对四川、浙江、安徽、河北、辽宁等地不同梨品种采集的6个梨黑星菌(Venturianashicola Tanaka et Yamamoto)的单孢分离物,采用鉴别寄主进行致病力测定和菌体酯酶同功酶测定。结果表明:在我国栽培梨上的黑星菌是存在生理分化的。并可将供...对四川、浙江、安徽、河北、辽宁等地不同梨品种采集的6个梨黑星菌(Venturianashicola Tanaka et Yamamoto)的单孢分离物,采用鉴别寄主进行致病力测定和菌体酯酶同功酶测定。结果表明:在我国栽培梨上的黑星菌是存在生理分化的。并可将供试6个分离物分成4个类型。展开更多
Resistance of Venturia inaequalis to the first IBS triazoles occurred in the 80’s in Italy and other countries. Successively number of applications sensibly decreased and problems of resistance to IBS generally disap...Resistance of Venturia inaequalis to the first IBS triazoles occurred in the 80’s in Italy and other countries. Successively number of applications sensibly decreased and problems of resistance to IBS generally disappeared. In 2010 suspects of resistance to the newer IBS difenoconazole, the actually most used IBS, appeared in several countries. In vitro tests the results confirmed the previous researches: the monoconidia from populations which were poorly controlled showed moderate reduced sensitivity respect to well controlled and wild-types. New in vivo tests were realized with preventive and curative applications on seedlings. No different activity among the three types of populations (poorly, well-controlled and wild-types) was found in preventive applications. On the contrary, in curative applications, wild-types and well controlled populations showed a visible and statistically significant activity respect to the poorly controlled. A survey of sensitivity to difenoconazole was carried out in two Italian apple areas in 2013-2015 and showed the presence of populations resistant to difenoconazole. Probably the cause of the resistance spread was the increase of the number of applications of this IBS in the last years. However the problem appears more complex because nowadays resistance regards about all fungicides and with a higher severity respect previous decades. An increase of virulence of V. inaequalis strains appears to be the cause of this situation also for the high presence of cultivars with high or moderate susceptibility to scab. Foreseeable remedies consist in a differentiate and appropriate setting of each chemical groups of fungicides in apple scab control, but in long terms new strategies in apple cultivation should be necessary.展开更多
The super line 03-04-034, which results from a cross between Pyrus bretchneideri cv Jingbaili and P.ussuriensis cv Yali, is highly resistant to pear scab.Specimens were inoculated with Venturia nashicola to generate a...The super line 03-04-034, which results from a cross between Pyrus bretchneideri cv Jingbaili and P.ussuriensis cv Yali, is highly resistant to pear scab.Specimens were inoculated with Venturia nashicola to generate a database of expressed sequence tags(ESTs) to be used as resources for transcripts induced in inoculated and uninoculated leaves. After performing subtractive suppression hybridization using cDNA of the inoculated and uninoculated leaves harvested 51 h after inoculation, 100 clones from the uninoculated and 100 clones from the inoculated cDNA library were selected and sequenced. BLASTN searches of each cDNA library against GenBank revealed eight unique sequences associated with the defense response, comprising four ESTs from the uninoculated cDNA library(ubiquitin extension protein, subtilisin-like protease, basic helix-loop-helix(bHLH) transcription factor and aspartic endopeptidase) and four ESTs from the inoculated cDNA library(S-adenosylmethionine synthase(SAMS), heat shock factor(HSF) domain class transcription factor, RNA-binding protein and polyphenol oxidase 5 precursor).Quantitative fluorescence real-time polymerase chain analysis revealed that the transcripts for SAMS and subtilisin-like protease were highly expressed in the incompatible interaction. The SAMS gene was more highly expressed in inoculated leaves than uninoculated leaves, while the reverse was true for subtilisin-like protease. The SAMS and subtilisin-like protease genes have been found to be associated with plant defense mechanisms. Further studies of greater detail are required to understand how these genes are expressed and regulated during infection with V.nashicola.展开更多
The phytopathogenic fungus Venturia inaequalis causes scab of apple. Once this fungus penetrates the plant surface, it forms a specialized body called a stroma between the inner cuticle surface and the epidermal cell ...The phytopathogenic fungus Venturia inaequalis causes scab of apple. Once this fungus penetrates the plant surface, it forms a specialized body called a stroma between the inner cuticle surface and the epidermal cell wall. A novel Venturia inaequalis 5704 (Cin3) and three expressed sequence tags (ESTs);38, 6987, and 4010 are strongly up-regulated in the early stages of infection. The CIN3 and three ESTs using two vectors pMAL-c2 and pET 21 were expressed in Escherichia coli. Recombinant proteins expression, solubility and yields were analyzed. 38, 5704 (Cin3) and 6987 re- combinant proteins were expressed in soluble form and while 4010 was expressed in inclusion bodies. Re- solution on native-PAGE, the recombinant proteins;38, 5704 (Cin3), 6987 were shown to be present in dimmer, tetramer and polymer. A method was de- veloped, consisting of induction of expression at va- rious temperatures, and using enriched broth with 4% glycerol together with slow shaking, led to a decrease in concentration of nascent polypeptide and production of soluble recombinant proteins of;38, 5704 (Cin3), 6987 and 4010. Resolution on native- PAGE, the recombinant proteins were shown to be present as monomer.展开更多
