G. De La Vina et al., Effects of CO2 and sugars on photosynthesis and composition of avocado leaves grown in vitro, PL PHYS BIO, 37(7-8), 1999, pp. 587-595
The effects of micropropagation conditions on avocado (Persea americana Mil
l.) have been measured in leaves and plants cultured in vitro. The conseque
nces of the type and concentration of sugar in the medium and of carbon dio
xide concentration in the atmosphere on the rates of photosynthesis and amo
unts of ribulose 1,5-biphosphate carboxylase-oxygenase (EC 4.1.1.39; Rubisc
o) and total soluble protein (TSP) were measured. At the highest sucrose su
pply (87.6 mM), Rubisco content was substantially decreased in leaves, and
even more when elevated CO2 (1 000 mu mol mol(-1)) was supplied. Maximum ph
otosynthetic rate (P-max) was significantly decreased when plants developed
in high sucrose and elevated CO2. However, Rubisco concentration was signi
ficantly greater when glucose was supplied at the same molar concentration
or when the concentration of sucrose was small (14.6 mM), and no difference
s were observed due to the CO2 concentration in the air in these treatments
. The ratio of Rubisco to total soluble protein (Rubisco/TSP) was dramatica
lly decreased in plants grown in the highest concentration of sucrose and w
ith elevated CO2. Leaf area and ratio of leaf fresh weight/(stem + root) fr
esh weight, were greater in plants grown with CO2, enriched air. However, u
pon transplanting, survival was poorer in plants grown on low sucrose/high
CO2 compared to those grown on high sucrose/high CO2. (C) Elsevier, Paris.