Vitis rupestris

The evalnation of phenolic snbstances in wine is a historical topic, and colorimetric methods were developed at hrst for qnality control of wine. Nowadays, it is still performed, and a parameter named optical density is still measnred as an index of color, while other indices have been developed for a rapid evalnation of phenolic componnd content. Moreover, the form of some phenolic compnnds (mono- or diglncoside) is nsed to distingnish between wines obtained by the fermentation of the jnice of Vitis vinifera or Vitis rupestris. 

In the first place, the green grape skin, covered by a thick cuticle, constitutes an effective barrier against parasites. Since Bonnet s (1903) initial research, a resistance scale of the principal Vitis species has been established based on the cuticle thickness of their respective berries. American varieties whose cuticle thickness varies from 4 p,m (Vitis rupestris) to 10 tim (Vitis coriacea) have better protected berries than European species (Vitis vinifera), whose cuticle thickness is from 1.5 to 3.8 p,m. This observation led to the production of V. vinifera and American species hybrids that are effectively more resistant to gray rot, but these hybrids do not usually produce quality grapes on the best terroirs. 

A (Teleki 5C X Bbmer) x [(Vitis berlandieri x Vitis rupestris) x Vitis cinerea] 16-1-6, 16-1-7, 16-2-5... 

Vitis rupestris Scheele is also called the sand grape. It occurs in the mid-South states of Arkansas, Kenmcky, Tennessee, and Oklahoma (Cousins, 2005). One especially positive trait of this species for breeding is resistance to phylloxera. It also roots easily, develops a deep root system, and has high vigor, but like V. riparia, it does not tolerate calcareous soils (Einset and Pratt, 1975 Snyder, 1937). St. George root-stock is a selection of V. rupestris (Cousins, 2005). 

Boubals (1966) was among the hrst to study phylloxera resistance and its heri-tability in both intraspecihc and interspecihc hybrids of V vinifera, V berlandieri, V. riparia, V. rupestris, V. cinerea and Vitis labrusca. In 1934, however, Carl Bbmer discovered total phylloxera resistance in V. cinerea Arnold and used this species in his breeding programme. V. cinerea shows a total resistance to this pest and was used to produce its hybrid with V. riparia 183 G, which was named Bomer (Becker and Bomer, 1988). Bomer responds to phylloxera infestation with a hypersensitive reaction, which results in local necrosis on leaves and roots so that the damage caused... 

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