Characterizing gene expression responses to colchicine in Dactylis smithii

Abstract

Tetraploid plant species are preferred in certain agricultural cases over their diploid counterparts for larger biomass and increased resistance to abiotic stresses. Naturally occurring tetraploids are thought to result through a breakdown in chromosome segregation during mitosis. In the lab, they can be produced synthetically using colchicine, a microtubule inhibitor. To better understand the mechanism of action of colchicine in chromosome doubling, Zhou et al. (in preparation) treated the roots of Dactylis smithii seedlings with colchicine, sampled the roots and leaves, and characterized changes in gene expression by RNA sequencing. The objectives of this study were to use quantitative PCR to verify changes in gene expression of 11 target genes that were identified in this RNA sequencing experiment, and to characterize the target gene expression responses to 24 hour colchicine treatment in two accessions of D. smithii. The expression of 5 genes in the UK accession was verified with 5 hour transcriptome data from Zhou et al. (in preparation). Three genes were expressed consistently between two accessions (distinct populations) of the D. smithii species. These genes, which function in mRNA splicing, membrane function, and as aquaporins, are candidates for additional research regarding their potential role in the process of chromosome doubling via colchicine. Additional research could use qPCR to assess gene expression in the D. smithii leaf samples to compare the effect of cell type and location. Future directions could also include assessing the changes in gene expression of D. mariana, a natural tetraploid subspecies of orchardgrass, compared to the synthetic tetraploid specimen produced by Zhou et al. (in preparation).