Is ITS2 more successful in angiosperm DNA barcoding than the entire ITS, ITS1, matK and trnH-psbA regions? A review

Abstract

The internal transcribed spacer 2 (ITS2) of the ribosomal cistron, functioning as a mini barcode, has proven successful in numerous angiosperm DNA barcoding studies. However, its efficiency has not been thoroughly questioned in the existing literature. This review statistically evaluates 197 angiosperm DNA barcoding studies that utilized the ITS2 mini barcode. The assessment encompasses not only the ease of amplification, sequencing, and species identification success of the ITS2 region but also a comparison with ITS1, the entire ITS region, matK, and trnH-psbA. The results align with the previous conclusion that ITS2 can be effectively utilized for angiosperm identification. While the amplification, sequencing, and identification to the genus level of the ITS2 region were high, the success in species identification was not as prominent. No significant differences were observed among the types of material or the primer pairs used in terms of the success of the region. The utilization of only the ITS2 region performed well in comparison to DNA barcode combinations. However, it is noteworthy that none of the reviewed regions can be considered a universal barcode for angiosperms. The results suggest that the ITS1 and ITS2 are equally effective as mini-DNA barcodes, followed by the entire ITS region, while matK and trnH-psbA should not be the primary choices.