The hidden origins of California's Zinfandel grape have at last been uncovered, according to prominent grapevine geneticist Carole Meredith, who is known for her discoveries of the parents of Cabernet Sauvignon, Chardonnay and Syrah.
Using DNA profiling techniques, Meredith and two Croatian scientists, Ivan Pejic and Edi Maletic, discovered in December that Zinfandel and an indigenous Croatian grape called Crljenak are one and the same.
The modern search for Zinfandel's roots, so to speak, dates back to the late 1960s. While traveling in Italy, USDA plant pathologist Austin Goheen noticed that the Primitivo grape widely cultivated in the Puglia region bore a strong resemblance to Zinfandel. He brought Primitivo cuttings back to the University of California, Davis, where he was based, for a closer look.
Goheen made his assumption based upon visual criteria, but he could never be sure that Primitivo and Zinfandel were exactly the same variety.
Other later tests backed up Goheen's theory, but a definitive answer didn't come until the 1990s, when Meredith -- a professor of enology and viticulture at UC Davis -- used DNA profiling techniques capable of establishing grapevine identity beyond doubt. Meredith determined that Primitivo and Zinfandel were indeed two clones of the identical variety.
But the question remained: Where did Zinfandel-Primitivo originate? Italian researchers had determined that Primitivo had only been cultivated in Puglia for about 150 to 250 years, but were not sure how it had arrived in the region. Available historical records first document Zinfandel's presence in the eastern United States in the 1820s and indicate that it was then brought to California in the mid-1800s.
An Italian colleague had told Goheen in the '60s that a grape variety similar to Primitivo grew in Croatia. Since there had long been an interchange of vines between Croatia and southern Italy, Goheen speculated that this Croatian variety, called Plavac Mali, might shed further light on the Zinfandel-Primitivo mystery. In 1977, he obtained Plavac Mali cuttings and cultivated them at Davis, but never determined whether it was the same variety or a related one.
Still on the trail of Zinfandel's origins in the '90s, Meredith decided to visit Croatia to gather DNA samples of Plavac Mali. In May 1998, Meredith, Pejic and Maletic searched many different vineyards on the Dalmatian coast and on some of the larger islands offshore. She brought back 150 samples to Davis for comparison with Zinfandel and Primitivo samples.
Although a definite relationship could be demonstrated between Zinfandel and Plavac Mali, Meredith's work showed they were definitely not the same variety. She believed that one was the offspring of the other, but could not tell which was parent and which was offspring. Pejic and Maletic continued to examine other old Croatian varieties, and in June 2001, the team determined that a grape called Dobricic and Zinfandel were clearly the parents of Plavac Mali. The discovery was compelling evidence, but still did not prove conclusively that Zinfandel had originated in Croatia.
Then, in December 2001, Pejic told Meredith he had found a sample of a grape called Crljenak, which he felt certain was Zinfandel. Pejic had the technology to do simple DNA comparisons in his Croatian lab, but wanted Meredith to do a more detailed, definitive analysis at Davis.
Meredith's tests indeed confirmed that Crljenak and Zinfandel were the same variety. At long last, Zinfandel's Croatian heritage has been established beyond doubt.
But Meredith pointed out that the grape's trail doesn't necessarily end there. She speculated that Crljenak could have been brought to Croatia from Albania or Greece. However, the presence of one confirmed offspring and many other similar vines in the region indicate that the variety has been in Croatia for a long time.
Read more about Carole Meredith's other work on grapevine parentage:
Researchers Reveal Hidden Roots of the Rhône's Great Grape
Study Discovers Lowly Parent of Noble White Grape
Cabernet Sauvignon's Roots Run Both Red and White