In vitro interaction studies between Glomus intraradices and Armillaria mellea in vines

Abstract

An interaction study was performed with mycorrhizal plants of the grapevine rootstock Richter 110 (Vitis berlandieri Planch × Vitis rupestris Scheele) and the root pathogenic fungus Armillaria mellea (Vahl:Fr.) P. Kumm using an autotrophic in vitro culture system. Micropropagated plantlets were transferred to Petri plates with MSR medium lacking sugar and vitamins. Inocula of Glomus intraradices (BEG 72) and of Armillaria mellea obtained from a root organ culture and from a mycelium colony grown in malt agar respectively, were added to the plates according to each treatment: non-inoculated, inoculated with G. intraradices, inoculated with A. mellea, and dual-inoculated plants. There were ten replicates per treatment. Fourteen weeks later, the pathogen's mycelium occupied most of the surface/volume of the plate and had produced rhizomorphs. In dual inoculated plates, A. mellea's growth was not affected by the presence of G. intraradices, but the latter produced a lower number of spores and its extraradical phase showed granulation, vacuolation and tip swelling. The pathogen induced necrosis and growth decrease in the root. Glomus intraradices alleviated these symptoms and there were no differences in root biomass between non-inoculated plants and plants inoculated with both fungi. There were no symptoms of the disease in shoots and G. intraradices stimulated shoot growth both, although mycorrhizal colonization was lower when A. mellea was present. No direct antagonism or antibiosis against the pathogen was observed, thus the protective effect exerted by the symbiotic fungus in grapevines must be indirect, mediated through the host plant physiology.Additional key words: control, disease symptoms, grapevine, in vitro culture, root pathogenic fungi, tolerance. Resumen Estudios de interacción in vitro entre el hongo formador de micorrizas arbusculares Glomus intraradices y el hongo patógeno Armillaria mellea en vidSe estudió la interacción entre plantas micorrizadas del portainjerto de vid 110 Richter (Vitis berlandieri Planch × Vitis rupestris Scheele) y Armillaria mellea (Vahl:Fr.) P. Kumm en cultivo autotrófico in vitro. Plantas micropropagadas fueron transferidas a placas de Petri con medio MSR sin azúcar ni vitaminas. Inóculo de Glomus intraradices Schenck and Smith (BEG 72) obtenido a partir de un cultivo axénico de raíces transformadas micorrizadas, e inócu-lo de A. mellea obtenido en medio agar-malta, se añadieron a las placas según tratamiento: no inoculado, inoculación con G. intraradices, inoculación con A. mellea e inoculación combinada, estableciéndose 10 réplicas por tratamiento. Catorce semanas después, el micelio del hongo patógeno ocupaba casi la totalidad de la superficie/volumen de la placa y había producido rizomorfos. En placas con inoculación mixta, el desarrollo de A. mellea no se vio afectado por la presencia de G. intraradices, mientras que éste produjo menos esporas, y su fase extraradical presentaba granulaciones, vacuolaciones y engrosamientos en las terminaciones. El patógeno indu...

Role of the arbuscular mycorrhizal symbiosis in tolerance response against Armillaria mellea in lavender

“…Using an in vitro system to study the interaction between white root rot infection caused by A. mellea and Glomus intraradices in the grapevine rootstock 110 Richter, Nogales et al (2010) showed a decrease in disease symptoms in mycorrhizal plants, confirming that the root colonization by a mycorrhizal fungus increased tolerance to white root rot, as reported in vineyard trials with mycorrhizal plants conducted by the same authors (Camprubi et al, 2008;Nogales et al, 2009). The AMF Glomus mosseae lowered mortality by Fusarium in basil (Ocimum basilicum L.), a plant species from the same family as lavender, and that effect was not related to P contents, which were similar in non-mycorrhizal and mycorrhizal plants (Toussaint et al, 2008).…”

“…Under such conditions, the root can be colonized by an AMF monoxenically grown on Agrobacterium rhizogenestransformed roots in a root organ culture (ROC) (Declerck et al, 1996). In our experiment, the procedure followed to obtain the tripartite association (lavender plant-AMF-root rot fungus) was basically the same described by Nogales et al (2010) for grapevine plants.…”

“…Lavandula angustifolia plants (10±2 cm height) obtained from rooted cuttings were inoculated with Rhizophagus irregularis (former Glomus intraradices BEG 72) [(Blaszk., Wubet, Renker & Buscot) 3 Arbuscular mycorrhizas induce tolerance to white root rot tainer and the root inside the growing medium. At the same time, the inoculation with the AMF in mycorrhizal treatments was performed using a six-month old ROC culture in a bi-compartmented dish of R. irregularis (Nogales et al, 2010). Two 1-cm 2 plugs containing 100 to 150 mycorrhizal spores were excised from the compartment lacking roots and introduced next to the root tips, following the same procedure used for A. mellea plugs.…”

Endophytes vs tree pathogens and pests: can they be used as biological control agents to improve tree health?

“…Mycorrhizae can influence tree susceptibility and tolerance to economically important root pathogens such as Heterobasidion spp. and Armillaria mellea, even in the absence of direct antagonism of the pathogen by the endophyte (Gonthier et al 2019;Nogales et al 2010). Mycorrhizae are well recognized for their positive influence on tree growth and health so may antagonise pathogens via plant-mediated responses or ecologically through inhabiting the same niche, as is seen in other endophytes.…”

A faster inoculation assay forArmillariausing herbaceous plants

“…Furthermore, the conventional assays are extremely slow: preparation of woody inocula usually takes 3 to 6 months, the host plants require years to establish prior to inoculation, and then assessment of disease often lasts several years (Cleary et al, 2013;Morrison, 2004;Shaw, MacKenzie, Toes, & Hood, 1981;Solla et al, 2011). Inoculation assays using alternative hosts or other types of inocula such as rhizomorphs or wood chips (Holdenrieder, 1987;Pellegrini et al, 2014;Perez-Sierra & Gorton, 2005) are not well established and whilst the available in vitro assays are useful in that they are faster (Baumgartner, Bhat, & Fujiyoshi, 2010;Baumgartner, Fujiyoshi, Browne, Leslie, & Kluepfel, 2013;Nogales, Camprubí, Estaún, Marfà, & Calvet, 2010), they involve the preparation of tissue cultured material and substantial microscopy and molecular work. For these reasons, a faster inoculation assay that could be conducted under controlled conditions requires limited preparation and permits a simple assessment of infection would be desirable.…”