engleski

Chloroplasts features in vegetative buds of spruce (Picea abies L. Karst.)

Vegetative buds of spruce originate on young shoots in spring. In autumn they get in the resting condition what remains until next year spring when they proliferate into young shoots. The objective of this research was to find out the distribution and ultrastructure of chloroplasts in vegetative buds of spruce (P. abies) during the period of dormancy in correlation with chlorophyll content. The distribution of chloroplasts was searched on fresh sections by using the advantage of primary chlorophyll fluorescence. The investigation of chloroplast ultrastructure was done by TEM. For this purpose buds were fixed following the standard procedure (1% glutaraldehyde, postfixation with 1%OsO4). Ultrathin sections were contrasted using uranyl-acetate and lead citrate. The concentration of chlorophylls was determined spectrophotometrically. In transversal sections of bud, the chloroplast presence in medulla and needle primordia was detected. In the cells making the ring between medulla and needle primordia there were no chloroplast. The longitudinal sections showed the stripe of cells with no chloroplast between medulla and needle primordia what confirmed that there is a cylinder of cells with no chloroplast around the medulla. The mean values of chlorophyll content (0.24 ± 0.05 mg/g fresh weight) during the dormancy period was seven times lower than those in needles (1.68 ± 0.15 mg/g fresh weight) in the same period. Congruently the study of ultrastructure showed poorly developed thylakoid system and the presence of starch in the bud chloroplasts.

Picea abies; vegetative buds; chloroplast; ultrastructure

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