Biological and genetic characterization of <i>Phytophthora capsici</i> mutants resistant to flumorph

Meng, Qingyong; Cui, Xiaogang; Bi, Yang; Wang, Q.; Hao, Jianjun; Liu, X. L.

doi:10.1111/j.1365-3059.2011.02454.x

Cited by 19 publications

(26 citation statements)

References 32 publications

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“…The large pepper farms in Wuwei and Tianshui with a higher proportion of resistant isolates develop new capsicum varieties and fungicides are applied frequently. Because many areas have sensitive isolates, mefenoxam or metalaxyl fungicides may be useful, although fungicide rotation using chemistries with different modes of action should be used to slow the inevitable development of resistance (29,31).…”

Section: Discussionmentioning

confidence: 99%

Genetically Diverse Long-Lived Clonal Lineages ofPhytophthora capsicifrom Pepper in Gansu, China

Hu¹,

Pang²,

Bi³

et al. 2013

Phytopathology®

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Phytophthora capsici causes significant loss to pepper production in China, and our objective was to investigate the population structure in Gansu province. Between 2007 and 2011, 279 isolates were collected from pepper at 24 locations. Isolates (or subsets) were assessed for simple sequence repeat (SSR) genotype, metalaxyl resistance, mating type, and physiological race using cultivars from the World Vegetable Center (AVRDC) and New Mexico recombinant inbred lines (NMRILs). The A1 and A2 mating types were recovered from nine locations and metalaxyl-resistant isolates from three locations. A total of 104 isolates tested on the AVRDC panel resolved five physiological races. None of 42 isolates tested on the NMRIL panel caused visible infection. SSR genotyping of 127 isolates revealed 59 unique genotypes, with 42 present as singletons and 17 having 2 to 13 isolates. Isolates with identical genotypes were recovered from multiple sites across multiple years and, in many cases, had different race types or metalaxyl sensitivities. Isolates clustered into three groups with each group having almost exclusively the A1 or A2 mating type. Overall it appears long-lived genetically diverse clonal lineages are dispersed across Gansu, outcrossing is rare, and functionally important variation exists within a clonal framework.

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Section: Discussionmentioning

confidence: 99%

Genetically Diverse Long-Lived Clonal Lineages ofPhytophthora capsicifrom Pepper in Gansu, China

Hu¹,

Pang²,

Bi³

et al. 2013

Phytopathology®

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“…This would explain why dimethomorph-resistant mutants of P. capsici could not be obtained from only one isolate by taming [21], but why CAA-resistance could be obtained by mass selection from zoospores and sexual progeny [22], [23].…”

Section: Discussionmentioning

confidence: 99%

Assessing the Risk That Phytophthora melonis Can Develop a Point Mutation (V1109L) in CesA3 Conferring Resistance to Carboxylic Acid Amide Fungicides

et al. 2012

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The risk that the plant pathogen Phytophthora melonis develops resistance to carboxylic acid amide (CAA) fungicides was determined by measuring baseline sensitivities of field isolates, generating resistant mutants, and measuring the fitness of the resistant mutants. The baseline sensitivities of 80 isolates to flumorph, dimethomorph and iprovalicarb were described by unimodal curves, with mean EC50 values of 0.986 (±0.245), 0.284 (±0.060) and 0.327 (±0.068) µg/ml, respectively. Seven isolates with different genetic background (as indicated by RAPD markers) were selected to generate CAA-resistance. Fifty-five resistant mutants were obtained from three out of seven isolates by spontaneous selection and UV-mutagenesis with frequencies of 1×10−7 and 1×10−6, respectively. CAA-resistance was stable for all mutants. The resistance factors of these mutants ranged from 7 to 601. The compound fitness index (CFI = mycelial growth × zoospore production × pathogenicity) was often lower for the CAA-resistant isolates than for wild-type isolates, suggesting that the risk of P. melonis developing resistance to CAA fungicides is low to moderate. Among the CAA-resistant isolates, a negative correlation between EC50 values was found for iprovalicarb vs. flumorph and for iprovalicarb vs. dimethomorph. Comparison of the full-length cellulose synthase 3 (CesA3) between wild-type and CAA-resistant isolates revealed only one point mutation at codon position 1109: a valine residue (codon GTG in wild-type isolates) was converted to leucine (codon CTG in resistant mutants). This represents a novel point mutation with respect to mutations in CesA3 conferring resistance to CAA fungicides. Based on this mutation, an efficient allelic-specific PCR (AS-PCR) method was developed for rapid detection of CAA-resistance in P. melonis populations.

