Hormonomic Changes Driving the Negative Impact of Broomrape on Plant Host Interactions with Arbuscular Mycorrhizal Fungi

Abstract

Belowground interactions of plants with other organisms in the rhizosphere rely on extensive small-molecule communication. Chemical signals released from host plant roots ensure the development of beneficial arbuscular mycorrhizal (AM) fungi which in turn modulate host plant growth and stress tolerance. However, parasitic plants have adopted the capacity to sense the same signaling molecules and to trigger their own seed germination in the immediate vicinity of host roots. The contribution of AM fungi and parasitic plants to the regulation of phytohormone levels in host plant roots and root exudates remains largely obscure. Here, we studied the hormonome in the model system comprising tobacco as a host plant, Phelipanche spp. as a holoparasitic plant, and the AM fungus Rhizophagus irregularis. Co-cultivation of tobacco with broomrape and AM fungi alone or in combination led to characteristic changes in the levels of endogenous and exuded abscisic acid, indole-3-acetic acid, cytokinins, salicylic acid, and orobanchol-type strigolactones. The hormonal content in exudates of broomrape-infested mycorrhizal roots resembled that in exudates of infested non-mycorrhizal roots and differed from that observed in exudates of non-infested mycorrhizal roots. Moreover, we observed a significant reduction in AM colonization of infested tobacco plants, pointing to a dominant role of the holoparasite within the tripartite system.

Arbuscular Mycorrhizal Fungi and Dry Raw Garlic Stalk Amendment Alleviate Continuous Monocropping Growth and Photosynthetic Declines in Eggplant by Bolstering Its Antioxidant System and Accumulation of Osmolytes and Secondary Metabolites

“…Furthermore, the incidence of Fusarium wilt was also reduced in AMF- and DRGS-treated eggplant. Our results are consistent with previous study of Ali M. et al (2021) and Mishev et al (2021) where AMF and garlic-derived allelochemicals regulated the phytohormones-signaling pathway and suppressed disease-causing pathogens in eggplant and tobacco. Furthermore, they also play an important role in regulating certain plant physiological responses, such as the antioxidant system, amino acid buildup, and soluble sugar levels ( Ali M. et al, 2021 ).…”

Population Response of Rhizosphere Microbiota of Garden Pea Genotypes to Inoculation with Arbuscular Mycorrhizal Fungi

“…Already mycorrhized plants have been found to secrete fewer signaling molecules of the strigolactone type required for AMF spore germination [ 30 , 63 , 64 ]. Our results showed a higher degree of AMF colonization of the roots of plants of the “afila” genotype and a decrease in the population density of Rhizobium bacteria.…”

Plant Systems Biology in 2022 and Beyond

“…resembled the exudates from infested plants without the AM fungus, whereas the exudates of non-infested plants colonized with R. irregularis were rather different. In particular, both roots and exudates from parasite infested plants not colonized with R. irregularis, and exudates from parasite infested plants colonized with R. irregularis showed elevated levels of ABA [6]. In contrast, tobacco plants that were not infested with Phelipanche spp.…”

“…In another study dedicated to biotic stress, Mishev et al (2021) investigated the plant hormonome in the tripartite system of tobacco (Nicotiana tabacum)-the arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis-and the parasite plant broomrape (Phelipanche spp.) [6]. Plant roots release chemical signals that stimulate the development of beneficial AM fungi but some parasitic plants utilize a few of these signals for their own germination and growth.…”

“…In these plants, the AM fungus R. irregularis was able to colonize the roots much better, suggesting that the parasite plant Phelipanche spp. has a high impact on the rhizosphere interactions of its host, since it is able to suppress the AM colonization [6] Genetic diversity plays a major role in plant responses to the environment and determines important agronomical traits and yield in crops. Nankar and Prat (2021) have studied the genetic diversity of six blue maize landraces located in North America [7].…”