Above: Turbiana vines on the Sansonina estate in Lugana (Peschiera).
In recent years, many wine writers and bloggers have written about the genetic kinship between Verdicchio and Trebbiano di Lugana (also known as Turbiana, the grape used to make Lugana).
Although some claim the show-stopping discovery to be news, in fact the genetic link, not to Turbiana but rather Trebbiano from Italy’s Veneto region (where Lugana is made), was revealed nearly 30 years ago.
As leading Italian ampelographer Ian D’Agata writes in his excellent survey of Italian grape varieties (Native Wine Grapes of Italy, UC Press, 2014), Italian ampelographers first identified the genetic connection between Verdicchio and Trebbiano di Soave (Trebbiano di Lugana’s sibling) in 1991.
“In 1991, on the basis of ampelographic descriptions and enzyme analysis, [leading Italian ampelographers] demonstrated that Trebbiano di Soave is identical to Verdicchio…”
But when it came to Trebbiano di Lugana (Turbiana), the kinship question became a little more complicated.
“Subsequently, [another group of scholars] performed DNA profiling not just on Verdicchio and Trebbiano di Soave but also on Trebbiano di Lugana” also known locally as Turbiana di Lugana.
“The varieties have identical alleles at all ten loci; the likelihood of that happening and the two varieties not being the same is one in eight billion.”
“But,” D’Agata continues, “the researchers also found an abnormal allele of five hundred nucleotide bases in the VVMD36 locus that allows genetic differentiation between Trebbiano di Soave and Trebbiano di Lugana, which on the basis of these results are probably more correctly viewed as biotypes.” (italics mine)
(“VVMD” is shorthand for a class of vitis vinifera microsatellites.)
Noting that question of the direct link between Turbiana and Verdicchio has not been definitely established, D’Agata writes that “clearly, further studies are needed.”
So it turns out that Turbiana and Verdicchio are related but not identical, at least according to D’Agata, the leading scholar in the field.
For the record, the authors of the landmark Wine Grapes (HarperCollins 2012) write that “Trebbiano di Soave, Trebbiano Valtenesi and Trebbiano di Lugana are all identical to VERDICCHIO BIANCO.”
It would seem that D’Agata has had the last word (even though the word is still out, as he notes).