AMF community diversity promotes grapevine growth parameters under high black foot disease pressure

Black foot disease is one of the main grapevine root diseases observed worldwide and is especially problematic in New Zealand. Arbuscular mycorrhizal fungi (AMF) have been shown to reduce infection and mitigate the effect of black foot disease on grapevine rootstocks. In contrast to prior studies, which have limited their focus to the effect of one, two or a combination of only a small number of AMF species, this study used whole AMF communities identified from 101-14, 5C and Schwarzmann rootstocks sampled from New Zealand vineyards. The effect of AMF on black foot disease was investigated in a ‘home’ and ‘away’ experiment using three commercial grapevine rootstocks. The study produced some evidence that AMF treatments lowered disease incidence at 5 cm and disease severity in vines by 40% to 50% compared to the vines inoculated with the pathogen only. This work also showed that the presence of high disease incidence may have limited the potential disease protective effect of AMF community. However, despite the high disease incidence and severity, AMF inoculation increased vine growth parameters by 60% to 80% compared to the vines inoculated with the pathogen only. This study is the first to provide an understanding on how young grapevine rootstocks inoculated with their ‘home’ and ‘away’ AMF communities would respond to challenge with a black foot pathogen species mixture. Further research is required to understand the mechanistic effect of AMF colonization on the increase of grapevine growth parameters under high black foot disease pressure

Les lactaires à lait rouge : Mycorhization contrôlée des pins et caractérisation moléculaire. Application à l'étude de la compétence écologique et de la compétitivité d'isolats de Lactarius deliciosus

*INRA, Centre de Montpellier (FRA) Diffusion du document : INRA, Centre de Montpellier (FRA) Diplôme : Dr. Ing

Effects of experimental conditions on mycorrhizal relationships between Pinus sylvestris and Lactarius deliciosus and unprecedented fruit-body formation of the Saffron milk cap under controlled soilless conditions

International audienc

Grapevine rootstocks drive the community structure of arbuscular mycorrhizal fungi in New Zealand vineyards

Aim: Arbuscular mycorrhizal fungi (AMF) are often regarded as non-specific symbionts, but some AMF communities show host preference in various ecosystems including vineyards. Grapevine plants are very responsive to AMF colonization. Although these fungi have potentially significant applications for sustainable agricultural ecosystems, there is a gap in knowledge regarding AMF–grapevine interactions worldwide and especially in New Zealand. This study focused on identifying AMF taxa colonizing grapevines in New Zealand vineyards and investigated the effect of grapevine rootstocks on AMF community diversity and composition. Methods and Results: Denaturing gradient gel electrophoresis (DGGE) and trap cultures were used to characterize the AMF communities. Grapevine roots from three vineyards and nine rootstocks were analysed by DGGE and used in trap cultures for AMF recovery. Trap cultures allowed the recovery of six AMF spore morphotypes that belonged to Ambispora sp., Claroideoglomus sp., Funneliformis sp. and Glomus sp. Bands excised, reamplified and sequenced from the DGGE were assigned to Glomus sp., Rhizophagus sp. and Claroideoglomus sp. The AMF community analyses demonstrated that rootstock significantly (P < 0·05) influenced the AMF community composition in all sites. Conclusions: The study showed that for a comprehensive identification of AMF, both results from trap culture and molecular work were needed and that the rootstock cultivar was the main driver of the arbuscular mycorrhizal community colonizing the roots. Significance and Impact of the Study: This study provides a firm foundation for future research exploring the beneficial use of AMF in enhancing grapevine production and sustainability

Effect of arbuscular mycorrhizal fungal communities on growth and nutrient uptake by grapevine rootstocks

Aim: Arbuscular mycorrhizal fungi (AMF) have been shown to have potentially significant applications for sustainable agricultural ecosystems. Yet, there is still lack of evidence showing how different AMF community compositions can benefit grapevines. Therefore, this study is the first to investigate the different responses of grapevine rootstock following their inoculation with different AM fungal communities. Methods: AMF communities were initially identified based on spore extracted from trap cultures and DNA extracted from roots. A glasshouse experiment was then set up to determine the interaction between rootstock variety and different AMF communities using AMF communities originating under their own (i.e., ‘home’) soil and other rootstocks’ (i.e., ‘away’) soil. Plant growth and physiological responses were measured and assessed. Results: This study showed that distinct AMF communities had differential effects on grapevine rootstock growth and nutrient uptake. It was revealed that a rootstock performed better in the presence of its “home” AMF community. Moreover, the AMF communities had a significant direct effect by increasing plant biomass and nutrient uptake and indirectly by influencing the chlorophyll content in grapevine leaves through the increase of specific nutrients such as K, Mn, and Zn. Also, the presence of different species in the different communities indicated that some AMF species may deliver particular benefits to grapevine plants. Conclusion: This work has enhanced our understanding of community level AMF-grapevine interaction and provided additional insight of the ecosystem services they deliver which will be of advantage to the wine growers and the viticulture industry

