the growth medium than that treated with M. citriensis FL01 alone. Overall, the postharvest biocontrol of citrus with M. citriensis FL01 containing 10 mmol/L tryptophan in the growth medium is a promising approach to protect these fruits from blue mold, sour rot and green mold., Competing Interests: Declaration of competing interest We declare that we do not have any personal, financial, commercial or associative interest that represents a conflict of interest in connection with the work submitted., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Background: Peel color regulated by pigment metabolism is one of the most crucial indicators affecting the commodity values of citrus fruit. Storage temperature is a vital environmental factor that regulates the fruit pigmentation., Results: Results showed that the peel coloring process was significantly inhibited when mandarin fruit were stored at 5 and 32 °C with normal coloring at 25 °C as the control. However, the inhibitive mechanisms of 5 and 32 °C storage were different. At 5 °C, higher levels of CcNYC and CcCHL2 were detected, which indicated that 5 °C induces the circulation of chlorophyll rather than inhibits chlorophyll degradation. CcPSY2, CcCHYB, and CcZEP exhibited higher expression levels in fruit stored at 5 °C, which accelerated the accumulation of carotenoids. In fruit stored at 32 °C, CcNYC, CcPAO, and CcCHL2 exhibited lower expression levels than those fruit stored at 5 °C, and the expressions of CcPSY2, CcCHYB, and CcZEP were down regulated, implying the carotenoid synthesis was suppressed., Conclusion: Storage at 5 °C inhibited the postharvest coloring of mandarin fruit mainly by activating the cycle of chlorophyll, although it promotes the accumulation of carotenoids at the same time, but chlorophyll covers the color of carotenoids. Storage at 32 °C inhibited mandarin fruit coloring mainly by inhibiting the degradation of chlorophyll. Compared with the change of individual chlorophyll or carotenoid content, the change of the ratio of chlorophyll and carotenoid had a more important role in the coloration of mandarin fruit. This research offers valuable details for understanding the effect of temperature on the coloring process of postharvest citrus fruit. © 2022 Society of Chemical Industry., (© 2022 Society of Chemical Industry.)

This study investigated the effect of arginine (Arg) on the antagonistic activity of Metschnikowia citriensis against sour rot caused by Geotrichum citri-aurantii in postharvest citrus, and evaluated the possible mechanism therein. Arg treatment up-regulated the PUL genes expression, and significantly induced the pulcherriminic acid (PA) production of M. citriensis, which related to the capability of iron depletion of M. citriensis. By comparing the biocontrol effects of Arg-treated and untreated yeast cells, it was found that Arg treatment significantly enhanced the biocontrol efficacy of M. citriensis, and 5 mmol L -1 Arg exerted the best effect. Additionally, the biofilm formation ability of M. citriensis was greatly enhanced by Arg, and the higher population density of yeast cells in citrus wounds was also observed in Arg treatment groups stored both at 25 °C and 4 °C. Moreover, Arg was shown to function as a cell protectant to elevate antioxidant enzyme activity [including catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPX)] and intracellular trehalose content to resist oxidative stress damage, that directly helped to enhance colonization ability of yeasts in fruit wounds. These results suggest the application of Arg is a useful approach to improve the biocontrol performance of M. citriensis., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Metschnikowia citriensis FL01 has great potential for biocontrol applications for its excellent biocontrol efficacy on postharvest diseases of citrus fruit, and the iron depletion by pulcherriminic acid (PA) and then formation of insoluble pigment pulcherrimin had been speculated as an important action mechanism. To identify the genes involved in pulcherrimin synthesis and reutilization in M. citriensis FL01, we de novo assembled the genome of M. citriensis FL01 based on long-read PacBio sequencing. The final assembled genome consisted of 12 contigs with a genome size of 25.74 Mb, G + C content of 49.16% and 9310 protein-coding genes. The genome-wide BLAST of the PUL genes of M. pulcherrima APC 1.2 showed that the four PUL genes were clustered and located on Contig 4 of M. citriensis FL01. In order to further clarify the role of pulcherrimin pigment on biocontrol of M. citriensis FL01, CRISPR/cas9 technology was used to knock out PUL2 gene that was responsible for PA synthesis and the pigmentless mutants with stable phenotype were obtained. The mutant strains of M. citriensis FL01 lost the ability to produce pulcherrimin pigment, and simultaneously lost the ability to inhibit the growth of Geotrichum citri-aurantii in vitro. Moreover, the biocontrol efficacy of pigmentless mutant strains against sour rot was about 80% lower than that of wild-type M. citriensis FL01. These results directly proved that the iron depletion was an important mechanism of M. citriensis FL01., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Penicillium digitatum is the primary pathogen that causes serious yield losses worldwide. In our previous study, CsWRKY transcription factors (TFs) and some genes associated with immunity were identified in citrus fruits after P. digitatum infection, but little information is available in the literature on the mechanisms of TFs in citrus disease resistance. In this study, the possible mechanisms of CsWRKY65 participating in the establishment of disease resistance were investigated. Results show that CsWRKY65 was a transcriptional activator in the nucleus. The dual-luciferase transient assays and electrophoretic mobility shift assays showed that CsWRKY65 bound with CsRbohB , CsRbohD , CsCDPK33 , and CsPR10 promoters to activate gene transcription. Besides, the transient overexpression of CsWRKY65 induced reactive oxygen species accumulation and increased PR gene expression in Nicotiana benthamiana leaves. The transient overexpression of CsWRKY65 in the citrus peel enhanced the disease resistance against P. digitatum . In conclusion, CsWRKY65 is likely to be involved in regulating the disease resistance to P. digitatum of citrus fruits by directly activating the expressions of CsRbohB , CsRbohD , CsCDPK33 , and CsPR10 . This study provides new information for the mechanism of citrus WRKY TFs participating in the establishment of disease resistance.

