Epidemiology and Physiological Impact of Aerial Phytophthora pluvialis in New Zealand and Oregon Forest Systems Mireia Gómez Gallego Primary Supervisor: Dr. Martin Bader Secondary Supervisor: Dr. Nari Williams A thesis submitted to Auckland University of Technology in fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) December, 2018 Table of contents List of figures .............................................................................................................................. 5 List of tables ................................................................................................................................ 8 Attestation of authorship ........................................................................................................... 9 Co-authored papers .................................................................................................................. 11 Acknowledgements .................................................................................................................. 13 Abstract ...................................................................................................................................... 15 Chapter 1. Introduction ............................................................................................................. 17 Rationale and thesis aims ....................................................................................................... 17 Thesis structure ...................................................................................................................... 19 Chapter 2. Understanding P. pluvialis infection dynamics: from needles to plants.......... 21 Prelude .................................................................................................................................... 22 Abstract ................................................................................................................................... 23 Introduction ............................................................................................................................. 24 Materials and Methods ........................................................................................................... 25 Inoculum preparation ........................................................................................................... 25 Detached-needle assay ....................................................................................................... 26 On-plant inoculation ............................................................................................................. 27 Model development .............................................................................................................. 29 Applying the epidemiological model .................................................................................... 33 Results .................................................................................................................................... 35 Detached-needle assay: comparing susceptible and resistant genotypes.......................... 36 On-plant inoculation ............................................................................................................. 38 Discussion ............................................................................................................................... 42 Comparing susceptible and resistant genotypes ................................................................. 42 Scaling up to whole-plant infection dynamics ...................................................................... 42 Comparing P. pluvialis assessment procedures .................................................................. 44 Supplementary material .......................................................................................................... 46 Analytical solution for the detached-needle assay model fit ................................................ 46 Detached-needle assay model fit details ............................................................................. 47 Simulations to verify stability of on-plant inoculation model fit............................................. 47 1 On-plant inoculation model fit details ................................................................................... 52 Chapter 3. The challenge of multiple pathogenic infections ................................................ 55 Prelude .................................................................................................................................... 56 Abstract ................................................................................................................................... 57 Introduction ............................................................................................................................. 58 Material and methods ............................................................................................................. 59 Phytophthora pluvialis detached needle assay ................................................................... 59 Nothophaeocryptopus gaeumannii suppression assays ..................................................... 60 Data analysis ....................................................................................................................... 61 Results .................................................................................................................................... 62 Phytophthora pluvialis detached needle assay ................................................................... 62 Nothophaeocryptopus gaeumannii suppression assays ..................................................... 63 Discussion ............................................................................................................................... 64 Chapter 4. Interaction between P. pluvialis and Nothophaeocryptopus gaeumannii infection on Douglas-fir ............................................................................................................ 66 Prelude .................................................................................................................................... 67 Abstract ................................................................................................................................... 68 Introduction ............................................................................................................................. 69 Material and methods ............................................................................................................. 70 Study sites and field sampling ............................................................................................. 71 Climate data ......................................................................................................................... 72 Isolation and identification of Phytophthora pluvialis ........................................................... 73 DNA extractions and real time qPCR .................................................................................. 74 Data analysis ....................................................................................................................... 75 Results .................................................................................................................................... 77 Fortnightly sampling ............................................................................................................. 77 Regional sampling ............................................................................................................... 81 Discussion ............................................................................................................................... 84 Phytophthora pluvialis epidemics and seasonality .............................................................. 85 Differences in the interaction between P. pluvialis and N. gaeumannii in the US Pacific Northwest and New Zealand ............................................................................................... 86 Supplementary material .......................................................................................................... 89 2 Chapter 5. Physiological impact of aerial Phytophthora pluvialis on Pinus radiata.......... 92 Prelude .................................................................................................................................... 93 Abstract ................................................................................................................................... 94 Introduction ............................................................................................................................. 95 Material and methods ............................................................................................................. 97 Plant material and defoliation treatments ............................................................................ 97 Biomass sampling and growth measurements .................................................................... 97 Gas exchange and chlorophyll fluorescence measurements .............................................. 98 Non-structural carbohydrates .............................................................................................. 99 Data analysis ....................................................................................................................