scholarly journals The Point Mutation G461S in the MfCYP51 Gene is Associated with Tebuconazole Resistance in Monilinia fructicola Populations in Brazil

2017 ◽  
Vol 107 (12) ◽  
pp. 1507-1514 ◽  
Author(s):  
Paulo S. F. Lichtemberg ◽  
Yong Luo ◽  
Rafael G. Morales ◽  
Juliana M. Muehlmann-Fischer ◽  
Themis J. Michailides ◽  
...  
Keyword(s):  
Gene Expression ◽  
Point Mutation ◽  
Molecular Mechanisms ◽  
Brown Rot ◽  
Polymerase Chain Reaction Method ◽  
Stone Fruit ◽  
Monilinia Fructicola ◽  
Nucleotide Position ◽  
Gene Encoding ◽  
Elevated Expression

The ascomycete Monilinia fructicola is the causal agent of brown rot of stone fruit in Brazil, causing major pre- and postharvest losses. For many years, the demethylation inhibitor (DMI) fungicide tebuconazole has been used as the most effective active ingredient for controlling brown rot and, as a result, strains of M. fructicola resistant to this ingredient have emerged in many Brazilian states producing stone fruit. The aim of this study was to investigate the mechanisms associated with the resistance of M. fructicola to DMI tebuconazole. By sequencing the M. fructicola CYP51 (MfCYP51) gene, encoding the azole target sterol 14α-demethylase, a mutation was identified at the nucleotide position 1,492, causing the amino acid substitution from glycine to serine at the codon position 461, associated with reduced tebuconazole sensitivity. In addition, it was observed that MfCYP51 gene expression could play a secondary role in DMI fungicide resistance of M. fructicola strains in Brazil. However, for the specific isolate found to exhibit elevated expression levels of MfCYP51, no insertions that would trigger gene expression were found. Based on the point mutation associated with tebuconazole resistance, an allele-specific polymerase chain reaction method was developed to quickly identify resistant genotypes within the Brazilian population. This is the first report determining molecular mechanisms for DMI resistance identification for M. fructicola isolates from Brazil. This information provides an important advancement for risk assessment of DMI fungicides used to manage brown rot of stone fruit.

Survey and genetic analysis of demethylation inhibitor fungicide resistance in Monilinia fructicola from Michigan orchards

Plant Disease ◽  
2020 ◽  
Author(s):  
Kim Lesniak ◽  
Jingyu Peng ◽  
Tyre J Proffer ◽  
Cory Outwater ◽  
Lauren Eldred ◽  
...  
Keyword(s):  
Point Mutations ◽  
Brown Rot ◽  
Stone Fruit ◽  
Monilinia Fructicola ◽  
Eastern United States ◽  
Sequence Element ◽  
Wide Range ◽  
Elevated Expression ◽  
Demethylation Inhibitor ◽  
Dmi Resistance

Resistance to sterol demethylation inhibitor fungicides (DMIs) in Monilinia fructicola, causal agent of brown rot of stone fruit, has been reported in the southeastern and eastern United States and in Brazil. DMI resistance of some M. fructicola isolates, in particular those recovered from the southeastern U.S., is associated with a sequence element termed ‘Mona’ that causes overexpression of the cytochrome demethylase target gene MfCYP51. In this study, we conducted statewide surveys of Michigan stone fruit orchards from 2009-2011 and in 2019, and determined the sensitivity to propiconazole of a total of 813 isolates of M. fructicola. A total of 80.7% of Michigan isolates were characterized as resistant to propiconazole by relative growth assays but the ‘Mona’ insert was not uniformly detected, and was present in some isolates that were not characterized as DMI resistant. Gene expression assays indicated that elevated expression of MfCYP51 was only weakly correlated with DMI-resistance in M. fructicola isolates from Michigan, and there was no obvious correlation between the presence of the ‘Mona’ element and elevated expression of MfCYP51. However, sequence analysis of MfCYP51 from 25 DMI-resistant isolates did not reveal any point mutations that could be correlated with resistance. Amplification and sequencing upstream of MfCYP51 resulted in detection of DNA insertions in a wide range of isolates typed by DMI phenotype and the presence of ‘Mona’ or other unique sequences. The function of these unique sequences or their presence upstream of MfCYP51 cannot be correlated to a DMI-resistant genotype at this time. Our results indicate that DMI resistance was established in Michigan populations of M. fructicola by 2009 to 2011, and that relative resistance levels have continued to increase to the point that practical resistance is present in most orchards. In addition, the presence of the ‘Mona’ insert is not a marker for identifying DMI-resistant isolates of M. fructicola in Michigan.

