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Smith GR, Ganley BJ, Chagné D, Nadarajan J, Pathirana RN, Ryan J, Arnst EA, Sutherland R, Soewarto J, Houliston G, Marsh AT, Koot E, Carnegie AJ, Menzies T, Lee DJ, Shuey LS, Pegg GS. Resistance of New Zealand Provenance Leptospermum scoparium, Kunzea robusta, Kunzea linearis, and Metrosideros excelsa to Austropuccinia psidii. Plant Dis 2020; 104:1771-1780. [PMID: 32272027 DOI: 10.1094/pdis-11-19-2302-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Resistance to the pandemic strain of Austropuccinia psidii was identified in New Zealand provenance Leptospermum scoparium, Kunzea robusta, and K. linearis plants. Only 1 Metrosideros excelsa-resistant plant was found (of the 570 tested) and no resistant plants of either Lophomyrtus bullata or L. obcordata were found. Three types of resistance were identified in Leptospermum scoparium. The first two, a putative immune response and a hypersensitive response, are leaf resistance mechanisms found in other myrtaceous species while on the lateral and main stems a putative immune stem resistance was also observed. Both leaf and stem infection were found on K. robusta and K. linearis plants as well as branch tip dieback that developed on almost 50% of the plants. L. scoparium, K. robusta, and K. linearis are the first myrtaceous species where consistent infection of stems has been observed in artificial inoculation trials. This new finding and the first observation of significant branch tip dieback of plants of the two Kunzea spp. resulted in the development of two new myrtle rust disease severity assessment scales. Significant seed family and provenance effects were found in L. scoparium, K. robusta, and K. linearis: some families produced significantly more plants with leaf, stem, and (in Kunzea spp.) branch tip dieback resistance, and provenances provided different percentages of resistant families and plants. The distribution of the disease symptoms on plants from the same seed family, and between plants from different seed families, suggested that the leaf, stem, and branch tip dieback resistances were the result of independent disease resistance mechanisms.
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Affiliation(s)
- Grant R Smith
- The New Zealand Institute for Plant and Food Research Limited, Lincoln 7608, New Zealand
| | - Beccy J Ganley
- The New Zealand Institute for Plant and Food Research Limited, Te Puke 3182, New Zealand
| | - David Chagné
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North 4410, New Zealand
| | - Jayanthi Nadarajan
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North 4410, New Zealand
| | - Ranjith N Pathirana
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North 4410, New Zealand
| | - Julie Ryan
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North 4410, New Zealand
| | - Elise A Arnst
- Manaaki Whenua Landcare Research, Lincoln 7608, New Zealand
| | | | | | - Gary Houliston
- Manaaki Whenua Landcare Research, Lincoln 7608, New Zealand
| | - Alby T Marsh
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North 4410, New Zealand
| | - Emily Koot
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North 4410, New Zealand
| | - Angus J Carnegie
- Forest Science, Department of Primary Industries-Forestry, Parramatta, NSW 2150 Australia
| | - Tracey Menzies
- The Queensland Department of Agriculture and Fisheries, Brisbane, Queensland 4001, Australia
| | - David J Lee
- The University of the Sunshine Coast, Maroochydore, Queensland 4558, Australia
| | - Louise S Shuey
- The Queensland Department of Agriculture and Fisheries, Brisbane, Queensland 4001, Australia
| | - Geoff S Pegg
- The Queensland Department of Agriculture and Fisheries, Brisbane, Queensland 4001, Australia
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