The Bro1-like domain-containing protein, AtBro1, modulates growth and abiotic stress responses in Arabidopsis.

Abscisic acid (ABA) affects plant physiology by altering gene expression, enabling plants to adapt to a wide range of environments. Plants have evolved protective mechanisms to allow seed germination in harsh conditions. Here, we explore a subset of these mechanisms involving the gene, which encodes one of a small family of poorly characterised Bro1-like domain-containing proteins, in plants subjected to multiple abiotic stresses. transcripts were upregulated by salt, ABA and mannitol stress, while -overexpression lines demonstrated robust tolerance to drought and salt stress. Furthermore, we found that ABA elicits stress-resistance responses in loss-of-function mutant plants and AtBro1 regulates drought resistance in Arabidopsis. When the promoter was fused to the β-glucuronidase (GUS) gene and introduced into plants, GUS was expressed mainly in rosette leaves and floral clusters, especially in anthers. Using a construct expressing an AtBro1-GFP fusion protein, AtBro1 was found to be localized in the plasma membrane in Arabidopsis protoplasts. A broad RNA-sequencing analysis revealed specific quantitative differences in the early transcriptional responses to ABA treatment between wild-type and loss-of-function mutant plants, suggesting that ABA stimulates stress-resistance responses AtBro1. Additionally, transcripts levels of , and were altered in plants exposed to different stress conditions. Collectively, our results show that AtBro1 plays a significant role in the regulation of the plant transcriptional response to ABA and the induction of resistance responses to abiotic stress.