This study aimed to investigate the effect of Pichia galeiformis on disease resistance and elucidate the changes in phenylpropane biosynthesis treated by P. galeiformis in postharvest citrus. The results showed that P. galeiformis reduced the disease incidence and lesion diameters without direct contact with the pathogen Penicillium digitatum . Transcriptome analysis revealed that phenylpropanoid biosynthesis was triggered by P. galeiformis . Genes encoding phenylpropanoid biosynthesis were upregulated, including phenylalanine ammonia-lyase (PAL), 4-coumaroyl-CoA ligase (4CL), cinnamate-4-hydroxylase (C4H), peroxidase (POD), cinnamyl alcohol dehydrogenase (CAD), O-methyltransferase, and hydroxyl cinnamoyl transferase. Moreover, P. galeiformis increased the activity of PAL, 4CL, C4H, POD, polyphenol oxidase, and CAD in citrus pericarp. In addition, P. galeiformis treated citrus displayed higher levels of total phenolic compounds, flavonoid, and lignin and higher amounts of ferulic and sinapic acid. In conclusion, these results suggested that P. galeiformis could induce resistance through modulating the pathway of phenylpropanoid biosynthesis in postharvest citrus.

Background: Penicillium digitatum is one of the most important pathogens causing citrus green mold, leading to significant economic losses. Traditionally, synthetic fungicides are used to control diseases. However, the side effects of fungicides should not be ignored. Thus, antagonistic yeasts were proposed to be safe and effective alternatives for managing diseases. Orchards are excellent sources of naturally occurring antagonists against pathogens. Therefore, in the present study, antagonistic yeasts obtained from orchards were screened, and the possible biocontrol mechanisms of the most promising yeast were investigated., Results: Seventy-eight isolates of yeasts (15 species of 10 genera) were obtained from citrus orchards. In in vitro assays, 16 strains showed antifungal activity against Pichia digitatum and 15 strains showed biocontrol potential against green mold on Olinda oranges. Pichia galeiformis (BAF03) exhibited the best antagonistic activity against P. digitatum during 6 days storage at 25 °C and a good antagonistic activity during 29 days at 4 °C. Pichia galeiformis (BAF03) could colonize and amplify quickly in wounded citrus. Scanning electron microscopy results showed that the citrus wound was colonised by the yeast. A total of eight volatile organic compounds (VOCs) were identified by gas chromatography-mass spectrometry The VOCs produced by P. galeiformis (BAF03) efficiently inhibited P. digitatum., Conclusion: Pichia galeiformis (BAF03) isolated from a citrus orchard showed potential to control postharvest green mold of citrus. The possible mechanisms of action likely include competition for space and nutrients as well as production of VOCs., (© 2020 Society of Chemical Industry.)

