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tion on the genetic structure of Turkish red pine (Pinus brutia Ten.) populations determined by RAPD markers. Silva Fennica 41(2): 211-220. To determine the possible impact of over-exploitation on the genetic structure of Turkish red pine (Pinus brutia Ten.) populations, three natural and three over-exploited (human degraded) populations of the species in the Mediterranean region of Turkey were investigated with Randomly Amplified Polymorphic DNA (RAPD). With the 80 RAPD primers tested, 12 of them yielded 137 polymorphic RAPD fragments. Four of the studied populations maintained unique fragments. The mean proportion of polymorphic fragments for all populations ranged from 89.8 to 98.9% and there were no significant differences between natural (94.8%) vs. over-exploited populations (92.7%). The estimated heterozygosity values suggested that Turkish red pine maintains high levels of genetic diversity (range 0.24-0.28) though studied populations and grouped ones as natural (H e = 0.28) vs. over-exploited (0.27) did not differ significantly. The mean F ST value indicated that the large portion of the total genetic diversity was within populations (93%), but this value was lower in the natural populations (92%) than in the over-exploited ones (94%). In over-exploited populations, excess of homozygosity was observed (about 6% higher) as compared to natural populations, indicating impacts of inbreeding in P. brutia.

Developing new sugarbeet varieties with conventional plant breeding methods is slow and labor intensive. Integrating tissue culture methods with conventional methods could facilitate this process for some traits. This study investigated the effect of culture media sucrose concentrations on phenolic concentration and tissue necrosis of explant, and shoot regeneration frequency. Petiole and leaf disc explants of three sugarbeet (Beta vulgaris L.) breeding lines were excised from sterile seedlings and cultured on media containing different sucrose concentrations. The lowest phenolic concentration and tissue necrosis were recorded from both explants of all lines at 0% sucrose concentration. However, at this concentration, explant growth slowed and no shoots were regenerated. The best shoot regeneration success was obtained from media supplemented with 1% sucrose, 1 mg l-1 6-benzylaminopurine (BAP) and 0.2 mg l-1 naphthaleneacetic acid (NAA). At higher sucrose concentrations in the culture media, phenolic concentration and tissue necrosis increased and sharp decreases were observed in shoot regeneration of the three sugarbeet lines.

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