
%0 Journal Article
%A Savitch, Leonid V. 
%A Pocock, Tessa 
%A Krol, Marianna 
%A Wilson, Kenneth E. 
%A Greenberg, Bruce M. 
%A Huner, Norman P. A. 
%T Effects of growth under UVA radiation on CO<emph type="8">2</emph> assimilation, carbon partitioning, PSII photochemistry and resistance to UVB radiation in <emph type="2">Brassica napus</emph> cv. Topas
%J Functional Plant Biology
%D 2001/03/07
%V 28
%N 3
%P 203-212
%K acclimation, Brassica napus L. cv. Topas, carbon metabolism, photodamage, UVA, UVB stress.
%R https://doi.org/10.1071/PP00116
%U https://www.publish.csiro.au/paper/PP00116 
%X The effects of growth of Brassica napus L. cv. Topas under PAR or PAR+UVA radiation was assessed with respect to sensitivity to subsequent exposure to UVB radiation. Despite the fact that growth under PAR+UVA induced minimal effects in photosystem II (PSII) photochemistry, growth under PAR+UVA inhibited the accumulation of the photosynthetic end products, sucrose and starch. This was associated with a decreased capacity for ribulose 1,5-bisphosphate (RuBP) regeneration, a decreased capacity for light- and CO 2 -saturated rates of CO2 assimilation, a decrease in the apparent quantum yield for CO2 assimilation, an over-reduction of chloroplast stroma, an increased susceptibility to the feedback effects on photosynthesis and a stimulation of glycolysis compared to controls grown under PAR. Subsequent exposure to UVB decreased the maximum Rubisco activity in leaves of both PAR- and PAR+UVA-grown plants. However, the decrease in the capacity for CO2 assimilation in PAR-grown plants exposed to UVB did not appear to be associated with limitations at the level of PSII linear electron transport, but rather with a decreased capacity for sucrose biosynthesis, limited triose-P utilization and a decreased capacity for RuBP regeneration. In contrast, the decreased capacity for CO 2 assimilation in PAR+UVA-grown plants exposed to UVB was associated with an inhibition of PSII photochemistry and a decreased supply of ATP. Thus, growth under UVA radiation appears to induce feedback-limited photosynthesis and does not enhance resistance of Brassica napus to UVB radiation. 
