D7l: Vanguards for research of myrtle , 08:30 - 10:30 Saturday, 5th October, 2019 Venue R19 - PG Congress Theme D. Biodiversity, Services and Biological Invasions Presentation Types Oral Chair Alistair Dr, Jane Dr, Stuart Dr

Session objectives: • This session will provide a platform for researchers of Austropuccinia psidii to share their findings and develop strategies for future research. • Establish the current and projected economic and environmental impact of further spread of A. psidii.• Insight into the expanding host range and levels of susceptibility of naïve species.• We will identify key knowledge gaps in the biology of A. psidii, and propose future research questions that should be studied by the community.• Several projects to sequence the genome of A. psidii are completed or underway. We must impress on the importance of accessibility of sequence data and co-ordinate research questions that can be addressed by the data soon available to the community.• Discuss the recent discoveries of the life cycle of A. psidii with regards to sexual reproduction and increasing genetic diversity on impact, disease management and biosecurity.• Discuss simplified ways to identify the strains of A. psidii and link genotypes to phenotypes in a central database that can be universally adopted as a powerful research tool.

08:30 - 08:45

D7l Global invasive threats of myrtle rust: genetic diversity and bioclimatic modeling of Austropuccinia psidii in the Americas and

Jane Stewart1, Amy Ross-Davis2,3, Rodrigo Graca4, Acelino Alfenas5, Tobin Peever6, John Hanna2, Janice Uchida7, Phil Cannon8, S Namba9, S Simeto10, Robert Hauff11, C Kadooka7, Carlos Pérez12, Min Rayamajhi13, Jean Lodge14, M Arguedas15, Paula Tennanet16, Morag Glen17, Patricia Machado5, Rosario Medel-Ortiz18, M.A López-Ramirez18, Alistair McTaggart19, Angus Carnegie20, Mee-Sook Kim21, Ned Klopfenstein2 1Colorado State University, Fort Collins, USA. 2USDA Forest Service, Rocky Mountain Research Station, Moscow Forestry Sciences Laboratory, Moscow, USA. 3Oregon State University, Corvallis, USA. 4FuturaGene Brasil Tecnologia, Itapetininga, . 5Department of , Universidade Federal de Viçosa, Viçosa, Brazil. 6Department of Plant Pathology, Washington State University, Pullman, USA. 7Department of Plant and Environmental Protection Sciences, University of Hawaii at Manoa, Honolulu, USA. 8USDA Forest Service, Forest Health Protection – Region 5, Vallejo, USA. 9Department of Agricultural and Environmental Biology, The University of Tokyo, Tokyo, Japan. 10National Forestry Research Program, Instituto Nacional de Investigación Agropecuaria (INIA), Tacuarembó, . 11Division of Forestry and Wildlife, Department of Lands and Natural Resources, Honolulu, USA. 12Departamento de Protección Vegetal, EEMAC, Facultad de Agronomía, Universidad de la República, Paysandú, Uruguay. 13USDA, Agricultural Research Service, Invasive Plant Research Laboratory, Fort Lauderdale, USA. 14USDA Forest Service, Northern Research Station, Luquillo, USA. 15Escuela de Ingeniería Forestal, Instituto Tecnológico de Costa Rica, Cartago, Costa Rica. 16The Biotechnology Centre, University of the West Indies, Mona, Jamaica. 17Tasmanian Institute of Agriculture, University of Tasmania, Hobart, . 18Instituto de Investigaciones Forestales, Universidad Veracruzana, Xalapa, Mexico. 19Queensland Alliance for Agriculture and Food Innovation, Brisbane, Australia. 20NSW Department of Primary Industries, NSW Forest Science, Parramatta, Australia. 21USDA Forest Service, Pacific Northwest Research Station, Corvallis, USA

Abstract

In recent decades, the myrtle rust pathogen, Austropuccinia psidii, has spread worldwide on diverse myrtaceous species. Genetic and genotypic diversities within and among A. psidii populations were evaluated in Brazil and other areas of myrtle rust emergence in the Americas and Hawaii. Several unique multilocus genotypes (MLGs) were identified by microsatellite markers, which were grouped into nine distinct genetic clusters: C1 - diverse hosts in Central America, Caribbean, and USA-Hawaii, and USA-; C2 - eucalypts ( spp.) in Brazil/Uruguay and rose apple ( jambos) in Brazil; C3 - eucalypts in Brazil; C4: from diverse hosts in USA-Florida; C5 - Java plum (Syzygium cumini) in Brazil; C6 - guava and Brazilian guava (Psidium guineense) in Brazil; C7 - pitanga ( uniflora) in Brazil; C8 - allspice (Pimenta dioica) in Jamaica and sweet flower (Myrrhinium atropurpureum) in Uruguay; and C9 - (Myrciaria cauliflora) in Brazil. One C1 MLG was associated with multiple hosts and diverse geographic regions. The C1 and C4 cluster are considered as a “Pandemic biotype,” associated with myrtle rust emergence in Central America, Caribbean, USA-Florida/Hawaii, Australia, China-Hainan, New Caledonia, Indonesia, and . Geographic locations with suitable climate for A. psidii that are at risk from invasion were predicted using maximum entropy bioclimatic modelling using 19 bioclimatic variables, documented occurrences of A. psidii, and sets of genetic clusters (subnetworks, considered as biotypes). When assessing the invasive threats posed by A. psidii around the globe, it is important to consider the genetic diversity of A. psidii and its biotypes. 08:45 - 09:00

