Defense Related Phytohormones Regulation in Arbuscular Mycorrhizal Symbioses Depends on the Partner Genotypes

Abstract

Arbuscular mycorrhizal (AM) symbioses are mutualistic associations between soil fungi and most vascular plants. Modulation of the hormonal and transcriptional profiles, including changes related to defense signalling, has been reported in many host plants during AM symbioses. These changes have been often related to the improved stress tolerance common in mycorrhizal plants. However, results on the alterations in phytohormones content and their role on the symbiosis are controversial.Here, an integrative analysis of the response of phylogenetically diverse plants (i.e., tomato, soybean, and maize) to two mycorrhizal fungi -Funneliformis mosseae and Rhizophagus irregularis-was performed. The analysis of the defense-related hormones salicylic acid, abscisic acid, and jasmonates, and the expression of marker genes of the pathways they regulate, revealed significant changes in the roots of mycorrhizal plants. These changes depended on both the plant and the AM fungus (AMF) involved. However, general trends can be identified: roots associated with the most effective colonizer R. irregularis showed fewer changes in these defense-related traits, while the colonization by F. mosseae led to significant modifications in all plants tested. The up-regulation of the jasmonate pathway by F. mosseae was found to be highly conserved among the different plant species, suggesting an important role of jasmonates during this AM interaction. Our study evidences a strong influence of the AMF genotype on the modulation of host defense signalling, and offers hints on the role of these changes in the symbiosis.

Arbuscular Mycorrhizal Fungi Regulate the Growth and Phyto-Active Compound of Salvia miltiorrhiza Seedlings

“…AMF colonization can promote plant absorption of mineral elements [21], regulate the synthesis and distribution of plant hormones [22,23], ameliorate the microbial environment of the plant rhizosphere, and enhance plant resistance to disease [24,25]. Then, it can strengthen plant tolerance to environmental stress [26,27] and improve overall growth conditions of host plants [28].…”

Phosphorus supply, arbuscular mycorrhizal fungal species, and plant genotype impact on the protective efficacy of mycorrhizal inoculation against wheat powdery mildew

“…Castellanos-Morales et al (2012) showed that R. irregularis, F. mosseae, and Gigaspora rosea colonized barley roots to different extents, although the three AMF species reduced similarly root infection by Gaeumannomyces graminis. Several authors have mentioned that high AMF root colonization is not necessary for effective protection against fungal pathogens (Caron et al 1986;García-Garrido and Ocampo 1988;St-Arnaud et al 1997;Kapoor 2008;Castellanos-Morales et al 2012), while others have shown that protection against pathogens is linked to mycorrhizal colonization levels prior to the challenge with the pathogen (Cordier et al 1998;Slezack et al 2000;Khaosaad et al 2006;Fernández et al 2014). Nevertheless, some studies have reported that F. mosseae has a greater bioprotective effect than R. irregularis against pathogens (Pozo et al 2002;Shrinkhala 2011).…”

“…Nevertheless, some studies have reported that F. mosseae has a greater bioprotective effect than R. irregularis against pathogens (Pozo et al 2002;Shrinkhala 2011). Also, it has been shown that F. mosseae can induce changes in the balance of plant defense-related phytohormones, such as salicylic acid, abscisic acid, and jasmonates, to a greater extent than R. irregularis (Fernández et al 2014).…”

Mycorrhizal symbiosis and growth of sorghum plants irrigated with saline water

“…Inoculation with Mycorriza INIFAP was where the most promotion in plant height, stem diameter and shoot and root biomass was recorded, in relation to Burize ST and the control, despite the fact both inoculants are formed with R. intraradices. The contribution of AMF to increased plant biomass is linked to the mechanism that leads to the production of phytohormones (Jindal et al, 1993;Smith & Read, 2008), although its modulation is due to the genotype-AMF strain interaction Fernández et al, 2014). Tian et al (2004) concluded that leaf biomass in cotton had a different effect when the symbiosis of two AMF strains of the same species was compared.…”

“…La inoculación con Micorriza INIFAP, fue donde se registró la mayor promoción en altura de planta, diámetro de tallo, biomasa aérea y radical, en relación con Burize ST y testigo, no obstante a que ambos inoculantes están conformados con R. intraradices. La contribución de los HMA al aumento de la biomasa vegetal, se encuentra ligado al mecanismo que conlleva la producción de fitohormonas (Jindal et al, 1993;Smith & Read, 2008), aunque su modulación obedece a la interacción genotipo-cepa HMA (Fernández et al, 2014). Tian et al (2004) concluyeron que la biomasa foliar en algodón tuvo un efecto diferente cuando comparó la simbiosis de dos cepas de HMA de la misma especie.…”