ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
The variegated leaves of the Crassulacean acid metabolism (CAM) species Agave americana have a large central longitudinal green band with narrow yellow bands on either side. The yellow bands had 97% less pigment content, 84% lower ribulose-1,5-bisphosphate carboxylase/oxygenase activity, but only 20% lower phosphoenolpyruvate carboxylase activity than the green band. The green bands exhibited gas exchange typical of CAM plants, with most CO2 uptake occurring at night, leading to a daily net CO2 uptake of 127 mmol m−2 day−1. The yellow bands had some nighttime net CO2 uptake but a larger loss during the daytime, indicating that they were sink tissues. Nocturnal citrate and malate accumulations for the yellow bands were 65 and 75%, respectively, of those of the green bands; sucrose supported 64-83% of their nocturnal acid accumulation. This is the first evidence that agaves, which are malic-enzyme-type CAM plants, use sucrose as the carbon source for nocturnal acid accumulation. About 44% of the carbon demand of the yellow bands can be supplied by sucrose diffusing via the symplast from the adjacent green band, about 25% from fructose and glucose diffusion, and some via the apoplast.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1034/j.1399-3054.1998.1030112.x
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