C. Polanco et Mp. Delavega, LENGTH POLYMORPHISM IN THE RIBOSOMAL DNA INTERGENIC SPACER OF RYE ANDSLENDER WILD OATS, The Journal of heredity, 86(5), 1995, pp. 402-407
Variation in ribosomal DNA spacer length was analyzed in nine populati
ons of three species of grasses by restriction fragment length polymor
phism analysis using non radioactive labeling. Three populations of ry
e. Secale cereale, four of the tetraploid slender wild oat, Avena barb
ata, and two of its diploid ancestor A. hirtula were analyzed. Extensi
ve spacer length polymer phism, attributed to the differences in numbe
r of spacer subrepeats within rDNA arrays, existed in the three specie
s. The fragment lengths generated by EcoRI in the two oat species rang
ed from 2.2 to 3.2 kb, while the fragments generated by BamHI in rye r
anged from 4.7 to 6.2 kb. The phenotypic variability observed agrees w
ith the expectations from the different mating types and number of rDN
A loci of these three species. In the two oats species, the most frequ
ent spacer length variants were shared for both oat species and were p
resent in all the populations; likewise, frequent spacer length varian
ts were present in the three rye populations. The results are compared
with previous data on rDNA polymorphism in rye and in slender oats po
pulations and on genetic variability for isozyme loci in the same popu
lations of both oats and rye.