Traditionally, the identification of grapevine variety and clones is obtained by "ampelography".
The word "ampelography" comes from the Greek words ampelos (grape) and grafo (describe) and literally means "description of grapevine". But actually the significance of the word "ampelography" is much wider, and it is more correct to use the word "ampelology" that in addition to the description of grapevine it also indicates the general study of grapevines (Calò, 2000).
The actual ampelographic methods are the following:
- descriptive methods, that describe the morphological characteristics of grapevine accession that allow to distinguish it from other accessions of another species, variety or clone;
- ampelometric methods, that require the measuring of some continuous organ parameters and are less subjective than the ampelographic methods;
- biochemical and biomolecular methods, that reveal the polymorphism of some metabolite or of some DNA specific regions.
The use of all three methods at the same time in the variety and clone identification allows us to obtain more accurate results.
In the 1983, the O.I.V. (Office International de la Vigne et du Vin) published the ‘Code des caractéres descriptifs des variétés et espèces de Vitis’ in four languages (French, English, Spanish, German); it reported the codification of ampelographic descriptive characters, that allow their informatics management, a method that subsequently has been adopted by other international organizations, e.g. the International Board for Plant Genetic Resource (IBPGR) and the International Union for the Protection of New Varieties of Plants (UPOV), for the identification of plant varieties. In the O.I.V. tables, each character and its expression level are identified by numeric codes. For the determination of the right level of expression of each characters some reference varieties were indicated. In this database the last edition of the O.I.V. method released in 2007, was adopted.
The ampelographic characters are grouped in qualitative characters (with discrete expression levels), quantitative characters (with continuous expression levels) and alternative characters (presence, absence).
The ampelometric methods introduced the biometry in the study of continuous ampelographic characters. These methods measure some parameters of some grapevine organs, like leaf and fruit, and compare these measurements with those obtained from other cultivars or clones.
The ampelometric methods are used essentially for two reasons:
- to obtain less subjective expression levels than ampelographic characteristics;
- to obtain continuous parameters characteristic of some accessions and to have the possibility to analyse these measurements with powerful statistical methods.
From the beginning of the use of ampelometric methods, leaves appeared as the most appropriate organs for biometric studies, because they could be collected from the plants over a long period, were weightless, occupied few space, could be easily transported and finally they could be easily preserved after drying. Another advantage of leaves in biometric studies is their only two dimensions (the leaf thickness is insignificant).
Among biochemical and biomolecular methods, the analysis of microsatellite polymorphism is the most used in the identification of grapevine varieties. In this database, the microsatellite profile represent the main class of data, and the profile of the 6 microsatellite loci internationally accepted (VVS2, VVMD5, VVMD7, VVM27, VrZAG62 e VrZAG79) it is necessary to insert a new accession in the database. Furthermore, any additional microsatellite locus profile could also be inserted in the database.