scholarly journals Overexpression of a Redox-Regulated Cutinase Gene, MfCUT1, Increases Virulence of the Brown Rot Pathogen Monilinia fructicola on Prunus spp.

2010 ◽  
Vol 23 (2) ◽  
pp. 176-186 ◽  
Author(s):  
Miin-Huey Lee ◽  
Chiu-Min Chiu ◽  
Tatiana Roubtsova ◽  
Chien-Ming Chou ◽  
Richard M. Bostock
Keyword(s):  
Gene Expression ◽  
Redox Regulation ◽  
Brown Rot ◽  
Gus Expression ◽  
Apple Fruit ◽  
Gus Activity ◽  
Monilinia Fructicola ◽  
Gus Reporter ◽  
Flanking Regions ◽  
Prunus Spp

A 4.5-kb genomic DNA containing a Monilinia fructicola cutinase gene, MfCUT1, and its flanking regions were isolated and characterized. Sequence analysis revealed that the genomic MfCUT1 carries a 63-bp intron and a promoter region with several transcription factor binding sites that may confer redox regulation of MfCUT1 expression. Redox regulation is indicated by the effect of antioxidants, shown previously to inhibit MfCUT1 gene expression in cutin-induced cultures, and in the present study, where H2O2 enhanced MfCUT1 gene expression. A β-glucuronidase (GUS) reporter gene (gusA) was fused to MfCUT1 under the control of the MfCUT1 promoter, and this construct was then used to generate an MfCUT1-GUS strain by Agrobacterium spp.-mediated transformation. The appearance of GUS activity in response to cutin and suppression of GUS activity by glucose in cutinase-inducing medium verified that the MfCUT1-GUS fusion protein was expressed correctly under the control of the MfCUT1 promoter. MfCUT1-GUS expression was detected following inoculation of peach and apple fruit, peach flower petals, and onion epidermis, and during brown rot symptom development on nectarine fruit at a relatively late stage of infection (24 h postinoculation). However, semiquantitative reverse-transcriptase polymerase chain reaction provided sensitive detection of MfCUT1 expression within 5 h of inoculation in both almond and peach petals. MfCUT1-GUS transformants expressed MfCUT1 transcripts at twice the level as the wild type and caused more severe symptoms on Prunus flower petals, consistent with MfCUT1 contributing to the virulence of M. fructicola.

scholarly journals Identification and Characterization of Benzimidazole Resistance in Monilinia fructicola from Stone Fruit Orchards in California

2003 ◽  
Vol 69 (12) ◽  
pp. 7145-7152 ◽  
Author(s):  
Zhonghua Ma ◽  
Michael A. Yoshimura ◽  
Themis J. Michailides
Keyword(s):  
Dna Sequences ◽  
Point Mutations ◽  
Brown Rot ◽  
Stone Fruit ◽  
Monilinia Fructicola ◽  
Tubulin Gene ◽  
Benzimidazole Fungicides ◽  
Specific Pcr ◽  
Allele Specific ◽  
Fruit Orchards

ABSTRACT Low and high levels of resistance to the benzimidazole fungicides benomyl and thiophanate-methyl were observed in field isolates of Monilinia fructicola, which is the causative agent of brown rot of stone fruit. Isolates that had low levels of resistance (hereafter referred to as LR isolates) and high levels of resistance (hereafter referred to as HR isolates) were also cold and heat sensitive, respectively. Results from microsatellite DNA fingerprints showed that genetic identities among the populations of sensitive (S), LR, and HR isolates were very high (>0.96). Analysis of DNA sequences of theβ -tubulin gene showed that the LR isolates had a point mutation at codon 6, causing a replacement of the amino acid histidine by tyrosine. Codon 198, which encodes a glutamic acid in S and LR isolates, was converted to a codon for alanine in HR isolates. Based on these point mutations in the β-tubulin gene, allele-specific PCR assays were developed for rapid detection of benzimidazole-resistant isolates of M. fructicola from stone fruit.

