Sorting the Wheat From the Chaff : Programmed Cell Death as a Marker of Stress Tolerance in Agriculturally Important Cereals

Chua, Alysha and Fitzhenry, Laurence and Daly, Cara T. (2019) Sorting the Wheat From the Chaff : Programmed Cell Death as a Marker of Stress Tolerance in Agriculturally Important Cereals. Frontiers in Plant Science, 10. ISSN 1664-462X

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Abstract

Conventional methods for screening for stress-tolerant cereal varieties rely on expensive, labour-intensive field testing and molecular biology techniques. Here, we use the root hair assay (RHA) as a rapid screening tool to identify stress-tolerant varieties at the early seedling stage. Wheat and barley seedlings had stress applied, and the response quantified in terms of programmed cell death (PCD), viability and necrosis. Heat shock experiments of seven barley varieties showed that winter and spring barley varieties could be partitioned into their two distinct seasonal groups based on their PCD susceptibility, allowing quick data-driven evaluation of their thermotolerance at an early seedling stage. In addition, evaluating the response of eight wheat varieties to heat and salt stress allowed identification of their PCD inflection points (35°C and 150 mM NaCl), where the largest differences in PCD levels arise. Using the PCD inflection points as a reference, we compared different stress effects and found that heat-susceptible wheat varieties displayed similar vulnerabilities to salt stress. Stress-induced PCD levels also facilitated the assessment of the basal, induced and cross-stress tolerance of wheat varieties using single, combined and multiple individual stress exposures by applying concurrent heat and salt stress in a time-course experiment. Two stress-susceptible varieties were found to have low constitutive resistance as illustrated by their high PCD levels in response to single and combined stress exposure. However, both varieties had a fast, adaptive response as PCD levels declined at the other time-points, showing that even with low constitutive resistance, the initial stress cue primes cross-stress tolerance adaptations for enhanced resistance even to a second, different stress type. Here, we demonstrate the RHA’s suitability for high-throughput analysis (∼4 days from germination to data collection) of multiple cereal varieties and stress treatments. We also showed the versatility of using stress-induced PCD levels to investigate the role of constitutive and adaptive resistance by exploring the temporal progression of cross-stress tolerance. Our results show that by identifying suboptimal PCD levels in vivo in a laboratory setting, we can preliminarily identify stress-susceptible cereal varieties and this information can guide further, more efficiently targeted, field-scale experimental testing.

Item Type:	Article
Additional Information:	Funding Information: This work was supported by postgraduate scholarship awarded to AC by Waterford Institute of Technology, Ireland. Seeds were provided by Seedtech® and KWS UK®. Funding Information: This work was supported by PhD scholarship awarded to AC by Waterford Institute of Technology. Cost of publishing was supported by the Waterford Institute of Technology, School of Science and Computing, Research Support Scheme. Publisher Copyright: © Copyright © 2019 Chua, Fitzhenry and Daly.
Uncontrolled Keywords:	/dk/atira/pure/subjectarea/asjc/1100/1110
Departments or Groups:
Depositing User:	Admin SSL
Date Deposited:	19 Oct 2022 23:09
Last Modified:	29 Jul 2023 16:05
URI:	http://repository-testing.wit.ie/id/eprint/4382

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