Page 93 - University of Pretoria Research Review 2017

Foreword
Introductory Messages
Resistance mechanisms against insect pests
Sanushka Naidoo, Department of Biochemistry, Genetics and Microbiology, and FABI
Climate change is a reality and South Africa’s local forest plantations only recently started recovering from a devastating drought. Drought conditions induce a stress response in trees, thereby compromising an adequate defence against pests and some pathogens. Worldwide, anthropogenic activity has resulted in the spread of pests and diseases and it is anticipated that climate change may extend the breeding period for certain insect pests and create favourable environments for pathogens not previously identified in certain regions
or hosts.
Sanushka Naidoo, Associate Professor in the Department of Biochemistry, Genetics and Microbiology, is leading a team of FABI researchers who study tree resilience. Together they have started
to unravel the complex defence network that exists in forest trees. The deep molecular analysis of the host- pest/pathogen interaction is made possible by the many molecular tools that are now available for studies such as transcriptomes for Eucalyptus and Pine, markers for Eucalyptus, and genomes for pests and pathogens.
In recent work, the team collaborated with Mondi Forests and the Trahar Technology Centre in South Africa, and identified markers associated with resistance against the gall-forming insect pest, Leptocybe
invasa. They coupled these findings with expression
Sanushka Naidoo and postgraduate student Stefan Ferreira
patterns that differed in resistant and susceptible genotypes. Many of these are candidate insect defence genes. Further collaboration with researchers at University of Pretoria, University of North Carolina (US), and Australian National University resulted in
the identification of specialised plant metabolites associated with resistance against this pest. Some of their recent work was published, in 2017, in journals Molecular Plant Pathology and Tree Physiology.
Future research will entail examining whether such metabolites act as attractants or repellents to the pests, or have direct anti-insect activity, in order to understand the mechanisms of resistance to Leptocybe invasa in forest trees. It is anticipated that some of
the approaches could be adopted in future forest management of pests, as part of climate change mitigation strategies.
DEVELOPMENT AND CHANGE
PEOPLE AND CONTEXTS
HEALTH AND WELL-BEING
PLANET AND SUSTAINABILITY
FABI, forests and fungi
Awards
Lead Researchers
91
Tree resistance mechanisms are integral components of the plant disease triangle. The magnitude and timing of a tree’s defence mechanisms will determine the extent of damage that can be caused by pests or pathogens.
Sanushka Naidoo was one of two recipients at UP, in a group of 18 in Africa, to receive the Next Einstein Forum Fellow Award in 2017, a distinct honour in recognition of exceptional academic talent. The other recipient is Dr Vinet Coetzee (see p.68).