Noble rot, the alchemist of wines, is setting fungal biology abuzz

In wine-making circles, 'noble rot' is an exalted name for the botrytis fungus (Botrytis cinerea).

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It infects grapes, penetrates the skin, causes the berries to lose water by evaporation and shrivel up, and thus concentrates the sugars and flavours in them. Since only a small percentage of grapes in a vineyard are infected, they must be picked by hand. This makes the picking process labour-intensive and drives up the cost. The crushed grape juice from rotted grapes is used to make high-quality sweet wines like the Sauternes of Bordeaux, the Trockenbeerenauslese of Germany and Austria, and the Tokaji Aszús of Hungary. They are also very expensive.

Befitting its exalted status, the botrytis fungus was also found recently to exhibit an unusual idiosyncrasy. In all animals, plants, and fungi, the nucleus of a cell contains one or more sets of all of the chromosomes of the organism. This property of nuclei allows us to clone animals. Scientists can transfer such a nucleus, which contains all the DNA instructions, into an egg cell whose own nucleus has been removed and, in the right conditions, prompt it to develop into a new organism. But because of the idiosyncrasy, botrytis fungus cannot be cloned - nor can another fungus called Sclerotinia sclerotiorum. A team of researchers from Sichuan University in China and the University of British Columbia in Canada have made a startling discovery: in these fungi, no single nucleus contains a complete set of chromosomes. Instead, the chromosome set is distributed across two or more nuclei, and any one nucleus contains only a subset.