As obligate biotrophs that colonize the roots of most land plants, arbuscular mycorrhizal fungi (AMF) are important members of the plant microbiota, since they are able to enhance host's nutrient acquisition. Some AMF possess endobacteria inside their cytoplasm, giving rise to a special type of endosymbiosis. Bacterial genome sequencing revealed a reduced genome and a dependence on the fungal host (Ghignone et al 2012, Torres et al..2015). Among them, Candidatus Glomeribacter gigasporarum (CaGg) has a positive influence on the physiology of its fungal host, the AMF Gigaspora margarita, rising its bioenergetic potential and enhancing its capability in detoxifying endogenous reactive oxygen species (Salvioli et al., 2016). Since a proteomic analysis revealed some changes in plant proteins which are markers of stress situations (Vannini et al, 2016), the purpose of this study was to verify whether the bacterial positive impact on the fungal physiology may be transmitted to the host plant. In order to test whether mycorrhizal plants were affected at transcriptional level depending on the endobacterial-fungal association, we performed an RNA-seq analysis of Lotus japonicus roots colonized by both the B+ (containing CaGg) and B- (without CaGg) G. margarita lines after 28 days. As expected, only a few genes (112) resulted to be differentially expressed: among them plant genes involved in hormones signaling, flavonoid biosynthesis and mineral exchange resulted to be sensitive to the presence or absence of the endobacterium inside the AMF. Interestingly, some genes involved in defense response to pathogens, such as PR10, were up-regulated in the B- colonized roots. The results suggest that endobacteria living inside the AM fungus may -directly or indirectly- influence the host plant responses.
Russian dolls: the transcriptional profile of Lotus japonicus mycorrhizal roots is affected not only by the fungus, but also by the fungal endobacterium
Ghignone S;
2016
Abstract
As obligate biotrophs that colonize the roots of most land plants, arbuscular mycorrhizal fungi (AMF) are important members of the plant microbiota, since they are able to enhance host's nutrient acquisition. Some AMF possess endobacteria inside their cytoplasm, giving rise to a special type of endosymbiosis. Bacterial genome sequencing revealed a reduced genome and a dependence on the fungal host (Ghignone et al 2012, Torres et al..2015). Among them, Candidatus Glomeribacter gigasporarum (CaGg) has a positive influence on the physiology of its fungal host, the AMF Gigaspora margarita, rising its bioenergetic potential and enhancing its capability in detoxifying endogenous reactive oxygen species (Salvioli et al., 2016). Since a proteomic analysis revealed some changes in plant proteins which are markers of stress situations (Vannini et al, 2016), the purpose of this study was to verify whether the bacterial positive impact on the fungal physiology may be transmitted to the host plant. In order to test whether mycorrhizal plants were affected at transcriptional level depending on the endobacterial-fungal association, we performed an RNA-seq analysis of Lotus japonicus roots colonized by both the B+ (containing CaGg) and B- (without CaGg) G. margarita lines after 28 days. As expected, only a few genes (112) resulted to be differentially expressed: among them plant genes involved in hormones signaling, flavonoid biosynthesis and mineral exchange resulted to be sensitive to the presence or absence of the endobacterium inside the AMF. Interestingly, some genes involved in defense response to pathogens, such as PR10, were up-regulated in the B- colonized roots. The results suggest that endobacteria living inside the AM fungus may -directly or indirectly- influence the host plant responses.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
