Mushrooms upright, sideways and inside-out

Morphogenesis is not simply a matter of playing out a predefined genetic programme. Expression of developmentally important genes is epigenetic and place- and time-dependent relying on previously-formed tissue structures. Most differentiated hyphal cells require reinforcement of their differentiation 'instructions'. This reinforcement is part of the context (chemical, electrical and structural/mechanical environment) within which they normally develop. Key words at each stage of development in fungi are: competence, induction and change. Fungal morphogenesis is compartmentalized into a collection of 'sub-routines' which are distinct genetically and physiologically. Flexibility in expression of developmental sub-routines illustrates that tolerance of imprecision is an important attribute of fungal morphogenesis.