Genetic mapping of monoterpene composition in an interspecific eucalypt hybrid

Mervyn Shepherd, Southern Cross University
Jose X. Chaparro
Robert D. Teasdale, ForBio Pty Ltd

Abstract

Genetic control of foliar oil composition was investigated amongst half-sib progeny of an interspecific eucalypt hybrid. The oil was found to be largely composed of the monoterpenes, limonene, α−pinene, γ−terpinene, 1,8 cineole and p-cymene. Due to difficulties in the interpretation of the compositional data based on raw proportions, further analysis was conducted using log-ratio variables. A high degree of intercorrelation amongst log-ratios was thought to be a consequence of commonality in the biosynthetic origins of the monoterpenes. Quantitative trait locus (QTL) analysis of log-ratio variables indicated that a significant (68–81%) proportion of the variation in four out of the ten possible log-ratios were controlled by a single genomic region of the maternal Eucalyptus grandis parent. The impact of this genomic region upon oil composition was thought to be a consequence of a gene, or genes, controlling the production of limonene, as limonene was the predominant oil constituent in many hybrid individuals and was common to all log-ratios associated with the identified genomic region.