The use of sexual progeny of Bremia Lactucae Regel to improve the efficiency of selection for race-specific resistance genes to this fungus in lettuce

Euphytica ◽  
1983 ◽  
Vol 32 (2) ◽  
pp. 475-478 ◽  
Author(s):  
I. R. Crute ◽  
Judith M. Norwood
Keyword(s):  
Resistance Genes ◽  
Specific Resistance ◽  
Bremia Lactucae ◽  
Selection For ◽  
Sexual Progeny ◽  
Efficiency Of Selection

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 Efficiency of Selection for Broiler Growth at Various Ages

1953 ◽  
Vol 32 (4) ◽  
pp. 716-720 ◽  
Author(s):  
G.A. Martin ◽  
E.W. Glazener ◽  
W.L. Blow
Keyword(s):  
Selection For ◽  
Efficiency Of Selection

scholarly journals The determination of the resistance inheritance against common bunt in wheat and half-diallel hybrids

2019 ◽  
Vol 55 (No. 4) ◽  
pp. 254-260
Author(s):  
Gülçin Akgören Palabiyik ◽  
İsmail Poyraz ◽  
Ahmet Umay
Keyword(s):  
Disease Resistance ◽  
Bread Wheat ◽  
Resistance Genes ◽  
Common Bunt ◽  
Wheat Varieties ◽  
Complete Dominance ◽  
Selection For ◽  
Half Diallel ◽  
Dominant Genes

This study was conducted to determine the inheritance of common bunt resistance in twelve bread wheat varieties and their half-diallel hybrids in Turkey. The disease ratings were performed on the F2 generations of the hybrids in field conditions. The obtained data were analysed by the χ2 test to determine the effective gene numbers and inheritance type in the disease resistance. In addition, the data were evaluated according to the Jinks-Hayman diallel analyses. In conclusion, it was found that of the twelve wheat parents, four contained three resistance genes and four of them contain two resistance genes. The dominant genes were prominent in the population and complete dominance was present. Therefore, the selection for disease resistance should be delayed until the following generations.

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.

RECURRENT SELECTION FOR FORAGE AND SEED YIELD IN ZIGZAG CLOVER

1984 ◽  
Vol 64 (1) ◽  
pp. 119-130 ◽  
Author(s):  
NORMAN L. TAYLOR ◽  
PAUL L. CORNELIUS ◽  
ROY E. SIGAFUS
Keyword(s):  
Recurrent Selection ◽  
Selection Process ◽  
Linear Increase ◽  
Rate Of Change ◽  
Forage Yield ◽  
Annual Basis ◽  
Phenotypic Recurrent Selection ◽  
Winter Temperatures ◽  
Selection For ◽  
Efficiency Of Selection

Phenotypic recurrent selection on an annual basis was conducted with zigzag clover (Trifolium medium L.) to determine the efficiency of selection for improved seed and forage yield and the relationships among these characters. Seedlings were exposed to winter temperatures in a cold frame before they were transplanted in a field in the spring. The undesirable types were mowed prior to flowering and the selected plants were allowed to cross. Heads and seeds were harvested from each plant, and after seed threshing and counting, plants were further selected on the basis of numbers of seeds and heads. The effectiveness of four cycles of selection was evaluated over a 2-yr period in an experiment initiated with remnant seed and with management similar to that imposed during the selection process. Recurrent selection was effective in increasing vigor, seeds per head, heads per plant, and seeds per plant. A significant linear increase over cycles was found for each character. Vigor was not correlated with seeds per head, but was correlated with the other characters. The more vigorous plants also exhibited less stand reduction. Data from the two evaluation years were correlated suggesting that materials selected on an annual basis performed similarly to those grown in a 2-yr stand. Although recurrent selection was effective for improving all traits, the rate of change, particularly for seeds per head, was limited. Many more cycles of such selection would be required to change zigzag clover into a useful forage species. It was suggested that the phenotypic recurrent selection program should be continued on an annual basis, but modified if possible to select against the vernalization requirement for flowering which may be associated with poor seedling growth and low aftermath vigor.Key words: Trifolium medium, recurrent selection, vigor, persistance, heads and seeds per plant

Identification and selection for salt tolerance in lucerne (Medicago sativa L.)

1984 ◽  
Vol 35 (2) ◽  
pp. 239 ◽  
Author(s):  
CL Noble ◽  
GM Halloran ◽  
DW West
Keyword(s):  
Salt Tolerance ◽  
Medicago Sativa ◽  
Recurrent Selection ◽  
Leaf Damage ◽  
Shoot Number ◽  
Two Generations ◽  
Medicago Sativa L ◽  
Selection For ◽  
Efficiency Of Selection ◽  
Chloride Concentrations

Variation existed between plants of the lucerne (Medicago sativa L.) cultivar CUF 101 for dry matter production, shoot number and length, and leaf damage when grown for 70 days under 250 mM NaCl (15 h photoperiod, 20�C day, 10�C night). Salt tolerance evaluation using the criteria percentage leaf damage (percentage of total number of leaves with complete or partial necrosis) and length of the main shoot, isolated plants which showed salt tolerance of reasonably high heritability (h2=0.41). Two generations of recurrent selection for tolerance significantly increased the mean population tolerance without decreasing production under non-saline conditions. While both sodium and chloride concentrations of the shoot were lower in the tolerant than in less tolerant plants, chloride was more closely associated with salt tolerance than sodium. Sodium and chloride concentrations in the roots did not vary with the level of salt tolerance. No association of shoot and root potassium concentration with tolerance was evident. Selection for salt tolerance in lucerne plants using percentage leaf damage of less than 10% as the main criterion should give a rapid response to selection. The efficiency of selection may be increased if selection is based on the efficiency of chloride exclusion from the shoots and/or the level of chloride tolerated by the shoots prior to leaf damage becoming evident.

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