Changing allele frequencies associated with specific resistance genes to leaf blast in backcross introgression lines of Khao Dawk Mali 105 developed from a conventional selection program

2011 ◽  
Vol 122 (1) ◽  
pp. 32-39 ◽  
Author(s):  
S. Korinsak ◽  
P. Sirithunya ◽  
P. Meakwatanakarn ◽  
S. Sarkarung ◽  
A. Vanavichit ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Specific Resistance ◽  
Introgression Lines ◽  
Allele Frequencies ◽  
Leaf Blast ◽  
Selection Program

scholarly journals Induced Rice Resistance to Blast Varies as a Function of Magnaporthe grisea Avirulence Genes

Plant Disease ◽  
2008 ◽  
Vol 92 (8) ◽  
pp. 1144-1149 ◽  
Author(s):  
N. Yasuda ◽  
M. T. Noguchi ◽  
Y. Fujita
Keyword(s):  
Genetic Analysis ◽  
Resistance Genes ◽  
Magnaporthe Grisea ◽  
Specific Resistance ◽  
Blast Disease ◽  
Avirulence Gene ◽  
Avirulence Genes ◽  
Leaf Blast ◽  
Incompatibility Reactions ◽  
Avirulent Isolate

Incompatibility reactions between rice and the blast fungus Magnaporthe grisea produce various degrees of lesions, from large brown flecks to small, nearly invisible lesions. We previously identified four avirulence genes (AvrPia, AvrPii, AvrPit, and Avr-Hattan3) in M. grisea isolates by genetic analysis of progeny from crosses between isolates with differing pathogenicity. Using progeny known to contain a specific avirulence gene, we demonstrated that the type of resistance lesion produced in rice by an avirulent isolate and the degree of leaf blast suppression by preinoculation with that isolate were determined by the combination of avirulence and resistance genes in the isolate and the cultivar. The degree of leaf blast suppression by preinoculation with an avirulent isolate increased with larger resistance lesions. When two genes were involved in an isolate's avirulence, lesions appeared that resembled those expected for the gene that produced the smaller lesion. The degree of leaf blast suppression by the isolate with two avirulence genes was comparable with that induced by the isolate with the avirulence gene that produced the smaller effect. The ability of specific resistance gene combinations that effectively suppress blast disease is discussed for each avirulence gene.

Changes in allele frequencies of avirulence genes in the blackleg fungus, Leptosphaeria maculans, over two decades in Australia

2018 ◽  
Vol 69 (1) ◽  
pp. 20 ◽  
Author(s):  
Angela P. Van de Wouw ◽  
Barbara J. Howlett ◽  
Alexander Idnurm
Keyword(s):  
Resistance Genes ◽  
Specific Resistance ◽  
Leptosphaeria Maculans ◽  
Allele Frequencies ◽  
Avirulence Genes ◽  
Time Analysis ◽  
Pathogen Population ◽  
Growing Seasons ◽  
The World ◽  
Blackleg Fungus

Cultivation of canola (oilseed rape, rapeseed; Brassica napus) in many parts of the world relies on the use of cultivars carrying resistance genes that recognise avirulence products of the major canola pathogen, Leptosphaeria maculans. However, widespread cultivation of plants with such resistance provides the potential for evolution of the pathogen population to overcome resistance by altering the proportion of avirulence v. virulence alleles. In this study, the frequencies of avirulence genes were measured for 2091 Australian isolates dating from the late 1980s to present. Frequencies of avirulence genes changed over time. Analysis of isolates from the Eyre Peninsula, where canola is intensively cultivated, indicated that changes in allele frequencies at the AvrLm1, AvrLm4 and AvrLm6 loci could be correlated with the widespread planting of cultivars carrying specific resistance genes. These data show that determining avirulence allele frequencies in L. maculans populations provides power to anticipate which cultivars will be most successful in future growing seasons.

scholarly journals Identification of Race-Specific Resistance in North American Vitis spp. Limiting Erysiphe necator Hyphal Growth

2012 ◽  
Vol 102 (1) ◽  
pp. 83-93 ◽  
Author(s):  
David W. Ramming ◽  
Franka Gabler ◽  
Joseph L. Smilanick ◽  
Dennis A. Margosan ◽  
Molly Cadle-Davidson ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Resistance Genes ◽  
Specific Resistance ◽  
Hyphal Growth ◽  
Resistance Mechanisms ◽  
Hybrid Breeding ◽  
Erysiphe Necator ◽  
Vitis Rotundifolia ◽  
Resistance Sources

Race-specific resistance against powdery mildews is well documented in small grains but, in other crops such as grapevine, controlled analysis of host–pathogen interactions on resistant plants is uncommon. In the current study, we attempted to confirm powdery mildew resistance phenotypes through vineyard, greenhouse, and in vitro inoculations for test cross-mapping populations for two resistance sources: (i) a complex hybrid breeding line, ‘Bloodworth 81-107-11', of at least Vitis rotundifolia, V. vinifera, V. berlandieri, V. rupestris, V. labrusca, and V. aestivalis background; and (ii) Vitis hybrid ‘Tamiami’ of V. aestivalis and V. vinifera origin. Statistical analysis of vineyard resistance data suggested the segregation of two and three race-specific resistance genes from the two sources, respectively. However, in each population, some resistant progeny were susceptible in greenhouse or in vitro screens, which suggested the presence of Erysiphe necator isolates virulent on progeny segregating for one or more resistance genes. Controlled inoculation of resistant and susceptible progeny with a diverse set of E. necator isolates clearly demonstrated the presence of fungal races differentially interacting with race-specific resistance genes, providing proof of race specificity in the grape powdery mildew pathosystem. Consistent with known race-specific resistance mechanisms, both resistance sources were characterized by programmed cell death of host epidermal cells under appressoria, which arrested or slowed hyphal growth; this response was also accompanied by collapse of conidia, germ tubes, appressoria, and secondary hyphae. The observation of prevalent isolates virulent on progeny with multiple race-specific resistance genes before resistance gene deployment has implications for grape breeding strategies. We suggest that grape breeders should characterize the mechanisms of resistance and pyramid multiple resistance genes with different mechanisms for improved durability.

