EXTRACELLULAR TRAPPING BY ROOT BORDER CELLS IN DEFENSE OF ROOTS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1014129
• Project Start Date: Oct 12, 2017
• Project End Date: Sep 30, 2022
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIVERSITY OF ARIZONA
888 N EUCLID AVE
TUCSON,AZ 85719-4824

Performing Department
Plant Science

Non Technical Summary
Charles Darwin (Power of Movement in Plants, 1927) pointed out that the root cap of higher plants is analogous to the brain stem in humans, in its comprehensive role in health of the organism. When damage is done to the root tip, immediate inhibition of growth and development occurs. Border cells function to prevent injury and damage to this vital organ, and thereby provide an important model system to understand how disease prevention occurs at the cellular level. They already have been used to identify a previously unknown link between the function of white blood cells in humans and border cells in plants, and mechanistic studies have revealed that the same tools are used in both systems. As such, they provide a tool to understand not just how disease occurs, but how it can be prevented.

Animal Health Component

20%

Research Effort Categories

Basic

80%

Applied

20%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
102	2499	1060	100%

Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships;

Subject Of Investigation
2499 - Plant research, general;

Field Of Science
1060 - Biology (whole systems);

Keywords

corn

pea

roots

rhizosphere

extracellular dna

Goals / Objectives
OBJECTIVES. The long term goal of my program is to define the role of border cells in plant health and to explore their agronomic potential for a broad-based method to understand and control root-microbe interactions. The specific goals of this work will be to examine the underlying mechanism(s) by which exDNA is synthesized, exported, and assembled into a functional extracellular trap along with associated polysaccharides, proteins and other metabolites. The work will be carried out using standard procedures that are routine in the Hawes lab (as described in cited references from work carried out at UA in the Hawes program).

Project Methods
PROCEDURES: Evaluation of the cellular site(s) of exDNA assembly and export, and sequence analysis of the functional extracellular complex is underway, and will comprise the focus of future work (American Journal of Botany 2017; 104:1-9). This process comprises a tool that has shown for the first time that border cells are the source of exDNA traps that are secreted as the cells disperse into water, and as such will be exploited to define mechanisms. As such, they provide a system that may facilitate the detailed characterization of structures that will yield insights into ways to control plant and human diseases without the need for toxic chemicals. Of particular interest is border cell trapping of toxic metals and the potential for using this as a tool for soil remediation. The procedures involve germination of seedlings in sterile conditions, immersing the emerging root tips into water to disperse border cells, and using the single-cell populations to observe, document, and control the interactions between plants, pathogens and toxins, as outlined in publications during recent decades (reviewed in Hawes et al., Annual Review of Phytopathology 2016; 54:5:1-5.

Progress 10/01/19 to 09/30/20

Outputs
Target Audience:Target audiences included graduate and undergraduate students in lectures at the University of Arizona, domestic and international groups through presentations at the American Phytopathological Society annual meetings, and collaborative projects in Australia (with Oliver Knox). Publications and presentations provided online access to our work for a broad audience. Changes/Problems:With a change in the leadership of this project, due to the retirement of Dr. Martha Hawes, we will expand the research scopes to include research on other biotic agents, including viruses, and on how they affect plant diseases and sustainable food production, and on how they can be manipulated to benefit public health. What opportunities for training and professional development has the project provided?Lectures on extracellular DNA of border cells in General Microbiology MIC 205A. Mentoring and training of one graduate student. Undergraduate research projects for Jiayu Zhu, Camy Parker, Elliott Hodge, Atoosa Bostani, Amaya Romanski, and Dillon Young. How have the results been disseminated to communities of interest?Lecturing in classes: Due to the COVID-19 situation, online classes provided the only opportunity to disseminate our research to 473 students in MIC205A, General Microbiology. What do you plan to do during the next reporting period to accomplish the goals?The primary focus will continue to apply our research to enhance agricultural production and improve environment. With a change of the leadership in this project due to retirement, we will also expand the research scopes to include interactions between border cells and extracellular DNA and other biotic agents, including viruses.

Impacts
What was accomplished under these goals? The correlation between the number of border cells and wheat drought tolerance, the finding of the trapping of toxic metals by border cells, and the demonstration of extracellular DNase in fungal pathogenesis have established border cells and extracellular DNA established as a baseline for its use as a tool in plant health.

