Category: ​​​Interactions Archives​

Spotlight on Early Career Researchers

Meet recently graduated student Dr. Alexandra Margets, aka “Allie,” from Prof. Roger Innes‘ lab at Indiana University Bloomington. Her research focuses on Identifying and understanding the intricate components of the plant-pathogen interface, which motivates her research questions. Allie was awarded the prestigious Agriculture and Food Research Initiative Predoctoral Fellowship by the USDA National Institute of Food and Agriculture to investigate the molecular mechanisms of soybean cyst nematode effector proteins. Her research work led to the identification of a key protease effector of soybean cyst nematode (SCN), and this work translated into her first-author paper recently published in the November issue of MPMI, which was selected as an Editor’s Pick. With her current and future research, she hopes to gain information that expands our knowledge of plant immunity and use that information to address problems that impact agriculture. We congratulate Allie on her recent achievements and wish her a stroke of good luck in her future endeavors.

1.What do you think is the most important or exciting finding from your paper?

The most exciting finding from my paper was identifying a soybean target of the SCN effector protease, CPR1. It was an important finding to not only to provide a snapshot as to where/how CPR1 functions in plant cells, but now we can use this target to identify CPR1’s preferred cleavage sequence to generate PBS1 decoys that elicit immune responses upon cleavage.

2.Was there a piece of data that was particularly challenging to obtain or a part of the project that was particularly difficult?

Identifying the soybean target of CPR1 was the most challenging piece of data to obtain. Before pursuing biotin-based proximity labeling (miniTurbo) in composite soybean roots, I tried several different approaches to identify soybean targets of CPR1 and other SCN proteases. I tried to optimize several different approaches to perform these experiments in soybean. The techniques I pursued before using the composite plant system included soybean protoplasts, transient expression in soybean, and hairy root cultures. At first, I was using GFP fluorescence to identify transgenic roots, which was challenging, but incorporating the screenable marker, RUBY, into these experiments was a game changer that saved me a lot of time! However, miniTurbo yielded a list of interesting targets to test, which meant there was a lot of cloning and negative results along the way. Once I confirmed GmBCAT1 as a target of CPR1, the challenge made the result that much more exciting.

3. What research project are you most excited about right now?

I have now defended my thesis work but am happy to see that my projects are continuing in the lab. I am most excited to see the Innes-Baum labs work together to generate and test PBS1 decoys for SCN resistance. Stay tuned, as we hope to publish our findings on this system in roots in the near future. I also left the lab with an idea for using the composite plant system to identify the R gene in soybean that recognizes PBS1 cleavage.

4. What drew you to your current lab?

Despite rotating through two other great labs where I learned a lot, I was fascinated by the complexity between plant-pathogen interactions. I had very little exposure to this field at the time but loved molecular plant biology and the idea of learning about not only plants, but the pathogens that infect them in agriculture. I also was drawn to the idea of doing research, with the goal of developing resistance strategies as I was interested in a future career in industry/biotechnology. During my rotation in the Innes lab, I had a great mentor who routinely took the time to discuss his projects and the field of molecular plant-pathogen interactions, while challenging me to think about potential future directions of the lab’s research. I felt like there was a great support system among the Innes lab members and thoroughly enjoyed showing up each day. Dr. Innes and I established good communication early on, and I felt that it was a place where I would be able to grow into an independent scientist.

5. How did you choose to join your current graduate program?

I was looking for a broad graduate program that would allow me to explore different areas of biology research before choosing a thesis lab. The Genome, Cell, Developmental Biology Ph.D. program at IU was exactly that. This program also allowed me to explore labs under microbiology, biochemistry, and evolution/ecology through rotations. Since I was coming from undergraduate studies, I didn’t want to “think” I knew what I wanted/needed but rather wanted to explore different labs and mentors through hands-on experiences. Before joining, there were several labs I was interested in, so I knew that I would be able to make an educated decision on where I would thrive. Upon visiting IU, I immediately got a sense of diversity at the university and within the community that reminded me of where I grew up in New York. The graduate students during my visit were extremely friendly and honest, which allowed me to truly envision what it would be like to be a student there. Additionally, Bloomington, IN, is a beautiful small town that had everything I needed to focus on my thesis work but enjoy where I was living.

