Analysis of molecular mechanisms associated with low temperature induced freezing tolerance and floral competence in Camelina sativa

Authors: Anderson, James; NEUBAUER, MCKAYLA - North Dakota State University; Horvath, David; BERTI, MARISOL - North Dakota State University; Chao, Wun

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/5/2021
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Camelina (Camelina sativa L., Crantz) is an oilseed crop consisting of spring- and winter-biotypes. Cold-acclimation of winter-biotypes allows for greater freezing tolerance compared with spring-biotypes. Winter-biotypes also require a low temperature treatment (vernalization) to induce flowering processes, while spring-biotypes do not. In this study, a winter-biotype of camelina (Joelle) exposed to a low temperature (5 C) treatment for 0, 1, 2, 4, or 6 weeks and subsequently exposed to a freezing treatment (-15 C for 4 h) demonstrated 0, 0, 20, 36, and 72% freezing survival, respectively. Plants that survived the freezing treatment (42 d post under greenhouse conditions) also flowered; plants receiving six weeks cold treatment flowered first, followed in order by plants exposed to four- and two-weeks cold treatment. No spring-biotype (CO46) plants exposed to the low temperature treatment (up to 8 weeks) survived this freezing treatment. To determine molecular components associated with regulation of low temperature acquired freezing tolerance and floral competence in camelina, we compared transcriptomes of the spring- and winter-biotype exposed to 0, 1, 2, 4, 6 and 8 weeks low temperature (5 C). A program called SCION was used to run network analyses on expressed genes (FPKM >2 for all replicates of at least one time point), which identified 21 and 22 coordinately regulated gene clusters across all time points in the spring- and winter-biotype, respectively. The SCION program also identified transcription factors (TFs) likely regulating genes within each cluster. Among 71 strongly down-regulated genes unique to the winter-biotype (FDR <0.05 and fold change in expression >4 between biotypes at any timepoint), bZIP, GRAS, and WRKY TFs were identified as potential dominant regulators. Among 168 strongly up-regulated genes unique to the winter-biotype, ERF, MYB and bZIP TFs were identified as the most prevalent regulators. Gene set enrichment analysis of individual gene clusters identified ontologies associated with biotic stress and defense responses as over-represented among clusters of down-regulated genes (from time 0) in both biotypes, and ontologies associated with growth-related processes were uniquely down-regulated in the winter-biotype. Likewise, among clusters with up-regulated genes, ontologies associated with abiotic stress, light quality responses, and photosynthesis were observed in both biotypes, and ontologies associated with secondary metabolism and sugar transport were more prevalent in the winter-biotype. Functional confirmation of candidate genes and TFs regulating freezing tolerance and flowering time will provide new knowledge for improving these traits in oilseed crops with industrial and agricultural importance.