NUCLEAR-DNA CONTENT OF PINUS-SYLVESTRIS (L) AS DETERMINED BY LASER FLOW-CYTOMETRY

Nuclear DNA content was determined in nuclei isolated from needles, st ems and roots of in vitro grown seedlings and from megagametophytes an d embryo of mature seeds in three accessions of Pinus sylvestris L. On e accession was from Inari, northern Finland at timber line, and two a ccessions were from the Alpine region in Italy. Nuclei were mechanical ly isolated by a chopping method, stained with propidium iodide, and D NA content was determined using an EPICS PROFILE laser flow cytometer. Nuclei isolated from leaves of barley (Hordeum vulgare L. cv. Sultan; 2C = 11.12 pg) were used as an internal standard for measurement of p ine nuclei. Mean 1C nuclear DNA content of P. sylvestris was 27.88 pg as determined from megagametophyte tissue. Mean 2C value was 52.25 pg as determined from stem and root tissue, and 55.58 pg as determined fr om embryo tissue. The ratio of 2C to 1C value was 1.87 and 1.99, respe ctively. Extracts of nuclei from needles contained propidium iodide-ab sorbing debris which may have interfered with measurements and resulte d in lower 2C values than those obtained from stem and root.