Possible role for wild genotypes of Pisum spp. to enhance ascochyta blight resistance in pea

1998 ◽  
Vol 38 (5) ◽  
pp. 469 ◽  
Author(s):  
J. M. Wroth
Keyword(s):  
Hypersensitive Response ◽  
Ascochyta Blight ◽  
Resistance Mechanism ◽  
Resistance Mechanisms ◽  
Effective Field ◽  
Field Resistance ◽  
Mycosphaerella Pinodes ◽  
Wild Type ◽  
Sources Of Resistance ◽  
The Cross

Summary. There are no cultivars with effective field resistance to ascochyta blight currently available in Australia but a number of wild genotypes of Pisum have been identified as possible sources of resistance and these were evaluated in crosses with a commercial cultivar. Pisum fulvum JI 1006, used as the pollen parent, was crossed with P. sativum cv. Wirrega using wild type P. sativum JI 252 as a bridging cross. JI 1006 and JI 252 both respond to Mycosphaerella pinodes infection by inducing a rapid hypersensitive response. All F2 seedlings (17–20-day-old) from the cross Wirrega × (JI 252 × JI 1006) were screened for their responses to M. pinodes infection in a controlled environment and plants with the highest levels of resistance were then screened as F3 progeny families in the field to determine their responses to natural M. pinodes infection. Nine percent of these families were significantly more resistant for both leaf and stem disease compared with Wirrega and among them were 9 lines which flowered at the same time or earlier than Wirrega. However, even the most resistant line had 30% of the foliage destroyed by disease, indicating disease control was insufficient. A second resistance mechanism which impeded M. pinodes hyphal penetration in leaves (P. sativum SA 1160) was combined with the hypersensitive response in the cross SA 1160 × (JI 252 × JI 1006). The level of resistance to disease was now significantly higher than any plant in the original F3 population, despite the wild-type growth habit of these plants. It is suggested that breeding programs should focus first on maximising field resistance through isolation of some optimal combinations of resistance mechanisms in wild genotypes before turning to improving the agronomic performance through backcrossing to advanced breeding lines.

The epidemiology and control of ascochyta blight in field peas: a review

2006 ◽  
Vol 57 (8) ◽  
pp. 883 ◽  
Author(s):  
T. W. Bretag ◽  
P. J. Keane ◽  
T. V. Price
Keyword(s):  
Current Knowledge ◽  
Ascochyta Blight ◽  
Mycosphaerella Pinodes ◽  
Sources Of Resistance ◽  
New Crops ◽  
Field Peas ◽  
Ascochyta Pisi ◽  
Almost All ◽  
The Cost ◽  
And Control

Ascochyta blight is one of the most important diseases affecting field peas. The disease occurs in almost all pea-growing regions of the world and can cause significant crop losses when conditions are favourable for an epidemic. Here we review current knowledge of the epidemiology of the disease. Details are provided of disease symptoms, the disease cycle and the taxonomy of the causal fungi, Ascochyta pisi, Mycosphaerella pinodes and Phoma pinodella. The importance of seed-, soil- and air-borne inoculum is discussed along with the factors that influence survival of the causal fungi in soil, on seed or associated with pea trash. Many studies have been reviewed to establish how the fungi responsible for the disease survives from year to year, how the disease becomes established in new crops and the conditions that favour disease development. Evidence is provided that crop rotation, destruction of infected pea trash and chemical seed treatments can significantly reduce the amount of primary inoculum. Later sowing of crops has been shown to reduce the incidence and severity of disease. Fungicides have been used successfully to control the disease, although the cost of their application can significantly reduce the profitability of the crop. The best long-term strategy for effective disease control appears to be the development of ascochyta blight resistant pea varieties. Reports of physiological specialisation in ascochyta blight fungi are also documented. Despite extensive screening of germplasm, relatively few sources of resistance to ascochyta blight fungi have been found in Pisum sativum. However, the discovery of much better sources of resistance in closely related species and the development of advanced breeding methods offer new possibilities for developing useful resistance.

scholarly journals Differential Potential of Phytophthora capsici Resistance Mechanisms to the Fungicide Metalaxyl in Peppers

