Genetic conversion of feed barley varieties to malting types

Abstract

Malting barley breeding programs have typically applied conservative strategies for the introgression of traits from non-malting germplasm, and this traditional approach can be considered as recognition for the genetic complexity of malt quality. However, these strategies intrinsically limit the rate of genetic gain for adaptation and the drought conditions in Australia have recently highlighted the superior adaptation of feed varieties, particularly in low rainfall environments. This paper presents preliminary results from a novel strategy that tests a new paradigm for breeding malting barley. The project aims to introduce key malting quality genes from a range of elite international malting varieties into the well adaptated feed variety Keel, while maintaining the superior adaptation and agronomic profile of the feed barley. This strategy implies that the genetics of malting quality is now better understood than the genetics of adaptation. Keel was used as the recurrent parent to produce backcross lines containing the key quality genes from Alexis, Haruna nijo and AC Metcalfe. The BC₁ and BC₂ generations for each introgression stream were screened using molecular markers for a range of malt quality loci. The subsequent populations were evaluated in double row trials in the 2002 and 2003 season. Agronomic selection was applied to identify individuals exhibiting the Keel phenotype, the subsequent grain samples were evaluated for grain size and NIR predicted malt quality. Populations derived from intercrosses between the introgression streams have also been developed, to pyramid the malt quality genes from the three international varieties into a Keel genetic background. The agronomic and malting quality profiles of this germplasm will be presented, and the prospects for developing malting quality barley using this novel breeding strategy will be discussed. Selected individuals were screened as BC₁F₂ single plants to identify individuals homozygous for the target loci. Elite lines were identified and promoted for further agronomic evaluation in yield plots in the 2003 season. Selected BC₁F₂ individuals were used to develop BC₂ generations for each of the introgression streams. This germplasm is currently in a double row trial for agronomic and predicted malt quality evaluation.