The mycorrhizal fungus Tricholoma matsutake stimulates Pinus densiflora seedling growth in vitro

International audienc

Saprobic potential of Tricholoma matsutake: growth over pine bark treated with surfactants

International audienc

AMF community diversity identification and their effects on grapevine growth parameters under black foot disease pressure

Arbuscular mycorrhizal fungi (AMF) have potentially significant applications for sustainable agricultural ecosystems. AMF have been also shown to reduce infection and mitigate the effect of black foot disease on grapevine rootstocks. However, limited information is available regarding AMF grapevine interactions worldwide and especially in New Zealand. Moreover, most studies to date have researched the effect of one, two or a combination of only a small number of AMF species on fungal pathogens associated with grapevines. Therefore, this work aimed to (i) characterise the AMF community diversity associated with different commercial grapevine rootstocks sampled from New Zealand vineyards, (ii) investigate the beneficial effect of AMF community on grapevine growth parameters, and (iii) evaluate how young grapevine rootstocks inoculated with their ‘home’ and ‘away’ whole AMF communities would respond to challenges with a black foot pathogen species mixture. The AMF communities identified from these rootstocks were assigned to Ambispora spp., Claroideoglomus spp., Funneliformis spp. and Glomus spp. The community analyses demonstrated that rootstock significantly influenced the AMF community composition in all sites. The findings of the second part of experiment showed that the AMF communities had a significant direct effect by increasing plant biomass and nutrient uptake and indirectly by influencing the chlorophyll content in grapevine leaves through the increase of specific nutrients such as K, Mn, and Zn. The outcome of the third part of experiment revealed that high disease incidence and severity did not reduce growth in vines with AMF inoculation compared to vines inoculated with the pathogen only. It also showed that the high level of disease present in rootstocks limited the effect of the AMF community with only little evidence that AMF treatments lowered disease incidence and severity in vines. Further research is required to understand the mechanistic effect of AMF colonisation on plant growth parameter especially under high disease pressure

An improved clearing and staining protocol for evaluation of arbuscular mycorrhizal colonisation in darkly pigmented woody roots

Arbuscular mycorrhizal fungi (AMF) establish symbiotic interactions with the roots of vascular plants, including grapevines. Verifying AMF colonisation routinely requires establishing the presence of hyphae, arbuscules and vesicles. Clearing roots with potassium hydroxide (KOH) followed by staining with trypan blue has been used previously to visualise fungal structures, however visualisation is difficult with darkly pigmented roots, such as those of grapevines so additional steps are required to ensure clear visualisation. Three fixing and clearing processes were evaluated prior to staining with trypan blue: 1) fixing grapevine roots in 70% v/v ethanol overnight; 2) clearing by heating the roots in either 2% or 10% w/v KOH; and 3) clearing the roots in 3% v/v hydrogen peroxide for 10 min. Roots were examined under a compound light microscope for the presence of AMF. A combination of fixing grapevine roots in 70% ethanol overnight and clearing by autoclaving in 10% KOH produced the greatest enhancement in subsequent staining of grapevine roots with trypan blue overnight. The best method tested enabled the discrimination of arbuscular mycorrhizal structures in fresh roots of grapevines without the use of toxic chemical fixatives

Preliminary investigations on host preferences of arbuscular mycorrhizal fungi colonizing grapevine rootstocks in New Zealand

Grape production and quality are strongly dependent on soil conditions and composition (1). Grapevine plants are normally mycorrhizal, establishing an interaction with arbuscular mycorrhizal fungi (AMF). These fungi are obligate biotrophs and establish a mutually beneficial relationship when penetrating inside the cortex of plant roots (2). Environmental factors and host plant species could impact the distribution and the composition of AMF communities (3, 4). While AMF are generally regarded as non-specific symbionts, preferred associations between specific fungi and plant species occur in various ecosystems, including vineyards. Due to difficulties in culturing and identifying mycorrhizae, there is a significant knowledge gap regarding the AMF communities associated with grapevines in New Zealand. In this paper, we present preliminary results on the morphological identification and diversity of grapevine AMF communities recovered from a root trap system under controlled conditions