It's possible to identify species variants via DNA barcoding by utilizing one or more short sequences of DNA in a standard portion of the genome.

Capsicum is a genus of plants of the Solanaceae family that is native to tropical and subtropical regions of America. It comprises about 40 species between solvent ones high abundance and cultivated accepted ones, although the cultivated species throughout the world have practically become perennial in favourable conditions.

Peppers and chillies, among others, are part of this family that has a variety of fruits according to their shape, colour, flavour, uses or origin.

According to researchers at the National University of Colombia in Palmira, there is no single, definitive classification of the genus Capsicum. Several investigations have contributed to the understanding of the genetic diversity of this genus by morphological characters, but the floral morphology in differentiating species of this genus isn't very effective and does not allow researchers to clearly distinguish species variants.

According to Professor Franco Alirio Vallejo, techniques using random amplified polymorphic DNA (RAPD) have allowed them to identify variants and the formation of groups based on morphological and molecular characters in Capsicum.

"Therefore, sequencing and bioinformatics applied to the field of taxonomy have provided a way of identifying species and variants beyond morphological characters through barcodes," said the researcher.

In addition, these codes allow complementing morphological studies and facilitate taxonomic identification, conservation and management of genetic resources stored in gene banks.

In this sense, Professor Vallejo with the collaboration of Professor Jaime Eduardo Muñoz and Agricultural Engineering student Ruben Dario Rojas, evaluated eight regions of the code as possible candidates for the identification of the Capsicum complex variability.

"We used ten gender introductions of existing seeds from the Germplasm Bank in the National University in Palmira. These seeds were planted in the field, and samples for analysis were taken from young leaf tissue without any symptoms of disease and then transferred to eppendorf tubes (properly identified), lyophilized and stored in a thermos of liquid nitrogen," explained Professor James Eduardo Muñoz.

Variations were observed in the eight regions. One was excluded from the experiment, others showed successful amplification in the PCR conditions set .

"The psbA-trnH chloroplast region showed a high efficiency amplification and allowed identifying 100% of the sequences. Using this region in the chloroplast genome presented desirable attributes such as bar codes, conserved genes and a high copy number in each cell, allowing the amplification of these regions, " said Professor Munoz.

In general, the study concluded that the previous region is a useful tool for identifying Capsicum complex species and its variants, considering the ease and reproducible PCR conditions.

"This DNA marker can be used to accurately identify species of the Capsicum complex, which until now was not possible to do," concluded Professor Vallejo.

Source: Universidad Nacional de Colombia