An effective protocol for the isolation of RNA from the pulp of ripening citrus fruits

Abstract

Isolating RNA is the primary step in the study of gene expression. However, isolating high-quality RNA from ripening citrus fruit tissue is difficult because of the high content of water, polysaccharides, and other secondary metabolites. The traditional protocols for RNA isolation from citrus fruits are usually deficient and result in poor yields. Here we describe a modified method for isolating RNA from citrus fruit, especially from the pulp, that involves a dehydrating step with absolute ethanol. By this step, most of the water in citrus pulp is eliminated, which consequently yields high quantities of RNA, at 50–70 μg per gram of fresh weight. The absorbance at 260/280 nm ranges from 1.70–1.80, indicating that the RNA is of high quality, as confirmed by reverse transcription-polymerase chain reaction (RT-PCR) and construction of cDNA libraries.