Effect of plant growth-promoting bacteria on freezing-tolerance for winter wheat (Triticum aestivum)

Student: Samantha Darling

Mentor: Mary Poulson


Winter wheat (Triticum aestivum L.) is of huge importance to global agriculture. Wheat is sown in the fall, germinates and then goes dormant to resume growth in the spring. Although winter wheat strains are bred to tolerate gradual changes in temperature, unexpected frosts in the spring can potentially cause cellular damage and decreased growth rates for young plants. Plant growth promoting bacteria (PGPB) have been shown to play an integral role in increasing plant tolerance to drought, salinity and pathogens but effects of PGPB on plant cold hardiness has not yet been well documented. In this project, young wheat plants were inoculated with three PGPB strains shown to enhance plant stress tolerance: Pseudomonas fluorescens, Bacillus subtilis and Paenibacillus polymyxa. After germination and a short growth period at 21oC, plants were exposed to cold (5oC or 12oC) salt (100 mM NaCl) or drought (25% of water given to control plants). Plant productivity was determined by measuring total plant biomass and freezing tolerance was assessed by measuring ion leakage from cells after freezing. Growth of plants was reduced by nearly 50% for plants at 12oC or 5oC. Salt did not affect plant growth. Drought reduced plant fresh weight by 40% but only 10% dry weight. PGPB did not affect plant growth or susceptibility to freezing tolerance for salt or drought plants. For plants not previously exposed to cold stress, however, inoculation with P. polymyxa did lend some protection from freezing stress.


View High-Resolution Version of the Poster Here.

19 thoughts on “Effect of plant growth-promoting bacteria on freezing-tolerance for winter wheat (Triticum aestivum)”

  1. BriAnna Reisinger

    Hi Samantha! I found this presentation very informative, and it was so great to learn something new. You did a wonderful job on this experiment. I was wondering what intrigued you to focus on winter wheat? and if you plan on doing this experiment with other plants/vegetation in the future?

    1. Thank you so much, I’m glad I got the opportunity to share my findings! Being winter when I started this project I wanted to do look into freezing tolerance in plants so winter wheat came up often. It would be very interesting to keep diving deeper and gain more knowledge in regards to PGPB and how it effects other types, as of right now I’m not sure if it will come up again. I do however plan to stay in the botany field after graduating!

  2. Well done Sam. I appreciate the time and effort you put into collecting your data in a rush in order to finish your project before we moved online. Nice poster. Go plants.

  3. Good work Sam! I am surprised salt had no effect on growth! Is wheat winter grown in salty soils? I wonder what physiological adaption they have against salt!

    1. Thank you! The salt showed very little effects.. we were thinking maybe because the dosage wasn’t strong enough. Not as far as I know, but it could be possible for them having some sort of adaption.

  4. Hi,

    If you ever conducted this experiment again would you use different plants? IF so what plants would be interested in using?

    1. I think if I repeated this experiment I would still use the winter wheat so I could compare and maybe up the dosages on everything.

  5. Great project! Was really interested to learn a little bit about PGPBs. However, do you think this experiment just didn’t work out for you or do PGPBs not help plants with chilling, drought, and salt-stress?

    1. Thank you! PGPB have been found to show protectant features with abiotic/biotic stresses. I think it could have to do with the amounts used and the limited time there was. But yes, PGPB are fascinating and I’d love to look deeper into them.

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