engleski

Estimate of intravarietal genetic variation as a prerequisite for successful clonal selection in grapevine

Modern winemaking relies mostly on old traditional cultivars which arose from seedlings developed centuries ago and spread over time and space by continuous asexual propagation retaining original genotype. Due to frequent and large scale cloning their populations accumulated random mutations resulting in genetically slightly heterogeneous individuals. The rate of mutations and their effects on agronomic traits are not well known. Since the most frequent type of beneficial mutations are point mutations it is not clear to what extent they can affect agronomic traits. The pre-selected virus-free vines of desired phenotype within populations of several old Croatian autochthonous cultivars have been propagated into clonal lines (grafted on the same rootstock) and grown in uniform field trials. Yield/vine ; number of clusters/vine ; weight and size of clusters ; berry weight ; type and content of sugars and acids, as well as compounds of aroma, have been analyzed over years to estimate the level of genetic variation among different clones. In addition, clones have been also assessed by molecular markers to estimate genetic variation on the DNA level. Yield/vine showed great variation (up to 20% from the mean value) among clones. In the case of ‘Plavac mali n.’, a cultivar with average cluster weight of 331.2 g and generally rather small variation among clones, clone PMC-95 was a significant exception with cluster weight of 512.7 g. Analyzed quality traits also exhibited significant variation. Volatile aroma compounds of the must assessed by GC-MS allowed differentiating most of the clones in spite of very different weather conditions over three consecutive years. Clones also demonstrated limited AFLP and S-SAP polymorphism (0.4-1.6%) even though it was not correlated with agronomic traits. The level of intravarietal genetic variation in studied cultivars was substantial which makes clonal selection an efficient method for improvement existing traditional cultivars both in yield and quality. Our results point to high improvement potential of well adapted autochthonous cultivars, usually considered to be inferior to international ones.

Vitis vinifera; mutation; AFLP; S-SAP; yield; cluster size; quality

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