Genomic approaches to selection in outcrossing perennials: focus on essential oil crops

Abstract

The yield of essential oil in commercially harvested perennial species (e.g. 'Oil Mallee' eucalypts, Tea Trees and Hop) is dependent on complex quantitative traits such as foliar oil concentration, biomass and adaptability. These often show large natural variation and some are highly heritable, which has enabled significant gains in oil yield via traditional phenotypic recurrent selection. Analysis of transcript abundance and allelic diversity has revealed that essential oil yield is likely to be controlled by large numbers of quantitative trait loci that range from a few of medium/large effect to many of small effect. Molecular breeding techniques that exploit this information could increase gains per unit time and address complications of traditional breeding such as genetic correlations between key traits and the lower heritability of biomass. Genomic selection (GS) is a technique that uses the information from markers genotyped across the whole genome in order to predict the phenotype of progeny well before they reach maturity, allowing selection at an earlier age. In this review, we investigate the feasibility of genomic selection (GS) for the improvement of essential oil yield. We explore the challenges facing breeders selecting for oil yield, and how GS might deal with them. We then assess the factors that affect the accuracy of genomic estimated breeding values, such as linkage disequilibrium (LD), heritability, relatedness and the genetic architecture of desirable traits. We conclude that GS has the potential to significantly improve the efficiency of selection for essential oil yield.

Potential of Genome-Wide Association Studies and Genomic Selection to Improve Productivity and Quality of Commercial Timber Species in Tropical Rainforest, a Case Study of Shorea platyclados

“…GWAS provides potential capacity to identify the genes that are causally associated with phenotypes of focal traits, especially traits that are strongly affected by one or a few genes. However, it has been less successful in identifying such genes in species with phenotypes that are mostly influenced by numerous minor quantitative trait loci (QTLs) [12,13].…”

Genome-wide identification of markers for selecting higher oil content in oil palm

“…The obvious dosage effect showed that pyramiding these two O/B QTL and one or two of the O/DM QTL has great potential for oil palm breeding. Oil yield relative traits are complex and often controlled by large numbers of genetic loci with small additive effect [39], hence combining multiple QTL with beneficial genotypes in an individual can be an effective strategy of oil yield improvement in palm breeding.…”

Plant-Derived Terpenes: A Feedstock for Specialty Biofuels

“…In plants, genetic and environmental factors regulate terpene biosynthesis at multiple levels, including transcription, protein accumulation, and posttranscriptional/translational regulation [29,61]. Understanding the molecular underpinnings of terpene metabolism in plants will benefit from a systems biology approach, where the goal is to quantitatively describe the cellular processes through global modeling of the interactions and dynamics of the molecular components.…”

“…For example, in a related tea tree, three cycles of phenotypic selection over 20 years resulted in doubling the oil yield from 148 to 300 kg ha -1 [87]. This process could be accelerated in undomesticated eucalypt species through molecular breeding techniques such as genomic selection [61]. Previous studies reported that the terpene content is limited by the storage gland capacity, which in turn is regulated by the leaf area and thickness [46].…”