Publications

• Type: Journal Articles Status: Published Year Published: 2020 Citation: Mwatuni, F.M., Nyende, A.B., Njuguna, J., Xiong, Z., Machuka, E., Stomeo, F., 2020. Occurrence, genetic diversity, and recombination of maize lethal necrosis disease-causing viruses in Kenya. Virus Res. 286. doi.org/10.1016/j.virusres.2020.198081.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Yu, N.T., Cai, Z.Y., Xiong, Z., Yang, Y., Liu, Z.X., 2020. Complete genomic sequence of Noni mosaic virus (NoMV) associated with a mosaic disease in Morinda citrifolia L. Eur. J. Plant Pathol. 156, 1005-1014
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Knox, O.G.G., Curlango-Rivera, G., Huskey, D.A., Hawes, M. C. Border cell counts of Bollgard3 cotton and extracellular DNA expression levels. Euphytica 216, 142. https://doi.org/10.1007/s10681-020-02678-8

Progress 10/01/18 to 09/30/19

Outputs
Target Audience:Target audiences included graduate and undergraduate students in lectures at the University of Arizona and University of California, Riverside, international groups through presentations at the American Phytopathological Society annual meeting and the Botanical Society of America annual meeting, and collaborative projects in Australia (with Oliver Knox) and the United Kingdom (Kerrie Farrar). Publications and presentations provided online access to our work for a broad audience. Changes/Problems:With a change in the leadership of this project, due to the retirement of Dr. Martha Hawes, we will expand the research scopes to include research on the interactions between border cells and extracellular DNA and other biotic agents, including viruses, and on how the interactions affect sustainable food production and public health. What opportunities for training and professional development has the project provided?Lectures on extracellular DNA of border cells in General Microbiology MIC 205A. Mentoring and training of two graduate students and a professional staff. Undergraduate research projects for Brooke d'Agostini, Leanne Castro, Shefale Patel, Nikkie Radfar, and Briauna Ramirez. How have the results been disseminated to communities of interest?Invited talks: Extracellular DNA traps in plant and animal defense: New insights into mechanisms of eukaryote immunity, Invited Seminar, Department of Microbiology and Plant Pathology, University of California, Riverside Lecturing in classes General microbiology, MIC205A Principles of Plant Microbiology, PLP 550 Meeting presentations: Root Border Cells and Extracellular Traps. The Plant Root System: Gateway to Plant-Beneficial Rhizosphere Microbiome Interactions. 2019 Plant Health Meeting: The Plant Root System Workshop, Saturday August 3, 2019 Plant root border cell interactions with uranium and cadmium: a potential phytoremediation tool. Botany 2019, July 27-31. What do you plan to do during the next reporting period to accomplish the goals?The primary focus will continue to apply our research on border cells to enhance agricultural production and improve environment. Research on border cell production in barley cultivars and drought tolerance in barley will be carried on to increase water use efficiency of crops during this time of dwindling water resources. With a change of the leadership in this project due to retirement, we will also expand the research scopes to include interactions between border cells and extracellular DNA and other biotic agents, including viruses.

Impacts
What was accomplished under these goals? The correlation between the number of border cells and wheat drought tolerance, the finding of the trapping of toxic metals by border cells, and the demonstration of extracellular DNase in fungal pathogenesis have established border cells and extracellular DNA established as a baseline for its use as a tool in plant health.

Publications

• Type: Journal Articles Status: Published Year Published: 2019 Citation: Huskey DA, Curlango-Rivera G, Hawes MC (2019) Use of rhodizonic acid for rapid detection of root border cell trapping of lead and reversal of trapping with DNase. American Journal of Botany, Applications in Plant Science 7:1-7.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Carter AY, Hawes MC, Ottman MJ (2019) Drought-Tolerant Barley: I. Field Observations of Growth and Development. Agronomy 9: 1-10.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Carter AY, Ottman MJ, Curlango-Rivera G, Huskey DA, Hawes MC (2019) Drought-Tolerant Barley: II. Root Tip characteristics in Emerging Roots. Agronomy 9: 11-20.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Park H, Wang W, Curlango-Rivera G, Xiong Z, Huskey DA, Hawes MC, Turgeon BG (2019) DNase from a fungal phytopathogen is a virulence factor likely deployed as counter defense against host-secreted sxtracellular DNA. mBIO 10: 1-10.
• Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Yu N, Cochran A, Trinh S, Hawes MC, Xiong Z (2018) Battles in the outer space: Extracellular DNases secreted by Pectobacterium carotovorum and its host plants. Phytopathology 108: 11.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Yu, N., Cai, Z.-Y., Xiong, Z., Yang, Y., Liu, Z. (2019). A novel species of potyvirus, Noni mosaic virus (NoMV), was identified in Morinda citrifolia L. Preprints. doi:10.20944/preprints201910.0156.v1
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Yu, N.-T., Xie, H.-M., Zhang, Y.-L., Wang, J.-H., Xiong, Z., Liu, Z.-X. (2019). Independent modulation of individual genomic component transcription and a cis-acting element related to high transcriptional
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Yu, N., Zhang, Y., Xiong, Z., Qu, L., Liu, Z. (2019). A simplified method for the simultaneous detection of nervous necrosis virus and iridovirus in grouper Epinephelus spp. ACTA VIROLOGICA, 63, 8087.

