WHIRLY1 regulates aliphatic glucosinolate biosynthesis in early seedling development of Arabidopsis

WHIRLY1 belongs to a family of plant-specific transcription regulators capable of binding DNA or RNA in all three plant cell compartments containing genetic materials. In Arabidopsis thaliana , WHIRLY1 has been studied at the later stages of plant development, including flowering and leaf senescence, as well as in biotic and abiotic stress responses. In this study, novel WHIRLY1 knock-out mutants of A. thaliana were prepared by CRISPR/Cas9 to investigate the role of AtWHIRLY1 during early seedling development. The loss-of-function of WHIRLY1 in 5-day-old seedlings did not cause differences in the phenotype and the photosynthetic performance of the emerging cotyledons compared to the wild type. Nevertheless, RNA sequencing analysis revealed that the knock-out of WHIRLY1 affected the expression of a small but specific set of genes during this critical phase of development. About 110 genes were found to be significantly deregulated in the knockout mutant. Among them, genes involved in the early steps of aliphatic glucosinolate biosynthesis happening in chloroplasts were suppressed in the knock-out mutants. The downregulation of these genes in the WHIRLY1 knock-out line coincided with reduced aliphatic glucosinolate content. Hence, AtWHIRLY1 plays a role in regulating of aliphatic glucosinolate biosynthesis during early seedling development.