scholarly journals Functional Modification of Pituitary Somatotropes in the Aromatase Knockout Mouse and the Effect of Estrogen Replacement

Endocrinology ◽  
2004 ◽  
Vol 145 (2) ◽  
pp. 604-612 ◽  
Author(s):  
Ming Yan ◽  
Margaret E. E. Jones ◽  
Maria Hernandez ◽  
Dongling Liu ◽  
Evan R. Simpson ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Molecular Mechanisms ◽  
Somatostatin Receptors ◽  
Mrna Levels ◽  
Gene Encoding ◽  
Gh Secretion ◽  
Ghrh Receptor ◽  
Elevated Expression ◽  
Cyp19 Gene

Abstract Available data on the influence of estradiol (E2) on GH levels remains controversial. A factor contributing to this uncertainty is a lack of knowledge of both E2 action on somatotropes as well as the molecular mechanisms involved. In this study we investigated gene expression implicated in GH secretion in somatotropes derived from female aromatase knockout (ArKO) mice. In these mice E2 production is blocked due to disruption of the Cyp19 gene encoding aromatase, the enzyme responsible for estrogen biosynthesis. The effect of E2 replacement was also studied by in vivo treatment of mice with E2 for 3 wk. It was demonstrated that somatotropes from ArKO mice had a low expression of GH, GH secretagogue receptor, GHRH receptor (GHRH-R), and pituitary-specific transcription factor (Pit-1). On the other hand, the somatotropes exhibited elevated expression of somatostatin receptors (sst1–5). Overall, these effects resulted in a reduction in GH secretion. E2 replacement increased GHRH-R, Pit-1, and GH mRNA levels to 185%, 193%, and 157% and reduced the levels of sst1, sst2, sst4, and sst5 mRNA expression in ArKO mice, respectively. E2 replacement did not affect the levels of pituitary estrogen (α and β) and androgen receptor mRNA expression. It is concluded that the expression of important genes involved in GH synthesis in somatotropes of the female ArKO mouse are functionally down-regulated, and such a down-regulation is reversed to normal levels by E2 replacement. The levels of GH secretagogue receptor, GHRH-R, and Pit-1 mRNA expression were also reduced, and sst1 and sst3 mRNA expression enhanced in aging ArKO and wild-type mice, resulting in a decrease in GH mRNA expression. It is suggested that aging is another important impact factor for the pituitary expression and regulation of GH mRNA in female mice.

scholarly journals Detection of Latent Monilinia Infections in Nectarine Flowers and Fruit by qPCR

Plant Disease ◽  
2017 ◽  
Vol 101 (6) ◽  
pp. 1002-1008 ◽  
Author(s):  
C. Garcia-Benitez ◽  
P. Melgarejo ◽  
A. De Cal
Keyword(s):  
Prunus Persica ◽  
Brown Rot ◽  
Stone Fruit ◽  
Monilinia Fructicola ◽  
Latent Infections ◽  
Established Method ◽  
Latently Infected ◽  
Dna Amounts

Most stone fruit with a latent brown rot infection caused by Monilinia do not develop visible signs of disease until the arrival of fruit at the markets or the consumer’s homes. The overnight freezing-incubation technique (ONFIT) is a well-established method for detecting latent brown rot infections, but it takes between 7 to 9 days. In this report, we inform on the advantages of applying a qPCR-based method to (i) detect a latent brown rot infection in the blossoms and fruit of nectarine trees (Prunus persica var. nucipersica) and (ii) distinguish between the Monilinia spp. in them. For applying this qPCR-based method, artificial latent infections were established in nectarine flowers and fruit using 10 Monilinia fructicola isolates, 8 M. fructigena isolates, and 10 M. laxa isolates. We detected greater amounts of M. fructicola DNA than M. laxa and M. fructigena DNA in latently infected flowers using qPCR. However, greater DNA amounts of M. laxa than M. fructicola were detected in the mesocarp of latently infected nectarines. We found that the qPCR-based method is more sensitive, reliable, and quicker than ONFIT for detecting a latent brown rot infection, and could be very useful in those countries where Monilinia spp. are classified as quarantine pathogens.

