Pinot Meunier - Ampelography

Ampelography

Pinot Meunier can be identified by ampelographers by its indented leaves that appear downy white, like flour has been dusted liberally on the underside, and lightly on the upper side, of the leaf. The name "Meunier" comes from the French word for miller with many of the grapevine's synonyms (see below) also hearkening to this association-such as "Dusty Miller" which is used in England, "Farineaux" and "Noirin Enfariné" used in France as well as "Müllerrebe" and "Müller-Traube" used in Germany. This characteristic derives from large numbers of fine white hairs on the leaves. However, some clones of Pinot Meunier have been found to be completely hairless -- a chimeric mutation, in fact -- which has led ampelographers to more closely draw a link between Meunier and Pinot noir.

In groundbreaking research, Paul K. Boss and Mark R. Thomas of the CSIRO Plant Industry and Cooperative Research Centre for Viticulture in Glen Osmond, Australia, found that Pinot Meunier has a mutation (VvGAI1) that stops it from responding to gibberellic acid, a plant growth hormone. This leads to different, white-haired, leaf and shoot growth, and also to a slight stunting in growth, explaining why Pinot meunier plants tend to be a bit smaller than Pinot noir. The mutation exist only in the outermost cell layer of the cultivar, the L1 or 'epidermal' layer, meaning Pinot Meunier is a chimera. Through tissue culture, it is thus possible to separate out plants containing both the mutant (L1) and non-mutant (L2) genotypes, yielding a normal Pinot noir -like genotype and an unusual looking L1-genotype vine with compressed internodes and thickly clustered leaves. The mutants could not produce full-grown tendrils, it seems that gibberellic acid converts grapevine flower buds into tendrils.