Raul Zavaliev

Brookhaven National Laboratory

Biology Department
Bldg. 463, Room B-211
P.O. Box 5000
Upton, NY 11973-5000

(631) 344-6292
rzavaliev@bnl.gov

Research | Publications

Research Activities

The Zavaliev Group investigates the molecular basis of plant immune mechanisms and their interplay with growth processes in monocot bioenergy crops. By using advanced tools in genetics, genomics, biochemistry, and cell biology, we aim to address the following big questions in plant immunity:

1. What are the spatiotemporal dynamics of immune signaling between infected and uninfected cells?
2. Which genes and pathways are activated during the establishment of pathogen resistance in systemic cells?
3. How activated immunity integrates into plant growth processes, such as photosynthesis, carbon allocation, and biomass accumulation?

Why We Study Systemic Immunity?

An effective immune system is one that enables an organism not only to rapidly mount its defenses against invading pathogens but also to precisely regulate the localization, magnitude, and duration of those responses. Such regulation is crucial for preventing autoimmunity, a self-destructive process that impairs growth and development, ultimately leading to plant death. Systemic acquired resistance (SAR) is a fundamental immune mechanism, providing plants with effective and long-lasting resistance against a wide range of pathogens and extreme environmental conditions. SAR is induced when signaling molecules released from initially infected cells prime distant uninfected cells throughout the plant, activating their resistance against subsequent biotic or abiotic stresses. This process involves major transcriptional reprogramming of systemic tissues, leading to a shift in resource allocation from growth to defense. Consequently, if systemic immunity is constitutively activated, plant growth is significantly inhibited. The goal of our research is to uncover genetic and genomic regulators of systemic immunity at the intersection of growth processes in monocot plants.

Our Approach

With a genomics-driven approach, we aim to identify novel genes and pathways involved in the establishment of SAR in bioenergy Sorghum using two bacterial disease models: Leaf streak disease caused by Xanthomonas vasicola pv. holcicola, and Leaf spot disease caused by Pseudomonas syringae pv. syringae van Hall. We analyze both virulent and avirulent host-pathogen interactions, to identify key susceptibility and resistance factors, as well as determine which pathways contribute most to host cell survival. We employ advanced bioimaging techniques, including super-resolution confocal microscopy, to visualize immune responses at the sub-cellular level and decode the activity of newly identified as well as conserved orthologous immune regulators. Using different protein production systems coupled with analytical biochemistry, we also characterize the molecular properties and activities of those immune regulators in vitro. To identify key genes involved in the growth-defense trade-offs, we use whole-plant bioluminescence- and fluorescence-based reporter assays to screen mutant populations of model monocot plant species. We utilize CRISPR-Cas9-based prime editing tools to introduce precision molecular switches to activate broad-spectrum immune regulators in Sorghum, ensuring that defense gene induction is restricted to a specific time and location of pathogen attack.

Our Impact

Our research will advance understanding of monocot defense and survival mechanisms against a wide range of adapted and emerging pathogens, as well as extreme environmental conditions. Through an integrative characterization of immune and developmental processes we can optimize systemic immunity with minimal growth penalties, enabling the development of high-yield disease-resistant bioenergy crops.

Selected Publications

• Powers J, Zhang X, Reyes AV, Zavaliev R, Ochakovski R, Xu SL, Dong X (2024) Next-generation mapping of the salicylic acid signaling hub and transcriptional cascade. Molecular Plant. https://doi.org/10.1016/j.molp.2024.08.008
• Zavaliev R, Dong X (2024) NPR1, a key immune regulator for plant survival under biotic and abiotic stresses. Molecular Cell 84:131–141. https://doi.org/10.1016/j.molcel.2023.11.018
• Powers J, Zhang X, Reyes AV, Zavaliev R, Xu SL, Dong X (2024) Next-generation mapping of the salicylic acid signaling hub and transcriptional cascade. BioRxiv. https://doi.org/10.1101/2024.01.03.574047
• Zhou P, Zavaliev R, Xiang Y, Dong X (2023) Seeing is believing: Understanding functions of NPR1 and its paralogs in plant immunity through cellular and structural analyses. Current Opinion in Plant Biology 73:102352. https://doi.org/10.1016/j.pbi.2023.102352
• Kumar* S, Zavaliev* R, Wu* Q, Zhou Y, Cheng J, Dillard L, Powers J, Withers J, Zhao J, Guan Z, Borgnia M, Bartesaghi A, Dong X. and Zhou P (2022) Structural basis of NPR1 in activating plant immunity. Nature 605:561–566. https://doi.org/10.1038/s41586-022-04699-w
• Zavaliev R, Mohan R, Chen T, Dong X (2020) Formation of NPR1 Condensates Promotes Cell Survival during the Plant Immune Response. Cell 182:1093-1108.e18. https://doi.org/10.1016/j.cell.2020.07.016
• Gu Y, Zavaliev R, Dong X (2017) Membrane Trafficking in Plant Immunity. Molecular Plant 10:1026–1034. https://doi.org/10.1016/j.molp.2017.07.001
• Zavaliev R, Dong X, Epel BL (2016) Glycosylphosphatidylinositol (GPI) modification serves as a primary plasmodesmal targeting signal. Plant Physiology 172: 1061-1073. https://doi.org/10.1104/pp.16.01026
• Saleh A, Withers J, Mohan R, Marques J, Gu Y, Yan S, Zavaliev R, Nomoto M, Tada Y, Dong X (2015) Posttranslational Modifications of the Master Transcriptional Regulator NPR1 Enable Dynamic but Tight Control of Plant Immune Responses. Cell Host & Microbe 18:169–182. https://doi.org/10.1016/j.chom.2015.07.005
• Zavaliev R, Epel BL (2015) Imaging Callose at Plasmodesmata Using Aniline Blue: Quantitative Confocal Microscopy. In "Plasmodesmata – methods and protocols" (M. Heinlein, ed.). Methods in Molecular Biology 1217, 105-119. https://doi.org/10.1007/978-1-4939-1523-1_7
• Zavaliev R, Levy A, Gera A, Epel BL (2013) Subcellular Dynamics and Role of Arabidopsis β-1,3-Glucanases in Cell-to-Cell Movement of Tobamoviruses. Molecular Plant-Microbe Interactions 26:1016–1030. https://doi.org/10.1094/mpmi-03-13-0062-r
• Zavaliev R, Ueki S, Epel BL, Citovsky V (2010) Biology of callose (β-1,3-glucan) turnover at plasmodesmata. Protoplasma 248:117–130. https://doi.org/10.1007/s00709-010-0247-0
• Zavaliev R, Sagi G, Gera A, Epel BL (2009) The constitutive expression of Arabidopsis plasmodesmal-associated class 1 reversibly glycosylated polypeptide impairs plant development and virus spread. Journal of Experimental Botany 61:131–142. https://doi.org/10.1093/jxb/erp301