6. What advice would you give to starting graduate students?

1. Find a thesis lab that is going to give you the support that you need to reach your scientific goals and communicate those goals with your PI as early as possible. If you are doing rotations, have this conversation during the rotation and before joining. It is reasonable for graduate students to have high expectations for their research mentor. However, it is easy to forget we are just one of their responsibilities among many others. Establishing healthy, clear, and direct communication early on will help you both get what you need out of the professional relationship.
2. Build your scientific community early on in your career. It is always intimidating to put yourself out there in those early years, as many of us of get self-conscious about the amount of data we have in year one or two (especially if we are working on a newer project)—but do it! Whether that is attending a meeting with a “future directions” poster or attending a mixer where you may not know anyone. Once you make connections, remember to maintain them. The relationships in your network should be a give and take. Don’t only reach out when you need something.
3. Try and leave the “self-doubt” at the door. Grad school is a marathon, not a race. There are going to be rough times and that’s okay. Find constructive ways to handle the lows and don’t resort to thinking you aren’t good enough. It’s normal to feel these things from time to time, but don’t let them consume you. Having a healthy perspective and trying to find the positive in these instances will keep you motivated and happier in the long run.

7. Who has inspired you scientifically? Why?

I have always been inspired by my undergraduate PI, Dr. Michelle Barthet, at Coastal Carolina University. She was the first to show me the great world of research during my first year as an undergrad. Being at a primarily undergraduate institution, there were the obvious restraints when it came to funding, resources, and time in the lab. However, this never stopped Dr. Barthet. She was so passionate about her research and the productivity of her lab, she always came up with a way to accomplish her research questions while mentoring several undergrads. Not only was she creative, but the passion she had for her students in her lab and in her classrooms was unmatched. She genuinely cared about our long-term goals and tailored our experiences around them. I am truly inspired by the scientist she is and the dedication she has to her role in academia. My time working with Dr. Barthet shaped how I approach my science today and interact with mentees and colleagues.

8. Are you or have you been involved in other scientific/professional development activities? And how have they contributed to your training?

At IU, I served as the vice president of my graduate student organization that we started during COVID. It allowed me to build upon my leadership skills and adapt to new ways to communicate with our graduate student community during a challenging time. The organization is thriving today, and I love seeing how the new leaders have used the organization to promote a supportive community. I also worked closely with Dr. Innes on outreach initiatives in the Bloomington community. Each fall, we would visit third-grade classrooms and teach students what plants needed to grow through a hands-on experiment. This experience helped me immensely with my communication skills, and it was rewarding to watch the students get excited about plant science. Since I loved outreach, I wanted to branch out beyond IU, which led me to getting involved in The American Phytopathological Society Office of Public Relations and Outreach (APS OPRO). For two years, I served as the graduate student representative, where I had the pleasure of communicating plant science with different target audiences. Since my program at IU was not plant-specific, APS gave me a great community that I had the pleasure of meeting with regularly.​

9. What is the greatest challenge you have encountered in your career? What did you do to overcome this challenge?

My greatest challenge during my academic career occurred during my undergrad studies. To pay for college, I was working full-time as a waitress at the Hard Rock Café. Luckily, I had a great support system there, and my managers fully supported my education. However, balancing work, school, and research was a real challenge both physically and mentally. Registering for the upcoming semesters was always a stressful time as I was working hard to pay off the current semester on time to be sure I could register for the classes I needed. To overcome this challenge, I had to become really (really) good with time management and sticking to a routine. Sometimes that meant having flash cards for an upcoming test in my apron at work or waking up before an 8 a.m. class to go to the library. I used my future goals as my source of motivation. At Coastal Carolina University, I got my first taste of research and really fell in love with it. Luckily, I was able to stay work in the same lab for the three years I was at Coastal, which helped me develop a routine. While I wouldn’t necessarily want go through this period again, it really shaped how I approached grad school, and I had such appreciation for being able to immerse 100% of myself in my research and education during my Ph.D. studies.

