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

Haiyan Liu,Haiyan Liu,Houying Chen,Kuaifen Li,Guijie Ding,Qifei Ren

doi:10.1186/s12870-020-02719-3

Abstract

BackgroundPinus 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.ResultOur 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.ConclusionsAltogether, 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.

Highlights

Pinus massoniana Lamb. is an important afforestation tree species with high economic, ecological and medicinal values
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
We found that inoculation with the ectomycorrhizal fungus species Suillus luteus (SL) promotes P. massoniana growth and imparts Al stress tolerance

Summary

Introduction

Pinus massoniana Lamb. is an important afforestation tree species with high economic, ecological and medicinal values. It contributes to meeting the growing demand of wood products and reduces pressures on natural forests and significantly contributes to restoration of degraded soils [7,8,9,10] Besides these economic and ecological values, several studies have demonstrated the pharmacological properties of P. massoniana bark and needles for the treatment of rheumatism, intestinal parasites, hypertension, neurasthenia, skin complaints and cancer [11,12,13,14]. It has been reported that ectomycorrhizal symbiosis establishment in the root system confers improved growth performance and tolerance to biotic and abiotic stress in host plants [20,21,22]. In Pinus, previous studies have shown that ectomycorrhizal fungi improve plant growth and tolerance to drought stress, salinity stress, low-phosphorous stress, heavy metals toxicity, etc. [4, 6, 25,26,27,28]

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