Carbohydrate distribution and cellular injuries in acid rain and cold-treated spruce needles

Abstract

The cellular structures of acid rain-irrigated needles of several provenances of Norway spruce (Picea abies L. Karst) seedlings were studied after winter experimental freezing. Frost injuries and recovery were characterized by visual damage scoring and classification of mesophyll cell alterations, also using histochemical methods for carbohydrate fluorescent staining. The treatment with -30~ during the late dormancy period was sufficient to cause significant injuries and intracellular degradation in the tissues of the green needles. The most affected seedlings in terms of visual injury scoring were found among those treated with clean water or at pH 3, while freezing injury, defined as an occlusion of phenolic substances in the central vacuole of the mesophyll cells, was most abundant in the needles from spruces irrigated either with clean water or at pH 4 or pH 3. Electron microscopy revealed the details of the injury, e.g. thinning out of the cytoplasm and chloroplast stroma, darkening of the chloroplasts and eventually swelling of the chloroplasts and protoplast. PAS and ConA reactions in the needle tissue revealed intense starch accumulation in the mesophyll and transfusion tissues as early as in March, with a tendency to increase, especially in the untreated needles during the recovery period. Plasma membrane disturbances were indicated by histochemical identification of callose deposits in the mesophyll cell walls, these being most abundant in the acid rain-treated needles. All these findings suggest that freezing at -30~ was more deleterious to the seedlings pretreated with acid or clean water than to those not given additional irrigation.

Imaging and Spectroscopy of Natural Fluorophores in Pine Needles

“…The comparative anatomy of pine needles has been studied in detail [ 43 , 44 ], but there have been few comprehensive histological studies of conifer needles. Investigations have focused on pathological or physiological effects such as fungal infection, acid rain, mineral deficiency, or CO 2 enrichment [ 2 , 42 , 45 , 46 , 47 ]. Autofluorescence in combination with histochemistry has been used to explain differences in the mechanical properties of pine needles between species due to variable lignification of the endodermis [ 34 ].…”

Cell ultrastructural evidence of accelerated ageing of Norway spruce needles in industrial areas

“…The appearance of cytoplasm also suggested a less advanced winter hardening stage in trees in industrial areas than at the control site. Back & Huttunen (1992) and Back, Huttunen & Kristen (1993) have found that acid rain irrigation for two and a half growing seasons disturbs the winter hardening processes of Norway spruce seedlings. They attributed the slightly reduced cold tolerance to the accumulation of starch in the autumn.…”

Calcium oxalate crystals in the mature seeds of Norway spruce, Picea abies (L.) Karst.

“…This view was strengthened by the observations that the undamaged seed coats were free from crystals. Also, the accumulation of Ca crystals present in the wood rotted by fungi (Muhammad and Micko 1984), in the nodular roots of Alnus saplings (Jones et al 1989), and in the damaged surface tissue of spruce needles (Huttunen et al 1990/91;Fink 1991a;Bäck et al 1993) support the theory of Ca crystals being part of the defense mechanism in plants. Obviously Ca, in excess of the normal physiological concentration, is phytotoxic for a plant and becomes precipitated as inactive Ca oxalate.…”