rbcLmatK

rbcLmatK refers to the combined chloroplast DNA barcode regions rbcL and matK, commonly used in plant identification and phylogenetics. The rbcL gene encodes the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase and is part of the chloroplast genome. MatK encodes maturase K and resides within the intron of the trnK gene in the chloroplast genome. Together, these regions provide complementary information for species discrimination and phylogenetic analysis.

Rationale and use. rbcL is highly conserved and generally easy to amplify and align across broad plant groups, offering robust recognition at higher taxonomic levels. MatK evolves more rapidly, providing greater resolution at lower taxonomic levels but can be more challenging to amplify and align due to primer specificity and sequence variability. The concatenation of rbcL and matK sequences creates a core barcode that enhances discriminatory power relative to either locus alone. This combination was proposed and promoted as a standard barcode for land plants by the CBOL Plant Working Group in 2009.

Methodological notes. Universal primers have been developed for both loci, enabling broad applicability across plant taxa. However, amplification success for matK can be variable in some groups, and the longer amplicon and higher evolutionary rate can complicate alignment and interpretation in closely related species. Because of these issues, rbcLmatK is frequently used in combination with additional markers, such as the psbA-trnH spacer or nuclear ITS, to improve identification in difficult groups.

Applications and data resources. rbcLmatK data underpin plant biodiversity surveys, systematics studies, and barcode-based identifications in public databases like GenBank and BOLD, supporting rapid species verification and comparative analyses.