Fluorescent protein-based imaging and tissue-specific RNA-seq analysis of Arabidopsis hydathodes

Abstract

Hydathodes are typically found at leaf teeth in vascular plants and involved in water release to the outside. Although morphological and physiological analysis of hydathodes has been performed in various plants, little is known about the genes involved in hydathode function. In this study, we performed fluorescent protein-based imaging and tissue-specific RNA-seq analysis in Arabidopsis hydathodes. We used the enhancer trap line E325, which has been reported to express green fluorescent protein (GFP) at its hydathodes. We found that E325-GFP was expressed in small cells found inside its hydathodes (named E cells) that were distributed between the water pores and xylem ends. No fluorescence of the phloem markers pSUC2:GFP and pSEOR1:SEOR1-YFP was observed in the hydathodes. These observations indicate that Arabidopsis hydathodes are composed of three major components: water pores, xylem ends, and E cells. In addition, we performed transcriptome analysis of the hydathode using the E325-GFP line. Microsamples were collected from GFP-positive or negative regions of E325 leaf margins with a needle-based device (~130 µm in diameter). RNA-seq was performed with each single microsample using a high-throughput library preparation method called Lasy-Seq. We identified 72 differentially expressed genes. Among them, 68 genes showed significantly higher expression in the hydathode, while four genes showed significantly lower expression in the hydathode. Our results provide new insights into the molecular basis for hydathode physiology and development.

An Arabidopsis vasculature distributed metal tolerance protein facilitates xylem magnesium diffusion to shoots under high‐magnesium environments

“…We also detected MTP10 expression in the vasculature of roots, cotyledons and the true leaves (Figures 4A–C, S10C‐J). As reported in the literature, the hydathode of plants are tiny pores through which guttation takes place; unlike stomata, they are always open (Yagi et al, 2021). We detected high expression of MTP10 in the leaf hydathode, suggesting that MTP10 may be involved in the regulation of hydathode regulated physiological processes (Figures 4C, S10K, L).…”

Stomatal development in the context of epidermal tissues

“…via SPCH ). Very recently, RNA-seq analysis of Arabidopsis hydathode regions was performed in an attempt to identify genes specifically expressed in hydathodes, which include several auxin biosynthesis and auxin-related genes ( Yagi et al , 2020 ). Such an analysis may reveal genes and pathways uniquely associated with water pore differentiation and additional overlapping features with stomata development.…”

Arabidopsis hydathodes are sites of intense auxin metabolism and nutrient scavenging

“…The copyright holder for this this version posted December 2, 2022. ; https://doi.org/10.1101/2022.12.01.518666 doi: bioRxiv preprint signaling are more expressed in Arabidopsis hydathodes compared to other leaf tissues (Kim et al, 2021;Yagi et al, 2021). The analysis of multiple mutants of the redundant YUCCA biosynthetic genes have shown the importance of auxin synthesis for leaf, veins and hydathode development (Cheng et al, 2006(Cheng et al, , 2007Wang et al, 2011;Chen et al, 2014).…”