Progress 10/12/17 to 09/30/18

Outputs
Target Audience:Target audiences included graduate and undergratuate students in lectures at the University of Arizona and University of Missouri, international groups through collaborative projects in Australia (with Oliver Knox) and the United Kingdom (Kerrie Farrar), as well at local growers through the Arizona Grain Council. Publications and presentations provided online access to our work for a broad audience. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Lectures on border cells in graduate course PLP 550. Undergraduate research projects for Brooke d'Agostini, Alicia Cochran, Sylvia Trinh, Leanne Castro, Briauna Ramirez How have the results been disseminated to communities of interest?Invited seminar, April 2018. University of Missouri, host Lloyd Sumner.Invited seminar, April 2018. University of Missouri, host Lloyd Sumner. SWESX talks: Impact of soil contaminants on the viability and production of plant root border cells: Implications for phytoremediation. CALS talk: Impact of soil contaminants on the viability and production of plant root border cells: Implications for phytoremediation. CALS talk: Living, not Dead Root Border Cells Release Extracellular DNA in Plant Defense Cotton Hub Annual Disease Forum (FUSCOM). Cotton root tip Exogenous DNA response to wilts. Oliver G. G. Knox1, Vadakattu, V.S.R. Gupta2, Fushi Wen3, Gilberto Curlango-Rivera3, David A. Huskey3 and Martha C. Hawes3 APS meeting 2018: Battles in the outer space: Extracellular DNases secreted by Pectobacterium carotovorum and its host plants. N. Yu, A. Cochran, S. Trinh, F. Wen, M. C. Hawes, Z. XIONG, Visiting scholars: Hosted a collaborative visit from Kerrie Farrar for the development of a BBSRC US Partnering Award. Kerrie Farrar, Aberystwyth University www.aber.ac.uk. University of the Year for Teaching Quality - The Times & The Sunday Times 2019. Case for support 'Beneficial plant-microbe interactions for sustainable agriculture' Related BBSRC major grants: BBSRC Core Strategic Programme in Resilient Crops: Miscanthus (BBS/E/W/0012843A) and BBSRC-NCG in Plant Phenotyping (BBS/E/W/0012844A). Hosted a collaborative visit with Professor Ann Hirsch, UCLA, to assess future work together. What do you plan to do during the next reporting period to accomplish the goals?The primary focus will be the path to putting our research on border cells to work in agriculture. With a grant funded by the Arizona Grain Council, we have identified altered border cell production in barley cultivars whose drought tolerance has been established in field studies over decades of replication. The potential for early, inexpensive screening for traits with key roles in water use is of particular importance during this time of dwindling water resources.

Impacts
What was accomplished under these goals? The delivery of exDNA from living cells, the distinction in sequence between exDNA and internal DNA, and its role in trapping of toxic metals have been established as a baseline for its use as a tool in plant health.

Publications

• Type: Journal Articles Status: Published Year Published: 2107 Citation: Visualization of extracellular DNA released during border cell separation from the root cap. American Journal of Botany 104: 1-9.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Trapping of lead (Pb) by corn and pea root border cells. Plant and Soil https://doi.org/10.1007/s11104-018-3716-4
• Type: Journal Articles Status: Under Review Year Published: 2109 Citation: Use of rhodizonic acid (RA) for rapid detection of root border cell trapping of lead (Pb) and reversal of trapping with DNase (2019) David A. Huskey, M.S.; Gilberto Curlango-Rivera, Ph.D.; Martha C. Hawes, Ph.D.. Applications in Plant Science, Special Issue on belowground applications.
• Type: Journal Articles Status: Awaiting Publication Year Published: 2019 Citation: Sequence comparison of genomic DNA (gDNA) vs extracellular DNA (exDNA). Fushi Wen, Xiong Zhongguo, Martha Hawes
• Type: Journal Articles Status: Accepted Year Published: 2019 Citation: A DNase from a fungal phytopathogen is a virulence factor likely deployed as counter defense against host-secreted extracellular DNA. mBio02805-18R1 Wang WW, Park, H-J, Curlango-Rivera G, Zhongguo Z, Hawes MC, Huskey DA, and Turgeon BG.