Fire and Drought: Soluble Carbohydrate Storage and Survival Mechanisms in Herbaceous Plants from the Cerrado

The Cerrado biome covers a large area of central Brazil, containing a mosaic of physiognomies determined by soil fertility, seasonal rainfall, and fire. The ground layer vegetation presents a high eudicot diversity and a high proportion of belowground phytomass, represented mainly by a diversity of underground organs storing carbohydrates. Fructans and other soluble carbohydrates are claimed to be more than reserves, conferring protection against abiotic stresses due to osmoregulation properties and rapid turnover. Inulin- and levan-type fructans are prominent and found respectively in the underground organs of Asteraceae and Amaranthaceae, abundant families in the herbaceous Cerrado flora. Poaceae, mainly Panicoideae, is also abundant and accumulates glucose, sucrose, and malto-oligosaccharides, but not fructans, in contrast with temperate grasses. Here, we review evidence that fructans in the herbaceous flora of the Cerrado play a significant role in tolerance to drought and fire, promoting the rapid recovery of the ground-layer vegetation after environmental disturbances.