10. How can people find you on social media?

X: @_acmargets

LinkedIn: https://www.linkedin.com/in/alexandra-margets

11. Is there anything else you would like to share? If so, what is it?

To students interested in pursuing a Ph.D. degree or those navigating grad school, always feel free to reach out to me if you need someone to talk to or have questions. I was lucky enough to have several more senior scientists to go to with my questions and concerns throughout my graduate experience, and I genuinely love helping others.

12. What’s your favorite pathogen or disease?

Soybean cyst nematode (but any sedentary plant parasitic nematode sparks my interest).​​

InterConnections: Plant-Microbe Interaction Careers in Government

Careers in plant-microbe interactions span more than research. Suma Chakravarthy is a senior science advisor at the USDA-APHIS-Biotechnology Regulatory Service. She earned her Ph.D. degree in genetics at Delhi University, working in plant biology, and was a postdoctoral researcher in Dr. Greg Martin‘s lab at the Boyce Thompson Institute. Read how she made her way to her current position and her role at APHIS.

1. What drew you to your current job?

The availability of new techniques for genome engineering allows developers to introduce desirable traits into plants and other organisms, with the promise of enhancing sustainability and food security. This is an exciting period for countries trying to enable innovation and revise or adapt their regulatory processes for the oversight of products of agricultural biotechnology. In my current job, I work with federal partners and coordinate international communication to support science- and risk-based regulatory decision-making, while also providing support for APHIS BRS regulatory processes.

The chance to learn constantly, provide technical advice and influence policy, and work on international cooperation with many countries and organizations is exciting and motivating for me and drew me to my current job.

2. How did you choose molecular plant-microbe interactions as your focus of research?

My Ph.D. degree was in the field of plant biotechnology and focused on modification of the CaMV 35S promoter for transgene expression. The “clever” 35S promoter is a perfect example of plant-pathogen coevolution, as this viral promoter has cis-elements found in plant promoters and is responsive to the defense hormone salicylic acid, among other stimuli. My interest in plant transcription serendipitously led me to the lab of Prof. Greg Martin, where I started my postdoc studying the role of transcription factors in plant defense responses. During my years in academia, I was fortunate to be able to study plant defense responses, as well as bacterial virulence strategies.

3. What advice would you give to starting graduate students?

Remember that graduate school is only the start of your career, which could take different turns in your life. During grad school, it is important to focus on your project, work hard, and not get disappointed by failures. Have a backup project (or two) in case your main project is not successful. This is a good time to develop writing skills. Most important, do not box yourself in a niche field: read broadly, network, be interested in what other graduate students do, and enjoy the journey. A side hobby is a great way to decompress and take a mental break.

4. What advice would you give to people starting out in the job market?

Take time to prepare a good resume tailored to the advertised job and seek feedback from someone senior in your organization to polish the resume. It may take a few iterations till the application looks sharp. Prepare a list of potential interview questions and practice your answers, preferably with a colleague or senior, paying attention to content and timing. Be focused on the requirements of the job during your preparation phase.

Do not be afraid to contact potential employers and express your interest to learn about their work. Networking is critical because it will improve your understanding of opportunities and the scope of jobs in your field. Although it is important to find the right job for your background, sometimes the dream job will not come your way and it may be more realistic to accept the next-best position and do your best in it. Over time, other opportunities for growth will present themselves. A very important piece of advice, in my opinion, for young professionals is not to switch jobs too quickly—take time to learn the subject area and contribute to the mission of your employer. Important skills that will make you successful in the job market are good teamwork, collaboration, clear communication, and integrity.

5. Who has inspired you scientifically? Why?

Gregor Johann Mendel, who laid the foundation of the science of genetics, has inspired me scientifically. Despite facing tremendous personal struggles, he had many aspirational qualities that contributed to his success in laying down the foundational rules of inheritance. He had astute powers of observation and was rigorous, methodical, analytical, and persistent. He displayed courage to stand up for what he believed was right.

