Molecular Mechanisms Underlying Fungicide Resistance in Citrus Postharvest Green Mold

The necrotrophic fungus Penicillium digitatum (Pd) is responsible for the green mold disease that occurs during postharvest of citrus and causes enormous economic losses around the world. Fungicides remain the main method used to control postharvest green mold in citrus fruit storage despite numerous occurrences of resistance to them. Hence, it is necessary to find new and more effective strategies to control this type of disease. This involves delving into the molecular mechanisms underlying the appearance of resistance to fungicides during the plant–pathogen interaction. Although mechanisms involved in resistance to fungicides have been studied for many years, there have now been great advances in the molecular aspects that drive fungicide resistance, which facilitates the design of new means to control green mold. A wide review allows the mechanisms underlying fungicide resistance in Pd to be unveiled, taking into account not only the chemical nature of the compounds and their target of action but also the general mechanism that could contribute to resistance to others compounds to generate what we call multidrug resistance (MDR) phenotypes. In this context, fungal transporters seem to play a relevant role, and their mode of action may be controlled along with other processes of interest, such as oxidative stress and fungal pathogenicity. Thus, the mechanisms for acquisition of resistance to fungicides seem to be part of a complex framework involving aspects of response to stress and processes of fungal virulence.

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Citrus Postharvest Green Mold: Recent Advances in Fungal Pathogenicity and Fruit Resistance

Microorganisms ◽

10.3390/microorganisms8030449 ◽

2020 ◽

Vol 8 (3) ◽

pp. 449 ◽

Cited By ~ 4

Author(s):

Yulin Cheng ◽

Yunlong Lin ◽

Haohao Cao ◽

Zhengguo Li

Keyword(s):

Molecular Mechanisms ◽

Citrus Fruit ◽

Plant Diseases ◽

Postharvest Disease ◽

Economic Losses ◽

Fruit Storage ◽

Green Mold ◽

Recent Advances ◽

Leaf Pathogen ◽

Plant Pathogen Interactions

As the major postharvest disease of citrus fruit, postharvest green mold is caused by the necrotrophic fungus Penicillium digitatum (Pd), which leads to huge economic losses worldwide. Fungicides are still the main method currently used to control postharvest green mold in citrus fruit storage. Investigating molecular mechanisms of plant–pathogen interactions, including pathogenicity and plant resistance, is crucial for developing novel and safer strategies for effectively controlling plant diseases. Despite fruit–pathogen interactions remaining relatively unexplored compared with well-studied leaf–pathogen interactions, progress has occurred in the citrus fruit–Pd interaction in recent years, mainly due to their genome sequencing and establishment or optimization of their genetic transformation systems. Recent advances in Pd pathogenicity on citrus fruit and fruit resistance against Pd infection are summarized in this review.

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PdMFS1 Transporter Contributes to Penicilliun digitatum Fungicide Resistance and Fungal Virulence during Citrus Fruit Infection

Journal of Fungi ◽

10.3390/jof5040100 ◽

2019 ◽

Vol 5 (4) ◽

pp. 100 ◽

Cited By ~ 6

Author(s):

Marta de Ramón-Carbonell ◽

Mario López-Pérez ◽

Luis González-Candelas ◽

Paloma Sánchez-Torres

Keyword(s):

Fungicide Resistance ◽

Citrus Fruit ◽

Major Facilitator Superfamily ◽

Fungal Virulence ◽

Disease Symptoms ◽

Knock Out ◽

Wide Range ◽

Major Facilitator ◽

Chemical Fungicides ◽

Mfs Transporter

A new Penicillium digitatum major facilitator superfamily (MFS) transporter (PdMFS1) was identified and functionally characterized in order to shed more light on the mechanisms underlying fungicide resistance. PdMFS1 can play an important role in the intensification of resistance to fungicides normally used in P. digitatum postharvest treatments. In the PdMFS1 disrupted mutants, a slight effect in response to chemical fungicides was observed, but fungicide sensitivity was highly affected in the overexpression mutants which became resistant to wide range of chemical fungicides. Moreover, P. digitatum knock-out mutants exhibited a lower rate of fungal virulence when infected oranges were stored at 20 °C. Disease symptoms were higher in the PdMFS1 overexpression mutants coming from the low-virulent P. digitatum parental strain. In addition, the gene expression analysis showed an induction of PdMFS1 transcription in all overexpression mutants regardless from which progenitor came from, and four-time intensification of the parental wild type strain during citrus infection reinforcing PdMFS1 role in fungal virulence. The P. digitatum MFS transporter PdMFS1 contributes not only to the acquisition of wide range of fungicide resistance but also in fungal virulence during citrus infection.

