The PCR Add-on kit contains a PCR Mix including a non-indexed Illumina P5 specific primer, a thermostable polymerase, and an Illumina P7 primer without a barcode (primer 7000).
By adding SYBR Green I to the PCR reaction a qPCR assay to determine the optimal number of cycles for the endpoint PCR of your QuantSeq or CORALL cDNA libraries can be determined.
The qPCR assay is recommended to determine the exact number of cycles for the endpoint PCR in order to prevent any under- or overcycling of your library. Undercycling may result in too little library while overcycling can lead to significant distortions in gene expression values.
The kit furthermore contains a reamplification primer that can be used to reamplify already barcoded libraries if they were undercycled to get enough material for sequencing.