LEE, DAVID W. Department of Biological Sciences, Florida International University, Miami, FL 33199. - Anthocyanins in leaves: history, phylogeny and development.
Anthocyanins have been intensely studied because of their expression
in flowers and fruits of economic importance, yet they are also
produced in vegetative organs, even in plants preceding the evolution
of angiosperms. There has been much speculation on the function of
this coloration, particularly by the physiological anatomists of the
19th century, but little serious research. A pre-condition to research
on their function is a thorough knowledge of anthocyanin patterns in
leaf tissue and their distribution among vascular plants. In a survey
of 463 tropical taxa these patterns were investigated; tissue
distributions in 399 taxa were mapped on the robust three-gene
molecular phylogeny of Soltis et al. (Nature 402:402-404),
pruned for these taxa with additional structure from other studies.
Incidence and patterns of anthocyanin production were strongly
associated with certain families, notably the Myrtaceae and
Combretaceae, and were poorly represented among the Asteridae.
Statistical analysis indicated that certain tissue distributions were
significantly influenced by phylogenetic drift, despite many
unresolved polytomies below the family level. Anthocyanin production
in other plant parts was significantly associated with that in leaves
in this sample of taxa. Most tissue patterns were limited to mesophyll
tissue, and a smaller number limited to epidermal layers. The rarity
of tissue combinations combining both germ lines (dermal and ground)
suggests strong developmental constraints on locations of anthocyanin
production in leaves. Only 13.5 % of these taxa produced anthocyanins
during senescence, contrasting strongly with a high 70 % of 91 taxa
sampled during senescence at Harvard Forest, in central Massachusetts.
Similar patterns of betacyanin distribution were observed in a smaller
sample of 21 taxa in the Caryophyllales. Similarities in absorbance
spectra in visible wavelengths and strong in vitro anti-oxidant
activities suggest that these two pigments may have similar
physiological functions in leaves.
Key words: anatomy, angiosperms, anthocyanins, development, leaf, phylogeny