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Synthesis and Antifungal Activities of Cinnamaldehyde Derivatives against Penicillium digitatum Causing Citrus Green Mold

Journal of Food Quality ◽

10.1155/2020/8898692 ◽

2020 ◽

Vol 2020 ◽

pp. 1-7

Author(s):

Zengyu Gan ◽

Jianping Huang ◽

Jinyin Chen ◽

Muhammad Farrukh Nisar ◽

Wenwen Qi

Keyword(s):

Reducing Sugars ◽

Citrus Fruit ◽

Pathogenic Fungi ◽

Penicillium Digitatum ◽

Economic Losses ◽

Fungal Cell ◽

Green Mold ◽

Antifungal Potential ◽

Germination And Growth ◽

Derivatives Of

Penicillium digitatum (green mold) is pathogenic fungi and causes citrus fruit postharvest rotting that leads to huge economic losses across the world. The current study was aimed to develop a new derivative of cinnamaldehyde (4-methoxycinnamaldehyde) through the cross-hydroxyaldehyde condensation method with benzaldehyde substituted by a benzene ring under the catalysis of alkaline reagent and, moreover, to test their antifungal potential against P. digitatum, the major citrus fruit rotting fungi. Multiple derivatives of cinnamaldehyde viz. 4-nitro CA, 4-chloro CA, 4-bromo CA, 4-methyl CA, 4-methoxy CA, and 2,4-dimethoxy CA were synthesized in the current study whereas the 4-methoxy CA showed highest antifungal actions for citrus fruit postharvest rotting fungi P. digitatum. Moreover, 4-methoxy CA was found to reduce the spore germination and growth by damaging the fungal cell membrane, as well as declined the levels of reducing sugars.

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The Effect of Gut Bacteria on the Physiology of Red Palm Weevil, Rhynchophorus ferrugineus Olivier and Their Potential for the Control of This Pest

Insects ◽

10.3390/insects12070594 ◽

2021 ◽

Vol 12 (7) ◽

pp. 594

Author(s):

Qian-Xia Liu ◽

Zhi-Ping Su ◽

Hui-Hui Liu ◽

Sheng-Ping Lu ◽

Bing Ma ◽

...

Keyword(s):

Molecular Mechanisms ◽

Current Knowledge ◽

Management Strategies ◽

Gut Bacteria ◽

Economic Losses ◽

Rhynchophorus Ferrugineus ◽

Intestinal Immunity ◽

Red Palm Weevil ◽

Nutrient Metabolism ◽

Palm Weevil

Red Palm Weevil (RPW), Rhynchophorus ferrugineus Olivier, is a notorious pest, which infests palm trees and has caused great economic losses worldwide. At present, insecticide applications are still the main way to control this pest. However, pesticide resistance has been detected in the field populations of RPW. Thus, future management strategies based on the novel association biological control need be developed. Recent studies have shown that the intestinal tract of RPW is often colonized by multiple microbial species as mammals and model insects, and gut bacteria have been found to promote the growth, development and immune activity of RPW larvae by modulating nutrient metabolism. Furthermore, two peptidoglycan recognition proteins (PGRPs), PGRP-LB and PGRP-S1, can act as the negative regulators to modulate the intestinal immunity to maintain the homeostasis of gut bacteria in RPW larvae. Here, we summarized the current knowledge on the gut bacterial composition of RPW and their impact on the physiological traits of RPW larvae. In contrast with metazoans, it is much easier to make genetic engineered microbes to produce some active molecules against pests. From this perspective, because of the profound effects of gut bacteria on host phenotypes, it is promising to dissect the molecular mechanisms behind their effect on host physiology and facilitate the development of microbial resource-based management methods for pest control.

