Identification of genetic loci associated with ear-emergence in bread wheat
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A doubled haploid population constructed from a cross between the South Australian wheat cultivars ‘Trident’ and ‘Molineux’ was grown under winter field conditions, under field conditions over summer and under artificial light both with and without vernalisation. The duration from planting to ear-emergence was recorded and QTL associated with heading date were detected using a previously constructed genetic linkage map. Associations were shown with chromosomal regions syntenous to previously identified photoperiod (Ppd-B1) and vernalisation (Vrn-A1) sensitive loci. Additional QTL associated with time to heading were also identified on chromosomes 1A, 2A, 2B, 6D, 7A and 7B. Comparisons between the genetic associations observed under the different growing conditions allowed the majority of these loci to be classified as having either photoperiod-sensitive, vernalisation-sensitive or earliness per se actions. The identification of a photoperiod-sensitive QTL on chromosome 1A provides evidence for a wheat gene possibly homoeologous to Ppd-H2 previously identified on chromosome 1H of barley. The occurrence of a putative major gene for photoperiod sensitivity observed on chromosome 7A is presented. The combined additive effects at these loci accounted for more than half the phenotypic variance in the duration from planting to ear-emergence in this population. The possible role of these loci on the adaptation of wheat in Australia is discussed.
KeywordsEar-emergence Earliness per se Photoperiod Quantitative trait locus Triticum aestivum Vernalisation
Quantitative trait locus
The authors would like to thank the Grains Research and Development Corporation, the Molecular Plant Breeding Cooperative Research Centre and Australian Grain Technologies for their financial assistance. They would also like to show their gratitude to Mr. J. Reinheimer, Dr. D. Mather and Dr. G. McDonald for their helpful comments and the staff at Australian Grain Technologies and the South Australian Research and Development Institute for their technical assistance in collecting genetic and phenotypic data.
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