D7l Myrtle rust – impact on native Australian and associated plant communities

Geoff Pegg1, Angus Carnegie2, Fiona Giblin1, Louise Shuey1 1Horticulture & Forestry Science, Department of Agriculture & Fisheries, Brisbane, Australia. 2NSW Department of Primary Industries - Forestry, Sydney, Australia

Abstract

Austropuccinia psidii (myrtle rust) has long been considered a significant threat to Australian plant industries and . The rust was first detected in Australia in April 2010 on the central coast of and has continued to spread with detections extending from Tasmania in the south, Cape York Peninsula in the north east, and west to Arnhem Land in the Northern Territory. The current host list for Australia includes >350 species from 57 genera. Austropuccinia psidii severely affects key species in natural ecosystems, with localised extinctions recorded ( psidioides and rubescens) and with many species no longer ecologically functional. Our studies have demonstrated severe impacts of myrtle rust on native plant communities. Austropuccinia psidii has caused significant disturbance in lowland subtropical rainforest and wet sclerophyll environments where Myrtaceae dominate the rainforest understorey. Similar impacts have been recorded in coastal heath environments affected by wildfire ( nodosa, spp.) with severe decline in once dominant species and little evidence of regeneration potential. Keystone species such as are also being impacted, with tree deaths and reduced flowering rates recorded. Future research programs are required to identify and monitor species and plant communities at greatest risk of decline. The implementation of a disease screening and tree breeding program may be required for some species as without intervention, regaining lost genetic diversity within these populations may not be possible. The rate of decline of some species is alarming and retaining viable germplasm for conservation purposes is essential. 09:00 - 09:15

D7l The impact of myrtle rust in New Zealand

Beccy Ganley1, Julia Soewarto2, Roanne Sutherland2 1The New Zealand Institute for Plant and Food Research Ltd, Te Puke, New Zealand. 2Scion, Rotorua, New Zealand

Abstract

Austropuccinia psidii was first found in New Zealand in spring 2017 and an incursion response was immediately instigated. During this response Myrtaceae across large areas of New Zealand were surveyed for the presence of myrtle rust. The disease has now spread across the majority of the North Island and the top of the South Island, and is known to be present in urban and native trees. Long-term monitoring plots have been established in native forests to determine the impact of myrtle rust on foliage, flowers and fruits of mature trees and on seedling survival. The monitoring plots established have focused on one of New Zealand’s most susceptible native species bullata (ramarama) and its natural hybrids with (rohutu), but also include a range of other myrtaceous present within the plots such as spp. and Leptospermum scorparium.Here we discuss the impact this disease has had on the plant species in these plots and the implications for native New Zealand Mrytaceae, as well as the long-term surveillance and management options underway for this disease. 09:15 - 09:30

D7l Alternative fungicides for the control of myrtle rust on

Karanjeet Sandhu1, Amin Pathan2, Mark Kimberly2, Robert Park1 1University of Sydney, Sydney, Australia. 2Ministry for Primary Industries, Rotorua, New Zealand

Abstract

Myrtle rust caused by Austropuccinia psidii was first detected in Australia and New Zealand in 2010 and 2017 respectively. Pathogen A. psidii with vast host range can be determinantal to numbers of potentially vulnerable native species of Myrtaceae. Metrosideros excelsa ‘Nana’ an evergreen native tree, also known as pohutukawa and culturally significant to Māori people, is highly susceptible to myrtle rust.

Greenhouse replicated trials were conducted to assess preventative and curative efficacy of different fungicides against myrtle rust on M. excelsa ‘Nana’ plants. Nineteen treatments included six fungicides alone (AmistarâXtra, Bayfidanâ 250 EC, Dedicateâ, Radialâ, Saprolâ and tea tree oil based organic fungicide TimorexGold®), each fungicide plus adjuvant ‘Hasten’ and ‘Spreadwett’ separately and only water treated controls. Treatments were applied 7 and 14 days before inoculation (DBI) and at 7, 14 and 21 days after inoculation (DAI) using 500 L ha-1 spray volume with Generation III spray booth. Post inoculation treatments were resprayed at 10 days interval from the previous treatment. Percent area infected (%LAI) with active sporulation on abaxial side of was recorded at 14DAI.