2020 ◽  
Vol 8 (2) ◽  
pp. 278 ◽  
Author(s):  
Weiyan Wang ◽  
Xiao Liu ◽  
Tao Han ◽  
Kunyuan Li ◽  
Yang Qu ◽  
...  
Keyword(s):  
Mutant Strain ◽  
Differentially Expressed Genes ◽  
Phytophthora Capsici ◽  
Resistance Mechanism ◽  
Resistant Mutant ◽  
Resistance Mechanisms ◽  
Differentially Expressed ◽  
Pathogenicity Test ◽  
Wild Type ◽  
Metalaxyl Resistance

Metalaxyl is one of the main fungicides used to control pepper blight caused by Phytophthora capsici. Metalaxyl resistance of P. capsici, caused by the long-term intense use of this fungicide, has become one of the most serious challenges facing pest management. To reveal the potential resistance mechanism of P. capsici to fungicide metalaxyl, a metalaxyl-resistant mutant strain SD1-9 was obtained under laboratory conditions. The pathogenicity test showed that mutant strain SD1-9 had different pathogenicity to different host plants with or without the treatment of metalaxyl compared with that of the wild type SD1. Comparative transcriptome sequencing of mutant strain SD1-9 and wild type SD1 led to the identification of 3845 differentially expressed genes, among them, 517 genes were upregulated, while 3328 genes were down-regulated in SD1-9 compared to that in the SD1. The expression levels of 10 genes were further verified by real-time RT-PCR. KEGG analysis showed that the differentially expressed genes were enriched in the peroxisome, endocytosis, alanine and tyrosine metabolism. The expression of the candidate gene XLOC_020226 during 10 life history stages was further studied, the results showed that expression level reached a maximum at the zoospores stage and basically showed a gradually increasing trend with increasing infection time in pepper leaves in SD1-9 strain, while its expression gradually increased in the SD1 strain throughout the 10 stages, indicated that XLOC_020226 may be related to the growth and pathogenicity of P. capsici. In summary, transcriptome analysis of plant pathogen P. capsici strains with different metalaxyl resistance not only provided database of the genes involved in the metalaxyl resistance of P. capsici, but also allowed us to gain novel insights into the potential resistance mechanism of P. capsici to metalaxyl in peppers.

Resistance mechanism development to the topoisomerase-I inhibitor Hoechst 33342 byLeishmania donovani

Parasitology ◽  
2005 ◽  
Vol 131 (2) ◽  
pp. 197-206 ◽  
Author(s):  
J.-F. MARQUIS ◽  
I. HARDY ◽  
M. OLIVIER
Keyword(s):  
Mammalian Cells ◽  
Topoisomerase I ◽  
Resistance Mechanism ◽  
Resistance Mechanisms ◽  
Drug Accumulation ◽  
Wild Type ◽  
Hoechst 33342 ◽  
In The Wild ◽  
Energy Dependent

The bisbenzimidazole compound Hoechst 33342 (Ho342) has been identified as a specific Topoisomerase-I (Topo-I) inhibitor in mammalian cells. More recently, we have reported the ability of Ho342 to targetL. donovaniTopo-I, leading to parasite growth inhibitionin vitroby mechanisms involving DNA breakage and apoptosis-like phenomenon. As the Ho342 lead molecule (2,5′-Bi-1H-benzimidazole) can be used as a starting structure for derivative compounds more effective againstLeishmania, defining the Ho342 resistance mechanism(s) inLeishmaniarepresents an important strategic tool. In the present study, we selected resistant parasites to Ho342 (LdRHo.300). While we observed an increase of the Topo-I gene expression correlated by a higher Topo-I DNA relaxation activity, the Topo-I genes (LdTOP1AandLdTOP1B) sequencing did not reveal any mutation for the resistant parasites. Moreover, our results on Ho342 cellular accumulation suggested the presence of a potential energy-dependent Ho342 transporter in the wild-type parasite, and that an alteration of this transporter has occurred inLdRHo.300, leading to an altered drug accumulation. Collectively, Ho342 resistance characterization provided results supporting that the resistance developed byLdRHo.300involves complex mechanisms, most likely dominated by an altered drug accumulation, providing new insight in the Ho342 resistance mechanisms.

