Nuclear volume, chromosome size and DNA content relationships in three species of Pinus.

Abstract

Nuclear volume, chromosome size, and DNA content relationships were determined for three species of Pinus; the species in decreasing order of these parameters were P. lambertiana, P. radiata, and P. rigida. Chromosome size varied widely between the species and was positively correlated with both DNA content and nuclear volume of root-tip cells; nuclear volume and DNA content were also positively correlated. The highest/lowest value ratios of DNA content, nuclear volume, and total haploid chromosome complement length between the species were 2.0, 1.8 and 1.4 respectively. The differences in DNA content between these species having the same chromosome number (n=12) and similar karyotypic pattern, are explained on the basis of change in chromosome length due to duplication or deletion as well as chromosome density possibly due to differential polynemy.