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“…Carrot agar (CA) was used to induce P. capsici sporangia (Brasier & Griffin, ). A 10% V8 juice agar was used to induce P. capsici oospores (Meng et al ., ). S + L medium (Ann & Ko, ) with 50 μ g mL −1 ampicillin and 50 μ g mL −1 penicillin was used to promote oospore germination.…”

Section: Methodsmentioning

confidence: 97%

“…The genetic basis of fungicide resistance affects the probability of resistance development, and parts of the genetic mechanisms underlying fungicide resistance have been determined in several oomycetes (Shattock, ; Gisi et al ., ; Meng et al ., ). For instance, resistance to metalaxyl in P. infestans is controlled by a single, semidominant gene, which results in the rapid development of metalaxyl resistance (Shattock, ).…”

Section: Introductionmentioning

confidence: 97%

“…Because the resistance of P. viticola to CAA fungicides is controlled by two recessive genes, the risk of CAA resistance is thought to be moderate and lower than the risk of phenylamide and QoI resistance, which are controlled by one semidominant nuclear gene and a mitochondrial gene, respectively (Gisi et al ., ). Moreover, the genetic mechanism of flumorph resistance in P. capsici is controlled by two dominant genes, indicating that resistance could easily spread once it has occurred via sexual reproduction in nature (Meng et al ., ). Sexual reproduction may create a homozygous allele that confers high resistance to a fungicide, and when the competitive ability of the resistant isolates is equal to or greater than that of sensitive isolates, fungicide resistance will spread and become dominant in the field (Cooke et al ., ).…”

Section: Introductionmentioning

confidence: 97%

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Sexual reproduction increases the possibility that Phytophthora capsici will develop resistance to dimethomorph in China

Cui

et al. 2014

Plant Pathology

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A total of 1511 isolates of Phytophthora capsici were collected from farms with no history of exposure to the carboxylic acid amide (CAA) fungicides in 32 provinces in China during 2006 to 2013. All 1511 isolates were assayed for mating type and 403 were assayed for sensitivity to dimethomorph (DMM) and metalaxyl. The DMM EC 50 values ranged from 0Á126 to 0Á339 lg mL À1 . Both A1 and A2 mating types were detected on the same farms in four provinces and with a 1:1 ratio. Most isolates were sensitive to metalaxyl but a few exhibited intermediate resistance or resistance to metalaxyl. The segregation of DMM resistance and sensitivity among 337 progeny obtained from hybridization or self-crossing in vitro indicated that the resistance of P. capsici to DMM is controlled by two dominant genes. Eighteen progeny that were derived from hybridization differed in DMM sensitivity and in fitness. Some progeny were as fit as parental isolates. Given the distribution of mating types and therefore the potential for sexual reproduction, the control of resistance by two dominant genes, and the fitness of hybrid progeny, the risk of P. capsici populations developing DMM resistance in China is substantial.

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Biological and genetic characterization of Phytophthora capsici mutants resistant to flumorph

Cited by 19 publications

References 32 publications

Genetically Diverse Long-Lived Clonal Lineages ofPhytophthora capsicifrom Pepper in Gansu, China

Genetically Diverse Long-Lived Clonal Lineages ofPhytophthora capsicifrom Pepper in Gansu, China

Assessing the Risk That Phytophthora melonis Can Develop a Point Mutation (V1109L) in CesA3 Conferring Resistance to Carboxylic Acid Amide Fungicides

Sexual reproduction increases the possibility that Phytophthora capsici will develop resistance to dimethomorph in China

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