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  • Formation of callus, new cambium and vascular tissue in wounded stems of Norway spruce
    Oven, Primož
    Development of callus and subsequent tissue changes were investigated in wounded stems of Norway spruce (Picea abies) with light microscopy. Pinning the cambium at weekly intervals was employed to ... examine the origin of callus at different times of the year. Larger superficial wounds of wood were induced to study tissue changes taking place in the callus. Resin pocket type II (RP) was investigated as a closed wound system characterized by absence of tissue exposition. Pinning experiments revealed that cambial cells were involved in formation of callus if the meristem was wounded before the beginning of the growing season. Undifferentiated tracheids in the enlargement stage, parenchyma cells of xylem rays, epithelial cells or regular radial as well as axial traumatic resin canals and cells of the cambium gave rise to callus during the growing season. Phloem parenchyma was additionally involved in formation of callus at the edge of larger wounds. Cambium and phloem parenchyma reassumed irregular growth when wounded soon after the cessation of the growing season. Callus formed in the xylem growth ring contributed to quick closure of relatively small pinning wounds and reestablishment of cambial continuity. Callus was exposed and positioned at the edge of superficial wounds. Formation of the rigid protective ligno-suberised layer on the surface of the callus was the first apparent change in this case. New phellogen and new cambium differentiated. New cambial cells occured inside the callus in continuation with pre-existing cambium. Production of wound-wood and wound-bark initiated wound closure process. Formation of resin pocket type II was initiated by separation of bark from the wood within cambial region. Microscopy of RP revealed that callus developed on the entire surface of the secondary xylem and phloem. Superficial callus developed predominantly from parenchyma of xylem rays as well as from developing tracheids at the enlargement stage on the abaxial surface, and presumably from phloem parenchyma on the adaxial surface of RP. New cambium and vascular tissue developed only on adaxial surface of RP. Cambium of RP produced new wood and phloem, so that the structure was growing toward the abaxial surface of the RP. Resulting lens-like structure showed topography opposite to regular tissue arrangement in tree. Ontogeny of callus in Norway spruce and anatomical changes inside this thissue were compared to different types of wounding of other tree species.
    Source: Proceedings (Str. 48)
    Type of material - conference contribution
    Publish date - 2004
    Language - english
    COBISS.SI-ID - 1262217

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