Production of betaine from Australian Melaleuca spp. for use in agriculture to reduce plant stress

Some of the Melaleuca spp., native to Australia, are unique in their ability to withstand environmental stresses. The stress tolerance of these species is attributable to their ability to accumulate large quantities of organic compounds known as osmoprotectants or proline (betaine) analogues. Osmoprotectants can be extracted easily from these plants and used in seed treatment and foliar application to increase the stress tolerance of economic crops. This paper examines the potential of 8 Melaleuca spp. for the production of osmoprotectants. Melaleuca bracteata, which accumulates the proline analogue trans 4hydroxy-N-methyl proline (MHP), was the most vigorous of all 8 species field tested in New South Wales and Queensland. A simple extraction protocol for commercial use is suggested. By growing M. bracteata, it is possible to achieve an average yield of 493 kg/ha of MHP along with 218 kg/ha of essential oil, with a gross economic return of AU$14505/ha. This return is better than that estimated for M. alternifolia, $3200/ha, which is currently grown for the production of tea tree oil. The cultivation of M. bracteata has the potential of creating a new industry for Australia, in addition to its positive role in the control of dryland salinity.