scholarly journals Cross-Resistance Among Demethylation Inhibitor Fungicides With Brazilian Monilinia fructicola Isolates as a Foundation to Discuss Brown Rot Control in Stone Fruit

Plant Disease ◽  
2020 ◽  
Vol 104 (11) ◽  
pp. 2843-2850
Author(s):  
Pamela Suellen Salvador Dutra ◽  
Paulo S. F. Lichtemberg ◽  
Maria Bernat Martinez ◽  
Themis J. Michailides ◽  
Louise Larissa May De Mio
Keyword(s):  
Brown Rot ◽  
Lesion Size ◽  
Stone Fruit ◽  
Cross Resistance ◽  
Monilinia Fructicola ◽  
Wild Type ◽  
Specific Test ◽  
Allele Specific ◽  
Fruit Orchards ◽  
Demethylation Inhibitor

Despite the resistance problems in Monilinia fructicola, demethylation inhibitor fungicides (DMIs) are still effective for the disease management of brown rot in commercial stone fruit orchards in Brazil. This study aims to investigate the sensitivity of M. fructicola isolates and efficiency of DMIs to reduce brown rot. A set of 93 isolates collected from Brazilian commercial orchards were tested for their sensitivities to tebuconazole, propiconazole, prothioconazole, and myclobutanil. The isolates were analyzed separately according to the presence or absence of the G461S mutation in MfCYP51 gene, determined by allele-specific test. The mean EC50 values for G461S mutants and wild-type isolates were respectively 8.443 and 1.13 µg/ml for myclobutanil, 0.236 and 0.026 µg/ml for propiconazole, 0.115 and 0.002 µg/ml for prothioconazole, and 1.482 and 0.096 µg/ml for tebuconazole. The density distribution curves of DMI sensitivity for both genotypes showed that myclobutanil and prothioconazole curves were mostly shifted toward resistance and sensitivity, respectively. Incomplete cross-resistance was detected among propiconazole and tebuconazole in both wild-type (r = 0.45) and G461S (r = 0.38) populations. No cross-sensitivity was observed among wild-type isolates to prothioconazole and the others DMIs tested. Fungicide treatments on detached fruit inoculated with M. fructicola genotypes showed significant DMI efficacy differences when fruit were inoculated with wild-type and G461S isolates. Protective applications with prothioconazole were more effective for control of both G461S and wild-type isolates compared with tebuconazole. Curative applications with tebuconazole were most effective in reducing the incidence and lesion size of G461S isolates. Sporulation occurred only for G461S isolates treated with tebuconazole under curative and preventative treatments. The differences found among the performance of triazoles against M. fructicola isolates will form the basis for recommendations of rational DMI usage to control brown rot in Brazil.

scholarly journals Xa7, a Small Orphan Gene Harboring Promoter Trap for AvrXa7, Leads to the Durable Resistance to Xanthomonas oryzae Pv. oryzae

Rice ◽  
2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Congying Wang ◽  
Shen Chen ◽  
Aiqing Feng ◽  
Jing Su ◽  
Wenjuan Wang ◽  
...  
Keyword(s):  
Wild Rice ◽  
Molecular Mechanisms ◽  
Durable Resistance ◽  
Bac Library ◽  
Xanthomonas Oryzae ◽  
Endoplasmic Reticulum Membrane ◽  
Gene Encoding ◽  
Orphan Gene ◽  
Promoter Trap ◽  
Elevated Expression

