Genome Editing to Integrate Seed Size and Abiotic Stress Tolerance Traits in Arabidopsis Reveals a Role for DPA4 and SOD7 in the Regulation of Inflorescence Architecture.

Siyu Chen,Sajjad Ahmed,Na Zhang,Ganghua Zhou,Qimeng Zhang,Hainan Tian,Tianya Wang,Shucai Wang,Saddam Hussain

doi:10.3390/ijms20112695

Siyu Chen, Sajjad Ahmed + Show 7 more

Open Access

https://doi.org/10.3390/ijms20112695

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Abstract

Both seed size and abiotic stress tolerance are important agronomic traits in crops. In Arabidopsis, two closely related transcription repressors DPA4 (Development-Related PcG Target in the APEX4)/NGAL3 and SOD7 (Suppressor of da1-1)/NGAL2 (NGATHA-like protein) function redundantly to regulate seed size, which was increased in the dpa4 sod7 double mutants. Whereas ABA-induced transcription repressors (AITRs) are involved in the regulation of ABA signaling and abiotic stress tolerance, Arabidopsis aitr2 aitr5 aitr6 (aitr256) triple mutant showed enhanced tolerance to drought and salt. Here we performed CRISPR/Cas9 genome editing to disrupt DPA4 and SOD7 in aitr256 mutant, trying to integrate seed size and abiotic stress tolerance traits in Arabidopsis, and also to examine whether DPA4 and SOD7 may regulate other aspects of plant growth and development. Indeed, seed size was increased in the dpa4 sod7 aitr256 quintuple mutants, and enhanced tolerance to drought was observed in the mutants. In addition, we found that shoot branching was affected in the dpa4 sod7 aitr256 mutants. The mutant plants failed to produce secondary branches, and flowers/siliques were distributed irregularly on the main stems of the plants. Floral organ number and fertility were also affected in the dpa4 sod7 aitr256 mutant plants. To examine if these phenotypes were dependent on loss-of-function of AITRs, dpa4 sod7 double mutants were generated in Col wild type background, and we found that the dpa4 sod7 mutant plants showed a phenotype similar to the dpa4 sod7 aitr256 quintuple mutants. Taken together, our results indicate that the integration of seed size and abiotic stress tolerance traits by CRISPR/Cas9 editing was successful, and our results also revealed a role of DPA4 and SOD7 in the regulation of inflorescence architecture in Arabidopsis.

Highlights

Seed size is one of the most important agronomic traits in plants
Seed Size is Increased in the dpa4 sod7 aitr256 Quintuple Mutant Plants
Our previously experiments showed that ABA-induced transcription repressors (AITRs) are a novel transcription factor family that is involved in the regulation of ABA signaling and plant response to abiotic stress tolerance, as the aitr256 triple mutants showed enhanced tolerance to ABA and abiotic stresses including drought and salt [23]

Summary

Introduction

Seed size is one of the most important agronomic traits in plants. Several different types of seed size regulators have been identified. Most of the seed size regulators identified so far in Arabidopsis are transcription factors, including the AP2 (APETALA2)/EREBP (Ethylene Responsive Element Binding Protein) family protein AP2 [7,8,9], the WRKY transcription factors TTG2 (Transparent Testa GLABRA2), MINI3 (MINISEED3) and SHB1 (Short Hypocotyl Under Blue1) [10,11,12,13,14], the auxin response factor ARF2 [15], the bHLH transcription factor ABI5 (ABA Insentive5) [16], the plant-specific VQ motif proteins IKU1 (HAIKU1) and IKU2 [17,18], and the B3 domain transcription factors DPA4 (Development-Related PcG Target in the APEX4)/NGAL3 and SOD7 (Suppressor of da1-1)/NGAL2 (NGATHA-like protein) [19,20]. Cotyledon and flower size was affected in the dpa sod double mutant [20], but it is unclear whether DPA4 and SOD7 may regulate other aspects of plant growth and development at mature stages

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