The research was focused on the persistence of resistance of V. inaequalis to strobilurins from resistant populations occurring in the field. It was studied with two types of experiments: the first in apple orchards w...The research was focused on the persistence of resistance of V. inaequalis to strobilurins from resistant populations occurring in the field. It was studied with two types of experiments: the first in apple orchards where resistance occurred in 2005 and employ of these fungicides was suspended from 2006 to 2011, realizing every year sensitivity/resistance assays on strobilurins. In the second was verified the sensitivity/resistance of the same 2015 populations, repeatedly multiplied (ten inoculations) in glasshouse on apple seedlings. Results showed that the resistance survived in orchards all the years of tests (six years), despite sensitivity fluctuations occurred on infected leaves due to sexual crosses, competition with sensible strains and soil management. In glasshouse, the level of resistance of all populations increased quickly in first inoculations and values remained high (EC50 > 10 mg·L-1) in all the following inoculations, until the last, the 10th. V. inaequalis resistant strains seemed to show high fitness: relevant persistence in the field, and a capacity of prevail on sensible ones in absence of factors of field variability.展开更多
Among the most economically important fruit crops in South and North Kyrgyzstan affected by scab disease are apples (Malus domestica). Natural isolates of Venturia inaequalis were isolated from diseased parts of apple...Among the most economically important fruit crops in South and North Kyrgyzstan affected by scab disease are apples (Malus domestica). Natural isolates of Venturia inaequalis were isolated from diseased parts of apple trees, selected from different regions, through sedimentation of air microflora on the crowns of fruit trees. Two biocontrol agents as Trichoderma viride and Streptomyces sр. were tested for apple scab control in vitro and field conditions. Two applications of Trichoderma viride within 35 days completely stopped the scab disease in seedling leaves. Within 40 days, the seedlings were recovered;the new leaves have blossomed on branches. The Streptomyces sp. antagonists were inferior in effectiveness compared to Trichoderma viride;nevertheless, they prevented progression of the disease in the leaves. Seedlings grew new shoots and leaves around 50 days after the second treatment. Orchard experiment results provide great hope that a biological product based on Trichoderma viride could work as an effective agent to suppress the development of the pathogen in the early spring, when leaves start to show scab disease symptoms.展开更多
Apple scab caused by </span><i><span style="font-family:Verdana;">Venturia inaequalis</span></i><span style="font-family:Verdana;"> (Cke.) Wint. is the most impo...Apple scab caused by </span><i><span style="font-family:Verdana;">Venturia inaequalis</span></i><span style="font-family:Verdana;"> (Cke.) Wint. is the most important disease of apple trees worldwide and requires a high number of fungicide applications. The G143A substitution in the inhibitor binding site of cytochrome </span><i><span style="font-family:Verdana;">b</span></i><span style="font-family:Verdana;"> of </span><i><span style="font-family:Verdana;">V. inaequalis</span></i><span style="font-family:Verdana;"> confers a high level of resistance to strobilurins targeting the </span><i><span style="font-family:Verdana;">bc</span></i><sub><span style="font-family:Verdana;">1</span></sub><span style="font-family:Verdana;"> complex. The aim of this work was to substitute the labor intensive </span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> assays, with the faster quantitative PCR. An allele-specific qPCR method with a newly designed primer set was successfully developed to quantitatively determine the frequency of QoI-resistant A143 allele in populations of </span><i><span style="font-family:Verdana;">V. inaequalis. </span></i><span style="font-family:Verdana;">To be able to suggest that the molecular method could be applied as unique and robust technique, we carried out </span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> sensitivity test to trifloxystrobin;first testing the relative germination and subsequently confirmed with the quantification of mutated allele frequencies by qPCR on forty-nine Italian </span><i><span style="font-family:Verdana;">V. inaequalis</span></i><span style="font-family:Verdana;"> populations. qPCR gave a similar pattern to that obtained using </span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> conidial germination test in predominantly sensitive and resistant populations, the variability between these two tests was observed in some heterogeneous populations. The qPCR assay developed in this study efficiently quantifies the A143 allele and we can conclude that this method could be useful for the study of the fungicide resistance at population level in the fields, giving a quick response also with a large amount of samples.展开更多
