Plasma membrane proteome analyses of Arabidopsis thaliana suspension-cultured cells during cold or ABA treatment: Relationship with freezing tolerance and growth phase.

Cold acclimation (CA) and abscisic acid (ABA) treatments affected freezing tolerance of Arabidopsis thaliana suspension-cultured cells: cells at the lag and log phases increased their freezing tolerance but cells at the stationery phase rather decreased after the treatments. To further characterize the differential responses of the cells to these treatments depending on growth phase, plasma membrane (PM) proteome were analyzed using label-free protein quantification technology. Abundance of 841 proteins changed during the progression of growth phase, CA and/or ABA treatment. Among them, 392 proteins changed in their abundance in cells during growth phase progression and were categorized into various functional groups, suggesting changes in physiological characteristics of the PM depending on the growth phase. Comparison of CA- and ABA-responsive proteins indicated that ABA is one of the important signals for PM proteome changes in response to CA, but multiple signals are required for the response of PM proteins to CA. Involvement of ABA in the CA process diminished with the progression of growth phase. Taken together, the results suggest that dynamic alterations of the PM proteome with the progression of growth phase influence the PM proteome responses to CA and ABA, which may effect the difference in freezing tolerance capability. SIGNIFICANCE: After cold acclimation (CA) or abscisic acid treatment (ABA), Arabidopsis thaliana suspension-cultured cells (T87 line) exhibited freezing tolerance capability dependent on the cell growth phase. However, whether the plasma membrane (PM) proteome profile differs among growth phases and the differences are associated with growth-phase-dependent freezing tolerance have not been elucidated. In the present study, PM proteomics was conducted in association with CA and ABA treatment of Arabidopsis suspension-cultured cells at three growth phases. Characteristics of the PM proteome changed considerably with progression of the growth phase and ABA was indicated to be an important signal for PM protein changes during CA. The results also revealed that multiple signals are required to complete the response of PM proteins to CA. Therefore, dynamic alterations of the PM proteome with the advance of the growth phase influence the responses of PM proteome to CA and ABA, which may result in the differences in freezing tolerance of the cultured cells.