DNA sequence organization and RNA complexity inMatthiola incana (Brassicaceae)

Abstract

The DNA of the cruciferMatthiola incana (Brassicaceae, Capparales) has been investigated for the pattern of sequence interspersion and RNA transcription. A short period pattern of interspersion (Xenopus-like interspersion pattern) is predominant (60%). Similar to a series of other Angiosperms (tobacco, soybean, parsley and some cereals) repetitive clusters orinter-se interspersion patterns of repetitive DNA occur inMatthiola genome and amount to 12%. From the hybridization of single copy DNA with poly(A)−-RNA and from cDNA/poly(A)+-RNA and cDNA/poly(A)−-RNA hybridizations a number of about 9,400 active genes can be estimated forM. incana seedlings. Both RNA constituents (poly(A)+-RNA and poly(A)−-RNA) contain mainly the same protein-coding mRNA sequences. Total mRNA is amounting to about 4% of theM. incana RNA population. A total of 1.2% (or about 30% of mRNA) of theM. incana RNA is represented by polyadenylated mRNA sequences. About 3.6% of single copy DNA hybridizes with poly(A)−-RNA. Approximately 7% of theM. incana genome, organized in a short period pattern of DNA sequence interspersion, is transcribed into RNA sequences (mRNA). About 6% of clustered repetitive DNA is expressed into RNA sequences such as rRNA and tRNA. Approximately 1.6 × 106 rRNA, 1.75 × 107 tRNA and 3.7 × 105 mRNA molecules are present perMatthiola seedling cell. The transcription rate of single rRNA and tRNA genes can be estimated to be about 1,400 or 1,100 copies per gene, respectively.