Section 8. Pyrethroid resistance: field resistance mechanisms

1993 ◽  
Vol 1 ◽  
pp. 54-61 ◽  
Author(s):  
Neil W. Forrester ◽  
Matthew Cahill ◽  
Lisa J. Bird ◽  
Jacquelyn K. Layland
Keyword(s):  
Selection Pressure ◽  
Pyrethroid Resistance ◽  
Life Stage ◽  
Resistance Mechanism ◽  
Resistance Mechanisms ◽  
Field Resistance ◽  
Monooxygenase System ◽  
Phenotypic Resistance ◽  
Nectar Feeding ◽  
Selection Of

SummaryThe dual insecticide ± synergist discriminating dose technique proved highly successful in determining the relative importance of pyrethroid resistance mechanisms present in field populations of Helicoverpa armigera, without the problems of alternative techniques. Synergist pre-treatment proved unnecessary therefore allowing use of the more convenient and labour efficient discriminating dose pre-mix.Oxidative metabolic detoxification, probably via a polysubstrate monooxygenase system, was the major pyrethroid resistance mechanism in both larval and adult H. armigera. Residual piperonyl butoxide insensitive resistance (presumably nerve insensitivity, possibly acting in combination with the penetration resistance factor) was also present but at a low level. This latter resistance mechanism was expressed in larvae but moths appeared to express only weak phenotypic resistance. The predominant pyrethroid resistance mechanism employed by insects is discussed in relation to their feeding habit. The tenet that nectar feeding adult Lepidoptera are unable to express metabolic pyrethroid resistance is challenged.Unrestrained pre-strategy pyrethroid selection pressure on sequential generations resulted in selection for elevated levels of kdr type nerve insensitivity and possibly even super kdr. Restriction of pyrethroid selection pressure to one generation per season favoured selection of the oxidative over the nerve insensitivity resistance mechanism. Two possibly complementary explanations are put forward for this; differential genetic dominance (semidominant oxidative mechanism versus recessive nerve insensitivity) and/or selection in more than one life stage (moths and larvae for the oxidative mechanism versus predominantly larvae only for the nerve insensitivity mechanism). It is suggested that insecticide resistance management strategies should be designed to avoid selection of elevated levels of the intractable nerve insensitivity resistance mechanism whereas low levels of this mechanism (normal kdr) are not considered difficult to manage. The demonstration that the strategy has favoured selection of the more amenable oxidative resistance mechanism invites the opportunity to develop possible chemical countermeasures.

Section 3. Evaluation of the impact of the strategy on pyrethroid resistance: F1 analyses

1993 ◽  
Vol 1 ◽  
pp. 21-27
Author(s):  
Neil W. Forrester ◽  
Matthew Cahill ◽  
Lisa J. Bird ◽  
Jacquelyn K. Layland
Keyword(s):  
Pyrethroid Resistance ◽  
Resistance Mechanism ◽  
Resistance Management ◽  
Resistance Mechanisms ◽  
Field Resistance ◽  
Relative Importance ◽  
Oxidative Resistance ◽  
Tolerance Curve ◽  
The Impact ◽  
Selection Of

SummaryThe classical resistance monitoring technique using full bioassay lines on laboratory reared F1 progeny of field material was compared to the previously described discriminating dose technique on field collected individuals. The Via tolerance curve analysis of the F1 data clearly indicated the predominance of the oxidative metabolic pyrethroid resistance mechanism from the 1984/85 season onwards. There appears to have been an abrupt change in the relative importance of field resistance mechanisms following the introduction of the insecticide resistance management (IRM) strategy in 1983/84. The strategy seems to have favoured the selection of the more amenable oxidative resistance mechanism over the intractable nerve insensitivity mechanism. The Beeman-Nanis analysis was applied to attempt to identify the relative importance of the various field resistance genes. However, it proved of little value in this study as one of the key assumptions underlying the analysis (full genetic dominance) was not satisfied.

scholarly journals The Strength of Synergistic Interaction between Posaconazole and Caspofungin Depends on the Underlying Azole Resistance Mechanism of Aspergillus fumigatus

2015 ◽  
Vol 59 (3) ◽  
pp. 1738-1744 ◽  
Author(s):  
Eleftheria Mavridou ◽  
Joseph Meletiadis ◽  
Antony Rijs ◽  
Johan W. Mouton ◽  
Paul E. Verweij
Keyword(s):  
Aspergillus Fumigatus ◽  
Resistance Mechanism ◽  
Fungal Growth ◽  
Resistance Mechanisms ◽  
Azole Resistance ◽  
Wild Type ◽  
Content Type ◽  
Synergistic Interactions ◽  
Drug Concentrations

