Mutation of GmAITR Genes by CRISPR/Cas9 Genome Editing Results in Enhanced Salinity Stress Tolerance in Soybean

Tianya Wang; Hongwei Xun; Wei Wang; Xiaoyang Ding; Hainan Tian; Saddam Hussain; Qianli Dong; Yingying Li; Yuxin Cheng; Chen Wang; Rao Lin; Guimin Li; Xueyan Qian; Jinsong Pang; Xianzhong Feng; Yingshan Dong; Bao Liu; Shucai Wang

doi:10.3389/fpls.2021.779598

Mutation of GmAITR Genes by CRISPR/Cas9 Genome Editing Results in Enhanced Salinity Stress Tolerance in Soybean

Front Plant Sci. 2021 Nov 26:12:779598. doi: 10.3389/fpls.2021.779598. eCollection 2021.

Authors

Tianya Wang¹, Hongwei Xun^{1

2}, Wei Wang³, Xiaoyang Ding², Hainan Tian¹, Saddam Hussain¹, Qianli Dong¹, Yingying Li¹, Yuxin Cheng¹, Chen Wang¹, Rao Lin¹, Guimin Li³, Xueyan Qian², Jinsong Pang¹, Xianzhong Feng⁴, Yingshan Dong², Bao Liu¹, Shucai Wang³

Affiliations

¹ Key Laboratory of Molecular Epigenetics of MOE, Northeast Normal University, Changchun, China.
² National Engineering Research Center for Soybean, Soybean Research Institute, Jilin Academy of Agricultural Sciences, Changchun, China.
³ Laboratory of Plant Molecular Genetics and Crop Gene Editing, School of Life Sciences, Linyi University, Linyi, China.
⁴ Key Laboratory of Soybean Molecular Design Breeding, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, China.

Abstract

Breeding of stress-tolerant plants is able to improve crop yield under stress conditions, whereas CRISPR/Cas9 genome editing has been shown to be an efficient way for molecular breeding to improve agronomic traits including stress tolerance in crops. However, genes can be targeted for genome editing to enhance crop abiotic stress tolerance remained largely unidentified. We have previously identified abscisic acid (ABA)-induced transcription repressors (AITRs) as a novel family of transcription factors that are involved in the regulation of ABA signaling, and we found that knockout of the entire family of AITR genes in Arabidopsis enhanced drought and salinity tolerance without fitness costs. Considering that AITRs are conserved in angiosperms, AITRs in crops may be targeted for genome editing to improve abiotic stress tolerance. We report here that mutation of GmAITR genes by CRISPR/Cas9 genome editing leads to enhanced salinity tolerance in soybean. By using quantitative RT-PCR analysis, we found that the expression levels of GmAITRs were increased in response to ABA and salt treatments. Transfection assays in soybean protoplasts show that GmAITRs are nucleus proteins, and have transcriptional repression activities. By using CRISPR/Cas9 to target the six GmAITRs simultaneously, we successfully generated Cas9-free gmaitr36 double and gmaitr23456 quintuple mutants. We found that ABA sensitivity in these mutants was increased. Consistent with this, ABA responses of some ABA signaling key regulator genes in the gmaitr mutants were altered. In both seed germination and seedling growth assays, the gmaitr mutants showed enhanced salt tolerance. Most importantly, enhanced salinity tolerance in the mutant plants was also observed in the field experiments. These results suggest that mutation of GmAITR genes by CRISPR/Cas9 is an efficient way to improve salinity tolerance in soybean.

Keywords: ABA; CRISPR/Cas9; GmAITRs; genome editing; salinity tolerance; soybean.