, Volume 182, Issue 2, pp 157–166 | Cite as

Mapping a dominant negative mutation for triforine sensitivity in lettuce and its use as a selectable marker for detecting hybrids

  • Ivan SimkoEmail author
  • Ryan J. Hayes
  • María José Truco
  • Richard W. Michelmore


Some lettuce cultivars are highly sensitive to triforine, an inhibitor of sterol biosynthesis found in some commercial systemic fungicides. First symptoms of a sensitive reaction are usually observed within 24–48 h after treatment and include severe wilting, necrosis and rapid plant death. We mapped a single dominant gene (Tr) that confers sensitivity of lettuce to triforine to linkage group 1 of the integrated genetic map of lettuce. The occurrence of sensitivity is not uniform across horticultural types of lettuce. While over 80% of green-romaine lettuce cultivars tested were sensitive, most cultivars of all other lettuce types were insensitive to triforine. All accessions of wild Lactuca spp. were insensitive to triforine. Allelism tests using F1 and F2 progeny revealed that sensitive cultivars of all horticultural types likely carry the same Tr gene. The dominant allele for sensitivity found in cultivated lettuce probably had a monophyletic origin. The reaction to triforine can be used as a marker for detecting hybrids originating from a cross between phenotypically similar parents with different responses to triforine treatment. It also provides an indication of genotypes for which applications of triforine-containing fungicides are inappropriate.


Dominant mutation Lettuce Selectable marker Sterol biosynthesis inhibitor Triforine 





Recombinant-inbred lines

Tr gene

A dominant gene that confers sensitivity to triforine in lettuce



The authors thank Amy Atallah, Mario Estrada, and Amy Folck for technical assistance and Zahi Atallah for valuable discussion. Sharon Benzen and Todd Bunnell provided fungicides for trials and Nina Simkova made corrections to the manuscript. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.


  1. Fungicide Resistance Action Committee (2010) FRAC code list: fungicides sorted by mode of action (including FRAC code numbering), p 10.
  2. Globerson D, Eliasi R (1979) The response to saprol (systemic fungicide) in lettuce species and cultivars and its inheritance. Euphytica 28:115–118CrossRefGoogle Scholar
  3. Karaoglanidis GS, Thanassoulopoulos CC (2003) Cross-resistance patterns among sterol biosynthesis inhibiting fungicides (SBIs) in Cercospora beticola. Eur J Plant Pathol 109:929–934CrossRefGoogle Scholar
  4. Maxon Smith JW (1979) Triforine sensitivity in lettuce: a potentially useful genetic marker. Euphytica 28:351–359CrossRefGoogle Scholar
  5. Mayer DF, Lunden JD (1986) Toxicity of fungicides and an acaricide to honey bees (Hymenoptera: Apidae) and their effects on bee foraging behavior and pollen viability on blooming apples and pears. Environ Entomol 15:1047–1049Google Scholar
  6. Rouchaud JP, Decallonne JR, Meyer JA (1977) Metabolism of the fungicide triforine in barley plants. Pestic Sci 8:65–70CrossRefGoogle Scholar
  7. Ryder EJ, Johnson AS (1974) Mist depollination of lettuce flowers. HortScience 9:584Google Scholar
  8. Sherald JL, Sisler HD (1975) Antifungal mode of action of triforine. Pestic Biochem Phys 5:477–488CrossRefGoogle Scholar
  9. Sherald JL, Ragsdale NN, Sisler HD (1973) Similarities between the systemic fungicides triforine and triarimol. Pestic Sci 4:719–727CrossRefGoogle Scholar
  10. Simko I (2009) Development of EST-SSR markers for the study of population structure in lettuce (Lactuca sativa). J Hered 100:256–262PubMedCrossRefGoogle Scholar
  11. Simko I, Hu J (2008) Population structure in cultivated lettuce and its impact on association mapping. J Am Soc Hort Sci 133:61–68Google Scholar
  12. Simko I, Pechenick DA, McHale LK, Truco MJ, Ochoa OE, Michelmore RW, Scheffler BE (2009) Association mapping and marker-assisted selection of the lettuce dieback resistance gene Tvr1. BMC Plant Biol 9:135PubMedCrossRefGoogle Scholar
  13. Stam P (1993) Construction of integrated genetic-linkage maps by means of a new computer package: JoinMap. Plant J 3:739–744CrossRefGoogle Scholar
  14. Truco MJ, Antonise R, Lavelle D, Ochoa O, Kozik A, Witsenboer H, Fort SB, Jeuken MJW, Kesseli RV, Lindhout P, Michelmore RW, Peleman J (2007) A high-density integrated genetic linkage map of lettuce (Lactuca spp.). Theor Appl Genet 115:735–746PubMedCrossRefGoogle Scholar
  15. United States Environmental Protection Agency (2008) Registration eligibility decision for triforine. Case no. 2720, p 40.

Copyright information

© Springer Science+Business Media B.V. (outside the USA) 2011

Authors and Affiliations

  • Ivan Simko
    • 1
    Email author
  • Ryan J. Hayes
    • 1
  • María José Truco
    • 2
  • Richard W. Michelmore
    • 2
  1. 1.Crop Improvement and Protection Research UnitUSDA-ARSSalinasUSA
  2. 2.The Genome Center and Department of Plant SciencesUniversity of CaliforniaDavisUSA

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