The inset cover image shows a cross-section of fresh unstained tissue of a sugar cane root (Saccharum officinarum, Poaceae) at 4cm from the tip. Root cell walls undertake modifications that lead to the formation of gas spaces (large cavities in the cortex, named aerenchyma). They are associated with specific gene expression, protein production, and activities of glycosyl hydrolases. These phenomena are synchronised so that functional moduli are activated during aerenchyma development. (see Grandis et al, pp. 1067–1089).