All fungicides significantly reduced %LAI as compared to controls in both pre and post inoculation treatments. Treatments at 7DBI followed by 7DAI were most effective and 21DAI timing was least effective. Among the fungicides, AmistarâXtra was most effective and TimorexGold® was least effective in reducing %LAI. Both adjuvants didn’t make any difference and results suggested that fungicides efficacy is reduced if used beyond 7DBI and 7DAI spray timings. 09:30 - 09:45

D7l Chemical and physical foliar response of Corymbia citriodora subsp. variegata inoculated with two pathogen species

Flavia Sarti Bonora, Andrew Hayes, David Lee, Helen Nahrung University of the Sunshine Coast, Sunshine Coast, Australia

Abstract

Spotted gums (Corymbia spp) are a valuable source of commercial timber, gaining importance in South Africa, Brazil, China and Australia. In Australia, spotted gums are severely damaged by the endemic fungal pathogen Quambalaria pitereka which infects new foliage, causing spotting, necrosis and distortion. Myrtle rust (Austropuccinia psidii), a highly invasive exotic fungal pathogen, also infects spotted gums and has been present in Australia for less than a decade. Both pathogen can reduce tree fitness and productivity. As well as differing co-evolutionary histories with spotted gums, the two pathogens have different mechanisms of infection and colonization, with Q. pitereka entering via stomata and only growing intercellularly, and A. psidii penetrating directly through the cuticle, entering the cell and producing haustoria. Both pathogens exhibit significant variation in their infection of spotted gum provenances. Leaf oil compounds such as terpenes are recognized for their fungicidal effects and may support plant protection strategies against fungal pathogens. Fungal pathogens may also affect - and be affected by - leaf physical traits such as leaf toughness. Seedlings of Corymbia citriodora subsp. variegata were inoculated with of Q. pitereka, A. psidii or no spores. Leaf samples were collected when the seedlings were showing signs of infection. We determined leaf toughness and leaf oils were identified by gas chromatography-mass spectrometry. This research examined the variation of fungal susceptibility and the interaction of pathogens with plant leaf oils and physical traits for Q. pitereka and A. psidii, considering their different mechanisms of infection. 09:45 - 10:00

D7l Does Austropuccinia psidii reproduce sexually in Australia?

Alistair McTaggart1, Louise Shuey2, Stuart Fraser3, Andre Drenth1, Geoff Pegg2 1University of , Brisbane, Australia. 2Department of Agriculture and Fisheries, Brisbane, Australia. 3Scion, Rotorua, New Zealand

Abstract

Invasions and epidemics of Austropuccinia psidii are caused by its clonal stage, . Recombination was thought uncommon, even in areas in which it was native. In a previous study, we showed that (the gametic spores) of A. psidii infected species of Myrtaceae and sexual reproduction was part of its life cycle. We supported this finding with evidence that recombination and infection of Myrtaceae by basidiospores occurred in natural ecosystems of New Zealand and South Africa. We used three lines of evidence to test for sexual reproduction, the sexual stage was present, there was high genotypic diversity and there was no linkage between microsatellite loci. Our current study tests whether sexual reproduction has occurred in Australia. We have sampled single pustules at one location over several years. We will screen over 50 single pustules with 12 microsatellite markers to determine whether the population at this field site is recombinant. Our research findings so far show that and basidiospores play a role in the life cycle and spread of disease. We have flagged questions relevant to Eucalyptus forestry such as whether different strains of A. psidii can outcross and overcome disease resistance. 10:00 - 10:15

D7l Assessment of the susceptibility of native New Zealand Myrtaceae to infection by the South African strain of Austropuccinia psidii

Julia Soewarto1, Chanatda Somchit1, Esna Du Plessis2, Irene Barnes2, Michael J. Wingfield2, Michael Bartlett1, Peter Scott3, Elizabeth Miller1, Louise Shuey4, Nick Waipara5, Ginna Granados2, Roanne Sutherland1, Beccy Ganley3 1SCION, Rotorua, New Zealand. 2Forestry and Agricultural Biotechnology Institute (FABI), Pretoria, South Africa. 3The New Zealand Institute for Plant & Food Research Ltd, Te Puke, New Zealand. 4Horticulture & Forestry Science, Department of Agriculture & Fisheries, Brisbane, Australia. 5The New Zealand Institute for Plant & Food Research Ltd, Auckland, New Zealand

Abstract

At least nine strains of Austropuccinia psidii (the myrtle rust pathogen) are known to occur internationally. Most of these are found in Central and and specifically associated with hosts in the Myrtaceae family. However, two aggressive and unique strains has been reported outside the presumed native range of A. psidii. One strain, known as the pandemic strain, infects a wide spectrum of hosts and has an extensive geographical range. It has been found in Colombia, California, Hawaii, Indonesia, Australia, New Caledonia and more recently in New Zealand. The other myrtle rust strain occurs in South Africa, where it infects both native and introduced Myrtaceae. Knowledge regarding the level of susceptibility of native Myrtaceae to the different strains of A. psidii and the biology of the pathogen is essential to address the best management options for Myrtle rust in New Zealand. In this study, we considered the levels of resistance and/or susceptibility of four native New Zealand species (Leptospermum scoparium, Metrosideros excelsa, Kunzea linearis and K. robusta) to the South African strain of A. psidii. Seeds from geographically distant populations were collected for screening that was conducted in a greenhouse in South Africa. The results revealed interspecific variability in susceptibility to the South African A. psidii strain, with the Kunzea species more tolerant and/or resistant than the other tested species. This study demonstrated the potential threat that the South African A. psidii strain could have in native forests, nurseries and plantations in New Zealand.