RNA‐seq analysis of laser microdissected <i>Arabidopsis thaliana</i> leaf epidermis, mesophyll and vasculature defines tissue‐specific transcriptional responses to multiple stress treatments
Oliver Berkowitz, Yue Xu, Lim Chee Liew, Yan Wang, Yanqiao Zhu, Bhavna Hurgobin, Mathew G. Lewsey, James Whelan
Abstract
Acclimation of plants to adverse conditions requires the coordination of gene expression and signalling pathways between tissues and cell types. As the energy and carbon capturing organs, leaves are significantly affected by abiotic and biotic stresses. However, tissue- or cell type-specific analyses of stress responses have focussed on the Arabidopsis root. Here, we comparatively explore the transcriptomes of three leaf tissues (epidermis, mesophyll, vasculature) after induction of diverse stress pathways by chemical stimuli (antimycin A, 3-amino-1,2,4-triazole, methyl viologen, salicylic acid) and ultraviolet light in Arabidopsis using laser capture microdissection followed by RNA sequencing. Stimulation of stress pathways caused an overall reduction in the number of genes expressed in a tissue-specific manner, though a small subset gained or changed their tissue specificity. We find no evidence of a common stress response, with only a few genes consistently responsive to two or more treatments in the analysed tissues. However, differentially expressed genes overlap between tissues for individual treatments. A focussed analysis provided evidence for an interaction of auxin and ethylene that mediates retrograde signalling during mitochondrial dysfunction specifically in the epidermis, and a gene regulatory network defined the hierarchy of interactions. Taken together, we have generated an extensive reference dataset that will be valuable for future experiments analysing transcriptional responses on a tissue or single-cell level. Our results will enable the tailoring of the tissue-specific engineering of stress-tolerant plants.