Affiliation:
1. Department of Biology, St. Mary's College of Maryland, St. Mary's City, Maryland 20686 (H.L.G.)
Abstract
Abstract
We used the Mixta+ and mixta- lines of Antirrhinum majus as a model system to investigate the effects of epidermal cell shape and pigmentation on tissue optical properties in the visible and ultraviolet (UV) spectral regions. Adaxial epidermal cells of Mixta+ flowers have a conical-papillate shape; in the mixta- line the cells are slightly domed. Mixta+ cells contained significantly more anthocyanin and other flavonoids than mixta- cells when plants were grown under either high- or low-UV conditions. Mixta+ cells focused light (3.5–4.7 times incident) within their pigmented interiors, whereas mixta- cells focused light (2.1–2.7 times incident) in the unpigmented mesophyll. UV light penetrated the epidermis (commonly 20–50% transmittance at 312 nm) mainly through the unpigmented peripheral regions of the cells that were similar for the two lines, so that overall penetration through Mixta+ and mixta- epidermises was equal. However, maximum UV absorption in the central region of epidermal cells was slightly greater in Mixta+ than mixta-, and intact Mixta+ flowers reflected less light in the spectral regions with intermediate flavonoid absorbance. In both cases, about 50 to 75% of the difference could be attributed to cell shape and resulting changes in the optical pathlength or focusing.
Publisher
Oxford University Press (OUP)
Subject
Plant Science,Genetics,Physiology
Cited by
117 articles.
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