Mechanisms of tolerance to saline stress in Chloris gayana

TALEISNIK E

Simposio; The International Symposium on the Molecular Breeding of Forage and Turf, MBFT; 2010

C. gayana, commonly known as Rhodesgrass, is one of the most salt-tolerant C4 forage grasses. Nevertheless, salinity restricts its establishment and persistence, as well as yield. Variability in salt tolerance within the species has led to the identification of various mechanisms that contribute to its relative success under saline conditions. The capacity to secrete Na+ through salt glands on leaves as well as the control of Na+ accumulation in shoots is associated to salt tolerance. There is some evidence that Na+ may be compartamentalized within the vacuole while cytoplasmic water potential balance kept by the accumulation of compatible organic solutes, especially betaine. Leaf growth impairment by salinity is associated mainly with reduced water availabilty, but increased activity of cell wall enzymes associated with wall loosening may contribute to the maintenance of growth under saline conditions despite hydraulic restrictions. A vigorous root system is essential for pasture establishment, for ensuring adequate regrowth after grazing, as well as for providing plant stability and anchorage to the pulling effects of grazing. The number and length of nodal roots is reduced by salinity and alterations in root ability to metabolize reserves may be more significant than reserve availability for maintaing elongation. Oxidative stress is more tightly controlled in salt tolerant genotypes and selections based on low oxidative stress parameters can enrich the original population with tolerant individuals. The widespread establishment of C. gayana pastures in saline soils speaks for itself on the adaptability of this species. Salt affected areas may be a source of alternative biofuels and pharmaceuticals that do not compete with feed production. Adequating the species for these uses requires effective genetic manipulation that will be achieved as it becomes subject of molecular intervention. Very little molecular work has been done on this species up to now.