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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Water Management and Systems Research » Research » Research Project #437775

Research Project: The Impact of Climate and Water Availability on Foliar Xylem Traits of Sunflower

Location: Water Management and Systems Research

Project Number: 3012-13000-010-13-N
Project Type: Non-Funded Cooperative Agreement

Start Date: Sep 15, 2020
End Date: Sep 14, 2022

Objective:
(1) Investigate xylem refilling after freeze/thaw-induced embolisms and drought-induced embolisms. (2) Identify how root systems potentially support greater stomatal opening and water transport capacity.

Approach:
The purpose of this NFCA is to facilitate close collaboration with a CSU PhD student. Given that she is just starting her program, the research approach has not been fully decided, and will not be decided for at least another year. Nevertheless, the most likely approaches will include these broad steps: 1) Determine the anatomical and physiological determinants of embolism resistance/tolerance in sunflower. This will require measuring embolism resistance and tolerance across many sunflower genotypes and quantifying the alignment of key plant traits that are aligned with this variation (e.g. the scaling of conduit diameter with distance from the stomata, the water potential initiating stomatal closure, the capacity to reverse embolism via root pressure). Conduit diameters will be measured by sectioning tissues at a standardized distance from the top of the plant (Olson et al in press) and using standard microscopy and image analysis techniques (Blackman et al 2018; doi: 10.1093/aob/mcy051). The optical method (Brodrib et al. 2016; doi: 10.1111/nph.13846) will be used to quantify the presence and reversal of embolism in xylem. Bivariate linear correlation and structural equation modeling (SEM) (Gleason et al. 2019; https://doi.org/10.1016/j.fcr.2019.02.001) will be used to quantify the alignment of plant traits and plant performance. 2) Perform genome-wide association study/analysis (GWAS) to determine the genetic underpinnings of embolism resistance, i.e., the traits conferring embolism resistance. Trait measurements will be carried out as described in Objective 1. These analyses will require close collaboration with CU-Boulder. The GWAS Pipeline model will be used for these analysis. This model is a "pipeline" tool for genome-wide association analysis (GWAS). It will be used to filter, create a kinship matrix, covariate files, run EMMAX, and compute Manhattan and QQ plots for all traits. This will allow us to link the traits conferring embolism resistance (as measured in Objective 1) to the genome, and thus create a useful tool for breeders and gene editors to manipulate the species to create more drought tolerant plants.