Analysis of natural variation of the stress-responsive gene OsSUI1 in rice

Abstract

Abstract Rice is subjected to various abiotic environmental stress throughout its lifetime and it has formed a complex regulatory network that balances growth and development with stress response. A stress-responsive gene, OsSUI1, was previously mined from microarray data, and transgenic studies revealed that overexpression of this gene caused abnormal floral organ development. However, the role of the OsSUI1 gene in stress response and how it is regulated is unclear. In this study, we obtained the ossui1 mutant by gene editing, and it exhibited high sensitivity to cold, heat and salt treatments compared to wild-type plants. RNA-seq analysis revealed that many transcription factors related to abiotic stress showed significant changes of expression in the ossui1, indicating a critical function of OsSUI1 in the response to abiotic stresses. Through polymorphic analysis, we found that the OsSUI1 gene in some japonica rice encodes a truncated protein product due to a single base deletion in the coding region compared to the sequence in indica rice. The promoter of OsSUI1 exhibited considerable similarity in japonica rice, whereas those of indica rice displayed polymorphism, a 4542-bp transposable element insertion in some indica varieties, which did not, however, impact the expression of OsSUI1. The YFP-tagged OsSUI1 protein found in indica accumulated in the nucleus, whereas the truncated protein in japonica indicated signals in both the cytoplasm and the nucleus. As an abiotic stress response gene, OsSUI1 has potential applications in rice breeding.