PINE GENOME SIZE DIVERSITY AND WATER RELATIONS

Important functions of water relations are considered to be related to genome size diversity in gymnosperms. We investigated relationships a mong genome size, dimensional characteristics of conductive cells, and water relations parameters by using young seedlings of six Pinus spec ies. Xylem hydraulic conductivity was not correlated with genome size and dimensional characteristics of conductive cells, but the water pot ential at the turgor loss point was. Pinus species with large genome s izes had thick cell walls and small ratios of lumen radii to cell wall thickness in their conductive cells, and those species lost their tur gor to tissue dehydration at low water potentials. The characteristics observed in the present study may contribute to pine drought toleranc e.