Cellular Changes that Promote Tannin Formation in Slash Pine
Tannin accumulation was observed by light microscopy in slash pine (Pinus elliottii var. elliottii) tissue cultures and seedlings. Specimens were fixed, dehydrated, embedded, sectioned, and stained according to a variety of published procedures. Examination of these specimens indicates that rapid cell division, hypertrophy of cells, or altered arrangements of cells during growth accompany tannin formation. In tissue cultures, tannin synthesis was increased by varying concentrations and sources of nutrients. Tannin was abundant in cultured cells with large amounts of starch grains and prominent nuclei. In seedlings, tannin deposition was not restricted to a specific tissue. When tannin accumulated in parenchyma cells, it did not appear to affect adjacent cells. This was true even for outer cortical cells, which accumulated tannin prior to forming bark by combining with sclereid cells. In wounds that had massive cellular disorganization, cells with tannins occurred in discrete units.
KeywordsCallus Culture Shikimic Acid Outer Cortex Prominent Nucleus Secondary Wall Formation
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