Abstract Background The rice (Oryza sativa) gene Xa7 has been hypothesized to be a typical executor resistance gene against Xanthomonas oryzae pv. oryzae (Xoo), and has conferred durable resistance in the field for decades. Its identity and the molecular mechanisms underlying this resistance remain elusive. Results Here, we filled in gaps of genome in Xa7 mapping locus via BAC library construction, revealing the presence of a 100-kb non-collinear sequence in the line IRBB7 compared with Nipponbare reference genomes. Complementary transformation with sequentially overlapping subclones of the BACs demonstrated that Xa7 is an orphan gene, encoding a small novel protein distinct from any other resistance proteins reported. A 27-bp effector binding element (EBE) in the Xa7 promoter is essential for AvrXa7-inducing expression model. XA7 is anchored in the endoplasmic reticulum membrane and triggers programmed cell death in rice and tobacco (Nicotiana benthamiana). The Xa7 gene is absent in most cultivars, landraces, and wild rice accessions, but highly homologs of XA7 were identified in Leersia perrieri, the nearest outgroup of the genus Oryza. Conclusions Xa7 acts as a trap to perceive AvrXa7 via EBEAvrXa7 in its promoter, leading to the initiation of resistant reaction. Since EBEAvrXa7 is ubiquitous in promoter of rice susceptible gene SWEET14, the elevated expression of which is conducive to the proliferation of Xoo, that lends a great benefit for the Xoo strains retaining AvrXa7. As a result, varieties harboring Xa7 would show more durable resistance in the field. Xa7 alleles analysis suggests that the discovery of new resistance genes could be extended beyond wild rice, to include wild grasses such as Leersia species.

scholarly journals First Report of the β-Tubulin E198A Mutation Conferring Resistance to Methyl Benzimidazole Carbamates in European Isolates of Monilinia fructicola

Plant Disease ◽  
2011 ◽  
Vol 95 (4) ◽  
pp. 497-497 ◽  
Author(s):  
J. Weger ◽  
M. Schanze ◽  
M. Hilber-Bodmer ◽  
T. H. M. Smits ◽  
A. Patocchi
Keyword(s):  
South Carolina ◽  
Molecular Mechanisms ◽  
Brown Rot ◽  
The United States ◽  
Monilinia Fructicola ◽  
Tubulin Gene ◽  
First Report ◽  
Benzimidazole Carbamates ◽  
High Level ◽  
Β Tubulin

The causal agent of brown rot on stone and pome fruits, Monilinia fructicola (G. Wint.), is a quarantine pathogen in Europe. It has been detected in Austria (later eradicated), Spain, the Czech Republic, Italy, Germany, and Switzerland (1). In the United States and other countries, M. fructicola isolates were reported to show resistance to different classes of fungicides, including methyl benzimidazole carbamates (MBC) (2). Lichou et al. (2) reported the presence of isolates resistant to the MBC carbendazim in France, but the mechanisms inducing MBC resistance in these isolates were not studied. Ma et al. (3) in California, and more recently, Zhu et al. (4) in South Carolina, demonstrated that the molecular mechanisms accounting for low and high levels of resistance to MBC fungicides in M. fructicola isolates were the mutations H6Y and E198A, respectively, in the β-tubulin gene. Four M. fructicola isolates each from Italy, France, Spain, and Switzerland (16 isolates total), all having an unknown level of MBC resistance, were selected. In each isolate, the section of the β-tubulin gene containing the two potentially mutant codons was PCR-amplified with the primers TubA and TubR1 (3) and the amplicons were sequenced directly. Sequence analysis revealed the amino acid histidine (H) at codon 6 in all the isolates, which would not predict MBC resistance, while alanine (A) at codon 198 (the mutation predictive of a high level of MBC resistance) was found in all isolates from Spain and Switzerland and in three isolates each from France and Italy. A representative sequence of the four identical partial β-tubulin gene sequences from the Swiss isolates was submitted to GenBank under the Accession No. HQ709265. All isolates were tested in a potato dextrose agar (PDA) petri dish assay for resistance to the MBC fungicide thiophanate-methyl (Nippon Soda Co., Ltd., Tokyo, Japan) at the discriminatory dose of 50 μg/ml (4). All isolates with the E198A mutation were able to grow on the media, while the two isolates without the E198A mutation were not able to grow. The result indicated that most isolates had a high level of resistance to the MBC fungicide. To our knowledge, this is the first report of the presence of the E198A mutation conferring resistance to MBC fungicides in European isolates of M. fructicola. As the mutation appears to be widely distributed, we anticipate that MBC fungicides may be ineffective at controlling brown rot in countries with occurrence of M. fructicola. References: (1) M. Hilber-Bodmer et al. Plant Dis. 94:643, 2010. (2) J. Lichou et al. Phytoma 547:22, 2002. (3) Z. H. Ma et al. Appl. Environ. Microbiol. 69:7145, 2003. (4) F. X. Zhu et al. Plant Dis. 94:1511, 2010.

