Abstract
In order to survive subzero temperatures, some plants undergo cold acclimation (CA) where low, nonfreezing temperatures, and/or shortened day lengths allow cold-hardening and survival during subsequent freeze events. Central to this response is the plasma membrane (PM), where low temperature is perceived and cellular homeostasis must be preserved by maintaining membrane integrity. Here, we present the first PM proteome of cold-acclimated Brachypodium distachyon, a model species for the study of monocot crops. A time-course experiment investigated CA-induced changes in the proteome following two-phase partitioning PM enrichment and label-free quantification by nano-liquid chromatography-mass spectrophotometry. Two days of CA were sufficient for membrane protection as well as an initial increase in sugar levels and coincided with a significant change in the abundance of 154 proteins. Prolonged CA resulted in further increases in soluble sugars and abundance changes in more than 680 proteins, suggesting both a necessary early response to low-temperature treatment, as well as a sustained CA response elicited over several days. A meta-analysis revealed that the identified PM proteins have known roles in low-temperature tolerance, metabolism, transport, and pathogen defense as well as drought, osmotic stress, and salt resistance suggesting crosstalk between stress responses, such that CA may prime plants for other abiotic and biotic stresses. The PM proteins identified here present keys to an understanding of cold tolerance in monocot crops and the hope of addressing economic losses associated with modern climate-mediated increases in frost events.
Highlights
Changing climatic conditions are associated with unpredictable weather patterns that can have devastating consequences on crop success (Raza et al 2019)
Our results suggest that freeze-tolerance in this species is a dynamic process, with an early frost-resistance response that can be achieved within 2 days of cold acclimation (CA), but thereafter, additional changes to the plasma membrane (PM) occur four or more days later that presumably allow for a sustained response for low-temperature survival
The presence of these two phases of freezing tolerance is supported by multiple lines of evidence, most notably: (1) the acquisition of PM protection in CA2 plants, (2) the rapid accumulation of sucrose by CA2, followed by further sucrose accumulation after 6 days, and (3) changes in relative protein abundance, demonstrated by heatmaps, functional profiles, as well as network analysis generated from the mass spectrometry (MS) protein discovery that could be divided into two groups: CA2–CA4 and CA6–CA8 (Figures 1–7)
Summary
Changing climatic conditions are associated with unpredictable weather patterns that can have devastating consequences on crop success (Raza et al 2019). Higher average temperaturesand an increased frequency of winter freeze-thaw events present major challenges in temperate regions and can result in delayed bud-burst and freeze-induced injury, with acute exposure to temperatures below a thermal optimum generating chilling stress (Aroca et al 2012; Tedla et al 2020). Low-temperature effects include lower rates of biochemical and metabolic reactions, a loss in membrane fluidity, increased water viscosity, decreased water uptake in roots, the attenuated activity of numerous proteins and enzymes, as well as delayed energy dissipation associated with reduced photosynthesis and cellular respiration (Aroca et al 2012). Prior to anthropogenic-induced climate change, plants in their native range would presumably only rarely be exposed to atypically acute and fatal exposure to freezing. Many plants undergo CA, but the degree of their subsequent freezing tolerance is primarily
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