Dithianon is a multi-site fungicide and has never been object of suspects and reports of reduced sensitivity and activity. Italian IFP technicians had the suspect of reductions of activity by this fungicide on </sp...Dithianon is a multi-site fungicide and has never been object of suspects and reports of reduced sensitivity and activity. Italian IFP technicians had the suspect of reductions of activity by this fungicide on </span><i><span style="font-family:Verdana;">Venturia inaequalis.</span></i><span style="font-family:Verdana;"> Methodologies, </span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">in vivo</span></i><span style="font-family:Verdana;"> were carried out to verify this suspect. Populations poorly controlled with suspects on dithianon and sensible ones </span><span><span style="font-family:Verdana;">were utilized. The tests </span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> permitted to evidence light and non-significant</span></span><span style="font-family:Verdana;"> reductions of sensitivity of poorly controlled populations </span></span><span style="font-family:Verdana;">with </span><span style="font-family:Verdana;">respect </span><span style="font-family:Verdana;">to </span><span style="font-family:""><span style="font-family:Verdana;">sensible ones. </span><i><span style="font-family:Verdana;">In vivo tests</span></i><span style="font-family:Verdana;"> on seedlings were non</span></span><span style="font-family:Verdana;">-</span><span style="font-family:""><span style="font-family:Verdana;">reliable for a general low activity of dithianon. On the contrary, the original </span><i><span style="font-family:Verdana;">in vivo</span></i><span style="font-family:Verdana;"> methodology on grafted apple plants showed several reductions of activity, with moderate levels and a spot distribution in orchards. The cause was probably due to the increase</span></span><span style="font-family:Verdana;">d</span><span style="font-family:Verdana;"> treatments with dithianon caused by problems on other groups of fungicides and by a high infective pressure in some years. It is discussed if this reduction can be considered a resistance phenomenon or a temporary modification of the interactions </span><span style="font-family:Verdana;">of </span><span style="font-family:Verdana;">plant-fungus-fungicide.展开更多
Biological methodologies (</span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> and </span><i><span ...Biological methodologies (</span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">in vivo</span></i><span style="font-family:Verdana;">) were tested on </span><i><span style="font-family:Verdana;">Venturia inaequalis</span></i><span style="font-family:Verdana;"> to assay sensitivity of populations treated with the SDHI penthiopyrad, fluxapyroxad and fluopyram that showed a field poor control in an experimental Centre. In comparison, sensible populations were tested. </span><i><span style="font-family:Verdana;">I</span></i><i><span style="font-family:Verdana;">n vitro</span></i><span style="font-family:Verdana;"> trials, the poorly controlled populations presented moderate increases of EC</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> and RF values in all three years in which tests were carried out. The </span><i><span style="font-family:Verdana;">in vivo</span></i><span style="font-family:Verdana;"> trials in glasshouse showed that the activity of SDHI fungicides on field poorly controlled populations was highly reduced. These populations can be defined as “resistant” as the high loss of sensitivity and activity were repeatedly assessed in field and glasshouse. Trials showed that these reductions were manifested by curative applications and not by preventive ones, as already ascertained for </span><i><span style="font-family:Verdana;">V. inaequalis </span></i><span style="font-family:Verdana;">populations resistant to AP and DMI fungicides. </span><span><span style="font-family:Verdana;">The cross-resistance of resistant populations to the three SDHIs was highly positive among them. In bibliography, there are only researches of cross-resistance among SDHIs starting from isolates resistant to boscalid, with results of different sensitivities and cross-resistance. These results with populations of </span><i><span style="font-family:Verdana;">V. inaequalis</span></i><span style="font-family:Verdana;"> resistant to the three SDHI offer practical evaluations in cross-resistance.展开更多