scholarly journals Candidate genes for panhypopituitarism identified by gene expression profiling

2011 ◽  
Vol 43 (19) ◽  
pp. 1105-1116 ◽  
Author(s):  
Amanda H. Mortensen ◽  
James W. MacDonald ◽  
Debashis Ghosh ◽  
Sally A. Camper
Keyword(s):  
Gene Expression ◽  
Molecular Mechanisms ◽  
Regulation Of Gene Expression ◽  
Hormone Deficiency ◽  
Pituitary Hormone ◽  
Human Pituitary ◽  
Temporal Regulation ◽  
Pituitary Development ◽  
Expression Of Genes ◽  
Elevated Expression

Mutations in the transcription factors PROP1 and PIT1 (POU1F1) lead to pituitary hormone deficiency and hypopituitarism in mice and humans. The dysmorphology of developing Prop1 mutant pituitaries readily distinguishes them from those of Pit1 mutants and normal mice. This and other features suggest that Prop1 controls the expression of genes besides Pit1 that are important for pituitary cell migration, survival, and differentiation. To identify genes involved in these processes we used microarray analysis of gene expression to compare pituitary RNA from newborn Prop1 and Pit1 mutants and wild-type littermates. Significant differences in gene expression were noted between each mutant and their normal littermates, as well as between Prop1 and Pit1 mutants. Otx2, a gene critical for normal eye and pituitary development in humans and mice, exhibited elevated expression specifically in Prop1 mutant pituitaries. We report the spatial and temporal regulation of Otx2 in normal mice and Prop1 mutants, and the results suggest Otx2 could influence pituitary development by affecting signaling from the ventral diencephalon and regulation of gene expression in Rathke's pouch. The discovery that Otx2 expression is affected by Prop1 deficiency provides support for our hypothesis that identifying molecular differences in mutants will contribute to understanding the molecular mechanisms that control pituitary organogenesis and lead to human pituitary disease.

scholarly journals Significance of Thinned Fruit as a Source of the Secondary Inoculum of Monilinia fructicola in California Nectarine Orchards

Plant Disease ◽  
1997 ◽  
Vol 81 (5) ◽  
pp. 519-524 ◽  
Author(s):  
Chuanxue Hong ◽  
Brent A. Holtz ◽  
David P. Morgan ◽  
Themis J. Michailides
Keyword(s):  
Brown Rot ◽  
Weather Conditions ◽  
San Joaquin Valley ◽  
Stone Fruit ◽  
Monilinia Fructicola ◽  
Inoculum Source ◽  
Secondary Infections ◽  
Fruit Orchards ◽  
Semi Arid

The significance of thinned fruit as a source of secondary inoculum in the spread of brown rot, caused by Monilinia fructicola, under semi-arid weather conditions of the San Joaquin Valley in California, was investigated in seven nectarine orchards in 1995 and 1996. Between 6 and 60% (depending on the orchard) of thinned fruit showed sporulation by M. fructicola. Brown rot was significantly less severe at preharvest (five orchards) and postharvest (one orchard) on fruit harvested from trees in plots from which thinned fruit were completely removed than on those in plots from which thinned fruit were not removed. M. fructicola sporulated more frequently on thinned fruit placed into irrigation trenches than on those left on the dry berms in tree rows. The incidence of preharvest fruit brown rot increased exponentially as the density of thinned fruit increased on the orchard floor. These results suggest that thinned fruit left on the floor of nectarine orchards can be a significant inoculum source of secondary infections. Removal or destruction of thinned fruit should reduce brown rot in nectarine and possibly other stone fruit orchards under semi-arid California conditions.

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