Fourth FABI Ph.D. for 2019 2019-04-23
Caryn Oates become the fourth FABIan to be awarded their Ph.D. this year. She presented a Prestige Seminar entitled “Eucalyptus morphological and molecular responses to Leptocybe invasa oviposition” on 10 April but her defence was only a week later on 17 April. The external examiners were Dr Helen Nahrung from the University of the Sunshine Coast, Prof. Richard Buggs of the Queen Mary University and the internal examiner, Prof. Brett Hurley. Caryn’s Ph.D. was completed under the primary supervision of Prof. Sanushka Naidoo and co-supervisors Professor Katherine Denby (University of York), Prof. Zander Myburg and Prof. Bernard Slippers.
Leptocybe invasa is a gall wasp that causes significant damage to Eucalyptus plantations in South Africa. It was discovered in Israel and is now present in all Eucalyptus-growing countries in the world. Caryn’s project aimed to gain a clearer understanding of the molecular basis of gall induction which is still poorly understood. Caryn compared the transcriptomic and terpene profiles responses of a resistant and susceptible Eucalyptus clone to L. invasa oviposition. She also examined the transcriptomic and morphological responses of a susceptible Eucalyptus clone to this gall wasp over time.
It was found that L. invasa oviposition induces extensive changes to both the transcriptome and terpene profiles in both resistant and susceptible genotypes. Gene expression changes primarily involve phytohormone signaling, secondary metabolism and cell wall modifications. The terpene profile changes suggest a disordering of the chemical signal in the susceptible genotype. Oviposition induces morphological and transcriptome responses within one-day post oviposition and an immature gall forms within seven day post oviposition. It was found that nine transcription factor subfamilies are putatively involved in the interaction through regulation of defence and metabolic processes leading to gall development.