Phenotyping the Chilling and Freezing Responses of Young Microspore Stage Wheat Spikes Using Targeted Metabolome and Lipidome Profiling

Abstract

Chilling and frost conditions impose major yield restraints to wheat crops in Australia and other temperate climate regions. Unpredictability and variability of field frost events are major impediments for cold tolerance breeding. Metabolome and lipidome profiling were used to compare the cold response in spikes of cold-tolerant Young and sensitive variety Wyalkatchem at the young microspore (YM) stage of pollen development. We aimed to identify metabolite markers that can reliably distinguish cold-tolerant and sensitive wheat varieties for future cold-tolerance phenotyping applications. We scored changes in spike metabolites and lipids for both varieties during cold acclimation after initial and prolonged exposure to combined chilling and freezing cycles (1 and 4 days, respectively) using controlled environment conditions. The two contrasting wheat varieties showed qualitative and quantitative differences in primary metabolites involved in osmoprotection, but differences in lipid accumulation most distinctively separated the cold response of the two wheat lines. These results resemble what we previously observed in flag leaves of the same two wheat varieties. The fact that this response occurs in tissue types with very different functions indicates that chilling and freezing tolerance in these wheat lines is associated with re-modelling of membrane lipid composition to maintain membrane fluidity.

The Metabolic Response of Brachypodium Roots to the Interaction with Beneficial Bacteria Is Affected by the Plant Nutritional Status

“…For polar metabolites analysis, a variation of the method described in Cheong et al [70] was used. 250 µL 100% LC-MS grade MeOH (Roth, Karlsruhe, Germany), containing 4% 13 C 6 sorbitol/valine (Sigma-Aldrich, Castle Hill, Australia) was added to approximately 25 mg of frozen root tissue from each pooled group.…”

An Arabidopsis lipid map reveals differences between tissues and dynamic changes throughout development

“…They constitute important structural components of membranes, serve as storage sources for energy, signaling molecules in various biological pathways, and modulators of cellular functions and diseases (Fahy et al , 2011 ; Mamode Cassim et al , 2019 ; Sud et al , 2007 ). Lipids are also involved in many developmental processes, including seed germination (Wang et al , 2016b ), organ differentiation (Wang et al , 2016b ), pollination (Wolters‐Arts et al , 1998 ) and environmental stress responses (Cheong et al , 2019 , 2020 ; Welti et al , 2007 ).…”

“…For example, recent studies using lipid imaging have shown that phosphatidylserine levels in plasma membranes change during Arabidopsis root development (Platre et al , 2019 ) and that the unsaturation of phosphatidylcholines decreases during the day and increases at night (Nakamura et al , 2014 ). The remodeling of membrane lipids caused by variations in hormone levels (Wang, 2002 ) and environmental stress conditions, such as heat (Higashi and Saito, 2019 ), cold (Barrero‐Sicilia et al , 2017 ; Cheong et al , 2019 , 2020 ), salinity (Sarabia et al , 2018 , 2020 ), pathogen and insect attacks (Farmer et al , 2003 ), and wounding (Vu et al , 2014 ), have also been extensively investigated and reported.…”

“…Recent ‘omics’ studies have hinted at the potential of integrating metabolomics, lipidomics, transcriptomics and genomics to explain the genetic mechanisms underlying the accumulation of metabolites in response to environmental cues, which could assist DNA marker‐based breeding approaches for stress‐tolerant crop varieties (Cheong et al , 2019 , 2020 ). To support such developments, web‐accessible databases collating ‘omics’ data are indispensable.…”

Data_Sheet_1.DOCX

“…The second is cold acclimation (Thomashow, 1999;Miura and Furumoto, 2013), which occurs in response to sudden cold stimuli and requires phenotypic plasticity to respond. Plants acclimate to low temperatures using a systemic response (Hincha and Zuther, 2020) that ranges from hormonal, auxin-dependent signaling (Shibasaki et al, 2009;Rahman, 2013), through primary metabolism (Kaplan et al, 2004;Zuther et al, 2019;Erban et al, 2020), and to membrane-lipidome compositional changes (Uemura et al, 1995;Cheong et al, 2019Cheong et al, , 2020. Typical cold responses have been divided according to the response time after the initial stimulus (Seki et al, 2002) and involve proteins that function as the principal modulators.…”