DNA extraction protocols for <i>Citrullus lanatus</i> and <i>Capsicum frutescens</i>: Effects of incubation temperatures and ethanol concentrations on DNA purity and quantity

Abstract

Citrullus lanatus has exceptional levels of oil (42 – 57%) and protein (33.8%) while Capsicum frutescens has high quantities of pro-vit A, C, B (B1, B2, B3). In spite of these endowments, no disease resistant variety of C. lanatus has been developed in Nigeria through conventional breeding. Likewise, C. frutescens improvements has been limited mainly by susceptibility to pepper veinal mottle virus which is incurable and which leads to huge economic losses. Molecular breeding is a tested technique for developing disease-resistant varieties of species. A fundamental step to any molecular biology study is the capability to isolate pure genomic DNA. Many of the published plant DNA extraction protocols are not suitable for all plants due to the presence of secondary metabolites. Since every step of a protocol should be optimized for each species, this study which is the first in a series was, therefore, undertaken to ascertain the best incubation temperature and ethanol concentration that can be suitable for DNA extraction from both species. Results showed that the following combinations were optimal for C. lanatus : 100%ethanol/60°C and 95%/60°C. Their A260/A280 ratios were 1.950 ± 0.014 and 1.860 ± 0.031, respectively, while their corresponding DNA concentrations were 3.087 and 2.973 μg/μl. For C. frutescens, the combinations, 100%/60°C and  95%/60°C were optimal and their A260/A280 ratios were 1.963 ± 0.004 and 1.803 ± 0.053 respectively while their corresponding DNA concentrations were 2.973 and 2.820 μg/μl. So it is recommended that any of the combinations for each species could be used for DNA extraction.

Keywords: DNA, extraction, protocol, pepper, egusi

African Journal of Biotechnology, Vol. 13(5), pp. 634-639, 29 January, 2014