Modulation of Plant and Fungal Gene Expression Upon Cd Exposure and Symbiosis in Ericoid Mycorrhizal Vaccinium myrtillus

Abstract

The success of Ericaceae in stressful habitats enriched in heavy metals has been ascribed to the distinctive abilities of their mycorrhizal fungal partners to withstand heavy metal stress and to enhance metal tolerance in the host plant. Whereas heavy metal tolerance has been extensively investigated in some ericoid mycorrhizal (ERM) fungi, the molecular and cellular mechanisms that extend tolerance to the host plant are currently unknown. Here, we show a reduced Cd content in Cd-exposed mycorrhizal roots of Vaccinium myrtillus colonized by a metal tolerant isolate of the fungus Oidiodendron maius as compared to non-mycorrhizal roots. To better understand this phenotype, we applied Next Generation Sequencing technologies to analyze gene expression in V. myrtillus and O. maius Zn grown under normal and Cd-stressed conditions, in the free living and in the mycorrhizal status. The results clearly showed that Cd had a stronger impact on plant gene expression than symbiosis, whereas fungal gene expression was mainly regulated by symbiosis. The higher abundance of transcripts coding for stress related proteins in non-mycorrhizal roots may be related to the higher Cd content. Regulated plant metal transporters have been identified that may play a role in reducing Cd content in mycorrhizal roots exposed to this metal.

Metabolomic adjustments in the orchid mycorrhizal fungus Tulasnella calospora during symbiosis with Serapias vomeracea

“…(2020) 228: 1939-1952 Ó 2020 The Authors New Phytologist Ó 2020 New Phytologist Trust www.newphytologist.com Although we cannot exclude the possibility that the conditions required to grow symbiotic and asymbiotic fungal mycelia had some influence on the metabolite profile, the major changes of metabolite profiles seen in MYC were most likely driven by protocorms. Previous studies on ericoid mycorrhiza revealed that the symbiotic interaction is a major determinant of transcriptomic changes in the fungus, much larger than environmental growth conditions (Casarrubia et al, 2020). In the OM symbiosis, all organic nutrients needed by the protocorms are thought to be provided by the fungus.…”

Advances in “Omics” Approaches for Improving Toxic Metals/Metalloids Tolerance in Plants

“…MicroRNAs have been reported to play a significant role in plant response and tolerance to toxic metals/metalloids stress by regulating chelation, antioxidant response, auxin signaling, and cytokinin signaling, among others ( Ding et al, 2020 ). For instance, Casarrubia et al (2020) reported microRNA to play a significant role in combination with the mycorrhizal association for regulating the response of Vaccinium myrtillus against Cd contamination. MicroRNA expression in terms of biosynthesis/biogenesis of various secondary metabolites has been found to play a major role in enhancing Al and Cd tolerance in transgenic tobacco ( Cedillo-Jimenez et al, 2020 ).…”

The role of zinc to mitigate heavy metals toxicity in crops

“…MicroRNAs play an appreciable role in metal tolerance by regulating plant's anti-oxidant responses, chelations, and auxin and cytokinin signaling (Ding et al, 2020). For example, Casarrubia et al (2020) noted that microRNA in combination with mycorrhizal plays a significant role in Vaccinium myrtillus in response to Cd stress. MicroRNA expression in the perspective of biosynthesis of secondary metabolites significantly improved the aluminum (Al) and Cd tolerance in tobacco (Cedillo-Jimenez et al, 2020).…”