Accelerated domestication of Australian native grasses

Australia is home to 10% of the world’s 10,000 grass species (Figure 1) and yet none of the currently cultivated species are native to this continent. The potential of several of Australia’s native species to be domesticated as new cereal crops was recorded by botanists as early as 1895 [1]. The most limiting factor for the use of native grasses, as either pasture or grain crops, is their lower yields when compared to domesticated species. In the case of grain yield addressing the issue of shattering at maturity greatly improves a species potential to be harvested and hence commercially exploited. Microlaena stipoides has been selected as the primary target species for accelerated domestication because of its favourable agronomic and genetic traits. Microlaena’s perennial growth cycle increases its water use efficiency while reducing tillage, and hence soil erosion. Its predominantly cleistogamous (selfing) breeding system allows the development of stable breeding lines and additionally this species also exhibits opportunistic chasmogamous (outcrossing) breeding cycles [2]. This will allow for cross breeding to be utilised to introgress beneficial traits from mutant individuals. Broad natural variation within the species occurs within and between populations across a wide range of environmental conditions [3] and collected ecotypes show tolerances to drought, acid soils, salinity, shade, frost and low fertiliser compared to current cereal crops [4, 5]. Microlaena is a dual purpose crop which can be grazed for about 6-8 months of the year and then locked up to set seed for grain harvest after rainfall events in the spring. Its high fodder value is due to a combination of good palatability, high digestibility (up to 79%), substantial biomass production (4-12t/ha) depending on water and nitrogen availability [6]. With respect to grain production Microlaena already has a good plant architecture, reasonable grain yield (130-1137kg/ha), large grain size in some accessions [4] and a similar endosperm morphology to rice [7].