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RNAseq Reveals Differential Gene Expression Contributing to Phytophthora nicotianae Adaptation to Partial Resistance in Tobacco

Agronomy ◽

10.3390/agronomy11040656 ◽

2021 ◽

Vol 11 (4) ◽

pp. 656

Author(s):

Jing Jin ◽

Rui Shi ◽

Ramsey Steven Lewis ◽

Howard David Shew

Keyword(s):

Partial Resistance ◽

Molecular Mechanisms ◽

Biological Activities ◽

Effective Means ◽

Phytophthora Nicotianae ◽

Economic Losses ◽

Black Shank ◽

Differential Gene ◽

Go Terms

Phytophthora nicotianae is a devastating oomycete plant pathogen with a wide host range. On tobacco, it causes black shank, a disease that can result in severe economic losses. Deployment of host resistance is one of the most effective means of controlling tobacco black shank, but adaptation to complete and partial resistance by P. nicotianae can limit the long-term effectiveness of the resistance. The molecular basis of adaptation to partial resistance is largely unknown. RNAseq was performed on two isolates of P. nicotianae (adapted to either the susceptible tobacco genotype Hicks or the partially resistant genotype K 326 Wz/Wz) to identify differentially expressed genes (DEGs) during their pathogenic interactions with K 326 Wz/Wz and Hicks. Approximately 69% of the up-regulated DEGs were associated with pathogenicity in the K 326 Wz/Wz-adapted isolate when sampled following infection of its adapted host K 326 Wz/Wz. Thirty-one percent of the up-regulated DEGs were associated with pathogenicity in the Hicks-adapted isolate on K 326 Wz/Wz. A broad spectrum of over-represented gene ontology (GO) terms were assigned to down-regulated genes in the Hicks-adapted isolate. In the host, a series of GO terms involved in nuclear biosynthesis processes were assigned to the down-regulated genes in K 326 Wz/Wz inoculated with K 326 Wz/Wz-adapted isolate. This study enhances our understanding of the molecular mechanisms of P. nicotianae adaptation to partial resistance in tobacco by elucidating how the pathogen recruits pathogenicity-associated genes that impact host biological activities.

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Morphology Characterization, Molecular Phylogeny, and Pathogenicity of Diaporthe passifloricola on Citrus reticulata cv. Nanfengmiju in Jiangxi Province, China

Plants ◽

10.3390/plants10020218 ◽

2021 ◽

Vol 10 (2) ◽

pp. 218

Author(s):

Chingchai Chaisiri ◽

Xiang-Yu Liu ◽

Wei-Xiao Yin ◽

Chao-Xi Luo ◽

Yang Lin

Keyword(s):

Phylogenetic Analyses ◽

Citrus Fruit ◽

Epidemiological Studies ◽

Morphological Characterization ◽

Jiangxi Province ◽

Citrus Reticulata ◽

Fruit Storage ◽

Pathogenicity Tests ◽

Rot Disease ◽

Morphology Characterization

The Nanfengmiju (Citrus reticulata cv. Nanfengmiju), a high-quality local variety of mandarin, is one of the major fruit crops in Jiangxi Province, China. Citrus melanose and stem-end rot, two common fungal diseases of Nanfengmiju, are both caused by Diaporthe spp. (syn. Phomopsis spp.). Identification of the Diaporthe species is essential for epidemiological studies, quarantine measures, and management of diseases caused by these fungi. Melanose disease was observed on Nanfengmiju fruit in Jiangxi Province of China in 2016. Based on morphological characterization and multi-locus phylogenetic analyses, three out of 39 isolates from diseased samples were identified as D. passifloricola. Since these three isolates did not cause melanose on citrus fruit in the pathogenicity tests, they were presumed to be endophytic fungi present in the diseased tissues. However, our results indicate that D. passifloricola may persist as a symptom-less endophyte in the peel of citrus fruit, yet it may cause stem-end if it invades the stem end during fruit storage. To the best of our knowledge, this is the first report of D. passifloricola as the causal agent of the stem-end rot disease in Citrusreticulata cv. Nanfengmiju.

