Alterations in Photosynthetic Pigment Synthesis in Tissue Cultured Tobacco Callus

Abstract

Tobacco stem pith in tissue culture forms green callus, followed by shoot regeneration. Inclusion of excess manganese (10 mM) in the medium leads to inhibition of growth and of photosynthetic pigment biosynthesis. Growth is inhibited about 40% throughout the 7 week period of study. Pigment synthesis is initially delayed in manganese treated cultures, then the extent of inhibition decreases. The amounts of lutein and β-carotene relative to chlorophyll a. are reduced during the first few weeks of manganese treatment7 while the relative amount of chlorophyll b remains the same. During later stages of manganese treatment, both lutein and chlorophyll b increase relative to chlorophyll a.