6. How did you make the transition from science to policy?

The Science and Technology Policy Fellowship (STPF) program of the American Association for the Advancement of Science (AAAS) helped me segue from science to policy. I listened to some lectures by invited scientists at Cornell University and became aware of the prospects the AAAS STPF gives to scientists to contribute their knowledge in the policy realm. The stories of former fellows were inspiring and offered a glimpse into an exciting and relevant career path. As a STPF Fellow in USDA APHIS BRS, the transition process was difficult, and I missed being on the bench and doing active research. I had to learn about biotechnology regulations, how they are implemented, how to apply science to perform risk assessments, and decision-making in the face of uncertainty. Every bit of my education, research experience, and soft skills were utilized during this transition. In my current position I am a regulatory scientist doing science and policy work, applying scientific skills to support complex evaluation of products to make regulatory determinations, and keeping up with advancements that will inform future policy.

7. What is the greatest challenge you have encountered in your career? What did you do to overcome this challenge?

I worked as regulatory manager at CropLife International (CLI), an international trade association that promotes agricultural technologies. The job at CLI pushed me out of my comfort zone because it was a new work environment and I had to interact with industry colleagues and a dynamic team of legal, trade policy, and communication professionals whose purpose was to promote trade and globally harmonized regulatory policies. This meant I had to zoom out and look at the big picture instead of focusing on details. I used the lessons from my academia workbook to overcome the challenge. I observed the workstyle of different member companies; learned about business pipelines and the importance of deadlines; was goal oriented; collected and organized information; used data for problem solving and presenting solutions; and was open to critical suggestions. My experience working in different sectors now helps me in my current job.

8. How can people find you on social media?

I have a LinkedIn profile, which is the easiest way to find me on social media.

9. What’s your favorite story from an IS-MPMI Society meeting?

The first IS-MPMI meeting I attended was in Madison, WI, in 2001, when I was a postdoc in Greg Martin’s lab working on the ethylene response factor Pti4. During the meeting, our lab met Charles Després who is now professor, biological sciences, at Brock University in Canada. Charles had an interest in studying plant signaling pathways, and after the meeting, we went on to become collaborators and coauthors on a 2003 paper on Pti4-mediated gene expression and its role in plant defense. This is a favorite story because it showcases the power of networking prior to the explosion of social media!

10. Have you ever conducted research in a country other than the United States? What were the challenges and good parts?

I completed my Ph.D. degree in India under the guidance of Dr. P.K. Burma and Dr. D. Pental. I was part of the first cohort of Ph.D. students from the lab and worked with researchers who focused on transformation and improvement of Brassica, cotton and pigeon pea using Agrobacterium and biolistic based methods. It was a stimulating environment, and I learned a lot though the discoveries and experiences of fellow scientists. At that time, it was challenging to access scientific literature, and I had to commute to a different institution to prepare photocopies of articles to read. Visits to the library often turned into a full-day event, which allowed me to detach from the bench and spend time browsing journals and books.

11. Is there anything else you would like to share? If so, what is it?

In my opinion, it is important to find ways to pay forward the support we obtain during our career to other colleagues and younger professionals. This could be by mentoring, offering career advice, or volunteering in schools and the local community.

12. Bonus question: What’s your favorite molecular plant pathology-related article?

This paper I am a co-author on is by far my favorite—it was published when I was a research associate in Dr. Alan Collmer‘s lab: “Genetic Disassembly and Combinatorial Reassembly Identify a Minimal Functional Repertoire of Type III Effectors in Pseudomonas syringae. (Cunnac, S., Chakravarthy, S., Kvitko, B. H., Russell, A. B., Martin, G. B., and Collmer, A. 2011. Proc. Natl. Acad. Sci. 108:2975-2980).​

Plan to Attend the 2025 IS-MPMI Congress!

Plan to attend the 2025 IS-MPMI Congress Sunday through Thursday, July 13–17, in Cologne, Germany. More information is available online. IS-MPMI members will receive discounted registration rates for the conference. Scientists from some countries are eligible for discounted membership in IS-MPMI.

InterView with Dr. Simona Radutoiu

Alicia Camuel ​

Alicia Camuel is a Ph.D. student at the Plant Health Institute of Montpellier working with Eric Giraud on the Symbiotic Mechanisms in Tropical Legumes team. Her current research is focused

on identifying an alternative symbiotic pathway independent of Nod factors by studying the symbiosis between Aeschynomene spp. and Bradyrhizobium spp. Alicia was the recipient of a Ko Shimamoto Travel Award to attend the 2023 IS-MPMI Congress.

