Research explores waterlogging tolerance links
GroundCover™ Issue: 138 January - February 2019 | Author: Rebecca Thyer
The links between waterlogging tolerance and phytophthora root rot (PRR) are being investigated via GRDC-invested research as a means of improving PRR resistance in chickpeas. The research is part of a capacity-building initiative within the Grains Agronomy and Pathology Partnership between the NSW Department of Primary Industries (DPI) and GRDC.
Spores of the water-borne pathogen proliferate in high-moisture environments and have motile zoospores that can travel through films of water towards the roots of a growing crop. This results in the pathogen Phytophthora medicaginis infecting the plant.
University of Adelaide PhD student Nicole Dron says that in a season with above-average rainfall, whole-crop loss can result from a combination of waterlogging and PRR infection. Partial crop losses are reported in most seasons, usually from low-lying areas of paddocks and watercourses. These areas, along with other host plants, carry inoculum into following seasons, where rapid multiplication can occur to create an ongoing PRR threat that can persist for up to 10 years.
Ms Dron’s broad objective is to identify and incorporate superior waterlogging tolerance in chickpeas, thus hopefully improving PRR resistance. Similar research has occurred successfully in soybeans. Her work aims to differentiate between waterlogging tolerance and PRR-resistant traits in chickpeas and, working with the chickpea-breeding program, provide ‘genetic points of interest’ or quantitative trait loci (QTL) for further investigation.
“For now we don’t know if the recently identified PRR resistance QTL being targeted through breeding and pre-breeding efforts can also confer tolerance to waterlogging in chickpeas. The ability to differentiate and identify additional QTL for waterlogging tolerance may provide the opportunity to pyramid the two traits, improving the robustness of current resistance levels.” Although some varieties, such as Yorker and PBA Seamer, have a level of resistance, they are only rated as moderately resistant. “Once waterlogging stress occurs in combination with the rapid increase in PRR inoculum load post-rainfall, the level of resistance in current varieties is inadequate.”
Ms Dron says PRR management is difficult. Once infected, the plant usually dies, and unlike ascochyta blight of chickpeas, in-crop management cannot readily or economically control the disease. “Genetic resistance is the best defence against PRR and will result in reduced crop losses and potentially inoculum load in a chickpea rotation.”
A scientific paper describing the genetics involved in this story has been published in the journal Theoretical and Applied Genetics.
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