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

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.

Advancing the protection of marine life through genomics

“…For example, to better understand acclimatory responses, the insertion and expression of the carp muscle form III of creatine kinase gene into the zebrafish genome allowed the transgenic fish to swim at low temperatures while the wild-type fish could not [ 53 ]. Knock-outs or overexpression of a gene may also enhance phenotypic traits, such as stress tolerance [ 54 , 55 ]. These emerging demonstrations of the tractability of gene editing in marine species provide important scientific knowledge and insight that may one day be used in natural systems.…”

CRISPR/Cas9 Technique for Temperature, Drought, and Salinity Stress Responses

“…Transgene-free Gmaitr mutants were generated using CRISPR/Cas9 genome editing to target GmAITR genes. Under salt treatment, Gmaitr mutant seeds showed a higher germination rate than the wild type, and the Gmaitr mutant plants were morphologically similar to the wild-type plants in the normal soil field, but grew better in the saline soil field [ 78 ]. Interestingly, CRISPR/Cas9-mediated mutation in the AITR gene enhanced salinity stress tolerance in Arabidopsis and soybean.…”

Genetic manipulation for abiotic stress resistance traits in crops

“…The ABA-induced transcription repressors (AITRs) are members of the transcription factor family involved in the ABA signaling pathway. It was reported that the targeted mutation of GmAITR in soybean via the CRISPR/Cas9 gene editing strategy leads to improved salinity tolerance in mutants grown in the field ( Wang et al., 2021 ). In a study by Lou et al.…”