Impact of Cre1, Cre8 and Cre3 genes on cereal cyst nematode resistance in wheat

The cereal cyst nematode (CCN; Heterodera avenae), a root disease of cereal crops, is a major economic constraint in many wheat (Triticum aestivum)-growing areas of the world. The objective of this study was to assess the impact of the Cre1, Cre8 and Cre3 genes on CCN resistance. A population of 92 doubled-haploid (DH) lines derived from a cross between wheat cvs. Frame and Silverstar as well as 1,851 wheat breeding lines were screened for CCN resistance at the Primary Industries Research Victoria (PIRVic). A second population of 9,470 wheat breeding lines was screened at the South Australian Research and Development Institute (SARDI). Cre3 had the largest impact on reducing the number of female cysts, followed by Cre1 and Cre8. There was no significant difference in number of cysts between DH lines with or without the Cre8 marker, suggesting that the marker is not perfectly linked to Cre8. The estimated heritabilities were 0.32 in the DH population, 0.48 in the PIRVic data set and 0.32 in the SARDI data set, which confirm that this is a trait of low heritability. The repeatability of CCN resistance improved with an increase in the number of plants assessed per line-up to ten. However, 85-88% of the improvement was achieved with the assessments of the first five plants.