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Physiologic and genetic analysis Of terminal drought tolerance in wheat

Cakir, M., Rebetzke, G., Conocono, E., Drake-Brockman, F., Waters, I., Stefanova, K., Wilson, R., Barclay, I., McLean, R. and Setter, T. (2011) Physiologic and genetic analysis Of terminal drought tolerance in wheat. In: XIX International Plant & Animal Genome Conference, 15 - 19 January 2011, Town & Country Convention Center, San Diego, CA.


Recent drought events has caused substantial yield loses in Australia and therefore genetic improvement of drought tolerance has become a high priority in wheat breeding programs. As some of the well-adapted Western Australian wheat varieties have shown high levels of water soluble carbohydrates (WSC) at anthesis understanding the role of WSC in the terminal drought tolerance has been the primary focus of our recent drought research. The objectives of this study were to evaluate the impact of stem WSC on drought tolerance at grain filling stage (terminal drought), map the genes responsible for the accumulation of stem carbohydrates and grain yield, and develop a pre-breeding germplasm. Two doubled-haploid (DH) populations, Westonia/Kauz (W/K) and Westonia*2/Janz (W/J), were studied in various field environments including the use of rainout shelters. The analysis of grain yield data showed a good variation with a genetic diversity of about 3-fold and 5-fold variation in 2004 and 2005, respectively, under drought conditions. Transgressive segregation was observed for the grain yield in both populations. Stem carbohydrate concentrations at anthesis varied 2.5 fold with concentrations ranging from 200 to 500 mg per g stem dry weight, i.e. 20-50% dry weight. From the 32 wheat varieties tested six varieties, had drought tolerance (i.e. grain yield under drought relative to control conditions) of 0.9 or better. Varieties with low WSC, i.e. <300 mg g-1 also had low drought tolerance (< 0.8). Genetic maps were constructed for W/J and W/K populations using 306 and 469 markers, respectively. QTL analysis indicated the presence of several genes for stem WSC concentration and content on chromosomes 3A, 4B, 4D and 7B for the WJ population, and 2D, 5B, 6B for the WK population. Further results with the grain yield data and the breeding value of some of the wheat DH lines will also be discussed.

Publication Type: Conference Item
Murdoch Affiliation: Western Australian State Agricultural Biotechnology Centre
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