Grain morphology of wild relatives of Australian rice

Rice production, exportation and consumption in Australia have increased substantially since 1985. However, unreliable rainfall patterns, soil salinity, high costs of production, unfavourable climate, and environmental concerns arising from farming practices are major constraints to production. Phenotypic and genotypic studies of wild rice germplasm may identify novel and beneficial trait variants which can be used for molecular breeding of cultivated rice to increase yields, quality and profits. Australia possesses a wide range of wild rice species within Oryza sp. and other related genera. Starch granule morphology influences the physicochemical characteristics of starch as well as the procedures employed in starch refining. Starch performances do not entirely depend on granule shape/ size but it is believed to be a contributing factor of their functional properties. Comparative scanning electron microscopy studies can reveal differences and/or similarities in starch granule morphology between wild and commercial cultivars. This study presents a qualitative evaluation of starch granule morphology of 19 spp. from four different genera (Oryza, Potamophila, Microlaena and Zizania) belonging to two different tribes (Oryzeae, Ehrharteae). The similarities between the starch granule morphology and aleurone layer composition across both wild and commercial species will be discussed.