Molecular genetic analysis in cotton (Gossypium hirsutum L.) is often limited by the availability of fresh tissue and the time necessary to extract deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein from it. An alternative would be the use of freeze-dried tissue. We compared nonfreeze-dried and freeze-dried leaf and root tissue as sources for DNA, RNA, and protein isolation. Our results showed that freeze-dried leaf tissue from either greenhouse-cultured or field-grown cotton yielded high molecular weight genomic DNA. The DNA was suitable for restriction-enzyme digestion and as a template for polymerase chain reaction (PCR) amplification. In contrast, freeze-drying led to complete degradation of RNA in leaf and root tissue. Total proteins of leaves and roots were unaffected by freeze-drying based on comparison of polypeptide profiles by denaturing polyacrylamide electrophoresis. While these results rule out freeze-dried tissue as a source for RNA isolation, the ability to freeze-dry, powder, and efficiently store voluminous tissue samples for later use in DNA and protein isolation could be of great benefit to laboratories involved in cotton molecular genetics.
