The main grape used to make Valtellina wine is the Chiavennasca (in dialect: "Ciùuinasca", meaning "plus wine" from grapes) or called Nebbiolo Valtellinese from which derives the Piemontese Nebbiolo too.
It's really true: The researcher Snaider has in fact found the Pignola in the genome of the DNA of thePiemontese Nebbiolo. Pignola is a typical autochthon grape in Valtellina. It's used to vinify this grapes into white wins obtaining a Metodo Classico sparkling wine too.
Others varieties that grown in Valtellina are: Rossola (native) and Brugnola (a clone from Emiliana Fortana). Brugnola nowadays is no longer vinified but used as table grapes.