Simona Radutoiu is currently a professor and group leader at the University of Aarhus in Denmark, and her main research area is the identification of the genes involved in nitrogen-fixing symbiosis, with the aim of designing biotechnological tools that will enable us to transfer this ability to nonlegumes.

Conversation with Dr. Radutoiu

Between two sessions at the 2023 IS-MPMI Congress in Providence, RI, and over a lunch break, I had the chance to chat with Simona Radutoiu. Of course, we talked about science—it could not

be any other way in such a context. But, we also talked about many other aspects of the life of a woman scientist, career choices, and building a personal life in line with her plans and wishes. In the following article, I recount this informal interview with Simona, which I will remember for a long time. Our conversation began with scientific topics. As I am also working on nitrogen-fixing symbiosis, I wanted Simona’s opinion on questions that were more or less open and that I thought would be useful to discuss later on in my thesis. However, unlike most legumes capable of associating with rhizobia, I am studying an alternative symbiotic model that does not depend on Nod factors but on the bacteria’s type 3 secretion system (T3SS). In a recent paper, Simona and colleagues described the importance of LysM domain receptors that have adapted for nodule organogenesis. I, therefore, asked her about the fact that in my subject of study, the bacteria bypass this signaling mediated by LysM receptors and whether, in her opinion, other key symbiotic players could also be avoided. Our opinion on this question was similar, since it could very well be that other players in the symbiotic pathway are not required. However, it should be noted that “infection by infection threads remains the most efficient…and that CCaMK and CYCLOPS are central players for nodulation.”

Furthermore, the symbiotic model that I use to observe this T3SS-dependent process (Aeschynomene spp./Bradyrhizobium spp.) can only be observed under in vitro conditions. Often genetically associated with the Nod genes, T3SS in nature does not play a role in nodule organogenesis on its own. Nevertheless, a large majority of Bradyrhizobium spp. able to nodulate soybean possess both nod and T3SS genes (1), suggesting that T3SS could play a decisive role in symbiotic efficiency. Indeed, during my Ph.D. study I was able to show that effectors could directly trigger nodulation (2). I asked Simona if there is any real interest in studying this alternative process. According to her, there is: “These two processes [Nod-dependent and T3SS-dependent] should work together” in order to optimize symbiotic efficiency. Indeed, bacteria are known to use T3SS to modulate host specificity, as observed for several legumes (3,4). In this symbiotic model, however, T3SS is not just a host specificity factor, and thus, its role would be broader and complementary with Nod factors in nature. A response like this reinforced my choice of subject for my thesis, which is very fundamental but could ultimately have a broader scope.

I immediately wanted to know what Simona thought about the “dream” of one day transferring the symbiotic capacity of legumes to cereals, which are plants of major agronomic interest. Indeed, as a member of the ENSA (Engineering Nitrogen Symbiosis for Africa) scientific consortium, she is at the heart of this question, which many scientists have been asking themselves for several years. For sure, it represents “a real challenge…coordination between organogenesis and infection is essential but difficult to achieve…and many players have yet to be discovered.” Despite more than 20 years of research, this transfer to cereals remains a real challenge, requiring a great deal of resources and rigor. ​

Our conversation then moved on to subjects that some might consider ‘lighter,’ but which taught me so much in such a short space of time and which are just as important in a woman’s

scientific career. Having completed her doctorate in Romania, Simona found her calling, so to speak, after her Ph.D. stage at the University of Tennessee in the United States. On her return, she became a mother, but this in no way hindered her career. On the contrary, she says she is “passionate about science,” but still attaches great importance to her family: “I talk a lot with my daughter.” I could see in her eyes how obvious and authentic this was for her, although “managing these two sides of life is a constant learning process.” Being a woman in science has not always been easy, and it still is not, depending on the laboratories and countries in which we work. In France, for example, only around 30% of scientists are women. So, I told Simona about my doubts and misgivings about this aspect, as well as about becoming a mother one day. Although she was happy and fulfilled to be a mother, she advised me “not to let motherhood get in the way, to continue your career and always believe in yourself so that you can keep moving forward.” In a laboratory or elsewhere, it is important to “share your doubts and experiences with other women, with people you trust.” I felt at that moment that this is also what gives us the strength that we do not think we have, but which is always deep within us. Her words touched me deeply, and I invite everyone else to follow her precious advice.