Apple scab caused by Venturia inaequalis has a tendency to spread and threatens the development of apple production in recent years in China.The genetic diversity and population structure were investigated by using si...Apple scab caused by Venturia inaequalis has a tendency to spread and threatens the development of apple production in recent years in China.The genetic diversity and population structure were investigated by using simple sequence repeat(SSR) markers.51 strains were classified into 3 groups by UPGMA method as Xunyi,Xingping and U.K.population,each of them mainly including strains from its original place.A relatively high level of genetic diversity was revealed: H=0.425 3,I=0.675 8,PPL=66.67%(at species level);H=0.149 1,I=0.228 0,PPL=44.44%(at population level).A high level of genetic differentiation was detected among/within populations with Nei’s Gst analysis and AMOVA.Molecular genetic variance within populations was greater than that among populations.Genetic variance among populations might result from barriers to gene flow(Nm=0.675 8).Genetic variance within populations might result from sexual pro-pagation of V.inaequalis.展开更多
文摘Resistance of Venturia inaequalis to the first IBS triazoles occurred in the 80’s in Italy and other countries. Successively number of applications sensibly decreased and problems of resistance to IBS generally disappeared. In 2010 suspects of resistance to the newer IBS difenoconazole, the actually most used IBS, appeared in several countries. In vitro tests the results confirmed the previous researches: the monoconidia from populations which were poorly controlled showed moderate reduced sensitivity respect to well controlled and wild-types. New in vivo tests were realized with preventive and curative applications on seedlings. No different activity among the three types of populations (poorly, well-controlled and wild-types) was found in preventive applications. On the contrary, in curative applications, wild-types and well controlled populations showed a visible and statistically significant activity respect to the poorly controlled. A survey of sensitivity to difenoconazole was carried out in two Italian apple areas in 2013-2015 and showed the presence of populations resistant to difenoconazole. Probably the cause of the resistance spread was the increase of the number of applications of this IBS in the last years. However the problem appears more complex because nowadays resistance regards about all fungicides and with a higher severity respect previous decades. An increase of virulence of V. inaequalis strains appears to be the cause of this situation also for the high presence of cultivars with high or moderate susceptibility to scab. Foreseeable remedies consist in a differentiate and appropriate setting of each chemical groups of fungicides in apple scab control, but in long terms new strategies in apple cultivation should be necessary.
基金Supported by the Science and Technology Plan Projects of Hebei Province(16226312D-3)the Changli Comprehensive Experimental Station of National Pearindustry Technology Research System of(CARS-29-23)Science and Technology Plan Innovation Team Projects of Hebei Province(494-0402-TBN-OG4L)
文摘The super line 03-04-034, which results from a cross between Pyrus bretchneideri cv Jingbaili and P.ussuriensis cv Yali, is highly resistant to pear scab.Specimens were inoculated with Venturia nashicola to generate a database of expressed sequence tags(ESTs) to be used as resources for transcripts induced in inoculated and uninoculated leaves. After performing subtractive suppression hybridization using cDNA of the inoculated and uninoculated leaves harvested 51 h after inoculation, 100 clones from the uninoculated and 100 clones from the inoculated cDNA library were selected and sequenced. BLASTN searches of each cDNA library against GenBank revealed eight unique sequences associated with the defense response, comprising four ESTs from the uninoculated cDNA library(ubiquitin extension protein, subtilisin-like protease, basic helix-loop-helix(bHLH) transcription factor and aspartic endopeptidase) and four ESTs from the inoculated cDNA library(S-adenosylmethionine synthase(SAMS), heat shock factor(HSF) domain class transcription factor, RNA-binding protein and polyphenol oxidase 5 precursor).Quantitative fluorescence real-time polymerase chain analysis revealed that the transcripts for SAMS and subtilisin-like protease were highly expressed in the incompatible interaction. The SAMS gene was more highly expressed in inoculated leaves than uninoculated leaves, while the reverse was true for subtilisin-like protease. The SAMS and subtilisin-like protease genes have been found to be associated with plant defense mechanisms. Further studies of greater detail are required to understand how these genes are expressed and regulated during infection with V.nashicola.
