Effective seed sterilization methods require optimization across maize genotypes

Authors: PARNELL, J. JACOB - North Carolina State University; PAL, GAURAV - North Carolina State University; AWAN, AYESHA - North Carolina State University; VINTILA, SIMINA - North Carolina State University; HOUDINET, GABRIELLA - North Carolina State University; HAWKES, CHRISTINE - North Carolina State University; Balint-Kurti, Peter; WAGNER, MAGGIE - University Of Kansas; KLEINER, MANUEL - North Carolina State University

Submitted to: Phytobiomes Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2024
Publication Date: 7/17/2024
Citation: Parnell, J., Pal, G., Awan, A., Vintila, S., Houdinet, G., Hawkes, C.V., Balint Kurti, P.J., Wagner, M.R., Kleiner, M. 2024. Effective seed sterilization methods require optimization across maize genotypes. Phytobiomes Journal. 8(4):418-424. https://doi.org/10.1094/PBIOMES-12-23-0137-R.
DOI: https://doi.org/10.1094/PBIOMES-12-23-0137-R

Interpretive Summary: Maize seed harbors a diversity of microbial species. When using seeds for experimental purposes, it is desirable to sterilize the seed as much as possible- killing the majority of these microbes without compromising the viability of the seed itself. A number of ways of doing this have been reported, including washing the outside of the seed with various disinfectants as well as heat treating the seed. We tested a number of protocols on seeds from two different varieties. We determined that their relative effectiveness depends not only on the variety but also on where and when the seed was generated.

Technical Abstract: Studies of plant-microbe interactions using syntheticmicrobial communities (SynComs) often require the removalof seed-associated microbes by seed sterilization priorto inoculation to provide gnotobiotic growth conditions. Diverseseed sterilization protocols have been developed and havebeen used on different plant species with various amounts ofvalidation. From these studies it has become clear that each plantspecies requires its own optimized sterilization protocol. It has,however, so far not been tested whether the same protocol worksequally well for different varieties and seed sources of one plantspecies. We evaluated six seed sterilization protocols on twodifferent varieties (Sugar Bun and B73) of maize. All unsterilizedmaize seeds showed fungal growth upon germination on 'lterpaper, highlighting the need for a sterilization protocol.A short sterilization protocol with hypochlorite and ethanol wassuf'cient to prevent fungal growth on Sugar Bun germinants;however a longer protocol with heat treatment and germinationin fungicide was needed to obtain clean B73 germinants. Thisdifference may have arisen from the effect of either genotypeor seed source. We then tested the protocol that performed bestfor B73 on three additional maize genotypes from four sources.Seed germination rates and fungal contamination levelsvaried widely by genotype and geographic source of seeds.Our study shows that consideration of both variety and seedsource is important when optimizing sterilization protocols andhighlights the importance of including seed source informationin plant-microbe interaction studies that use sterilized seeds.