I then asked her about choosing a postdoc position; what would be her career advice in light of her own experience? Should I change my research subject or move to another country? For Simona, it is essential to change subjects and above all to learn new techniques. She invited me to leave my comfort zone and start researching at least one year in advance. Even if changing subjects and leaving your country may seem like a challenge that is not so easy to overcome, you have to “believe in yourself and have confidence in yourself.”

Finally, now living in Denmark, Simona is far from her family and her country of origin. So, I wanted to find out if it had been difficult and how she managed this aspect of her life. For her, it was important for her career to leave Romania, and she was able to find a place where she and her family could blossom and make new friends with the people living there. In the end, she told me that although part of her family is still far away, “having moments to share with them becomes even more precious given the distance.”

Our whole exchange was a real pleasure, both on the scientific side and on the personal side. I hope that my feedback on the time I spent with Simona will also be of interest to young women like me, who are starting out on their scientific careers while trying to make the most of their life choices.

References

1. Teulet, A., Gully, D., Rouy, Z., et al. 2020. Phylogenetic distribution and evolutionary dynamics of nod and T3SS genes in the genus Bradyrhizobium. Microb. Genom. 6(9):mgen000407. DOI: 10.1099/mgen.0.000407

2. Camuel, A., Teulet, A., Carcagno, M., et al. 2023. Widespread Bradyrhizobium distribution of diverse type III effectors that trigger legume nodulation in the absence of Nod factor. ISME J. DOI: 10.1038/s41396-023-01458-1

3. Yang, S., Tang, F., Gao, M., Krishnan, H. B., and Zhu, H. 2010. R gene-controlled host specificity in the legume-rhizobia symbiosis. Proc. Natl. Acad. Sci. U.S.A. 107:18735-18740. DOI: 10.1073/pnas.1011957107

4. Miwa, H., and Okazaki, S. 2017. How effectors promote beneficial interactions. Curr. Opin. Plant Biol. 38:148-154. DOI: 10.1016/j.pbi.2017.05.011

MPMI Best Student Paper Awards

Best Student Paper​

Phytophthora i​​nfestans RxLR Effector PITG06478 Hijacks 14-3-3 to Suppress PMA Activity Leading to Necrotrophic Cell Death

Pathogens often induce cell death to successfully proliferate in the host plant. Plasma membrane H⁺-ATPases (PMAs) are targeted by eithe​r pathogens or plant immune receptors in immune response regulation. Although PMAs play pivotal roles in host cell death, the molecular mechanism of effector-mediated regulation of PMA activity has not been described. In this year’s MPMI Best Student Paper Award-winning article, Ye-Eun Seo et al. report that the Phytophthora infestans RxLR effector PITG06478 can induce cell death in Nicotiana benthamiana, but the induced cell death is inhibited by fusicoccin (FC), an irreversible PMA activator.

Honorable Mentions

Grapevine Fanleaf Virus RNA1-Encoded Proteins 1A and 1B^Hel Suppress RNA Silencing

Grapevine fanleaf virus (GFLV) (genus Nepovirus, family Secoviridae) causes fanleaf degeneration, one of the most damaging viral diseases of grapevines. Despite the substantial advances made in deciphering GFLV-host interactions, how this virus overcomes the host antiviral pathways of RNA silencing is still poorly understood. In this study, Jiyeong Choi et al. identified viral suppressors of RNA silencing (VSRs) encoded by GFLV, using fluorescence assays, and tested their capacity to modify host gene expression in transgenic Nicotiana benthamiana expressing the enhanced green fluorescent protein gene (EGFP).

