Livermore Valley AVA unique east-west orientation, unlike many other winegrowing valleys. Due to a reliable onshore afternoon/evening breeze off of the San Francisco Bay a wide fluctuation in temperature between sites and a large diurnal temperature swing occur. Livermore Valley is considered a Winkler Region III grape growing zone with temperatures comparable to northern Napa Valley appellations such as St. Helena or Calistoga. The relatively obscure Petite Sirah grape produced Livermore's best historically known red wine, although the climate also makes for interesting dessert wines as well as excellent Cabernet Sauvignon, Merlot and Rhone varieties. The original plantings of Sémillon and Sauvignon blanc
Petite mutation petite negative mutants. Potentially, these yeasts have a different inheritance system in place for their mitchondrial genome than "S. cerevisiae" does. The frequency at which "S. castellii" spontaneously produces petites is similar to that of "S. cerevisiae", with the mitochondrial DNA of those petites being highly altered via deletion and rearrangement. Suppressive petites of "S. cerevisiae" are the most commonly observed spontaneously created mutants, whereas in "S. castellii," the most commonly observed spontaneous mutant is the neutral petite, further leading to speculation that the transference of this mutation differs between species. Petite mutation petite (ρ–) is a mutant first discovered