A Modified CTAB Method for Genomic DNA Isolation from Ceiba spp., a Native Forest Species of the Peruvian Amazon

Ceiba spp. are native Amazonian forest trees of ecological and economic importance; however, genetic information on this genus remains limited. Genomic approaches such as genotyping-by-sequencing (GBS) require high-quality DNA, which can be challenging to obtain from leaf tissue. This study aimed to develop and evaluate a protocol for extracting high-quality genomic DNA from silica gel–preserved leaves of Ceiba spp. collected in the Loreto, Ucayali, and Madre de Dios regions of the Peruvian Amazon. Genomic DNA was extracted from 20 samples using a modified cetyltrimethylammonium bromide (CTAB) protocol incorporating a sorbitol-buffer prewash. DNA quantity and quality were assessed by microvolume spectrophotometry and Qubit fluorometry. A260/A280 ratios ranged from 1.70 to 1.99 (mean, 1.84), while spectrophotometric DNA concentrations ranged from 220.8 to 1294.1 ng/µL (mean, 696.5 ng/µL). Qubit measurements indicated detectable double-stranded DNA in all samples, although half of the readings (10/20) exceeded the upper limit of the assay range used. DNA suitability for polymerase chain reaction (PCR) was assessed by amplifying the rbcL gene with universal primers, yielding amplification products in all 20 samples. The protocol yielded genomic DNA with quality characteristics compatible with downstream molecular applications and may support future GBS studies, subject to additional validation.