Our lab focuses on the molecular and ecological dynamics of plant-microbe interactions, with an emphasis on understanding disease resistance mechanisms in key crops such as soybean and potato, as well as microbial virulence and biocontrol strategies for crop improvement and sustainable disease management. Through interdisciplinary research in molecular genetics, disease resistance, pathogen biology, and comparative genomics, we aim to develop novel insights and innovative strategies for environmentally friendly and sustainable crop protection that minimize chemical inputs without reducing yield. Our mission is to contribute to the scientific community through high-impact research, foster collaborations across disciplines, and train the next generation of plant pathologists and crop scientists to address national and global agricultural challenges.
Toward these goals, we have been working on the following plant diseases and research areas:
1. Crop Disease Resistance: From Molecular Mechanisms to Field Applications – The lab studies various plant diseases caused by fungi and bacteria in soybeans and potatoes.
White Mold of Soybean
Soybean, a key crop, is vulnerable to Sclerotinia sclerotiorum, a broad-host fungus causing white mold or Sclerotinia stem rot (SSR) on 400+ plant species. No soybean line offers full resistance. Understanding molecular plant resistance mechanisms to S. sclerotiorum could deliver novel strategies to deploy resistant soybean varieties. We aim to characterize crucial genes involved in soybean resistance/susceptibility to S. sclerotiorum. One major part of Ranjan’s soybean research program is identifying soybean genes for resistance to S. sclerotiorum.
The current study involves the following major projects -
Characterizing and bioengineering soybean phenylpropanoid pathway genes for resistance against Sclerotinia sclerotiorum.
Screening soybean lines for resistance in the field and controlled plant growth facilities.
Watch this video about Plant growth facility at UMN that we are using for screening studies -
Verticillium Wilt of Potato
Verticillium wilt of potatoes is caused primarily by two species of fungal pathogens called Verticillium dahliae and Verticillium albo-atrum. Verticillium wilt can cause a yield loss of about 10-50%, depending on the conducive environment and susceptible host. Verticillium dahliae is a soil-borne pathogen that can infect more than 200 plant species, including herbaceous and woody plants, and many economically important crops. For more info on Verticillium wilt of potato, watch the following video -
The current study involves the following major projects -
- Evaluating commercial and newly developed potato lines for Verticillium wilt resistance in the field and controlled environment.
- Developing resistance tools:
- Understanding potato and tomato plant defense strategies against Verticillium wilt using multiomics and molecular approaches.
- Screening potato wild and newly advanced lines/varieties for Verticillium race-specific resistance
Potato Common Scab
Potato common scab (PCS) can be caused by many Streptomyces spp. While PCS does not directly reduce yield, scab lesions, characterized by corky, raised, deep-pitted marks on tubers, can lead to economic losses due to the rejection of affected potatoes. Potato common scab occurs worldwide.
- Screening potato varieties to develop PCS-resistant potato varieties.
- Studying the tolerance mechanism in potato to PCS using molecular and multiomics approaches.
2. Pathogen biology: From phylogenomics to Virulence factors Phylogenomics and Comparative genomics
We apply phylogenomics and comparative genomics approaches for studying plant pathogens such as Verticillium dhaliae, Colletotrichum spp. and Streptomyces spp. to understand their evolution, adaptation, and host interactions.
Virulence factors and Race study
Besides phylogenomics and comparative genomics, we use transcriptomics approaches to identify and characterize key virulence factors of pathogenic microbes.
Currently, we are using molecular typing to identify races of Verticillium dhaliae and Identifying novel species of Streptomyces.
3. Sustainable Crop Protection using Friendly Microbes: From biostimulants to Biological Control
Our research focuses on advancing sustainable crop protection through innovative microbial solutions, bridging biostimulants and biological control to promote resilient agriculture. We harness beneficial microbes, such as plant growth-promoting rhizobacteria (PGPR) and Trichoderma fungi, to develop eco-friendly alternatives to chemical inputs. We harness biostimulants to enhance plant resilience and biocontrol agents to target pathogens. Integrating genomics and field trials, we aim to optimize microbial efficacy, reduce agrochemical dependency, and support soil health for sustainable food systems.
4. Role of Extracellular vesicles in transkingdom interaction
Extracellular vesicles (EVs) serve as critical mediators of transkingdom interactions, enabling communication between hosts and microbes through the exchange of proteins, RNAs, and metabolites. Host EVs deliver defense molecules like small RNA and antimicrobials, while microbial EVs transport effectors, influencing infection outcomes and community dynamics. This bidirectional communication offers insights into host-pathogen coevolution and opportunities for therapeutic innovations.