Heterogeneity of plant mitochondrial responses underpinning respiratory acclimation to the cold in Arabidopsis thaliana leaves

Abstract

In this study, we investigated whether changes in mitochondrial abundance, ultrastructure and activity are involved in the respiratory cold acclimation response in leaves of the cold-hardy plant Arabidopsis thaliana . Confocal microscopy [using plants with green fluorescence protein (GFP) targeted to the mitochondria] and transmission electron microscopy (TEM) were used to visualize changes in mitochondrial morphology, abundance and ultrastructure. Measurements of respiratory flux in isolated mitochondria and intact leaf tissue were also made. Warm-grown (WG, 25/ 20 ∞ C day/night), 3-week cold-treated (CT) and cold-developed (CD) leaves were sampled. Although CT leaves exhibited some evidence of acclimation (as evidenced by higher rates of respiration at moderate measurement temperatures), it was only the CD leaves that were able to reestablish respiratory flux within the cold. Associated with the recovery of respiratory flux in the CD leaves were: (1) an increase in the total volume of mitochondria per unit volume of tissue in epidermal cells; (2) an increase in the ratio of cristae to matrix within mesophyll cell mitochondria; and (3) an increase in the capacity of the energyproducing cytochrome pathway in mitochondria isolated from whole leaf homogenates. Regardless of growth temperature, we found that contrasting cell types exhibited distinct differences in mitochondrial ultrastructure, morphology and abundance. Collectively, our data demonstrated the diversity and tissue-specific nature of mitochondrial responses that underpin respiratory acclimation to the cold, and revealed the heterogeneity of mitochondrial structure and abundance that exists within leaves.

Changes in Respiratory Mitochondrial Machinery and Cytochrome and Alternative Pathway Activities in Response to Energy Demand Underlie the Acclimation of Respiration to Elevated CO2 in the Invasive Opuntia ficus-indica

“…2). Therefore, the active mitochondrial compartment seem to provide sufficient capacity to carry out the photorespiratory cycle during phase IV, maybe by increasing the concentration of photorespiratory enzymes in mitochondria as suggested in Armstrong et al (2006). Our data also suggests that changes in respiratory active mitochondria Figure 5.…”

General patterns of acclimation of leaf respiration to elevated temperatures across biomes and plant types

“…Longer exposure enables the plant to make a more complete thermal adjustment-for example, through changes in mitochondrial size and density in leaves (Armstrong et al 2006). We would therefore expect the duration of warming to have a positive effect on the degree of acclimation.…”

“…Despite an increasing interest in the role of acclimation of physiological processes to environmental changes from the modeling community in recent years (e.g. Arneth et al 2012;Booth et al 2012;Smith and Dukes 2013), little is known about global variation in thermal acclimation potential of plant respiration.…”

Confocal Fluorescence Microscopy of Mung Beanleaves

“…There have been numerous scientific papers employing confocal microscope in plant biology since it was first used in plant science research (Hepler and Gunning, 1998;Taira et al, 2004;Meckel et al, 2007). Confocal microscope has been applied to determine heterogeneity of plant mitochondrial responses (Armstrong et al, 2006), chloroplast structure and arrangement of chlorophyll-protein complexes (Garstka et al, 2007), oxidative stress in plant cells (Li et al, 2007), microtubule arrays and arabidopsis stomatal development (Lucas et al, 2006), and mitochondrial localization (Yang et al, 2006). However, previous reports mainly concern the cultured plant cells, and there are few reports about analyzing the whole plant leaves.…”