A Coculture of Enterobacter and Comamonas Species Reduces Cadmium Accumulation in Rice

The accumulation of cadmium (Cd) in plants is strongly impacted by soil microbes, but its mechanism remains poorly understood. In this study, Xing Wang et al. report the mechanism of reduced Cd accumulation in rice by coculture of Enterobacter and Comamonas species. In pot experiments, inoculation with the coculture decreased Cd content in rice grain, immobilized Cd in soils, and enhanced soil nutrients and enzyme activities. The coculture also colonized the rice rhizosphere, activated defense responses, and regulated Cd uptake and efflux in rice, suggesting it protects rice against Cd stress.

Guido Sessa (1964–2023)—A Pillar of Molecular Plant-Microbe Biology Research in Israel and Beyond

Professor Guido Sessa, plant-microbe biologist, educator, mentor, and former head of the School of Plant Sciences and Food Security at Tel Aviv University, died unexpectedly on July 4,

2023,  in Tel Aviv. He was 59. Guido was known for his research on the molecular basis of bacterial pathogenesis and plant immunity using multiple experimental systems, including the interaction of Xanthomonas euvesicatoria with tomato and Arabidopsis. He was a respected colleague and a cherished friend. 

Born April 26, 1964, in Rome, Guido immigrated to Israel in 1983. After military service, he earned a bachelor’s degree at the Faculty of Agriculture, Food and Environment in Rehovot. His interest in plant-microbe biology began as a graduate student with Prof. Robert Fluhr at the Weizmann Institute of Science, where he investigated transcriptional control of pathogenesis-related genes and earned master’s and Ph.D. degrees in plant biology. In 1997, Guido was awarded a fellowship from the Israel-US Binational Agricultural Research and Development Fund (BARD) and moved to the United States for postdoctoral research with Greg Martin, first at Purdue University and then at Cornell University. 

In 2000, Guido returned to Israel and established a research laboratory at Tel Aviv University in the Department of Plant Sciences, which is now the School of Plant Sciences and Food Security. He progressed through the academic ranks to full professor and was a senior and esteemed member of the faculty’s academic staff and research team. Between 2018 and 2022, while serving as the head of the School of Plant Sciences and Food Security, Guido led the restoration and reopening to visitors of the Yehuda Naftali Botanical Garden. In 2023, he was appointed head of the Institute of Cereal Crops Research at Tel Aviv University and led projects to improve wheat, in particular wheat resistance to rust disease. 

Guido guided a dynamic research program focused on understanding molecular mechanisms in bacterial pathogenesis of plants and in plant stress responses and immunity. Early in his career he established the tomato–X. euvesicatoria interaction as a model system, and this became the foundation of many of his important discoveries over the years. His lab was an early adopter of genome-wide gene expression profiling methods, and this work revealed the importance of certain transcription factors and MAP kinases in the tomato immune response. From his postdoctoral work onward Guido’s skill in applying protein biochemistry techniques to understand signaling events drove numerous pioneering advances. One example is his finding that a MAP kinase in tomato, MPK3, autophosphorylates on a specific tyrosine residue that is critical for its role in both the wound response and defense. His lab also made important discoveries in how type III effectors from Xanthomonas suppress host defenses. One study, a collaboration with Mary Beth Mudgett, showed how a widely conserved effector XopQ interacts with a host 14-3-3 protein to compromise MAPK signaling and immunity to X. euvesicatoria. In recent years, the Sessa lab published a series of studies on the roles of type III and VI secretion in the pathogenicity of a Pantoea agglomerans pathovar that causes a serious disease of beets. He was also the editor of a comprehensive overview of the field in 2012, titled Molecular Plant Immunity. These and many other contributions over the years from Guido and his lab enriched our molecular understanding of bacterial interactions with plants and plant defense and laid the foundation for more effective disease control. 

