Generating Buffel Grass Cultivars with Greatly Enhanced Nutritive Value

Summary

Buffel grass (Cenchrus ciliarius) is the most widely sown grass in the 400 – 800mm rainfall region of southern Queensland.  The species is known for it hardiness and drought tolerance and has led to large benefits to beef producers (Hall 2000) but is only moderately palatable and can be invasive in some environments and management regimes.

This project used induced mutagenesis to derive buffel grass mutants with the brown-midrib phenotype.  Brown midrib mutants are known to exist in the genus Pennisetum and brown mid-rib mutants have been successfully developed using induced mutagenesis (Sattler et al. 2010).  Cenchrus  is very closely related to Pennisetum  suggesting that this methodology may be successful in buffel grass.  Previous attempts to use mutagenesis to improve kikuyu did not lead to increased digestibility  (Lowe et al.  2010) but these did not target the brown midrib mutation.

This approach has the advantage that relatively large advances in forage quality may be made in a short time, the only other comparable advances would be made through transgenesis with the concomitant regulatory issues and deregulation costs.  Conventional breeding methodologies to achieve this would require cycles of recurrent selection and the use of sexually compatible genotypes to allow recombination.  The risk associated with a mutagenesis breeding program is that it is impossible to target mutations (although loss of function mutants are more common) and thereby the target phenotype may not be achieved, this risk can mitigated through producing a large enough mutagenised population and the availability of a readily scored  phenotype such as the brown midrib mutation.

This project used mutagenesis to attempt to derive brown midrib mutants in buffelgrass and to validate the genetic and phenotypic basis of these mutants prior to field evaluation and commercial release.