Ozone-induced changes in biosynthesis of Rubisco and associated compensation to stress in foliage of hybrid poplar

Abstract

Experiments were conducted during the growing seasons of 1993-1995 to determine whether exposure to ozone (O(3)) affected the synthesis of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in hybrid poplar, Populus maximowizii A. Henry x trichocarpa Torr. & A. Gray, Clone 245. As the canopy aged, the concentration of Rubisco decreased at a more rapid rate in lower leaves of hyrid poplar ramets subjected to chronic O(3) exposure in open-top chambers than in comparable foliage of plants grown in charcoal-filtered air. There was no difference in rate of synthesis of Rubisco between treatments, suggesting that loss of this protein in O(3)-treated leaves was caused by an accelerated rate of proteolysis. In foliage higher in the canopy, both concentration and rate of synthesis of Rubisco were stimulated by O(3) for a brief period when the leaves were young. Quantification of mRNA for the small (rbcS) and large (rbcL) transcripts of Rubisco did not reveal changes that were likely to reflect altered synthesis of Rubisco as a prime response to O(3). Analyses of Rubisco concentration and rate of Rubisco synthesis in foliage connected by vascular traces within the canopy indicated that loss of Rubisco in older leaves was associated with an increase in this protein in younger leaves higher in the canopy. These data support the notion that accelerated senescence may provide some compensatory benefit to the plant. In 1995, the rate of synthesis of Rubisco was almost always higher in O(3)-treated foliage than in nontreated foliage, even when the concentration of Rubisco was adversely affected by the O(3) treatment. Because accelerated foliar abscission in response to O(3) was minimal in 1995 compared to other years, we speculate that, when abscission is delayed, Rubisco synthesis and concentration become uncoupled.

Interactive effects of elevated ozone and springtime frost on growth and physiology of birch (Betula pendula) in field conditions

“…Consequently, increased final wood biomass under ozone exposure was probably mainly due to ozone-induced height increment during the first growing season 2003. Enhanced growth in our study might be a compensatory response by which seedlings compensate losses in leaflevel photosynthesis, pigments and Rubisco, as reported by Brendley and Pell (1998), even thought we did not found any consistent ozone-induced decrease in 2004 net photosynthesis measurements. Pigment concentrations, however, were clearly reduced due to ozone exposure in our study.…”

“…Populus species (e.g., Brendley andPell 1998, Bielenberg et al 2001). However, prolonged exposures over several growing seasons have resulted in cumulative growth losses in birch (Oksanen 2003;Oksanen et al 2007).…”

Effects of ozone on nitrogen metabolism in the leaves of Fagus crenata seedlings under different soil nitrogen loads

“…Different letters above the bar indicate significant difference among the 12 treatments (Tukey's HSD test, P \ 0.05) Trees (2010) 24:175-184 181 O 3 -induced alteration in foliar N metabolism regardless of the amount of N loaded to the soil and the growing season. It has been suggested that the O 3 -induced reduction in the concentration of proteins such as Rubisco is primarily caused by enhanced degradation of proteins (Brendley and Pell 1998), and that the amino acids derived from catabolism of proteins is exported via the phloem (Hörtensteiner and Feller 2002). The acidic amino acids, glutamic acid and aspartic acid are necessary to synthesize glutamine and asparagines, which are important amino acids for N remobilization in plants (Delrot et al 2001).…”

Deciphering the ozone-induced changes in cellular processes: a prerequisite for ozone risk assessment at the tree and forest levels

“…In angiosperms also, multiple works supported the idea of O 3 -driven alteration of Rubisco activity (Gaucher et al 2003;Lutz et al 2000;Matyssek et al 1991;Pell et al 1992). However, it remains unclear whether the decrease in Rubisco activity is due to enhanced degradation, ROS-mediated protein oxidation, decreased Rubisco activase activity or altered gene expression (Brendley and Pell 1998;Dizengremel 2001;Heath 2008;Pell et al 1994). It is well documented that chronic as well as acute O 3 exposures impact gene regulation (Ernst 2013;Renaut et al 2009) even though acute episodes could provoke more important changes than chronic ones (Ainsworth et al 2012;Ernst 2013).…”