Abstract: Effects of γ-aminobutyric acid（GABA）on chlorophyll content，relative water content，osmotic adjustment，reactive oxygen accumulation，protein carbonyl content，cell membrane stability，antioxidant defense，and differential expression of stress-related genes in leaves of creeping bentgrass （Agrostis stolonifera）‘Pencross’seedlings exposed to aluminum（AlCl3）stress were studied. Exogenous application of 0.5 mmol ? L -1 GABA could significantly increase chlorophyll content and relative water content and induce accumulation of soluble protein，soluble sugar，and free proline leading to the decrease in cell osmotic potential and increase in osmotic adjustment in leaves of creeping bentgrass under aluminum stress. Exogenous GABA also could significantly improve activities of key antioxidant enzymes CAT，POD，and SOD as well as their genes expression levels associated with the significantly lower reactive oxygen accumulation，electrolyte leakage，malondialdehyde content，and protein carbonyl content in leaves under aluminum stress，hence the application of GABA effectively alleviated the oxidative damage caused by aluminum stress. Exogenous GABA also promoted the creeping creeping growth under normal condition. In addition，exogenous GABA significantly induced the expression of the dehydrins-encoded gene DHN3 under aluminum stress. These results showed that GABA significantly increased aluminum tolerance of creeping bentgrass associated with the accumulation of organic osmolytes and enhancement of osmotic adjustment and antioxidant defense，thereby effectively alleviating oxidative damage under aluminum stress. GABA-induced dehydrins-encoded gene DHN3 expression may be also involved in GABA- regulated aluminum tolerance in creeping bentgrass.

Key words: Agrostis stolonifera, γ-aminobutyric acid, aluminum stress, osmotic adjustment, antioxidant, gene expression, dehydrins, metallothionein