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Analysis of the Role of Bradysiaimpatiens (Diptera: Sciaridae) as a Vector Transmitting Peanut Stunt Virus on the Model Plant Nicotiana benthamiana

Cells ◽

10.3390/cells10061546 ◽

2021 ◽

Vol 10 (6) ◽

pp. 1546

Author(s):

Marta Budziszewska ◽

Patryk Frąckowiak ◽

Aleksandra Obrępalska-Stęplowska

Keyword(s):

Nicotiana Benthamiana ◽

Molecular Mechanisms ◽

Virus Transmission ◽

Pathogenic Fungi ◽

Economic Losses ◽

Fungus Gnats ◽

Droplet Pcr ◽

Viral Coat ◽

Peanut Stunt Virus

Bradysia species, commonly known as fungus gnats, are ubiquitous in greenhouses, nurseries of horticultural plants, and commercial mushroom houses, causing significant economic losses. Moreover, the insects from the Bradysia genus have a well-documented role in plant pathogenic fungi transmission. Here, a study on the potential of Bradysia impatiens to acquire and transmit the peanut stunt virus (PSV) from plant to plant was undertaken. Four-day-old larvae of B. impatiens were exposed to PSV-P strain by feeding on virus-infected leaves of Nicotiana benthamiana and then transferred to healthy plants in laboratory conditions. Using the reverse transcription-polymerase chain reaction (RT-PCR), real-time PCR (RT-qPCR), and digital droplet PCR (RT-ddPCR), the PSV RNAs in the larva, pupa, and imago of B. impatiens were detected and quantified. The presence of PSV genomic RNA strands as well as viral coat protein in N. benthamiana, on which the viruliferous larvae were feeding, was also confirmed at the molecular level, even though the characteristic symptoms of PSV infection were not observed. The results have shown that larvae of B. impatiens could acquire the virus and transmit it to healthy plants. Moreover, it has been proven that PSV might persist in the insect body transstadially. Although the molecular mechanisms of virion acquisition and retention during insect development need further studies, this is the first report on B. impatiens playing a potential role in plant virus transmission.

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Mitochondrial Dynamics in Drug-Induced Liver Injury

Livers ◽

10.3390/livers1030010 ◽

2021 ◽

Vol 1 (3) ◽

pp. 102-115

Author(s):

Anup Ramachandran ◽

David S. Umbaugh ◽

Hartmut Jaeschke

Keyword(s):

Liver Injury ◽

Molecular Mechanisms ◽

Membrane Lipids ◽

Mitochondrial Dynamics ◽

Adaptive Responses ◽

Drug Induced ◽

Biologically Relevant ◽

Drug Induced Liver Injury ◽

Relevant Role ◽

Atp Generation

Mitochondria have been studied for decades from the standpoint of metabolism and ATP generation. However, in recent years mitochondrial dynamics and its influence on bioenergetics and cellular homeostasis is also being appreciated. Mitochondria undergo regular cycles of fusion and fission regulated by various cues including cellular energy requirements and pathophysiological stimuli, and the network of critical proteins and membrane lipids involved in mitochondrial dynamics is being revealed. Hepatocytes are highly metabolic cells which have abundant mitochondria suggesting a biologically relevant role for mitochondrial dynamics in hepatocyte injury and recovery. Here we review information on molecular mediators of mitochondrial dynamics and their alteration in drug-induced liver injury. Based on current information, it is evident that changes in mitochondrial fusion and fission are hallmarks of liver pathophysiology ranging from acetaminophen-induced or cholestatic liver injury to chronic liver diseases. These alterations in mitochondrial dynamics influence multiple related mitochondrial responses such as mitophagy and mitochondrial biogenesis, which are important adaptive responses facilitating liver recovery in several contexts, including drug-induced liver injury. The current focus on characterization of molecular mechanisms of mitochondrial dynamics is of immense relevance to liver pathophysiology and have the potential to provide significant insight into mechanisms of liver recovery and regeneration after injury.

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Efficacy and Application Strategies for Propiconazole as a New Postharvest Fungicide for Managing Sour Rot and Green Mold of Citrus Fruit

Plant Disease ◽

10.1094/pdis-06-11-0525 ◽

2012 ◽

Vol 96 (2) ◽

pp. 235-242 ◽

Cited By ~ 32

Author(s):

A. H. McKay ◽

H. Förster ◽

J. E. Adaskaveg

Keyword(s):

