EAPSI: Identifying Fungi Associated with the Ancient Conifer Agathis Australis and Testing their Potential as Biological Control Agents against Harmful Pathogen

Jackson Lauren W, St. Paul MN

Investigators

Abstract

Kauri (Agathis australis) are economically and culturally important trees that are native to New Zealand and are currently threatened by a devastating soil pathogen that causes a disease known as kauri dieback. In collaboration with Dr. Maj Padamsee of Landcare Research in Auckland, New Zealand, who has expertise working with kauri dieback and fungi that associate with kauri, this work aims to (1) identify beneficial fungi that associate with the roots of kauri; and (2) evaluate their potential to inhibit infection or slow the progression of the pathogen. The network formed to complete this work will be beneficial for professional development and future international collaborations. Findings from this research have the potential to improve control methods for kauri dieback and diseases caused by similar pathogens such as sudden oak death, soybean root rot and cocoa black pod disease that threaten economically and culturally important trees in other regions around the globe. Agathis australis (Araucariaceae), commonly referred to as kauri, is an ancient, long-lived, economically important and culturally significant conifer that is endemic to New Zealand. Kauri have been reduced from 1.6 million hectares to only ca. 7500 hectares since European arrival and the remaining trees are currently threatened by Phytophthora agathicida, an oomycete pathogen that causes a devastating collar rot known as kauri dieback. Padamsee and colleagues characterized mycorrhizal associations with kauri roots and found evidence of dark septate endophytes (DSEs) also being present in association with the roots via microscopic analyses. The scope of the present work is to (1) identify kauri-associated DSE fungi at the species level by sequencing their internal transcribed spacer (ITS) regions; and (2) evaluate the potential of DSE fungi to inhibit vegetative growth and spore germination rates of P. agathicida via two in vitro inhibition assays. Results from this investigation may serve as the basis for biocontrol methods that can be applied to kauri dieback and other important diseases that are caused by Phytophthora spp. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Royal Society of New Zealand.