engleski

The succession of chromoplast structures in Impatiens noli-tangere flowers

The differentiation of chromoplasts in the petals and sepals of Impatiens noli-tangere flowers was studied by ultrastructural, pigment and protein analyses. The differentiation of chromoplasts in both tissues started in the buds with young chloroplasts which, in their stroma, contained lightly stained globules (LSGs), 20 to 40 nm in diameter. In petal chromoplasts of open flowers these LSGs gradually disappeared and long tubules of 15 to 20 nm diameter developed, possibly by outgrowth from the LSGs. Later on the tubules arranged into tight bundles. In most chromoplasts of sepals the LSGs remained in the stroma throughout the life span of the flower, while the tubules appeared only in chromoplasts of some cell groups. The sepals contained more carotenoids (0.564 mg/g fr. wt.) than petals (0.384 mg/g fr. wt.). On the other hand, the sepal tissue of open flowers was poorer in the characteristic tubular protein of 32 - 35 kD, having about 60% of that present in petal chromoplasts. These results indicated that the differentiation of sepal chromoplasts occurred at a slower rate and rarely proceeded beyond the LSG-stage.

impatiens noli-tangere L.; flower; differentiation of chromoplasts; ultrastructure

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