PAG-IV Plant Genome IV Conference

Town & Country Conference Center, San Diego, CA, January, 1995.

W8
RAPD Marker Linkage to Loci Controlling Monoterpenes in a Tropical Forestry Species

M. SHEPHERD(1), Jose X. Chaparro(2), Graham Jones(3) and Robert Teasdale(2)
1. Botany Department, University of Queensland, Australia
2. Forbio Research Pty. Ltd., 50 Meiers Rd, Indooroopilly, Q4068 Brisbane, Australia
3. Department of Horticulture and Viticulture and Oenology, University of Adelaide, Waite Campus, Australia

Eucalyptus grandis is an important species in plantation pulpwood forests in tropical regions. The interspecific E. grandis X E. urophylla hybrid combination has been used widely in clonal selection programs in Brazil for its superior performance, wood characteristics and disease resistance traits. We have generated a linkage map for the maternal parent for one family of this hybrid based on a sample of 165 progeny. Foliar essential oil samples for 111 of these progeny where analysed by gas chromatography (GC). Oil yields averaged 0.3%w/w and 0.7%w/w for two sites sampled. Approximately 30 compounds were separated by GC analysis however the bulk of the yield of the ethanol extracted compounds was composed of 5 cyclic monoterpenes. Some of compounds exhibited extensive variation within a site for yields expressed as a percentage of total oil yield (e.g. 0.1-76%). RAPD markers have been identified which are linked to the percentage yields of a number of these major monoterpenes. Quantitative trait analysis indicates that a single locus controls a large portion of the variation for 3 major monoterpene components in this hybrid. This is in agreement with the properties of a number of characterised cyclase-isomerases which control multiple product levels in other species. These findings suggest that manipulation of some oil characteristics may be relatively straight forward for Eucalyptus.

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