ABSTRACTThe majority of azole resistance mechanisms inAspergillus fumigatuscorrespond to mutations in thecyp51Agene. As azoles are less effective against infections caused by multiply azole-resistantA. fumigatusisolates, new therapeutic options are warranted for treating these infections. We therefore investigated thein vitrocombination of posaconazole (POSA) and caspofungin (CAS) against 20 wild-type and resistantA. fumigatusisolates with 10 different resistance mechanisms. Fungal growth was assessed with the XTT [2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt] method. Pharmacodynamic interactions were assessed with the fractional inhibitory concentration (FIC) index (FICi) on the basis of 10% (FICi-0), 25% (FICi-1), or 53 0% (FICi-2) growth, and FICs were correlated with POSA and CAS concentrations. Synergy and antagonism were concluded when the FICi values were statistically significantly (ttest,P< 0.05) lower than 1 and higher than 1.25, respectively. Significant synergy was found for all isolates with mean FICi-0 values ranging from 0.28 to 0.75 (median, 0.46). Stronger synergistic interactions were found with FICi-1 (median, 0.18; range, 0.07 to 0.47) and FICi-2 (0.31; 0.07 to 0.6). The FICi-2 values of isolates with tandem-repeat-containing mutations or codon M220 were lower than those seen with the other isolates (P< 0.01). FIC-2 values were inversely correlated with POSA MICs (rs= −0.52,P= 0.0006) and linearly with the ratio of drug concentrations in combination over the MIC of POSA (rs= 0.76,P< 0.0001) and CAS (rs= 0.52,P= 0.0004). The synergistic effect of the combination of POSA and CAS (POSA/CAS) againstA. fumigatusisolates depended on the underlying azole resistance mechanism. Moreover, the drug combination synergy was found to be increased against isolates with elevated POSA MICs compared to wild-type isolates.

The resistance of cereals to yellow rust and its exploitation by plant breeding

1972 ◽  
Vol 181 (1064) ◽  
pp. 281-301 ◽  
Keyword(s):  
Yellow Rust ◽  
Major Gene ◽  
Resistance Mechanisms ◽  
Field Resistance ◽  
Sources Of Resistance ◽  
Wheat Varieties ◽  
New Approach ◽  
Stable Forms ◽  
Temperate Cereal ◽  
Fungus Disease

Yellow rust is a fungus disease of considerable importance in cereal production in Britain and in other temperate cereal-growing areas. Breeding for resistance in wheat started in 1905, but in 1971 the three potentially most productive wheat varieties in Britain were susceptible to the disease. Wheat varieties are being bred using both ‘major gene' and ‘field-resistance' mechanisms. Evidence at present suggests that these methods used singly will be inadequate to introduce stable forms of resistance into the crops; a combination of both types offers more promise but presents practical difficulties. Resistance is predominantly transmitted as a dominant character. A new approach to wheat and barley breeding - the use of F 1 -hybrid varieties - offers a more flexible method of exploiting the inter-varietal and inter-specific sources of resistance.

RESISTANCE TO MILDEW OF SELECTION FAMILY OF RED CURRANT THE BELAYA POTAPENKO × № 1426-21-80

1970 ◽  
pp. 38-40
Author(s):  
O. O. Kalinina ◽  
O. D. Golyaeva ◽  
O. V. Panfilova ◽  
А. V. Pikunova
Keyword(s):  
Powdery Mildew ◽  
Field Resistance ◽  
Disease Development ◽  
Artificial Infection ◽  
Sources Of Resistance ◽  
Climate Conditions ◽  
High Productivity ◽  
Local Soil ◽  
The Family ◽  
Red Currant

