Carbohydrate metabolism in photosynthetic and nonphotosynthetic tissues of variegated leaves of Coleus blumei Benth

Journal Article · Fri Jun 01 00:00:00 EDT 1990 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.93.2.617· OSTI ID:5957588

Madore, M A ^[1]

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1. Univ. of California, Riverside (USA)

Mature, variegated leaves of Coleus blumei Benth. contained stachyose and other raffinose series sugars in both green, photosynthetic and white, nonphotosynthetic tissues. However, unlike the green tissues, white tissues had no detectable level of galactinol synthase activity and a low level of sucrose phosphate synthase indicating that stachyose and possibly sucrose present in white tissues may have originated in green tissues. Uptake of exogenously supplied ({sup 14}C)stachyose or ({sup 14}C)sucrose into either tissue type showed conventional kinetic profiles indicating combined operation of liner first-order and saturable systems. Autoradiographs of white discs showed no detectable minor vein labeling with ({sup 14}C)stachyose, but some degree of vein labeling with ({sup 14}C)sucrose. Autoradiographs of green discs showed substantial vein loading with either sugar. In both tissues, p-chloromercuribenzenesulfonic acid had no effect on the linear component of sucrose or stachyose uptake but inhibited the saturable component. Both tissues contained high levels of invertase, sucrose synthase and {alpha}-galactosidase and extensively metabolized exogenously supplied {sup 14}C-sugars. In green tissues, label from exogenous sugars was recovered as raffinose-series sugars. In white tissues, exogenous sugars were hydrolyzed and converted to amino acids and organic acids. The results indicate that variegated Coleus leaves may be useful for studies on both phloem loading and phloem unloading processes in stachyose-transporting species.

• OSTI ID: 5957588
• Journal Information: Plant Physiology; (USA), Vol. 93:2; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CARBOHYDRATES
METABOLISM
PLANTS
AUTORADIOGRAPHY
CARBON 14 COMPOUNDS
ENZYME ACTIVITY
LEAVES
OLIGOSACCHARIDES
PHOTOSYNTHESIS
TRACER TECHNIQUES
CHEMICAL REACTIONS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
SACCHARIDES
SYNTHESIS
551001* - Physiological Systems- Tracer Techniques