VARIABILITY IN VITIS BERLANDIERI

Abstract

The invasion of phylloxera during the 19th century nearly led to the collapse of viticulture in Europe. This could only be prevented by the introduction of phylloxera tolerant American wild grapevine species, used henceforth as rootstocks for grapevine grafting. While phylloxera control is the major aim of rootstock breeding, a wide ranged suitability to different abiotic environmental stress factors, particularly with regards to soil adaptation, is of great importance as well. The majority of the European vineyards, typically characterized by higher lime contents, are not compatible with most of the American wild Vitis species. However, the American species Vitis berlandieri is very well adapted to limey soils, and thus makes it an interesting partner for rootstock breeding. In the beginnings of rootstock breeding only a few V. berlandieri individuals had been available. So most of all of the rootstock cultivars used today comprise only a very small fraction of V. berlandieri?s genetic information. To study the variability of Vitis berlandieri, seeds were collected in their natural habitat in Texas in the year 2005 (Schmid et al., 2009) and have been germinated and planted in an observation block at Geisenheim. This population of nearly 3500 individuals should be very well suited to represent a more complete picture of V. berlandieri?s gene pool. In our ongoing project, the phenotypic and genetic characteristics of these Vitis berlandieri individuals are being evaluated continuously. Currently, 2000 seedlings of 21 different mother plants are being monitored by using ampelographic and physiological characteristics and genetic markers. Results point out that the offspring of different accessions are showing various distinctive characteristic features, either within one accession, or between different accessions. This indicates a larger variability of V. berlandieri than primarily assumed, and it offers a more ample spectrum for future rootstock breeding programs.