Phytoplasmas are intracellular bacterial plant pathogens that cause devastating diseases in crops and ornamental plants through the secretion of effector proteins. One of these effector proteins, termed SAP54, leads to the degradation of a specific subset of floral homeotic proteins of the MIKC-type MADS-domain family via the ubiquitin-proteasome pathway. Aurin et al. report that, based on biophysical and molecular biological analyses, SAP54 folds into an alpha-helical structure.
Liu et al. explored the mechanism by which Bacillus pumilus LZP02 promotes growth in rice roots through proteomic, transcriptomic, and metabolomic techniques. The results indicated that B. pumilus LZP02 promoted the growth of rice roots by enhancing carbohydrate metabolism and phenylpropanoid biosynthesis.
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Wednesday, December 2, 2020
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Wheat stem rust, a previously well-controlled disease, has reemerged as a major threat to wheat, with major outbreaks in Africa, Europe, and central Asia. The stem rust resistance gene Sr22 encodes a nucleotide-binding and leucine-rich repeat receptor, which confers resistance to the highly virulent African stem rust isolate, Ug99. Hatta et al. show that the Sr22 gene is conserved among grasses in the Triticeae and Poeae lineages.
Pamela Ronald, University of California, Davis, has been named a 2020 World Agriculture Prize Laureate by the Global Confederation of Higher Education Associations for Agricultural and Life Sciences. This award recognizes exceptional lifetime achievement in agriculture. She is the first woman whose work is recognized by the award. Read more about this announcement in ASPB News.
Barbara Kunkel, Washington University, has been selected to begome a Fellow of the AAAS in recognition of her distinguished discoveries related to Pseudomonas syringae. She will be inducted at the 2021 AAAS Meeting in February. Learn more about this Fellowship here.
Clark and colleagues investigate the role of the Liberibacter effector SDE1, finding that it promotes colonization by Liberibacter, the causative agent of citrus greening disease, or huanglongbing, likely by inducing premature senescence responses in leaves.
Jawahar Singh, MPMI Assistant Features Editor
Ryan DelPercio is a postdoctoral researcher at the University of California, Davis, Genome Center, where he works with Dr. Blake Meyers to investigate the transcriptional and regulatory networks underlying symbiotic nitrogen fixation (SNF) and to develop advanced CRISPR-based molecular tools for crop improvement. His work bridges discovery and application-linking RNA biology, gene editing, and synthetic biology to improve nitrogen use efficiency and sustainability in agriculture. During his Ph.D. research at the University of Missouri–Columbia (with research at the Donald Danforth Plant Science Center), Ryan uncovered how soybean and its symbiotic partner Bradyrhizobium diazoefficiens coordinate their transcriptional programs through time. His recent MPMI paper coauthored with Madison McGregor, Stewart Morley, Nazhin Nikaeen, Blake Meyers, and Patricia Baldrich, “Transcriptional Dynamics of Symbiotic Nitrogen Fixation and Senescence in Soybean Nodules: A Dual Perspective on Host and Bradyrhizobium Regulation,” reveals that nitrogen fixation follows a striking molecular rhythm in which both partners synchronize their gene expression during development, peak activity, and senescence.
We discovered that symbiosis has a rhythm. The soybean–Bradyrhizobium partnership shows a coordinated, temporal cadence in gene expression, where both partners adjust their transcriptional programs in sync throughout the nodule’s life cycle. This rhythm reflects the well-defined stages of nodule development formation, active nitrogen fixation, and senescence.
What surprised me most was that Bradyrhizobium maintains specific gene-expression programs even during nodule senescence, suggesting it prepares for survival beyond the symbiosis. This finding highlights the remarkable flexibility of rhizobia and provides new insights into how plant and bacterial partners sustain and ultimately conclude their cooperative relationship.
