New Zealand Journal of Crop and Horticultural Science abstracts
Inheritance of seedling resistance to stripe rust (Puccinia striiformis
f. sp. tritici) in ‘Otane’ and ‘Tiritea’ wheat (Triticum aestivum)
Muhammad Imtiaz
Soil, Plant and Ecological Sciences Division
P.O. Box 84, Lincoln University
Christchurch, New Zealand
M. G. Cromey*
New Zealand Institute for Crop & Food
Research Limited
Private Bag 4704
Christchurch, New Zealand
email: cromeym@crop.cri.nz
*Corresponding author.
J. G. Hampton
M. J. Hill
New Zealand Seed Technology Institute
P.O. Box 84, Lincoln University
Christchurch, New Zealand
Abstract Two spring wheat (Triticum aestivum)
cultivars, ‘Tiritea’ and ‘Otane’, were crossed and the reactions of the F1-derived
double haploid (DH) population to the stripe rust pathogen (Puccinia striiformis
f. sp. tritici) at the seedling stage were examined in glasshouse and field
experiments. Both parental cultivars were susceptible to stripe rust pathotype
106E139A+, but transgressive segregation in the DH progenies indicated
that both parents possess resistance genes. The distribution of DH lines
fitted a trigenic ratio with epistatic gene action. In a proposed model,
resistant DH lines were produced when all three loci involved were homozygous
recessive, moderately resistant DH lines were produced when the t
gene was homozygous recessive with at least one recessive allele at either
the B or the C locus, and susceptible DH lines were produced when either
t, b, or c were present alone or had a dominant gene
at the B and the C loci. The susceptible phenotype of all F1 progenies
indicated that the resistance factors segregated were all recessive. The
susceptible reaction of both cultivars could be attributed to the presence
of genes that may suppress the expression of resistance genes when they coexist
in the parents. The use of these cultivars as parents in different wheat
breeding strategies is briefly discussed.
Keywords Triticum aestivum; Puccinia striiformis;
disease resistance; resistance suppression; transgressive segregation; genetic
models
H02057 Received 14 August 2002; accepted 20 December 2002; published 26
March 2003
New Zealand Journal of Crop and Horticultural Science, 2003, Vol. 31:
15-22
0014-0671/03/3101-0015 $7.00 © The Royal Society of New Zealand
2003
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