College of Forestry, Guizhou University/Institute for Forest Resources & Environment of Guizhou, Guiyang, 550025, Guizhou, China.
Guizhou Botanical Garden, Guiyang, 550004, Guizhou, China.
BMC Plant Biol. 2020 Nov 16;20(1):521. doi: 10.1186/s12870-020-02719-3.
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.
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.
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.
马尾松是一种重要的造林树种，具有很高的经济、生态和药用价值。土壤酸化导致的铝（Al）毒性会导致马尾松人工林衰退。先前的研究表明，外生菌根真菌可以减轻 Pinus 中的 Al 胁迫损伤，但在 Al 胁迫下，外生菌根真菌接种诱导的 Pinus 分子机制和关键基因尚未得到探索。在此，我们用 Al 胁迫处理马尾松幼苗 60 天，这些幼苗接种了硫黄革裥菌（SL），而有些则没有接种。然后，我们比较了它们的生长参数和转录组，以检测由 SL 诱导的在 P. massoniana 中赋予 Al 耐受性的候选基因。
与未接种的幼苗相比，SL 接种通过提高生长性能、增强抗氧化酶活性和减少丙二醛积累，赋予 P. massoniana 对 Al 胁迫的耐受性。转录组测序进一步支持了这些发现，因为与未接种的植物相比，在 SL 接种的植物中，只有很少的基因（51 个基因）被 Al 转录改变（2140 个基因）。我们鉴定了三个核心基因（cox1、cox3 和 Nd1），它们在 SL 接种的植物中被 Al 强烈上调，但在未接种的植物中被下调。我们还鉴定了 42 个在 Al 胁迫下仅由 SL 接种的植物特异性调控的基因，这些基因涉及广泛的生物学过程，如抗氧化反应、转运蛋白、激素信号和植物病原体感染反应。
总的来说，我们的数据表明，SL 接种诱导关键应激反应途径的启动，并触发特定基因，有效地缓解 P. massoniana 中的 Al 胁迫效应。本研究中生成的候选基因资源对于提高植物 Al 耐受性的功能特征和分子研究至关重要。