Coordinating multi-omics datasets—RNA-seq and small RNA-seq—for both host and symbiont, alongside weekly acetylene reduction assays (ARAs), was incredibly demanding. The ARAs, a classic but labor-intensive method for measuring nitrogenase activity, had to be performed with precise timing across four weeks.
Maintaining experimental consistency required extraordinary teamwork. Every nodule had to be harvested and processed within hours to ensure accurate nitrogenase activity calculations. This experience ultimately inspired me to invent LERN-FASt (leaf expression ratio for nitrogen fixation activity status), a nondestructive diagnostic tool that estimates nitrogen fixation activity from leaf transcripts—an innovation I hope to publish soon.
I’m currently developing a new CRISPR-based gene-editing platform that makes targeted gene integrations easier to identify and validate in plants. By improving detection of precise genetic events, this tool could accelerate studies on gene function, regulatory networks, and synthetic biology across diverse crops.
Start by thinking about what comes next—choose projects that build the skills you’ll need for your future goals. Balance high-risk, high-reward experiments with steadier projects to ensure continued progress. And, when you feel nervous before presenting your work, take it as a good sign because it means you care, and that energy will help you perform your best.
My greatest scientific inspiration is my wife, Dr. Patricia Baldrich. She leads by example, combining rigorous science with collaboration and compassion. Her thoughtful approach to experimental design and mentorship reminds me that great science is not only about discovery, but also about responsibility, communication, and purpose.
Mentorship and outreach have been central to my scientific journey. I’ve mentored high school and undergraduate students through NSF-REU programs, cochaired the Committee for Scientific Training and Mentoring at the Danforth Center, and led community outreach through the Jackie Joyner-Kersee Foundation. These experiences reinforced my belief that science grows stronger when knowledge and opportunity are shared.
Transitioning across vastly different careers—from the U.S. Air Force and oil refining to plant molecular biology—was my biggest challenge. Each shift demanded learning new disciplines from the ground up. However, those experiences have broadened my perspective, teaching me resilience, adaptability, and empathy. They remind me daily that it’s never too late to start over and that diverse experiences can shape creative solutions in science.
I’m always happy to connect on LinkedIn.
Never lose sight of your “why.” Understanding and communicating why your research matters is as important as the research itself. This philosophy inspired the Next Big Idea sessions that Patricia and I organized at ICAR 2022 (Belfast) and the 2023 IS-MPMI Congress (Providence), encouraging scientists to articulate the passion behind their work. When people sense that you care deeply, they are more likely to care too.
I’ve always been fascinated by rhizobia bacteria that form symbiotic rather than pathogenic relationships. These microbes enrich soils and feed the world by supplying legumes with nitrogen. If we can extend this partnership to non-legumes, we could revolutionize agriculture by reducing fertilizer use, mitigating greenhouse gases, and promoting sustainability at a global scale.
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Broad-spectrum resistance to bacterial blight in rice using genome editing
Leveraging gene silencing approaches to protect plants from fungi
Epichloë fungal endophytes — From a biological curiosity in wild grasses to an essential component of resilient high performing ryegrass and fescue pastures
Continuing with the theme of translational plant research, IS-MPMI is hosting a second international virtual seminar with leaders in the field of molecular plant-microbe interactions who are taking molecular advances in plant science and translating these discoveries to develop disease resistant and high performing crops in agriculture. This meeting will highlight the use of genome editing, transcriptional gene silencing, new computational tools and beneficial microbes to study the complexities of plant responses to microbes. The goal is to share new developments that are at the forefront of the field and discuss key strategies used to translate these advances for biotechnology and industry applications.
The format will include four research presentations, each followed by an open question & answer period where participants can interact with the speakers. The event will be moderated by Mary Beth Mudgett (IS-MPMI President), Jeanne Harris (EIC, MPMI Journal), and Dennis Halterman (EIC, IS-MPMI Interactions). We encourage broad participation of graduate students, post-doctoral scholars, research scientists, principle investigators, funding agencies, and policy makers to provide diverse perspectives.
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