This study investigated the biocontrol efficiency of Metschnikowia citriensis strain FL01 against Geotrichum citri-aurantii, and evaluated possible mechanisms. The results showed that M. citriensis could effectively control the development of sour rot, and significantly inhibit the mycelial growth and spore germination of G. citri-aurantii. The population dynamics results and Scanning electron microscopy (SEM) analysis indicated that M. citriensis could rapidly colonize wounds and tightly adhere to the surface of the wounds to compete with G. citri-aurantii for nutrition and space. M. citriensis also showed the biofilm formation action in vitro. The response of G. citri-aurantii to different components of M. citriensis culture showed that only the yeast cells but not the extracellular metabolites and the volatile organic compounds (VOCs) exhibited inhibitory effect on the growth of G. citri-aurantii. M. citriensis adhered to the hyphae of G. citri-aurantii loosely and sparsely, and the production of lytic enzymes β-1, 3-glucanase (GLU) and Chitinase (CHI) could not be induced by G. citri-auranti. Iron affected the pulcherrimin pigment production and antagonism of M. citriensis indicating iron depletion as the most important antagonistic mechanism. Besides, M. citriensis also induced resistance of fruit against sour rot. These results suggested that M. citriensis could be used as the potential alternative of fungicides to control postharvest pathogens on citrus fruit., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Yellow or green spots related to pigment changes found at the early stage of oleocellosis can cause severe economic damage. However, little information exists on pigment changes during oleocellosis development, so this study investigated the main changes in chlorophyll and carotenoid metabolites and related gene expression. Among the variations, the increased contents of chlorophyll a and b, and decreased concentrations of lutein, β-cryptoxanthin, zeaxanthin, violaxanthin, α-carotene and β-carotene were responsible for chlorophyll and carotenoid changes, respectively. Regarding gene expression, the up-regulated genes, magnesium chelatase subunit H (MgCh), magnesium-protoporphyrin IX monomethyl ester (oxidative) cyclase 1/2 (MPEC1/2), protochlorophyllide reductase a, chloroplastic 1/2 (PORA1/2) and chlorophyllide a oxygenase (CAO), regarding chlorophyll synthesis as well as the down-regulated genes, phytoene synthase (PSY), phytoene dehydrogenase (PDS), lycopene β-cyclase (LCYb), and zeaxanthin epoxidase 1/2 (ZEP 1/2) and the up-regulated genes (+)-abscisic acid 8'-hydroxylase 1/2 (ABA-HX 1/2), regarding carotenoid metabolism, constituted the major variations in oleocellosis peels., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Oleocellosis is a serious physiological disorder in citrus fruit that mainly results in appearance and quality deterioration. It has been well established that the occurrence of oleocellosis is highly correlated with the release of peel oil from citrus fruit, while there is little information on the dynamic changes in the content of the volatile constituents and the expression of genes involved in terpenoid metabolism during oleocellosis development. In the present research, large changes in the volatile profiles and gene expression in terpenoid metabolism were observed in oleocellosis peels compared to healthy ones. Among volatiles, the decreased contents of α-pinene, d-limonene, β-myrcene, linalool, β-caryophyllene, α-terpineol, nonanal, neryl acetate and (-)-carvone played a major role in these changes. For gene expressions in terpenoid metabolism, the up-regulated genes aldehyde dehydrogenase (NAD+) (ALDH) and the down-regulated genes β-caryophyllene synthase 1 (BCS1), α-terpineol synthase 2 (TES2) and myrcene synthase (MS) were the main differences in oleocellosis peels., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Although citrus fruits are not climacteric, exogenous ethylene is widely used in the degreening treatment of citrus fruits. Irradiation with blue light-emitting diode (LED) light (450 nm) for 10 h can promote the formation of good coloration of ethephon-degreened fruit. This study evaluated the effect of blue LED light irradiation on the pigments contents of ethephon-degreened fruit and evaluated whether the blue LED light irradiation could influence the sensitivity of mandarin fruit to ethylene. The results indicated that blue light can accelerate the color change of ethephon-degreened fruit, accompanied by changes in plastid ultrastructure and chlorophyll and carotenoid contents. Ethephon-induced expressions of CitACS1, CitACO, CitETR1, CitEIN2, CitEIL1, and CitERF2 were enhanced by blue LED light irradiation, which increased the sensitivity to ethylene in ethephon-degreened fruits. These results indicate that blue LED light-induced changes in sensitivity to ethylene in mandarin fruit may be responsible for the improved coloration of ethephon-degreened mandarin fruits.

