Functional gene markers for polyphenol oxidase locus in bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) |
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Authors: | Rosy Raman Harsh Raman Peter Martin |
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Institution: | (1) NSW Department of Primary Industries and NSW Agricultural Genomics Centre, Wagga Wagga Agricultural Institute, Pine Gully Road, Wagga Wagga, NSW, 2650, Australia |
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Abstract: | Higher polyphenol oxidase (PPO) activity in wheat kernels and flour has been implicated in the time dependent darkening of
various end-products. Previous study conducted on a bread wheat (Triticum aestivum L.) doubled haploid (DH) mapping population derived from Chara (medium-high PPO) and WW2449 (low PPO) identified a major
QTL for PPO activity located on the long arm of chromosome 2A. Physical mapping of SSR markers accounting for up to 84% of
phenotypic variation for PPO activities suggests that the candidate PPO locus is localised in the deletion bin delimited by
2AL 0.77–0.85. In order to develop functional gene markers, nine wheat ESTs mapped to this deletion bin and partial PPO reference
genes were explored for their sequence identities and linkage with PPO locus in a mapping population. In the present study,
two markers: one SNP and one CAPS based upon BQ161439 sequence variation between the parents were identified which exhibited
a tight linkage (0–0.6 cM) with the PPO loci designated as XTc1 and XPPO-
LDOPA. We also mapped the reference PPO gene (GenBank AY526268) characterised from developing kernels of wheat, on the long
arm of chromosome 2A which exhibited a complete linkage with XPPO-
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DOPA locus. Results suggest that PPO variation displayed in the DH population from Chara/WW2449 is due to the same reference PPO
gene. Allelic homoplasy of tightly linked markers, indicated that these markers are ‘diagnostic’ for the selection of low
PPO gene in a range of germplasm being used in different Australian breeding programs. Identification and validation of ‘functional
gene markers’ would facilitate in enhancing the selection efficiency for low PPO activity in wheat breeding programs. |
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Keywords: | ESTs SNP Polyphenol oxidase Linkage mapping Allelic diversity |
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