Pathogenicity and molecular detection of nectriaceous fungi associated with black root rot of avocado

Black root rot of avocado associated with soilborne nectriaceous fungi is an aggressive disease of nursery trees and young orchards transplants, causing tree stunting, wilt, severe root necrosis, rapid decline and death within a year after planting. This study aimed to identify the fungal genera associated with the disease, determine the causal agents of black root rot, and develop a rapid molecular test for detection of key pathogens in avocado roots. A disease survey in all Australian growing regions collected 153 nectriaceous fungal isolates from roots of 91 symptomatic and healthy avocado trees and other hosts including peanut, papaya, blueberry, custard apple and grapevine. The fungal isolates were identified with phylogenetic analyses of ITS, β-tubulin and Histone H3 sequenced genes. Six genera were found associated with black root rot; Calonectria, Cylindrocladiella, Dactylonectria, Gliocladiopsis, Ilyonectria and Mariannaea. Glasshouse pathogenicity tests on 3–6 month-old avocado cv. Reed seedlings determined Calonectria ilicicola to be an aggressive pathogen, causing stunting and death within 5 weeks of inoculation. C. ilicicola isolated from peanut, papaya and custard apple also caused black root rot in avocado, demonstrating a broad host range. Calonectria sp. from blueberry and Dactylonectria macrodidyma, D. novozelandica, D. pauciseptata and D. anthuriicola from avocado caused significant root rot but not stunting within 5–9 weeks. Ilyonectria sp. from grapevine, and Cylindrocladiella pseudoinfestans, Gliocladiopsis peggii and Ilyonectria sp. isolates from avocado were determined to be non-pathogenic. Three loopmediated isothermal amplification (LAMP) assays were developed for the detection of C. ilicicola, D. macrodidyma and the Dactylonectria genus. The assays were sensitive and specific at DNA concentrations of 1 pg/µl, 0.01 ng/µl and 0.1ng/µl for C. ilicicola, D. macrodidyma, and Dactylonectria spp. respectively. Detection in avocado roots averaged from 12–26 min for C. ilicicola and D. macrodidyma and 14–30 min for Dactylonectria spp

Fungal Planet description sheets: 1383-1435

Novel species of fungi described in this study include those from various countries as follows: Australia, Agaricus albofoetidus, Agaricus aureoelephanti and Agaricus parviumbrus on soil, Fusarium ramsdenii from stem cankers of Araucaria cunninghamii, Keissleriella sporoboli from stem of Sporobolus natalensis, Leptosphaerulina queenslandica and Pestalotiopsis chiaroscuro from leaves of Sporobolus natalensis, Serendipita petricolae as endophyte from roots of Eriochilus petricola, Stagonospora tauntonensis from stem of Sporobolus natalensis, Teratosphaeria carnegiei from leaves of Eucalyptus grandis x E. camaldulensis and Wongia ficherai from roots of Eragrostis curvula. Canada, Lulworthia fundyensis from intertidal wood and Newbrunswickomyces abietophilus (incl. Newbrunswickomyces gen. nov.)on buds of Abies balsamea. Czech Republic, Geosmithia funiculosa from a bark beetle gallery on Ulmus minor and Neoherpotrichiella juglandicola (incl. Neoherpotrichiella gen. nov.)from wood of Juglans regia. France, Aspergillus rouenensis and Neoacrodontium gallica (incl. Neoacrodontium gen. nov.)from bore dust of Xestobium rufovillosum feeding on Quercus wood, Endoradiciella communis (incl. Endoradiciella gen. nov.)endophyticin roots of Microthlaspi perfoliatum and Entoloma simulans on soil. India, Amanita konajensis on soil and Keithomyces indicus from soil. Israel, Microascus rothbergiorum from Stylophora pistillata. Italy, Calonarius ligusticus on soil. Netherlands , Appendopyricularia juncicola (incl. Appendopyricularia gen. nov.), Eriospora juncicola and Tetraploa juncicola on dead culms of Juncus effusus, Gonatophragmium physciae on Physcia caesia and Paracosmospora physciae (incl. Paracosmospora gen. nov.)on Physcia tenella, Myrmecridium phragmitigenum on dead culm of Phragmites australis, Neochalara lolae on stems of Pteridium aquilinum, Niesslia nieuwwulvenica on dead culm of undetermined Poaceae, Nothodevriesia narthecii (incl. Nothodevriesia gen. nov.) on dead leaves of Narthecium ossifragum and Parastenospora pini (incl. Parastenospora gen. nov.)on dead twigs of Pinus sylvestris. Norway, Verticillium bjoernoeyanum from sand grains attached to a piece of driftwood on a sandy beach. Portugal, Collybiopsis cimrmanii on the base of living Quercus ilex and amongst dead leaves of Laurus and herbs. South Africa , Paraproliferophorum hyphaenes (incl. Paraproliferophorum gen. nov.) on living leaves of Hyphaene sp. and Saccothecium widdringtoniae on twigs of Widdringtonia wallichii. Spain, Cortinarius dryosalor on soil, Cyphellophora endoradicis endophytic in roots of Microthlaspi perfoliatum, Geoglossum laurisilvae on soil, Leptographium gemmatum from fluvial sediments, Physalacria auricularioides from a dead twig of Castanea sativa , Terfezia bertae and Tuber davidlopezii in soil. Sweden, Alpova larskersii, Inocybe alpestris and Inocybe boreogodeyi on soil. Thailand, Russula banwatchanensis, Russula purpureoviridis and Russula lilacina on soil. Ukraine, Nectriella adonidis on over wintered stems of Adonis vernalis. USA, Microcyclus jacquiniae from living leaves of Jacquinia keyensis and Penicillium neoherquei from a minute mushroom sporocarp. Morphological and culture characteristics are supported by DNA barcodes

Online identification guides for Australian smut fungi (Ustilaginomycotina) and rust fungi (Pucciniales)

Interactive identification keys for Australian smut fungi (Ustilaginomycotina and Pucciniomycotina, Microbotryales) and rust fungi (Pucciniomycotina, Pucciniales) are available online at http://collections.daff.qld.gov.au. The keys were built using Lucid software, and facilitate the identification of all known Australian smut fungi (317 species in 37 genera) and 100 rust fungi (from approximately 360 species in 37 genera). The smut and rust keys are illustrated with over 1,600 and 570 images respectively. The keys are designed to assist a wide range of end-users including mycologists, plant health diagnosticians, biosecurity scientists, plant pathologists, and university students. The keys are dynamic and will be regularly updated to include taxonomic changes and incorporate new detections, taxa, distributions and images. Researchers working with Australian smut and rust fungi are encouraged to participate in the on-going development and improvement of these keys