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Influence of Temperature on Expression of Resistance to Rust in Diploid Alfalfa
Author(s) -
Skinner D. Z.,
Stuteville D. L.
Publication year - 1989
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1989.0011183x002900030027x
Subject(s) - biology , diallel cross , rust (programming language) , ploidy , medicago sativa , horticulture , wheat leaf rust , botany , cultivar , agronomy , virulence , genetics , gene , hybrid , computer science , programming language
Some alfalfa ( Medicago sativa L.) plants resistant to the rust fungus ( Uromyces striatus Schroet.) in the field have proven susceptible under laboratory conditions. These differences have been attributed to environmental conditions suboptimal for rust development in the field. Our objectives were to study the effects of temperature on resistance to rust in diploid alfalfa. We used a six‐parent diallel cross to measure the inheritance of factors that influence latent period at 20, 25, and 30 °C. Infection‐type data and latent period data were highly correlated ( r = 0.97, P < 0.0001). Pustules developed on 37% of all S 1 and F 1 plants (combined) at 20 °C, on 50% at 25 °C, and on 30% at 30 °C. However, when plants in tests completed at 20 or 30 °C were moved to 25 °C, pustules developed on additional plants until the percentages of plants with pustules were not significantly different ( P > 0.05) from those of plants held continuously at 25 °C. The degree of dominance was 0.59, 0.32, and 0.98 at 20, 25, and 30 °C, respectively; thus, resistance appeared most dominant at temperatures suboptimal for disease development. These results indicated that temperature altered the genetic behavior of factors involved in alfalfa resistance to rust, and that the optimum temperature for rust development with the materials we used was about 25 °C.