Management Practices ◽

Citrus Fruit ◽

The United States ◽

Optimal Time ◽

Inoculum Concentration ◽

Time Of Application ◽

Sour Rot ◽

Green Mold ◽

Highly Effective ◽

Moderately Resistant

Few postharvest treatments are available for managing sour rot of citrus caused by Galactomyces citri-aurantii and they are generally not very effective. The demethylation-inhibiting (DMI) triazole fungicides propiconazole and cyproconazole were found to be highly effective and more efficacious than other DMIs evaluated, such as metconazole and tebuconazole, in reducing postharvest sour rot of citrus. Additional studies were conducted with propiconazole as a postharvest treatment because it has favorable toxicological characteristics for food crop registration in the United States and the registrant supports a worldwide registration. Regression and covariance analyses were performed to determine optimal time of application after inoculation and fungicide rate. In laboratory studies, decay incidence increased when propiconazole applications were delayed from 8 to 24 h (lemon) or 18 to 42 h (grapefruit) after inoculation. Effective rates of the fungicide were 64 to 512 μg/ml and were dependent on inoculum concentration of the sour rot pathogen and on the type of citrus fruit. Propiconazole was found to be compatible with sodium hypochlorite at 100 μg/ml and 1 to 3% sodium bicarbonate without loss of efficacy for decay control on lemon. The addition of hydrogen peroxide/peroxyacetic acid at 80 μg/ml slightly decreased the effectiveness of propiconazole. Heated (48°C) solutions of propiconazole did not significantly improve the efficacy compared with solutions at 22°C. In experimental packing-line studies, aqueous in-line drenches applied alone or followed by applications of the fungicide in storage or packing fruit coatings were highly effective, reducing sour rot to between 0 and 1.2% compared with 83.8% decay incidence in the control when treatments were made up to 16 h after inoculation. When the fungicide was applied in either fruit coating, decay was only reduced to 49.1 to 57.1% incidence. Tank mixtures of propiconazole with the citrus postharvest fungicides fludioxonil and azoxystrobin were highly effective in reducing green mold caused by isolates of Penicillium digitatum sensitive or moderately resistant to imazalil and sour rot. Propiconazole will be an important postharvest fungicide for managing sour rot of citrus and potentially can be integrated into current management practices to reduce postharvest crop losses caused by DMI-sensitive isolates of P. digitatum.

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Comparative Transcriptomic Analysis of Riptortus pedestris (Hemiptera: Alydidae) to Characterize Wing Formation across All Developmental Stages

Insects ◽

10.3390/insects12030226 ◽

2021 ◽

Vol 12 (3) ◽

pp. 226

Author(s):

Siying Fu ◽

Yujie Duan ◽

Siqi Wang ◽

Yipeng Ren ◽

Wenjun Bu

Keyword(s):

Molecular Mechanisms ◽

Developmental Stages ◽

Average Length ◽

Transcriptome Assembly ◽

Expression Profiles ◽

Economic Losses ◽

Future Research ◽

Economic Damage ◽

Wing Formation ◽

Riptortus Pedestris

Riptortus pedestris (Hemiptera: Alydidae) is a major agricultural pest in East Asia that causes considerable economic losses to the soybean crop each year. However, the molecular mechanisms governing the growth and development of R. pedestris have not been fully elucidated. In this study, the Illumina HiSeq6000 platform was employed to perform de novo transcriptome assembly and determine the gene expression profiles of this species across all developmental stages, including eggs, first-, second-, third-, fourth-, and fifth-instar nymphs, and adults. In this study, a total of 60,058 unigenes were assembled from numerous raw reads, exhibiting an N50 length of 2126 bp and an average length of 1199 bp, and the unigenes were annotated and classified with various databases, such as the Kyoto Encyclopedia of Genes and Genomes (KEGG), Clusters of Orthologous Groups (COG), and Gene Ontology (GO). Furthermore, various numbers of differentially expressed genes (DEGs) were calculated through pairwise comparisons of all life stages, and some of these DEGs were associated with immunity, metabolism, and development by GO and KEGG enrichment. In addition, 35,158 simple sequence repeats (SSRs) and 715,604 potential single nucleotide polymorphisms (SNPs) were identified from the seven transcriptome libraries of R. pedestris. Finally, we identified and summarized ten wing formation-related signaling pathways, and the molecular properties and expression levels of five wing development-related genes were analyzed using quantitative real-time PCR for all developmental stages of R. pedestris. Taken together, the results of this study may establish a foundation for future research investigating developmental processes and wing formation in hemimetabolous insects and may provide valuable data for pest control efforts attempting to reduce the economic damage caused by this pest.

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