Powdery mildew is one of the most harmful fungal diseases that causes economically significant damage to berry plantations. The disease is common in all areas of currant cultivation in the Russian Federation. In this regard, in modern conditions of intensive berry growing, the problem of breeding cultivars that are highly resistant to diseases and pests becomes urgent. Breeders have a difficult task to combine the adaptive potential of the cultivar with its annual high productivity and resistance to biotic environmental factors. When studying the adaptability of introduced cultivars of red currant and selected forms of the Institute to local soil and climate conditions, the following cultivars were identified as sources of economic and useful characteristics and involved in selection: ‘Belaya Potapenko’ as a complex source of resistance powdery mildew and high marketable and taste qualities of berries; SS 1426-21-80 as a source of high productivity and long racemes (raceme length 11-13 cm; up to 20 berries in the raceme). On their base the selection family of red currant has been developed: Belaya Potapenko × ♂SS 1426-21-80. The study of data on the destruction of hybrid seedlings of the selection family by powdery mildew showed that in epiphytotic conditions, the percentage of intensity of the disease development varies over the periods of screening from 0.2% in May to 20.4% in June. Such indicators served as a prerequisite for conducting a comparative test of breeding material in the field under artificial infection with powdery mildew. After artificial infection on the background of epiphytosis, the rate of intensity of the disease development increased slightly and amounted to 35.6% for the family. There were 30 highly resistant seedlings in the family, 10 of which have remained stable and highly resistant since 2018. In these plants we can assume the presence of the so-called field resistance, controlled by polygens, each of which does not give a visible effect of stability, but with different combinations determines one or another of its degree. Highly resistant seedlings will be used in further breeding studies to identify new sources of resistance to powdery mildew.

scholarly journals Characterization of resistance mechanisms of Enterobacter cloacae Complex co-resistant to carbapenem and colistin

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Shixing Liu ◽  
Renchi Fang ◽  
Ying Zhang ◽  
Lijiang Chen ◽  
Na Huang ◽  
...  
Keyword(s):  
Lipid A ◽  
Efflux Pump ◽  
Resistance Mechanism ◽  
Carbapenem Resistance ◽  
Enterobacter Cloacae ◽  
Resistance Mechanisms ◽  
Colistin Resistance ◽  
Carbapenem Resistant ◽  
Horizontal Spread

Abstract Background The emergence of carbapenem-resistant and colistin-resistant ECC pose a huge challenge to infection control. The purpose of this study was to clarify the mechanism of the carbapenems and colistin co-resistance in Enterobacter cloacae Complex (ECC) strains. Results This study showed that the mechanisms of carbapenem resistance in this study are: 1. Generating carbapenemase (7 of 19); 2. The production of AmpC or ESBLs combined with decreased expression of out membrane protein (12 of 19). hsp60 sequence analysis suggested 10 of 19 the strains belong to colistin hetero-resistant clusters and the mechanism of colistin resistance is increasing expression of acrA in the efflux pump AcrAB-TolC alone (18 of 19) or accompanied by a decrease of affinity between colistin and outer membrane caused by the modification of lipid A (14 of 19). Moreover, an ECC strain co-harboring plasmid-mediated mcr-4.3 and blaNDM-1 has been found. Conclusions This study suggested that there is no overlap between the resistance mechanism of co-resistant ECC strains to carbapenem and colistin. However, the emergence of strain co-harboring plasmid-mediated resistance genes indicated that ECC is a potential carrier for the horizontal spread of carbapenems and colistin resistance.

The Effect of Mismatch Repair and Heteroduplex Formation on Sexual Isolation in Bacillus

Genetics ◽  
1998 ◽  
Vol 148 (1) ◽  
pp. 13-18 ◽  
Author(s):  
Jacek Majewski ◽  
Frederick M Cohan
Keyword(s):  
Mismatch Repair ◽  
Wild Type Strain ◽  
Resistance Mechanism ◽  
Sequence Divergence ◽  
Sexual Isolation ◽  
Wild Type ◽  
Exponential Relationship ◽  
Dna Strands ◽  
The Relationship ◽  
Heteroduplex Formation

AbstractIn Bacillus transformation, sexual isolation is known to be an exponential function of the sequence divergence between donor and recipient. Here, we have investigated the mechanism under which sequence divergence results in sexual isolation. We tested the effect of mismatch repair by comparing a wild-type strain and an isogenic mismatch-repair mutant for the relationship between sexual isolation and sequence divergence. Mismatch repair was shown to contribute to sexual isolation but was responsible for only a small fraction of the sexual isolation observed. Another possible mechanism of sexual isolation is that more divergent recipient and donor DNA strands have greater difficulty forming a heteroduplex because a region of perfect identity between donor and recipient is required for initiation of the heteroduplex. A mathematical model showed that this heteroduplex-resistance mechanism yields an exponential relationship between sexual isolation and sequence divergence. Moreover, this model yields an estimate of the size of the region of perfect identity that is comparable to independent estimates for Escherichia coli. For these reasons, and because all other mechanisms of sexual isolation may be ruled out, we conclude that resistance to heteroduplex formation is predominantly responsible for the exponential relationship between sexual isolation and sequence divergence in Bacillus transformation.

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