Response of mycorrhizal grapevine to Armillaria mellea inoculation: disease development and polyamines

Abstract

A study was conducted with the vine rootstock Richter 110 (Vitis berlandieri Planch. x Vitis rupestris L.) in order to assess whether the colonisation by the arbuscular mycorrhizal fungus (AMF) Glomus intraradices (BEG 72) can delay the disease development in plants inoculated with the root-rot fungus Armillaria mellea (Vahl:Fr) Kummer, and to elucidate if the levels of polyamines (PAs) are modified in response to G. intraradices, A. mellea or by the dual infection. Four treatments were considered: control and G. intraradices-inoculated plants infected or not with A. mellea. Plant growth, mycorrhizal colonisation and disease development were monitored throughout the experiment. High performance liquid chromatography (HPLC) in combination with fluorescence spectrophotometry was used to separate and quantify free root and leaf polyamines. The slower development of pathogenic symptoms and the higher plant biomass of mycorrhizal plants inoculated with A. mellea indicate an increase of tolerance due to the AMF inoculation. The variations in free PA levels detected at the beginning of the pathogenic infection suggest that PAs may have a potential role in the signalling mechanisms of the tolerance of mycorrhizal plants against A. mellea.

Managing arbuscular mycorrhizal fungi for bioprotection: Mn toxicity

“…Our results clearly indicate that AM colonization can protect wheat against Mn toxicity, confirming earlier findings (Nogueira and Cardoso, 2002). However, in our study the protection depended on the presence of an intact ERM when wheat was sown.…”

“…Nevertheless, such communities seem to exhibit a greater potential for protection (Tchabi et al, 2010). The great diversity of the microbial population present in the mycorrhizosphere (Toljander et al, 2007) also plays an important role in protecting against biotic (Neeraj and Singh, 2011;Siasou et al, 2009) and abiotic stresses (Nogueira and Cardoso, 2002). Despite the complexity of all these interactions, it is recognized that a well-established AM is crucial for an adequate degree of protection (Khaosaad et al, 2007;Garg and Chandel, 2010).…”

“…Despite the complexity of all these interactions, it is recognized that a well-established AM is crucial for an adequate degree of protection (Khaosaad et al, 2007;Garg and Chandel, 2010). The mycorrhiza must be created and be wellestablished before contact with the stressor, to achieve a high level of protection (Rufyikiri et al, 2000;Petit and Gubler, 2006;Nogales et al, 2009). However, under field conditions, when the stressor is already present in the soil, the role of AMF in protection is challenged by the time required to achieve an adequate level of AMF colonization, together with the cost associated with the largescale application of commercial inoculum (Sikora et al, 2008).…”

“…For cereals, concentrations of Mn in the shoots above 100 mg kg À1 are considered high (Walsh and Beaton, 1973). AMF species and the associated microbial population seem to have different abilities to protect the plants against Mn toxicity (Posta et al, 1994;Nogueira and Cardoso, 2002). The mechanisms of protection are not fully understood, but a reduction of Mn absorption in AM colonized plants has been reported (Nogueira et al, 2004(Nogueira et al, , 2007.…”

Dynamic response of ginsenosides in American ginseng to root fungal pathogens

“…Through the dramatic influence to surrounding soil, root pathogens could not only affect root growth, but also could affect the levels of phytochemicals in plants (Resendes et al 2008;Nogales et al 2009;Bais et al 2005). In our results, three ginsenosides, Rb 1 , Re and Rg 1 in ginseng roots, were influenced differently by soilborne pathogens F. solani and F. oxysporum-mediated infection.…”