Euphytica

, Volume 136, Issue 1, pp 37–44

Employment of flanking codominant STS markers to estimate allelic substitution effects of a nematode resistance locus in carrot

  • L.S. Boiteux
  • J.R. Hyman
  • I.C. Bach
  • M.E.N. Fonseca
  • W.C. Matthews
  • P.A. Roberts
  • P.W. Simon
Article

DOI: 10.1023/B:EUPH.0000019508.78153.dd

Cite this article as:
Boiteux, L., Hyman, J., Bach, I. et al. Euphytica (2004) 136: 37. doi:10.1023/B:EUPH.0000019508.78153.dd
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Abstract

In carrot, two codominant sequence-tagged site (STS) markers, flanking in tight linkage the Meloidogyne javanica resistance (Mj-1) locus, were employed to investigate the association between expression of resistance and locus dosage. Phenotypic expression of homozygous resistant (R); heterozygous; and homozygous susceptible (S) individuals in an F2 population of 396 F2 plants from ‘Brasília-1252’ (R) × ‘B6274’ (S) was estimated for three resistance criteria: total egg production per plant (TEP), egg production per gram of fibrous root (EPG) and root gall index (RGI). The homozygous resistant class had average values of 403.9 for TEP; 147.5 for EPG and 0.8 for RGI. The heterozygous class had 1,673; 477.3; and 0.16 whereas the homozygous susceptible class had 68,604; 11,877; and 2.54, respectively. The dominance ratio (d/a) indicated that genomic region(s) derived from the resistant parent encompass genetic factor(s) with almost complete dominance for RGI (d/a = 0.93–0.94) and incomplete dominance for transformed (TEP)0.25 and (EPG)0.25 (d/a = 0.63–0.65). Broad sense heritabilities were high varying from 72.9% for (EPG)0.25 to 86.0% for RGI. Narrow sense heritability values ranged from 55.9% for RGI to 64.3%for (TEP)0.25. Highly significant orthogonal contrasts were observed between homozygous resistant vs. heterozygous for (TEP)0.25 and (EPG)0.25. Marker-assisted selection could greatly facilitate the incorporation of the Mj-1 allele in both male-fertile and male-sterile counterpart lines in order to obtain F1 hybrids with the most effective levels of resistance.

Daucus carotamarkersMeloidogyne javanicaresistanceroot-knot nematode

Copyright information

© Kluwer Academic Publishers 2004

Authors and Affiliations

  • L.S. Boiteux
    • 1
    • 2
  • J.R. Hyman
    • 3
  • I.C. Bach
    • 4
  • M.E.N. Fonseca
    • 1
    • 2
  • W.C. Matthews
    • 5
  • P.A. Roberts
    • 5
  • P.W. Simon
    • 3
  1. 1.Plant Breeding & Plant Genetics ProgramUniversity of WisconsinMadisonUSA
  2. 2.CNPH (Centro Nacional de Pesquisa de Hortaliças)/ EMBRAPA HortaliçasBrasília-DFBrazil
  3. 3.USDA/ARS, Vegetable Crops Research Unit, Department of HorticultureUniversity of WisconsinMadisonUSA
  4. 4.Department of Agricultural Sciences, Plant Breeding and Crop SciencesThe Royal Veterinary and Agricultural UniversityFrederiksberg C, CopenhagenDenmark
  5. 5.Department of NematologyUniversity of CaliforniaRiversideUSA