What the hell is a biotype?

If you are into Italian wines you have probably encountered the word “biotype”: Sangiovese Grosso (encompassing Brunello and Prugnolo Gentile) is a biotype of Sangiovese; Aglianico del Vulture is a biotype of Aglianico and its wines have a more intense red fruit character than its Campanian counterpart; Pigato is a biotype of Vermentino, even though some growers do not like the idea and still consider them separate grape varieties; Catarratto Comune and Catarratto Bianco Lucido are two different biotypes of the same variety.

And so on and so forth.

Thus the question arises: what is a biotype? Is it the same as a clone? Something else?
The answer is less straightforward than you may imagine.

I think that we can all agree on what a grape variety is: when a male grapevine flower pollinates a female grapevine flower a berry forms. If any of the seed inside the berry is planted and allowed to grow, the resulting plant will be a new grape variety, different from both of its parents. Furthermore, since my brother is not an exact copy of me, two seeds from the same vine, if planted and grown, will result in two new distinct grape varieties.

Of course commercial grapevines are not propagated this way, otherwise you’ll have a vineyard filled with different grape varieties. Commonly we take a piece of the plant that we want to replicate and we propagate it vegetatively by cuttings or by layering. The new vine will then be an exact copy of the original one.

Now, to the main issue.

First, let’s turn to the Pontifex Maximus of any WSET student out there (no sarcasm): Jancis Robinson.

In her monumental work “Wine Grapes” the word “biotype” appears only once, in the bibliography. There is no other mention of it, it is completely ignored.
In the first pages Jancis and her co-authors clarify some terms that they are going to use throughout the book. A “grape variety” is explained as above, while “mutation” and “clone” are defined as follows.

At each cell division during plant growth, when the DNA is replicated, errors are likely to occur, resulting in spontaneous mutations. (Note that the word mutation may be used to refer to the natural process described below as well as the result of that process.)

After decades or centuries of vegetative propagation, each grapevine plant harbours hundreds of thousands of new mutations. Most of them will go unnoticed, and only those having a desired effect that is observable to the human eye – smaller berries, bigger crops, for example – will be noticed and propagated separately: these are clones.

Simple and clear. A grapevine naturally develops mutations: when these mutations lead to new, desirable features, the plant in question will be put aside and vegetatively replicated on a wide scale. A “new clone” is born.

No space for “biotype”. So, can we just forget about the term and stop employing it?
Not so fast: the word is still widely used out there. At least we need to understand why and how.

Since we are talking about Italian wine, what does Ian d’Agata, the Big Boss of all Italian wine lovers (again, no sarcasm) tell us about this topic? Contrary to what happens with Jancis Robinson he writes extensively of biotypes in his “Native Wine Grapes of Italy”. He clearly states:

Biotypes are members of a grape variety that exhibit phenotypic plasticity, by spreading out geographically and adapting to different environments over the centuries (see chapter 2). In so doing, they have built up mutations.

And also:

Once reproductive cycles occur, there is a reshuffling of the parental genes, and the offspring will be genetically different from the parents. At each cell division, errors can happen and mutations are born.” […]
Though we habitually describe these new and different grapevines as “clones,” this is incorrect, as clones are by definition genetically identical to the mother plant. It is more accurate to refer to these new and different plants as biotypes.

So, if I am getting this right, according to Ian D’Agata a grape variety which underwent a clonal mutation should not be called a “clone” because the word technically indicates a perfect copy of the original plant. Having a mutation, it cannot be a perfect copy. This makes sense. For this mutated vine, he prefers the term “biotype”. Sangiovese Grosso developed a mutation from Sangiovese: it is a new biotype. Aglianico del Vulture developed a mutation from an original Aglianico vine: it is a new biotype.
In this sense the term seems similar to Jancis Robinson’s “clone”. Similar, but not equivalent: as we saw above a clone for Jancis is not just a mutated plant, it is a mutated plant with desirable characteristics chosen to be replicated on a wider scale. (1)

The problem arises in how the term “biotype” is generally employed: there are many mutations of Sangiovese developed in Montalcino and used for Brunello di Montalcino, like BF 10, BF 30, TIN-10, TIN-50, JANUS-10, JANUS-20, SG-CDO-4, SG-CDO-6. These are commonly called “Brunello” or “Sangiovese Grosso”, but what really are they? Maybe the first Sangiovese mutation showing bigger bunches and berries could have been called Sangiovese Grosso, but what about the others developed afterwards from it? They can’t be all just “Sangiovese Grosso” according to the definition given by Ian D’Agata, because each other is different: they are new biotypes of Sangiovese. So what is Sangiovese Grosso? Does it really exist?
Or maybe we are saying that a biotype is a “group” of similar mutations, showing analogous characters? This definition would be problematic though: where should we draw the line?

The term “biotype” seems to be the “minerality” of biology: a brief search over the internet returns definitions such as “a group of genetically identical plants within a species, produced by apomixis” (link) or “any of a number of strains of a species of microorganisms having differentiable physiologic characteristics.” (link)
The concept is so vague that there is even a study exploring all the different ways in which it has been employed by biologist over history. The text is freely availabe here, but it suffices to cite the extract:

It is argued here that the term ‘biotype’ and its applications are overly simplistic, confused, have not proved useful in current pest management, and lack predictive power for future management.

A look at a couple of technical dictionaries, the Oxford Dictionary of Biology by Robert Hine and the Oxford Dictionary of Biochemistry and Molecular Biology by Anthony Smith, reveals that there is no entry for “biotype”. The term is ignored.
At this point I start thinking that Jancis’ decision is the wisest possible: the term “biotype” is ill defined, vague and inconsistent. It is simply better to avoid it.

On the other hand I also see D’Agata’s point when he says that “clone” is by definition a being identical to the original. So how should we call a grapevine that developed a mutation?
The answer is mutant.

Mutant: a gene or an organism that has undergone a heritable change, especially one with visible effects (i.e. the change in *genotype is associated with a change in *phenotype).
Oxford Dictionary of Biology, Robert Hine

Mutant: 1 a any organism that has arisen by or has undergone mutation, or one that carries a mutant gene that is expressed in the phenotype of that organism, b a mutant gene. 2 produced by or following a mutation; having the attributes of a mutant (def. 1).
Oxford Dictionary of Biochemistry and Molecular Biology, Anthony Smith

That seems to be it.
However, are we really going to call our vines “mutants”? The terms is not very pleasant, even less than clone, and it evokes the image of monstrous people-eating zombies developed by evil corporations. Or at best, the X-Men.
Imagine your favorite winemaker calling a vine nursery: “Hi Bob, yeah this year’s crop is doing great, but listen: could you please send me some Chardonnay, MUTANT 117?” (2)

I think that for the time being I will stick with “clone” as defined by Jancis Robinson, even if it is not 100% precise.

In conclusion

Finally, going back to the question in the title: what the hell is a biotype?

My answer: biotype is a ill defined, vague term employed to alternatively indicate a clone, a group of clones or even a synonym of a grape variety name used in a specific area. Avoid it!

(1) Notice that Ian D’Agata himself in his book goes back employing the word “clone” over and over, adding even more confusion.

(2) Well, as already stated, the word mutation can indicate both the process and the result, making it a slightly more pleasant synonym for mutant. If you like it.