Identification of candidate genes conferring tolerance to aluminum stress in Pinus massoniana inoculated with ectomycorrhizal fungus

Abstract

Background Pinus massoniana Lamb. is an important afforestation tree species with high economic, ecological and medicinal values. Aluminum (Al) toxicity driven by soil acidification causes dieback of P. massoniana plantations. Previous studies showed that ectomycorrhizal fungi alleviate Al stress damages in Pinus, but the underlying molecular mechanisms and key genes induced by ectomycorrhizal fungi inoculation under Al stress in Pinus have not been explored. Herein, we applied Al stress for 60 days to P. massoniana seedlings inoculated with Suillus luteus (SL) and those non-inoculated. Then, we compared their growth parameters and transcriptome in order to detect candidate genes induced by SL conferring Al tolerance in P. massoniana. Result Our results showed that SL inoculation confers Al stress tolerance in P. massoniana through improved growth performance, strong antioxidant enzyme activities and reduced malondialdehyde accumulation as compared to non-inoculated seedlings. Transcriptome sequencing further supported these findings as very few genes (51 genes) were transcriptionally altered by Al in SL inoculated plants as compared to non-inoculated plants (2140 genes). We identified three core genes (cox1, cox3 and Nd1) that were strongly up-regulated by Al in the SL inoculated plants but were down-regulated in the non-inoculated plants. We also identified 42 genes specifically regulated by SL inoculated plants under Al stress, which are involved in a wide range of biological processes such as antioxidative response, transporters, hormone signaling and plant pathogen infection responses. Conclusions Altogether, our data suggest that SL inoculation induces priming of key stress response pathways and triggers specific genes that efficiently alleviate Al stress effects in P. massoniana. The candidate genes resources generated in this study are of utmost importance for functional characterization and molecular studies aiming at improving Al tolerance in plants.

Role of Ectomycorrhizal Symbiosis Behind the Host Plants Ameliorated Tolerance Against Heavy Metal Stress

“…The lower MDA content corresponds to the stronger antioxidant activities of an organism. The reduction in MDA content of host Pinus massoniana under Al stress has also been reported upon their inoculation with Suillus luteus compared to non-ECM plants ( Liu H. et al, 2020 ). It thus suggests the ECM-mediated improved antioxidant machinery of the host plant as one of the essential mechanisms for their enhanced HM tolerance.…”

Transcriptomic and metabolomic insights into the role of the <i>flgK</i> gene in the pathogenicity of <i>Pseudomonas plecoglossicida</i> to orange-spotted grouper (<i>Epinephelus coioides</i>)

“…Confirmation of RNA-seq results by qRT-PCR: Six up-regulated and six down-regulated DEGs were randomly selected from the RNA-seq results for validation by qRT-PCR and Pearson correlation analysis was performed to confirm the accuracy and repeatability of the RNA-seq data ( Liu et al, 2020a ). Expression levels of the orange-spotted grouper genes were standardized using β-actin ( Wang et al, 2020 ).…”

Mechanisms of stress tolerance and their effects on the ecology and evolution of mycorrhizal fungi

“…In addition, Suillus species are known for mediating and alleviating partner plant metal uptake. Species in the genus are known to confer Al, Cu, and Zn tolerance to pine plant partners (Adriaensen et al, 2005;Ruytinx et al, 2013;Liu et al, 2020) and can reduce metal transfer and accumulation in plant tissues (Adriaensen et al, 2005;Krznaric et al, 2009;Colpaert et al, 2011). Suillus-induced pine metal tolerance has been associated with specific differences in gene and protein expression.…”

“…Suillus-induced pine metal tolerance has been associated with specific differences in gene and protein expression. For example, when colonizing Pinus massoniana roots, S. luteus confers Al tolerance by triggering key stress pathways, including inducing transcriptomic and proteomic differences in antioxidative stress response, transport of substances, hormone signaling, and pathogen infection response (Liu et al, 2020(Liu et al, , 2021. Suillus luteus has also been shown to mediate plant Zn uptake.…”