文摘The phytopathogenic fungus Venturia inaequalis causes scab of apple. Once this fungus penetrates the plant surface, it forms a specialized body called a stroma between the inner cuticle surface and the epidermal cell wall. A novel Venturia inaequalis 5704 (Cin3) and three expressed sequence tags (ESTs);38, 6987, and 4010 are strongly up-regulated in the early stages of infection. The CIN3 and three ESTs using two vectors pMAL-c2 and pET 21 were expressed in Escherichia coli. Recombinant proteins expression, solubility and yields were analyzed. 38, 5704 (Cin3) and 6987 re- combinant proteins were expressed in soluble form and while 4010 was expressed in inclusion bodies. Re- solution on native-PAGE, the recombinant proteins;38, 5704 (Cin3), 6987 were shown to be present in dimmer, tetramer and polymer. A method was de- veloped, consisting of induction of expression at va- rious temperatures, and using enriched broth with 4% glycerol together with slow shaking, led to a decrease in concentration of nascent polypeptide and production of soluble recombinant proteins of;38, 5704 (Cin3), 6987 and 4010. Resolution on native- PAGE, the recombinant proteins were shown to be present as monomer.
文摘The research was focused on the persistence of resistance of V. inaequalis to strobilurins from resistant populations occurring in the field. It was studied with two types of experiments: the first in apple orchards where resistance occurred in 2005 and employ of these fungicides was suspended from 2006 to 2011, realizing every year sensitivity/resistance assays on strobilurins. In the second was verified the sensitivity/resistance of the same 2015 populations, repeatedly multiplied (ten inoculations) in glasshouse on apple seedlings. Results showed that the resistance survived in orchards all the years of tests (six years), despite sensitivity fluctuations occurred on infected leaves due to sexual crosses, competition with sensible strains and soil management. In glasshouse, the level of resistance of all populations increased quickly in first inoculations and values remained high (EC50 > 10 mg·L-1) in all the following inoculations, until the last, the 10th. V. inaequalis resistant strains seemed to show high fitness: relevant persistence in the field, and a capacity of prevail on sensible ones in absence of factors of field variability.
文摘Among the most economically important fruit crops in South and North Kyrgyzstan affected by scab disease are apples (Malus domestica). Natural isolates of Venturia inaequalis were isolated from diseased parts of apple trees, selected from different regions, through sedimentation of air microflora on the crowns of fruit trees. Two biocontrol agents as Trichoderma viride and Streptomyces sр. were tested for apple scab control in vitro and field conditions. Two applications of Trichoderma viride within 35 days completely stopped the scab disease in seedling leaves. Within 40 days, the seedlings were recovered;the new leaves have blossomed on branches. The Streptomyces sp. antagonists were inferior in effectiveness compared to Trichoderma viride;nevertheless, they prevented progression of the disease in the leaves. Seedlings grew new shoots and leaves around 50 days after the second treatment. Orchard experiment results provide great hope that a biological product based on Trichoderma viride could work as an effective agent to suppress the development of the pathogen in the early spring, when leaves start to show scab disease symptoms.
文摘Apple scab caused by </span><i><span style="font-family:Verdana;">Venturia inaequalis</span></i><span style="font-family:Verdana;"> (Cke.) Wint. is the most important disease of apple trees worldwide and requires a high number of fungicide applications. The G143A substitution in the inhibitor binding site of cytochrome </span><i><span style="font-family:Verdana;">b</span></i><span style="font-family:Verdana;"> of </span><i><span style="font-family:Verdana;">V. inaequalis</span></i><span style="font-family:Verdana;"> confers a high level of resistance to strobilurins targeting the </span><i><span style="font-family:Verdana;">bc</span></i><sub><span style="font-family:Verdana;">1</span></sub><span style="font-family:Verdana;"> complex. The aim of this work was to substitute the labor intensive </span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> assays, with the faster quantitative PCR. An allele-specific qPCR method with a newly designed primer set was successfully developed to quantitatively determine the frequency of QoI-resistant A143 allele in populations of </span><i><span style="font-family:Verdana;">V. inaequalis. </span></i><span style="font-family:Verdana;">To be able to suggest that the molecular method could be applied as unique and robust technique, we carried out </span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> sensitivity test to trifloxystrobin;first testing the relative germination and subsequently confirmed with the quantification of mutated allele frequencies by qPCR on forty-nine Italian </span><i><span style="font-family:Verdana;">V. inaequalis</span></i><span style="font-family:Verdana;"> populations. qPCR gave a similar pattern to that obtained using </span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> conidial germination test in predominantly sensitive and resistant populations, the variability between these two tests was observed in some heterogeneous populations. The qPCR assay developed in this study efficiently quantifies the A143 allele and we can conclude that this method could be useful for the study of the fungicide resistance at population level in the fields, giving a quick response also with a large amount of samples.
