Articles
CLONING AND VARIATION OF RIBOSOMAL DNA FROM ASPARAGUS OFFICINALIS L.
The 18 S, 5.8 S and 25 S genes are clustered and intergenic spacer (IGS) region located between 18 S and 25 S genes.
Ribosomal DNA are highly variable both in copy number and length of IGS region.
This variability exists among the members on the same genus or species.
In this study, we have analyzed the structure and the variation of rDNA in Asparagus species and especially in A. officinalis.
The restriction pattern of rDNA repeats of A. officinalis L. (cv.
Mary Washington 500W) was analyzed by Southern hybridization with rice rDNA clone as probe.
Since XbaI cuts rDNA repeats into one fragment, rDNA of A. officinalis was cloned into XbaI site of pBluescript vector.
The restriction map of asparagus rDNA showed that the size of the rDNA repeat was about 10 kb.
To investigate the restriction pattern of rDNA, total DNAs were prepared from 9 cultivars of A. officinalis, namely, Cito, Larac, Gijnlim, Franklim, UC157F1, Mary Washington 500W, Tainan No.1, Hokkai 100, Zuiyou, and the two wild species, A. schoberioides and A. cochinchinensis which are distributed in Asia.
These total DNAs were digested with XbaI, EcoRI, and BamHI and Southern hybridization was carried out with asparagus rDNA as probe.
The restriction pattern of rDNA of A. officinalis was differed from those of two other species, however, there are no variation of restriction pattern within 9 cultivars of A. officinalis. This indicates that the cultivars investigated in this study are closely related.