scholarly journals Development of barley introgression lines carrying the leaf rust resistance genes Rph1 to Rph15

Crop Science ◽  
2020 ◽  
Vol 60 (1) ◽  
pp. 282-302 ◽  
Author(s):  
Matthew J. Martin ◽  
Oswaldo Chicaiza ◽  
Juan C. Caffarel ◽  
Ahmad H. Sallam ◽  
Arnis Druka ◽  
...  
Keyword(s):  
Leaf Rust ◽  
Resistance Genes ◽  
Rust Resistance ◽  
Leaf Rust Resistance ◽  
Introgression Lines ◽  
Rust Resistance Genes ◽  
Leaf Rust Resistance Genes

scholarly journals Specific Resistance of Barley to Powdery Mildew, Its Use and Beyond: A Concise Critical Review

Genes ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 971 ◽  
Author(s):  
Antonín Dreiseitl
Keyword(s):  
Powdery Mildew ◽  
Resistance Genes ◽  
Plant Pathogens ◽  
Specific Resistance ◽  
Wide Spectrum ◽  
Quantitative Resistance ◽  
Spring Barley ◽  
Durable Resistance ◽  
Genetic Resistance ◽  
Barley Cultivars

Powdery mildew caused by the airborne ascomycete fungus Blumeria graminis f. sp. hordei (Bgh) is one of most common diseases of barley (Hordeum vulgare). This, as with many other plant pathogens, can be efficiently controlled by inexpensive and environmentally-friendly genetic resistance. General requirements for resistance to the pathogens are effectiveness and durability. Resistance of barley to Bgh has been studied intensively, and this review describes recent research and summarizes the specific resistance genes found in barley varieties since the last conspectus. Bgh is extraordinarily adaptable, and some commonly recommended strategies for using genetic resistance, including pyramiding of specific genes, may not be effective because they can only contribute to a limited extent to obtain sufficient resistance durability of widely-grown cultivars. In spring barley, breeding the nonspecific mlo gene is a valuable source of durable resistance. Pyramiding of nonspecific quantitative resistance genes or using introgressions derived from bulbous barley (Hordeum bulbosum) are promising ways for breeding future winter barley cultivars. The utilization of a wide spectrum of nonhost resistances can also be adopted once practical methods have been developed.

scholarly journals A Computer Program to Improve the Efficiency and Accuracy of Postulating Race-Specific Resistance Genes

Plant Disease ◽  
2004 ◽  
Vol 88 (5) ◽  
pp. 545-549 ◽  
Author(s):  
Yeshi A. Wamishe ◽  
Kevin C. Thompson ◽  
Eugene A. Milus
Keyword(s):  
Computer Program ◽  
Resistance Genes ◽  
Specific Resistance ◽  
Infection Type ◽  
Puccinia Triticina ◽  
Lr Genes ◽  
Soft Red Winter Wheat ◽  
Gene Concept ◽  
Infection Types ◽  
Gene For Gene

Gene postulation has been the most widely used technique to determine the presence of particular rust resistance genes in lines of small grains. It applies the principles of gene-for-gene specificity to determine the most probable race-specific resistance genes present in host lines. As the numbers of lines, resistance genes, and races increase, postulation based on visual comparisons of infection types becomes more complex and laborious, and errors may occur. A computer program was developed to facilitate identification of race-specific leaf rust (Lr) genes in wheat (Triticum aestivum). Seedlings of 116 contemporary lines of soft red winter wheat and 24 Thatcher isolines (each Thatcher isoline with a single Lr gene) were inoculated with 22 races of Puccinia triticina. Infection types were recorded on the standard 0 to 4 scale where infection types 3 and 4 were considered high (line was susceptible; race was virulent) and others were low (line was resistant; race was avirulent). Based on the gene-for-gene concept, lines susceptible to a particular race cannot have an Lr gene for which the race is avirulent. For each line, step 1 of the program summarized results from races that were virulent on the line to definitively exclude Lr genes from the line, and this exclusion resulted in a relatively short list of Lr genes that could be present. Step 2 of the program utilized data from races that were avirulent on the line, and the output listed the low infection types produced on the line and the isolines with Lr genes that were not excluded in step 1. Of these Lr genes, a gene was considered present if the low infection type produced on the line by one or more races matched the low infection type on the corresponding isoline. Otherwise, the gene was considered possibly present. Epistatic effects of one or more Lr genes prevented definitive inclusion or exclusion of genes considered possibly present. If the low infection type produced on the line was lower than that on any of the isolines listed in step 2, then the line was considered to have an unidentified Lr gene; i.e., a gene that was not in the set of 24 isolines. This program facilitated the objective and accurate postulation of Lr genes and could be adapted to other host-pathogen systems.

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