A hallmark of Guido’s research was the many collaborations he developed with scientists in Israel and around the world. A particularly fruitful collaboration was with Greg Martin, which began during Guido’s postdoctoral period and continued for 25 years. Their joint work spanned a range of fundamental topics, including early work on gene expression profiling of the tomato defense response to bacterial pathogens, the role of GRAS family transcription factors in immunity, the discovery and characterization of MAPKKKe and MAPKKKa, which play key roles in activating immunity-associated MAPK cascades, and, most recently, a broad investigation of the negative regulation of immune signaling by PP2C protein phosphatases in tomato. Their collaboration was supported by seven successive BARD research grants, one of which is still active, and resulted in more than 30 publications, dozens of presentations at scientific meetings and the training of many students and postdoctoral associates. Guido was also a PI on four other BARD-funded research projects, and co-organized with Mary Beth Mudgett and Avi Avni a BARD- and NSF-supported workshop at Tel Aviv University on Microbial Virulence Determinants and Plant Innate Immunity, which aimed to assemble junior and senior colleagues in the field to share their insights and forge new collaborations. 

Guido was a strong supporter of basic and applied plant sciences in Israel, most notably through his service to the BARD Program. He served for seven years on grant evaluation committees, where he played an important role in setting and maintaining BARD’s high scientific standards. In addition, Guido frequently reviewed proposals on an ad hoc basis, even on short notice, provided advice on technical issues, and helped identify scientists to serve on BARD committees. He also provided scientists who wished to pursue BARD funding assistance in finding an Israeli or U.S. partner. 

As a long-time member of the Association of Italian Scholars and Scientists, Guido avidly and effectively promoted research relationships between researchers from Italy and Israel in the field of plant-microbe biology, with support from the Italian Embassy in Tel Aviv. Most recently, he organized a joint conference in Israel with the participation of researchers from both countries. Unfortunately, he did not get to participate in the conference, as it was held the day before his death. 

Guido was an exemplary mentor to young researchers throughout Israel and to his students and postdocs in particular. He excelled at identifying important and appropriate research projects for his lab members and allowed them great independence in pursuing their research, while at the same time always being available with advice and challenging questions. Many of his students went on to careers in academia or the biotech industry in Israel and around the world. Guido’s genuine interest in others and his collegiality sparked many collaborations and connections in Israel, and these often led to invitations to serve on graduate student committees at universities within Israel in addition to his own. Guido, thus, had a major impact on both established and upcoming scientists in the plant-microbe biology field. 

In addition to being an exceptional scientist and insightful, supportive colleague, Guido was a great friend to many. He had a warm smile, a subtle sense of humor, and a quiet laugh. He was kind and generous. He loved traveling, playing soccer, and skiing in the Italian Alps, and he had a lifelong interest in opera. Ying-Tsu Loh, a graduate student who overlapped with Guido at Purdue University writes, “I will always remember Guido for our ‘opera Saturdays’ at the lab, really loud opera, that you could hear walking down the hall. You knew then that Guido was in and that Saturday at the lab would be fun.” Greg Martin remembers many good times with Guido, including during visits to Israel, where “we once spontaneously met his parents who happened to be out for a walk as we drove into Jerusalem, visited Masada, which was close to where Guido had done his military service, floated in the Dead Sea, and, memorably, in March of this year enjoyed a long lunch at Guido’s favorite Italian restaurant in northern Tel Aviv. Those are great memories to have of a great friend.” Adam Bogdanove, who was a postdoc with Martin at the same time as Guido, says of his lab mate and longtime friend, “I learned a lot from Guido. To this day, my lab uses Guido’s western blot protocol. And, I’ll always remember coffee breaks with Guido outside the Martin lab. We’d talk about science, and other topics, and laugh often. Those kinds of conversations continued throughout our careers and are what I will miss most.” Mary Beth Mudgett shares, “Some of my best days as a scientist were brainstorming with Guido and drafting project ideas on napkins in cafes around the world. He was a critical thinker, thought provoking, down-to-earth and always warmhearted. I am missing Guido deeply.” 

Guido is survived by his mother, a brother, and by the light of his life, his daughter Shira, whom many of his colleagues were privileged to know as he often invited her to join him at scientific conferences and visits with collaborators. He will be greatly missed. 

Gregory B. Martin,^1,2 Adam J. Bogdanove,¹ and Mary Beth Mudgett³ 

¹ Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
² Boyce Thompson Institute for Plant Research, Ithaca, NY, USA
³ Department of Biology, Stanford University, Stanford, CA, USA ​​

Acknowledgments

We thank Guy Sobol, Dor Salomon, Saul Burdman, and Haim Katz for helpful information. ​