Dr. Pushan Bag
- Please tell us about yourself and your research/institution.
My name is Pushan Bag, and I’m a Human Frontiers Science Program research fellow at the Department of Biology, University of Oxford. I work in Prof. Paul Jarvis’s lab, in the field of chloroplast protein transport. My current research focuses on how proteins are imported into chloroplasts, particularly how this process changes during different developmental stages. I'm especially interested in the structural biology of these transport machineries. The long-term goal is to engineer the protein transport machinery to influence plant development, which could have significant implications for improving crop performance.
Since protein transport into chloroplasts is heavily light-dependent, it’s clear that this process is directly or indirectly regulated by photosynthesis. During my PhD, I worked extensively on photosynthesis, which gave me a strong foundation in chloroplast energy metabolism. Now, I aim to integrate that expertise with my current work to explore how chloroplast energy status and redox metabolism influence—and are influenced by—organelle biogenesis and development. Ultimately, I hope to build a unified understanding of how chloroplasts function and adapt under different environmental and developmental conditions.
This field is also incredibly fascinating from an evolutionary perspective. Chloroplast protein transport is believed to have evolved from ancient bacterial toxin ejection systems. As life on Earth progressed from unicellular to multicellular organisms and eventually to higher plants, these primitive systems were repurposed—from ejecting toxins to importing proteins. One hypothesis is that, following the endosymbiotic origin of chloroplasts from cyanobacteria, most of the endosymbiont’s genes were transferred to the host nucleus, which then forced the evolution of a protein import system from what was originally an ejection system. But we don’t yet know exactly how this transition occurred—or if it happened in that way at all.
To shed light on this question, I’m examining the structure of these protein transporters across organisms throughout the evolutionary tree. By doing so, I hope to understand how this transformation took place. This research could also provide insights into mitochondrial evolution, as both chloroplasts and mitochondria originated via endosymbiosis. Understanding one may help us better understand the other.
- What motivated you to get into plant science?
Well, to be honest, I wasn’t very enthusiastic about plant science early in my academic journey. During my bachelor’s studies, I focused on microbiology, physics, and chemistry. I still remember the first time I saw the Z-scheme of photosynthesis in a textbook—I thought it looked too complicated and skipped that chapter altogether!
Later, I pursued a Master’s in Molecular Microbiology, which wasn’t plant-focused either, although it was offered by the Department of Plant Sciences at the University of Hyderabad. My entry into plant biology was more of a happy accident. Due to lower first-semester grades, I had limited options for my master’s thesis lab and ended up in a plant biology lab that no one else from my program had chosen. That turned out to be a blessing in disguise: I had a great experience and even got a good paper out of it. That was the moment I got properly introduced to plant science—and since then, it's been green all the way!
After my Master’s, I joined Prof. Rajagopal’s lab, where I first started working with chloroplasts and photosynthesis. I began to wonder: when we treat plants in the lab and observe how they respond, how does that compare to how they naturally behave in the wild? That curiosity led me to do my PhD with Prof. Stefan Jansson in Umeå, working on conifers in natural and extreme conditions, which felt like a very natural progression. From there, moving into protein transport with Prof. Jarvis and thinking about how we can engineer plants for agriculture has been a very fulfilling path.
And looking back on it all, I’m reminded of that quote from Steve Jobs: “You can’t connect the dots looking forward; you can only connect them looking backwards.” At the time of choosing my Master’s lab, I had absolutely no idea what I was doing—just taking the only open opportunity. And now here I am, giving an interview to Agrisera about plant protein antibodies. That’s the beauty of the journey.
- How have you used (Agrisera) antibodies in your research?
The first time I used Agrisera antibodies was in Prof. Rajagopal’s lab—probably for a western blot of Photosystem II subunit A (PsbA). Before that, I hadn’t even heard of Agrisera. But once you get into photosynthesis research, you quickly realize how essential Agrisera is, especially given their extensive collection of antibodies targeting photosynthetic proteins.
During my PhD in Umeå, I got to work closely with Agrisera for multiple reasons. First, they were part of my Marie Skłodowska-Curie Horizon 2020 EU project. Second, in Prof. Jansson’s lab, many light-harvesting complex antibodies were co-developed with Agrisera. I also had a particularly rewarding experience working with spruce and pine, which required antibody optimization. Agrisera was extremely helpful and responsive throughout that process. We even developed spruce-specific Lhcb1 antibodies in collaboration with them, and the whole process was smooth and enriching.
Now that I’m in the UK, I’m still planning to design more antibodies with Agrisera. Beyond their research tools, I also want to highlight the educational posters and illustrations they create. Those were incredibly helpful during my PhD and even contributed to how I structured my thesis. It really shows how a company can go beyond commercial products to play an educational and academic role in the scientific community.
- Any further comments?
I truly value the role of well-characterized molecular tools in advancing plant science, and Agrisera has been a key part of that journey for me. As the field moves toward more integrative and synthetic approaches—combining insights from photosynthesis, organelle biology, and systems biology—having reliable, specific, and customizable reagents is more critical than ever. I’m particularly excited about the potential to unravel how chloroplast energy status regulates development and function, and how that understanding can be applied to improve crop productivity in a changing world.
Links
• Dr. Pushan Bag
• Agrisera Photosynthesis Antibodies