Ribosomal RNA contents of maize genotypes with different ribosomal RNA gene numbers

✍ Scribed by P. J. Buescher; R. L. Phillips; R. Brambl

• Publisher: Springer
• Year: 1984
• Tongue: English
• Weight: 425 KB
• Volume: 22
• Category: Article
• ISSN: 0006-2928
• DOI: 10.1007/bf00499483

✦ Synopsis

Ribosomal R N A (rRNA) contents were determined in 16 maize genotypes whose individual rRNA gene numbers varied from 5000 to 23,000 per 2C nucleus. Analytical polyacrylamide gel electrophoresis of total R N A showed that no obvious relation existed between rRNA gene number and rRNA content. Only two of nine common inbred lines contained more rRNA than W-23, the inbred with the lowest rRNA gene number. Two of four lines with altered protein content (due to long-term experimental selection) had rRNA contents significantly reduced from those of W-23. A line with an apparent duplication of the nucleolus organizer region of chromosome 6 (called 2-NOR) was expected to possess an elevated quantity of rRNA because it possesses a larger nucleolus; however, we produced a 2-NOR isogenic version and found no difference in rRNA content. The rRNA genes in maize are distributed throughout the NOR-heterochromatin and the NOR-secondary constriction portions of the NOR. The absence of an obvious correlation between rRNA gene number and cellular rRNA content may reflect the presence of a large number of rRNA genes in an inactive state, at least during the stage of growth examined in these experiments.