In the present study, we investigated whether the postharvest application of oligochitosan and chitosan could be used as potential alternatives to 2,4-dichlorophenoxyacetic acid (2,4-D) treatment to prevent calyx senescence of mandarin fruits induced by degreening treatment. The results of scanning electron microscopy indicated that the ethephon degreening treatment could accelerate the formation of pedicel abscission layers. Treatments with 15 g kg -1 oligochitosan, 5 g kg -1 chitosan, and 50 mg kg -1 2,4-D significantly suppressed the formation of pedicel abscission layers of ethephon degreening fruit and inhibited the browning of the calyx. These two treatments delayed the degradation of protopectin, cellulose, and lignin. Inhibition of the increase in the abscisic acid (ABA) content was also observed in these two treatments. In conclusion, these two treatments, particularly 15 g kg -1 oligochitosan, could be potentially used as alternatives to 2,4-D to improve calyx alterations induced by the ethephon degreening treatment in mandarin fruits.

Aims: To optimize a protective medium for freeze-dried Pichia membranifaciens and to evaluate biocontrol efficacies of agents against blue and green mould and anthracnose in citrus fruit., Methods and Results: Based on the screening assays of saccharides and antioxidants, response surface methodology was used to optimize sucrose, sodium glutamate and skim milk to improve viability of freeze-dried Pi. membranifaciens. Biocontrol assays were conducted between fresh and freeze-dried Pi. membranifaciens against Penicillium italicum, Penicillium digitatum and Colletotrichum gloeosporioides in citrus fruit. Solving the regression equation indicated that the optimal protective medium was 6·06% (w/v) sucrose combined with 3·40% (w/v) sodium glutamate and 5·43% (w/v) skim milk. Pi. membranifaciens freeze-dried in the optimal protective medium showed 76·80% viability, and retained biocontrol efficacy against Pe. italicum, Pe. digitatum and Co. gloeosporioides in citrus fruit., Conclusions: The optimal protective medium showed more effective protective properties than each of the three protectants used alone. The viability of freeze-dried Pi. membranifaciens finally reached 76·80%. Meanwhile, the biocontrol efficacies showed no significant difference between fresh and freeze-dried yeast against Pe. italicum, Pe. digitatum and Co. gloeosporioides in citrus fruit., Significance and Impact of the Study: The results showed the potential value of Pi. membranifaciens CICC 32259 for commercialization., (© 2016 The Society for Applied Microbiology.)

Background: Nitric oxide (NO) is an important signaling molecule involved in numerous plant responses to biotic and abiotic stresses. To investigate the effects of NO on the control of postharvest anthracnose caused by Colletotrichum gloeosporioides in citrus fruit and its possible mechanisms, citrus fruit were treated with an NO donor., Results: The results showed that exogenous NO released from 50 µmol L(-1) sodium nitroprusside aqueous solution could effectively reduce the disease incidence and lesion diameter of citrus fruit inoculated with C. gloeosporioides during storage at 20 °C. Exogenous NO could regulate hydrogen peroxide levels, stimulate the synthesis of phenolic compounds, and induce phenylalanine ammonia-lyase, peroxidase, polyphenol oxidase, catalase activities, and the ascorbate-glutathione cycle. Furthermore, exogenous NO could inhibit weight loss, improve the ascorbic acid and titratable acidity content, and delay the increase in total soluble solids content in citrus fruit during storage at 20 °C., Conclusions: The results suggest that the use of exogenous NO is a potential method for inducing the disease resistance of fruit to fungal pathogens and for extending the postharvest life of citrus fruit., (© 2015 Society of Chemical Industry.)