Tests hope to confirm PHS resistance transfer

Tests are running to determine if pre-harvest sprouting (PHS) resistance has been successfully transferred into breeding lines from a range of slow germinating candidates with heightened seed dormancy.

PHS generates high levels of alpha-amylase in grain, which attacks the starch needed to ensure good bread structure and body. Estimates suggest that in a bad year, the downgrading of sprouted grain can cost the Australian industry up to $40 million.

Research at Victoria"s Department of Primary Industries has developed wheat germplasm with enhanced seed dormancy using wild relatives (Aegilops tauschii) and wheat landraces.

“We"re understanding the dormancy mechanisms and resultant PHS resistance in wheat and its wild relatives and incorporating it into commercial wheat,” project leader Francis Ogbonnaya says.

Advanced breeding lines have expressed varying levels of the dormancy needed to combat PHS, while Dr Ogbonnaya and his team are zeroing in on molecular markers to ensure that future crosses regularly capture the desired characteristics.

Aegilops tauschii is a diploid (an organism which has two of each chromosome) and so it is easier to develop molecular markers which will facilitate the use of these resistances in marker assisted selection.”

Crossing the diploid species with traditional hexaploid wheats is not always successful, and so all progeny were screened to ensure the artificial hybridisation had not caused abnormalities in the chromosomes.

A related GRDC project* has tested a range of prospects for PHS resistance, including crosses made by Dr Ogbonnaya.

“When seeds from the lines derived from our crosses were tested in a petri-dish at 20ºC, some took up to 28 days to germinate,” Dr Ogbonnaya reports.

Lines with these high levels of dormancy were selected and bulked up for field trials, and the best lines will be made available to breeding programs for the development of PHS-resistant commercial wheat varieties.

For more information:
Dr Francis Ogbonnaya, 03 5362 2111, Fc.Ogbonnaya@nre.vic.gov.au
GRDC Research code: DAV 436, program 1

For more information:
Daryl Mares, 08 8303 7480, daryl.mares@adelaide.edu.au
*GRDC Research code: UA 00034

Region South