Porphyrin metabolism in chill-stressed seedlings of Scots pine (Pinus sylvestris)

Scots pine ( Pinus sylvestris L.) is generally resistant to chilling temperatures. Porphyrin metabolism under low temperature stress was studied in etiolated seedlings of Scots pine. Low temperatures affect porphyrin accumulation in at least 3 different temperature sensitive sites: 1) the light activated accumulation of 5-aminolevulinic acid, a porphyrin precursor, 2) the metabolism of 5-aminolevulinic acid to form porphyrins and 3) a preferential accumulation of chlorophyll a over chlorophyll b . The temperature sensitivity of pine is compared to maize ( Zea mays L.), a chilling sensitive plant.