Transcriptome Analysis Revealed the Mechanisms Involved in Ultrasonic Seed Treatment-Induced Aluminum Tolerance in Peanut.

Gegen Bao,Xiaorong Wan,Shengyu Li,Qi Zhou,Umair Ashraf,Aimin Miao,Yixiong Zheng,Zhishang Cheng,Suihua Huang

doi:10.3389/fpls.2021.807021

Abstract

Ultrasonic (US) treatment is an efficient method to induce crop tolerance against heavy metal toxicity; however, US-induced aluminum (Al) tolerance in peanuts was rarely studied. This study was comprised of two treatments, namely, CK, without ultrasonic treatment, and US, an ultrasonic seed treatment, for 15 min. Both treated and non-treated treatments were applied with Al in the form of AlCl3.18H2O at 5 mmol L–1 in Hoagland solution at one leaf stage. Results depicted that plant height, main root length, and number of lateral roots increased significantly under US treatment. Transcriptome analysis revealed that plant hormone signal transduction and transcription factors (TFs) were significantly enriched in the differentially expressed genes (DEGs) in US treatment, and the plant hormones were measured, including salicylic acid (SA) and abscisic acid (ABA) contents, were substantially increased, while indole acetic acid (IAA) and jasmonic acid (JA) contents were decreased significantly in US treatment. The TFs were verified using quantitative real-time (qRT)-PCR, and it was found that multiple TFs genes were significantly upregulated in US treatment, and ALMT9 and FRDL1 genes were also significantly upregulated in US treatment. Overall, the US treatment induced the regulation of hormone content and regulated gene expression by regulating TFs to improve Al tolerance in peanuts. This study provided a theoretical rationale for US treatment to improve Al tolerance in peanuts.

Highlights

As much as 40–50% of the potentially arable lands are acidic in the world, and more than 40% of the arable lands in China are acidic soil, distributed in South China, with a total area of 2.04 × 107 km, including Guangdong Province (Kochian et al, 2015; Li, 2019)
We have found that the expression of the ALMT9 gene was significantly upregulated under US treatment (Figure 3A), indicating that US treatment could increase the expression of the FRDL1 and ALMT9 genes to increase the external Al excretion mechanism of peanut
This study found that the gene expression of many transcription factors (TFs) was upregulated under US treatment (Figure 7A), and the expression of ALMT9 and FRDL1 genes were upregulated

Summary

Introduction

As much as 40–50% of the potentially arable lands are acidic in the world, and more than 40% of the arable lands in China are acidic soil, distributed in South China, with a total area of 2.04 × 107 km, including Guangdong Province (Kochian et al, 2015; Li, 2019). When the soil was acidified (pH ≤ 5.5), Al3+ would be Peanut Aluminum Resistance released. The inorganic phosphorus was mainly iron phosphate and aluminum salt. The total phosphorus content of red soil was generally 0.01–0.03%, and the total potassium content was 0.9–0.4%, respectively. In the second soil survey, the pH of the soil was mostly 6.0–6.5 in South China. The acidic red soil in this area was dominated by kaolin. The growth and development of peanuts had been impaired by Al toxicity for a long time in South China, and the average yield had been reduced by more than 20% which is the most important reason for low peanut yield in this region than the national average (Zhang et al, 2009; Zhang and Hu, 2020)

Methods

Results

Discussion

Conclusion