The focus of the Raizada Lab is to conduct fundamental and applied research in crop probiotics to help Canadian farmers, and to research inexpensive and sustainable technologies that improve the lives of small scale indigenous farmers. We have 3 ongoing projects, and you can learn more at www.RaizadaLab.ca.

Project 1 - Plant Microbiome Inheritance

We are conducting basic research about the inheritance and transmission of the plant microbiome, using corn (maize) as a model system. Our Lab has made 3 fundamental contributions. In 2011, we provided initial evidence that seeds contain a heritable microbiome that is under long-term selection by farmers. Previously, it was thought that plants only took up microbes from their environment, rather than inherit them through seed. In 2016, we provided initial evidence that the rhizosphere microbiome (at the root-soil interface) of seedlings can originate from seeds. Previously, it was believed that rhizosphere bacteria are solely recruited from bulk soil. The rhizosphere is described as the "gut" of a plant, because it is the primary location of uptake of mineral nutrients. In 2023-2024, in two papers, we provided initial evidence that a crop pollen microbiome is not randomly acquired from the air and hence full of opportunistic pathogens (both common beliefs), but rather may be under selection by farmers to carry potentially beneficial microbes for their crops. 

Selected publications
Shrestha, A., Limay-Rios, V., Brettingham, D.J.L. and Raizada M.N. (2024) Maize pollen carry bacteria that suppress a fungal pathogen that enters through the male gamete fertilization route. Frontiers in Plant Science  14, 1286199.

Khalaf, E.M.*, Shrestha, A.*, Reid, M., McFadyen, B.J. and Raizada M.N. (2023) Conservation and diversity of the pollen microbiome of pan-American maize using PacBio and MiSeq. Frontiers in Microbiology 14, 1276241. (*co-equal first authors)

Johnston-Monje D,  Lundberg DS, Lazarovits G, Reis VM and Raizada M.N. (2016) Bacterial populations in juvenile maize rhizospheres originate from both seed and soil. Plant and Soil 405: 337

Johnston-Monje D. and Raizada, M.N. (2011) Conservation and diversity of seed associated endophytes in Zea across boundaries of evolution, ethnography and ecology. PLoS One 6: e20396.

Project 2 - Evolving Bacteria for Farmers

We are developing novel, rapid evolution strategies to improve crop probiotics and adapt them to field conditions, to help farmers reduce their dependency on synthetic nitrogen fertilizer which contributes to greenhouse gas emissions. 

A current project involves legume crops (e.g. soybeans, cowpea, common bean, lentil, alfalfa). These crops have special rhizobia bacteria that convert atmospheric nitrogen gas into organic fertilizer, which enables their grain to be rich in protein; the decomposing root/shoot residue can also organically fertilize rotating cereal crops such as corn, rice and wheat. The rhizobia bacteria inhabit root organs called nodules. Until now, if the correct rhizobia bacteria were not in their soil, farmers would need to purchase 'inoculant' from companies, which is not feasible for millions of remote indigenous farmers. In 2023, we reported that it was possible to inoculate seed with rhizobia bacteria simply by crushing nodules onto seeds -- including under field conditions. We propose that farmers can now distribute, sell and trade nodules, as they have trading seeds for thousands of years. Nodule crushing is intended to democratize and decentralize microbial inoculants and empower farmers to deliberately breed their own microbes for the first time -- to improve native bacteria and indigenize elite strains. The technology has been featured on global U.N. Food & Agricultural Organization webinars. 

We are also uncovering how indigenous farmers evolved microbes over thousands of years, while learning lessons from natural selection. From these findings, starting in 2015-2016, we proposed that plants, which have immobile cells that are locked in by cell walls, evolved mobile endophytic microbes in their vascular system, as a complementary defence system to seek and destroy pathogens, analogous to circulating immunity cells in the human lymphatic system. 

