Cotton Breeding Australia
Improving Host Plant Resistance to pests and diseases
Significant progress has been made regarding the Verticillium Wilt (VW) resistance component of the project.vIn the first instance, fields suitable to evaluate material for resistance to VW have been identified. They have allowed screening of a range of Gossypium germplasm and a few genotypes within them have been targeted for introgression of VW resistance into elite material.
Furthermore, lines developed to validate molecular markers associated with VW resistance have been phenotyped and the most resistant lines selected to develop additional VW resistant lines.
Finally, the level of VW resistance of a number of advanced and pre-commercial lines from the core breeding program have been assessed and will be used as an additional trait for the final selection of these lines.
Regarding host plant resistance to Silver Leaf Whitefly (SLW), one Okra-Glabrous B3F breeding line has been tested in large field plots and proven to harbour a lower population of SLW compared to a commercial cultivar in these conditions, suggesting that whole fields planted with a variety having Okra and Glabrous traits will still maintain their high level of resistance to this pest and therefore could be an alternative option if the SLW threat became even more serious a problem. Backcross breeding lines selected for resistance to Two Spotted Spider Mites have also been validated in the field.
The development of molecular markers appears very positive as well, with plant material being developed to use for the marker validation experiments next year and preliminary results showing that two markers are needed in order to have a high level of resistance in glasshouse conditions. Field experiments will show the feasibility of using these markers as a routine screening tool to speed up the selection process in the breeding program.