Diversity assessment of seedlings from self-pollinated Sangiovese grapevines by ampelography and microsatellite DNA analysis

Abstract

A population of Vitis vinifera L. seedlings deriving from a single self-pollinated Sangiovese vine were assayed for diversity by ampelographic and genetic techniques. After field-transplantation in 1987, the seedlings were initially screened in 1995. Twenty-four seedlings were of standard Vigour and grape production. Woody cuttings from the 24 seedlings and the mother plant were self-rooted in 1995, and each Vine was morphologically analysed and compared in 1997 using 31 descriptors of the ampelographic data sheet (OIV 1983) which are also recommended by UPOV for varietal identification - three for young shoots, 7 for shoots at bloom, 17 for adult leaves, one for flowers and 3 for berries. - In 1996 DNA was extracted from young apical leaves of the mother plant and the 24 seedlings. Ten molecular microsatellites, VVS1, VVS2, VVS5, VVS16, VVS29, VVMD5, VVMD6, VVMD7, VVMD17 and VVMD28, were used for progeny and mother plant comparison. The descriptor-based analysis showed that 12 of the 24 seedlings were morphologically similar amongst themselves and not different fr-om the mother; the remaining 12 differing from each other and from the parent. The microsatellite analysis differentiated all 24 seedlings from the mother plant. Only two seedlings showed the same allele patterns at the 10 tested loci, although they differed morphologically. The results of both analyses indicate that self-pollination can generate phenotypically similar individuals that are difficult to distinguish morphologically, while their genetic polymorphism can easily be detected by microsatellite analysis. Thus it is possible, as suggested by RIVES (1961), that certain ancient cultivars comprise a number of clones that derive via vegetative propagation from closely related mother plants. Corroboration of the polyclonal origin in such cases can be performed by techniques combining morphological and molecular approaches.