Gene expression and physiological differences in neo-octoploid switchgrass subjected to drought stress

Authors: Chanbusarakum, Lisa; Bragg, Jennifer; Cheng, Prisca; AUCAR, SHEYLA - Former ARS Employee; Sarath, Gautam; Palmer, Nathan - Nate; Edme, Serge; Tobias, Christian

Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2020
Publication Date: 2/6/2020
Citation: Chanbusarakum, L.J., Bragg, J.N., Cheng, P.K., Aucar, S., Sarath, G., Palmer, N.A., Edme, S.J., Tobias, C.M. 2020. Gene expression and physiological differences in neo-octoploid switchgrass subjected to drought stress. BioEnergy Research. 13:63-78. https://doi.org/10.1007/s12155-020-10092-0.
DOI: https://doi.org/10.1007/s12155-020-10092-0

Interpretive Summary: Patterns of growth, metabolism, and gene expression were measured in a high-yielding cultivar of switchgrass and related individuals that had undergone recent whole genome duplication. Measurements were made under well-watered, water-stress, and recovery from water-stress treatments. Growth of all individuals was reduced under water stress but one line with a genome duplication performed better than the rest. Gene expression in the crown of the plant indicated reprogramming of gene expression as a response to water-stress with all individuals behaving similarly. A small number of genes showed significant differences in expression between the control cultivar and the recent whole genome duplication lines.

Technical Abstract: Switchgrass (Panicum virgatum L.) has been subject to breeding to improve its yield and composition for bioenergy, but improving its tolerance to environmental variability is just beginning. Different ploidy populations act as somewhat distinct gene pools which can only be bridged through whole genome reduction or duplication events. In order to document potential wide-ranging effects of whole genome duplication, we examined the effects of water stress on growth, physiology, and gene expression in individual tetraploid clones of the switchgrass cultivar ‘Liberty’ as well as neo-octoploid lines derived from it. The neo-octoploids behaved similarly to Liberty under water-stress and recovery conditions. Growth rates, photosynthesis, gas exchange, node numbers, and height were reduced in plants under water stress while proline levels were increased. A total of 6134 differentially expressed genes (8% of the annotated genes with detectable expression in crown tissue) were detected under water deficit stress, while 3310 differentially expressed genes were detected in crown tissue after 1 week of recovery from water deficit stress relative to well-watered treatments. Only a small number of genes were identified as being differentially expressed between 4x Liberty and its 8x derivative.