Classifying Abies species (Pinaceae) based on the sequence variation of a tandemly repeated array found in the chloroplast DNA trnL and trnF intergenic spacer

Abstract

DNA sequences of the chloroplast spacer region between the trnL and trnF genes were determined in 18 species of Abies MILL. and another five species of Pinaceae (Keteleeria davidiana, Tsuga sieboldii, Larix kaempferi, Pseudotsuga menziesii, and Picea bicolor). A tandem repeat sequence composed of a 14-bp core sequence was found in all Abies species analyzed. This tandem repeat array was specific for genus Abies, since this array was not detected in the other five species of Pinaceae. Comparison of the tandem repeat region of Abies species revealed variation in the number of repeats and in the nucleotide sequences of the units among species. The number of repeats varied from two to five, and there were eight different unit types in nucleotide sequences. Eighteen Abies species were divided into nine groups by the tandem repeat type, which was defined by both the number of repeats and the unit type. This grouping was compared with two conventional classifications based on morphological traits. There were some differences between the results of this study and the conventional classifications.