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Ontario Grain Farmer Magazine

Improving winter hardiness in wheat using genomic technologies

Principal Investigator: Peter Pauls and Alireza Navabi  

Research Institution: University of Guelph

Timeline: September 2016 – March 2023  

Objectives:

  • Understand the adaptation of winter and spring wheat as influenced by Vrn and Ppd genes.
  • Identify the genomic regions and candidate genes that influence winter hardiness in winter wheat.
  • Understand the physiology of cold acclimation maintenance in winter wheat.
  • Compare transcriptome profiles under cold acclimation induction in natural vs artificial acclimation.
  • Understand the interaction of Vrn-Ppd genotypic combinations with planting date in winter and spring wheat.

Impacts:

  • A better understanding of the adaptive traits utilized by Eastern Canadian winter wheat varieties will allow the University of Guelph Winter Wheat Breeding Program to develop more resilient, well-adapted varieties for Ontario consumers.
  • The potential facultative growth habit of Ontario winter wheat varieties may allow for more flexibility in planting date without compromising yield. This is being studied in a current GFO/OMAFRA funded research project [UG-T1-2021-100940].

Scientific Summary:

The University of Guelph Wheat Breeding Program strives to improve the genetics of winter wheat for specific traits of interest, such as low-temperature (LT) tolerance and winter hardiness. However, an in-depth understanding of the physiological, biochemical, and molecular mechanisms that control cold acclimation is required before meaningful improvements can be made. Physiological traits associated with cold acclimation (including lethal temperature [LT50], threshold induction temperature and vegetative-to-reproductive transition) were examined in five elite Ontario winter wheat cultivars (Branson, 25R46, CM614, Priesley and Secord) and three check cultivars (Norstar, Gaines and AC Carberry). Biochemical analyses, including total non-structural carbohydrates (TNSC) and abscisic acid (ABA) were measured every seven days over a 98-day acclimation period (at a constant 4°C) to complement LT50 measurements to determine variation for these traits across elite Ontario cultivars.

Differential gene expression during cold acclimation and de-acclimation was examined in a hardy (Branson) and a non-hardy (Gaines) winter wheat variety grown at 4°C and 20°C controlled environments.

The hypotheses for these activities were:

  1. Hardy winter wheat cultivars will perceive cold temperature stress at a higher temperature, develop and maintain a lower LT50 for a longer period of time, and will take longer to vernalize compared to a non-hardy winter wheat cultivar (i.e., Gaines).
  2. Increased accumulation of TNSC and ABA will confer greater LT tolerance and prolong cold acclimation maintenance.
  3. Genetic variability in winter wheat cultivars, as well as physiological and phenological mechanisms related to cold acclimation, will influence gene expression patters in the affected cells and highlight major cold response pathways.

Results

Threshold induction temperature, vegetative to reproduction transition and lethal temperature experiments have been completed. The results indicate that Ontario wheat varieties share similarities to the known non-hardy winter wheat check, Gaines. Ontario varieties are able to transition from vegetative to reproductive growth without exposure to vernalizing temperatures, begin cold acclimation at ~14°C, can withstand temperatures of -12°C when fully acclimated (at 28 days acclimation at 4°C/10h days), and maintain hardiness between 8-10°C for at least 98 days acclimation.

Carbohydrate and biochemical analysis – Fructans were accumulated in both Branson and Gaines to a similar degree in the acclimated treatments and did not accumulate in either variety in the control treatments. Simple sugars and sucrose levels rose slightly over time in the acclimated treatments, but not to the significant extent that fructans accumulated. Measurements of ABA were not possible due to the delays caused by travel restrictions and the instability of plant hormones in storage even under ideal conditions.

The RNAseq identified gene families of interest associated with general stress, reactive oxygen species, and cold-regulated genes/pathways in both Branson and Gaines when exposed to 35, 63 and 98 days acclimation compared to 0 days. However, there were significant differences in the pathways that were activated in Branson versus Gaines, suggesting these varieties may use different adaptive strategies to survive cold stress. Further investigation showed that a number of pathways, including those in metabolism and amino acid accumulation (i.e., leucine) were activated in Branson compared to Gaines. It is likely that epigenetic modifications are the driver for differences observed between plants that were cold-acclimated versus not. The research has created data that will be helpful in elucidating this response and pathway moving forward and will be valuable for future winter hardiness selection of varieties.

Summary of main findings

  • The presence of photoperiod insensitive alleles at Ppd-D1 and Ppd-A1 result in superior adaptation to Eastern Canadian environments.
  • A genome-wide association study (GWAS) identified two putative candidate genes for winter survival, Vrn-A1 and an ortholog of OsRC12-5.
  • Eastern Canadian winter wheat varieties share physiological similarities to the non-hardy check variety, Gaines, in terms of cold perception and low-temperature tolerance.
  • Eastern Canadian winter wheat varieties did not require exposure to cold temperatures to achieve reproductive growth, a trait associated with facultative wheat.
  • Eastern Canadian winter wheat varieties have distinct genetic pathways that are activated during cold acclimation, suggesting a regional adaptation.
  • Unmanned aerial vehicle (UAV) based imagery resulted in accurate field indices for winter survival note-taking.

A better understanding of the adaptive traits utilized by Eastern Canadian winter wheat varieties will allow the University of Guelph Winter Wheat Breeding Program to develop more resilient, well-adapted varieties for Ontario consumers.

The potential facultative growth habit of Ontario winter wheat varieties may allow for more flexibility in planting date without compromising yield. This is being studied in a current GFO/OMAFRA funded research project [UG-T1-2021-100940].

External Funding Partners:

We acknowledge the support of the Natural Sciences and Engineering Research Council of Canada.

SeCan

Project Related Publications:

Chen, Y., Sidhu, H.S., Kaviani, M., McElroy, M.S., Pozniak, C.J., and Navabi, A. 2019. Application of image-based phenotyping tools to identify QTL for in-field winter survival of winter wheat (Triticum aestivum L.) Theoretical and Applied Genetics. 132(9): 2591-2604.

Seifi, H.S., Serajazari, M., Kaviani, M., Pauls, P., Booker, H., and Navabi, A. 2021. Immunity to stripe rust in wheat: A case study of a hypersensitive response (HR) – independent resistance to Puccinia striiformis f. sp. Tritici in Avocet-Yr15. Canadian Journal of Plant Pathology. 2021:1907448.

Serajazari, M., Torkamaneh, D., Gordon, E., Lee, E., Booker, H., Pauls, K.P., and Navabi, A. 2023. Mining Fusarium head blight resistant genes in a CIMMYT spring synthetic hexaploid wheat panel. Submitted to BMC Plant Biology. Jan 4, 2023.

Whittal, A., Kaviani, M., Graf, R., Humphreys, G., and Navabi, A. 2018. Allelic variation of vernalization and photoperiod response genes in a diverse set of North American high latitude winter wheat genotypes. PloS one. 13(8).