文摘Dithianon is a multi-site fungicide and has never been object of suspects and reports of reduced sensitivity and activity. Italian IFP technicians had the suspect of reductions of activity by this fungicide on </span><i><span style="font-family:Verdana;">Venturia inaequalis.</span></i><span style="font-family:Verdana;"> Methodologies, </span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">in vivo</span></i><span style="font-family:Verdana;"> were carried out to verify this suspect. Populations poorly controlled with suspects on dithianon and sensible ones </span><span><span style="font-family:Verdana;">were utilized. The tests </span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> permitted to evidence light and non-significant</span></span><span style="font-family:Verdana;"> reductions of sensitivity of poorly controlled populations </span></span><span style="font-family:Verdana;">with </span><span style="font-family:Verdana;">respect </span><span style="font-family:Verdana;">to </span><span style="font-family:""><span style="font-family:Verdana;">sensible ones. </span><i><span style="font-family:Verdana;">In vivo tests</span></i><span style="font-family:Verdana;"> on seedlings were non</span></span><span style="font-family:Verdana;">-</span><span style="font-family:""><span style="font-family:Verdana;">reliable for a general low activity of dithianon. On the contrary, the original </span><i><span style="font-family:Verdana;">in vivo</span></i><span style="font-family:Verdana;"> methodology on grafted apple plants showed several reductions of activity, with moderate levels and a spot distribution in orchards. The cause was probably due to the increase</span></span><span style="font-family:Verdana;">d</span><span style="font-family:Verdana;"> treatments with dithianon caused by problems on other groups of fungicides and by a high infective pressure in some years. It is discussed if this reduction can be considered a resistance phenomenon or a temporary modification of the interactions </span><span style="font-family:Verdana;">of </span><span style="font-family:Verdana;">plant-fungus-fungicide.
文摘Biological methodologies (</span><i><span style="font-family:Verdana;">in vitro</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">in vivo</span></i><span style="font-family:Verdana;">) were tested on </span><i><span style="font-family:Verdana;">Venturia inaequalis</span></i><span style="font-family:Verdana;"> to assay sensitivity of populations treated with the SDHI penthiopyrad, fluxapyroxad and fluopyram that showed a field poor control in an experimental Centre. In comparison, sensible populations were tested. </span><i><span style="font-family:Verdana;">I</span></i><i><span style="font-family:Verdana;">n vitro</span></i><span style="font-family:Verdana;"> trials, the poorly controlled populations presented moderate increases of EC</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> and RF values in all three years in which tests were carried out. The </span><i><span style="font-family:Verdana;">in vivo</span></i><span style="font-family:Verdana;"> trials in glasshouse showed that the activity of SDHI fungicides on field poorly controlled populations was highly reduced. These populations can be defined as “resistant” as the high loss of sensitivity and activity were repeatedly assessed in field and glasshouse. Trials showed that these reductions were manifested by curative applications and not by preventive ones, as already ascertained for </span><i><span style="font-family:Verdana;">V. inaequalis </span></i><span style="font-family:Verdana;">populations resistant to AP and DMI fungicides. </span><span><span style="font-family:Verdana;">The cross-resistance of resistant populations to the three SDHIs was highly positive among them. In bibliography, there are only researches of cross-resistance among SDHIs starting from isolates resistant to boscalid, with results of different sensitivities and cross-resistance. These results with populations of </span><i><span style="font-family:Verdana;">V. inaequalis</span></i><span style="font-family:Verdana;"> resistant to the three SDHI offer practical evaluations in cross-resistance.
文摘Apple scab caused by Venturia inaequalis has a tendency to spread and threatens the development of apple production in recent years in China.The genetic diversity and population structure were investigated by using simple sequence repeat(SSR) markers.51 strains were classified into 3 groups by UPGMA method as Xunyi,Xingping and U.K.population,each of them mainly including strains from its original place.A relatively high level of genetic diversity was revealed: H=0.425 3,I=0.675 8,PPL=66.67%(at species level);H=0.149 1,I=0.228 0,PPL=44.44%(at population level).A high level of genetic differentiation was detected among/within populations with Nei’s Gst analysis and AMOVA.Molecular genetic variance within populations was greater than that among populations.Genetic variance among populations might result from barriers to gene flow(Nm=0.675 8).Genetic variance within populations might result from sexual pro-pagation of V.inaequalis.
