Genetic and molecular dissection of hydathode and vascular immunity in plants – NEPHRON

Transcriptomic analysis of healthy or infected hydathodes will be conducted using either macro- or micro-dissection. In parallel, composition of pre- and post-hydathode guttation fluid will be determined. A combination of reverse and forward genetics will be used to identify Arabidopsis genes important for hydathode development, physiology and immunity. TILLING or CRISPR mutants will be selected in Brassica in order to translate the most promising results in an economically-relevant crop plant.

With these first 18 months, we obtained a first transcriptome of healthy Arabidopsis hydathode which identified limited but marked differences with neighboring tissues: enhanced auxin biosynthesis and signaling, increased transporter activities, reduced glucosinolate biosynthesis, modified cell wall and wax biosynthesis,… In parallel, a first transcriptome of infected cauliflower hydathodes was produced indicating a very potent inhibition of plant immunity by Xanthomonas type 3 effector proteins. A negative regulator of transcriptional gene silencing in antibacterial vascular resistance and the regulation of immune-responsive genes that are directly controlled by such TGS repressor was identified and characterized (Submitted to eLife). Finally, we published a review on the anatomy, development, physiology and immunity of hydathodes in Annual Review of Phytopathology. It thus confers a strong international recognition to the NEPHRON consortium on hydathode biology.

The results acquired in Arabidopsis and in different elite Brassica varieties will help to design knowledge-based strategies to better control vascular pathogens.

Cerutti A., Jauneau A., Laufs P., Leonhardt N., Schattat M., Berthomé R., Routaboul J.-M. and Noël L.D. (2019) Mangroves in the Leaves: Anatomy, Physiology, and Immunity of Epithemal Hydathodes. Ann. Rev. Phytopathol. 57:91-116.
Gluck-Thaler E.*, Cerutti A.*, Perez-Quintero A.*, Butchacas J., Roman-Reyna V., Narayanan MadhavenV., Shantharaj D., Merfa M. V., Pesce C., Jauneau A., Vancheva T., Lang J. M., Allen C., Verdier V., Gagnevin L., Szurek B., Cunnac S., Beckham G., de la Fuente L., Kumar Patel H., Sonti R. V., Bragard C., Leach J. E., Noël L. D., Slot J. C., Koebnik R., Jacobs J.M. (In press) Repeated gain and loss of a single gene modulates the evolution of vascular pathogen lifestyles. Science Advances.
Jauneau A., Cerutti A., Auriac M.-C., Noël L. D. (In press) Anatomy of leaf apical hydathodes in four monocotyledon plants of economic and academic relevance. PLoS One.
Halter T., Wang, J., Amesefe, D., Lastrucci E., Charvin M., Singla-Rastogi M., Navarro L. (submitted). The Arabidopsis active demethylase ROS1 cis-regulates immune-responsive genes by pruning DNA methylation at promoter-regulatory regions (eLife).

Plant pathogens such as Ralstonia, Xylella or Xanthomonas are responsible for devastating vascular systemic infections in crops. The genetic basis of plant vascular immunity are poorly understood thus limiting the design of resistant or tolerant crops. With a focus on black rot disease of Brassicaceae caused by the devastating crop pest Xanthomonas campestris (Xc), the NEPHRON project aims to identify and characterize different layers of plant immunity at the hydathodes which are natural entry points for Xc. Hydathodes are plant organs located at the leaf margin and where guttation occurs. The NEPHRON project will establish the genetics of hydathode differentiation and physiology and its importance for the susceptibility to black rot disease. The results acquired in Arabidopsis and in different elite Brassica varieties will help to design knowledge-based strategies to better control vascular pathogens.