Uncovering the defence responses of Eucalyptus to pests and pathogens in the genomics age

Sanushka Naidoo; Carsten Külheim; Lizahn Zwart; Ronishree Mangwanda; Caryn N Oates; Erik A Visser; Febé E Wilken; Thandekile B Mamni; Alexander A Myburg

doi:10.1093/treephys/tpu075

Uncovering the defence responses of Eucalyptus to pests and pathogens in the genomics age

Tree Physiol. 2014 Sep;34(9):931-43. doi: 10.1093/treephys/tpu075.

Authors

Sanushka Naidoo¹, Carsten Külheim², Lizahn Zwart³, Ronishree Mangwanda³, Caryn N Oates³, Erik A Visser³, Febé E Wilken³, Thandekile B Mamni³, Alexander A Myburg³

Affiliations

¹ Department of Genetics, Genomics Research Institute (GRI), Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Private Bag X20, Pretoria 0028, South Africa; sanushka.naidoo@fabi.up.ac.za.
² Research School of Biology, Australian National University, Canberra, ACT 0200, Australia.
³ Department of Genetics, Genomics Research Institute (GRI), Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Private Bag X20, Pretoria 0028, South Africa;

PMID: 25261123
DOI: 10.1093/treephys/tpu075

Abstract

Long-lived tree species are subject to attack by various pests and pathogens during their lifetime. This problem is exacerbated by climate change, which may increase the host range for pathogens and extend the period of infestation by pests. Plant defences may involve preformed barriers or induced resistance mechanisms based on recognition of the invader, complex signalling cascades, hormone signalling, activation of transcription factors and production of pathogenesis-related (PR) proteins with direct antimicrobial or anti-insect activity. Trees have evolved some unique defence mechanisms compared with well-studied model plants, which are mostly herbaceous annuals. The genome sequence of Eucalyptus grandis W. Hill ex Maiden has recently become available and provides a resource to extend our understanding of defence in large woody perennials. This review synthesizes existing knowledge of defence mechanisms in model plants and tree species and features mechanisms that may be important for defence in Eucalyptus, such as anatomical variants and the role of chemicals and proteins. Based on the E. grandis genome sequence, we have identified putative PR proteins based on sequence identity to the previously described plant PR proteins. Putative orthologues for PR-1, PR-2, PR-4, PR-5, PR-6, PR-7, PR-8, PR-9, PR-10, PR-12, PR-14, PR-15 and PR-17 have been identified and compared with their orthologues in Populus trichocarpa Torr. & A. Gray ex Hook and Arabidopsis thaliana (L.) Heynh. The survey of PR genes in Eucalyptus provides a first step in identifying defence gene targets that may be employed for protection of the species in future. Genomic resources available for Eucalyptus are discussed and approaches for improving resistance in these hardwood trees, earmarked as a bioenergy source in future, are considered.

Keywords: anatomical defences; biotechnology; breeding; genomic resources; phytohormone; plant immunity; terpenoid; transcriptomics.

Publication types

Research Support, Non-U.S. Gov't
Review

MeSH terms

Eucalyptus / genetics*
Eucalyptus / immunology*
Eucalyptus / metabolism
Plant Diseases / etiology
Plant Diseases / immunology
Plant Immunity*
Plant Proteins / genetics*
Plant Proteins / metabolism

Substances

Plant Proteins
pathogenesis-related proteins, plant