Selected publications
Pudasaini R., Hewedy O, and Raizada MN  (2023) Improving field legume nodulation by crushing nodules onto seeds: implications for small-scale farmers. Frontiers in Agronomy 5, 1161978

Mousa WK, Shearer C, Limay-Rios V, Ettinger CL, Eisen JA, Raizada MN (2016) Root hair-endophyte stacking (RHESt) in finger millet creates a physico-chemical barrier to trap the fungal pathogen Fusarium graminearum. Nature Microbiology  1: 16167 

Soliman SM, Greenwood JS, Bombarely A, Mueller LA, Tsao R, Mosser DD and Raizada MN (2015) An endophyte constructs fungicide-containing extracellular barriers for its host plant. Current Biology 25, 1-7

Project 3 - Empowering Small Scale Farmers

In addition to nodule crushing (above), we have various projects to empower and share wisdom from indigenous, small scale farmers in developing nations, including evaluating a menu of >150 sustainable technologies (e.g. tools) and agronomic practices that are low cost, simple, affordable, gender-friendly, drudgery-reducing, and nutrition-promoting. When combined, this menu is called the Sustainable Agriculture Kit (SAK), which has thus far improved the livelihoods of up to 260,000 rural peoples, albeit modestly. In ongoing projects, we have also developed training materials for low-literacy farmers including free picture based lessons (www.SAKBooks.com) and an online encyclopedia for small scale farmers (www.Farmpedia.org), which is translatable into 108 local languages. In 2023, Farmpedia had 8,000 visitors per month and growing.

Selected publications
Devkota R , Hambly Odame H, Fitzsimons J, Pudasaini R, and Raizada MN (2020) Evaluating the Effectiveness of Picture-Based Agricultural Extension Lessons Developed Using Participatory Testing and Editing with Smallholder Women Farmers in Nepal. Sustainability 12, 9699

Sousa EC and Raizada MN (2020) Contributions of African crops to American culture and beyond: The Slave Trade and other journeys of resilient peoples and crops. Frontiers in Sustainable Food Systems 4: 586340

 Thilakarathna MS, Chapagain T, Ghimire B, Pudasaini R, Tamang BB, Gurung K, Choi K, Rai L, Magar S, Bishnu BK, Gaire S, Raizada MN (2019) Evaluating the effectiveness of rhizobium inoculants and micronutrients as technologies for Nepalese common bean smallholder farmers in the real-world context of highly variable hillside environments and indigenous farming practices. Agriculture 9: 20

Chapagain, T., B. Ghimire, R. Pudasaini, K. Gurung, K. Choi, L. Rai, S. Magar, B. BK. and MN Raizada (2019) The underutilized terrace wall can be intensified to improve farmer livelihoods. Agronomy for Sustainable Development 39:29

Chapagain T, Ghirmire B, Pudasaini R, Gurung K, Choi K, Rai L, Magar S, Bishnu BK and Raizada MN (2018)  Intercropping of maize, millet, mustard, wheat and ginger increased land productivity and potential economic returns for smallholder terrace farmers in Nepal. Field Crops Research 227: 91-101

Chapagain T and Raizada MN (2017) Impacts of natural disasters on smallholder farmers: Gaps and recommendations. Agriculture and Food Security 6:39

Chapagain T and Raizada MN (2017) Agronomic challenges and opportunities for smallholder terrace agriculture in developing countries. Frontiers in Plant Science 8: 331 

Small FAA and Raizada MN (2017) Mitigating dry season food insecurity in the subtropics by prospecting drought-tolerant, nitrogen-fixing weeds. Agriculture & Food Security 6:23

Thilakarathna MS and Raizada MN (2015)  A Review of Nutrient Management Studies Involving Finger Millet in the Semi-Arid Tropics of Asia and Africa. Agronomy 5: 262-290

Goron, TL and Raizada MN (2015) Genetic diversity and genomic resources available in the small millet crops to accelerate a New Green Revolution. Frontiers in Plant Science  6: 157

Bargout, R.N. and Raizada, M.N. (2013) Soil Nutrient Management in Haiti, Pre-Columbus to the Present Day: Lessons for Future Agricultural Interventions. Agriculture & Food Security 2: 11. 

For further information about the Raizada Lab, please visit: http://www.raizadalab.ca