A parentage and a paternity-based approach were tested for estimation of pollen-mediated gene flow in wild grapevine (Vitis vinifera L. subsp. silvestris), a wind-pollinated species occurring in Mediterranean Europe and southwestern Asia. For this purpose, 305 seedlings collected in 2 years at 2 locations in France from 4 wild female individuals and 417 wild individuals prospected from France and Italy were analyzed using 20 highly polymorphic microsatellite loci. Their profiles were compared with a database consisting of 3203 accessions from the Institut National de la Recherche Agronomique Vassal collection including cultivars, rootstocks, interspecific hybrids, and other wild individuals. Paternity was assigned for 202 (66.2%) of the 305 seedlings, confirming the feasibility of the method. Most of the fertilizing pollen could be assigned to wild males growing nearby. Estimates of pollen immigration from the cultivated compartment (i.e., the totality of cultivars) ranged from 4.2% to 26% from nearby vineyards and from hidden pollinators such as cultivars and rootstocks that had escaped from farms. In an open landscape, the pollen flow was correlated to the distance between individuals, the main pollinator being the closest wild male (accounting for 51.4-86.2% of the pollen flow). In a closed landscape, more complex pollination occurred. Analysis of the parentage of the 417 wild individuals also revealed relationships between nearby wild individuals, but in the case of 12 individuals (3%), analysis revealed pollen immigration from vineyards, confirming the fitness of the hybrid seedlings. These pollen fluxes may have a significant effect on the evolution of wild populations: on the one hand, the low level of pollen-mediated gene flow from cultivated to wild grapevine could contribute to a risk of extinction of the wild compartment (i.e., the totality of the wild individuals). On the other hand, pollen dispersal within the wild populations may induce inbreeding depression of wild grapevines.

Genetic structuring and parentage analysis were performed on a very large database comprising 2786 unique multilocus genotypes [20 nuclear simple sequence repeats (nSSRs)] of Vitis vinifera L. ssp. sativa (DC.) Hegi with a special focus on Tuscan cultivars to reveal the parentage and history of the cultivar Sangiovese, the most important cultivar of Italy. For this cultivar, the authors also analyzed clones and synonyms, investigating its genetic origin and intracultivar diversity. Known synonyms of ‘Sangiovese’ were confirmed and new ones were revealed with cultivars outside Tuscany. Some synonyms were invalidated, and unexpected homonyms were identified. The absence of true intracultivar variability leads to the rejection of a polyclonal origin for ‘Sangiovese’. The existence of an Italian genetic pool composed of ancient cultivars including Sangiovese was demonstrated by analyzing the entire set of 2786 cultivars. Ten individuals compose the kin group of ‘Sangiovese’, including two offspring: ‘Ciliegiolo’ and ‘Catarratto bianco faux’. Despite the large presence and long history of ‘Sangiovese’ in the Tyrrenian area, its kin group is unexpectedly composed of a majority of ancient cultivars that are largely diffused in far southern Italy, which leads to the hypothesis of a Sicilian origin for ‘Sangiovese’. Analysis of the Tuscan pool revealed large kin groups for cultivars Mammolo and Garganega, demonstrating their contribution to the genetic diversification in the Tyrrenian area. This work contributes to the understanding of grapevine diversification, evolution, and history in Italy and Europe.

Oxygen fluxes into and from root cells of Vitis rupestris (flooding sensitive), V. riparia (flooding tolerant) and V. vinifera (medium tolerance to flooding) were measured under different levels of O2 availability using a recently developed polarographic O2-selective, vibrating-microelectrode system. The system enables fluxes to be measured with a spatial resolution of 2-3 microm and a temporal resolution of 10 s. No difference in root porosity was found among the genotypes when grown for 30 days in an aerated solution. Under normoxic conditions, O2 influx was characterised by two distinct peaks, one in the division zone and the other in the elongation zone of the roots. This pattern was found in all three species studied, although the fluxes showed a different magnitude. The peak in the elongation zone coincided with maximum relative elemental growth rates. When the energetics of the cell was disturbed by cyanide, both growth and oxygen O2 influxes ceased at the same time. Under hypoxic conditions, V. riparia plants showed a precise strategy directed toward the maintenance of enough O2 for the respiratory needs of mitosis in the apical meristem of the roots. Thus, whereas in the division zone of V. rupestris and V. vinifera, at bulk O2 concentrations of 0.094 mol x m(-3), the O2 influx was reduced by 70.5 and 38.5%, respectively, for V. riparia no variation in the O2 influx was detected down to bulk O2 concentrations of 0.078 mol x m(-3). Moreover, in accordance with the different tolerances of the plants, the Vitis genotypes were found to differ in their radial O2 loss from the adventitious roots when in an O2-free environment. The results are discussed in terms of possible mechanisms of response to anoxia in Vitis species with different tolerances to flooding.