Genomic profiling: The strengths and limitations of chloroplast genome-based plant variety authentication.

Genomic profiling is a suitable tool for variety authentication and has applications in both operational quality and regulatory raw material control. It can be used to differentiate species or varieties and to identify admixtures as well as field contaminants. To establish a molecular profile, reliable and very accurate sequence data are required. Due to the influence of the pollinator plant, nuclear genome-based authentication is in most cases not suitable for a direct application on the fruit. Sequences must be used which come exclusively from the localized mother plant. Parts of the fruit of maternal origin, e.g. components derived from the blossom, are suitable as a basis for this. Alternatively, DNA from cell organelles that are maternally inherited, such as mitochondria or chloroplasts, can be used. The latter will be discussed in this article in closer detail. Although individual gene segments on the chloroplast genome are already used for species differentiation in barcoding studies on plants, little is known about the usefulness of the entire chloroplast genome for intraspecies differentiation in general and for differentiation between modern varieties in particular. Results from the literature as well as from our own work suggest that chloroplast genome sequences are indeed very well suited for the differentiation of old varieties. On the other hand, they are less or not suitable for the genetic differentiation of modern cultivars, as they are often too closely related.