Water stress induces in pear leaves the rise of betaine level that is associated with drought tolerance in pear

SummaryMild water stress signi®cantly induced the accumulation of betaine in the leaves of young pear plants (Pyrus bretschneideri Rehd. `Suly'). The betaine induced by water stress in mature leaves was maintained for about two weeks of re-watering after water stress, and gradually declined two weeks after the relief of water stress, dropping to the normal level one month later. Exogenously foliar-applied betaine slightly improved the shoot growth and the ability of the leaves to resist dehydration, alleviated wilting of leaves under water stress, and promoted recovery of leaves from wilting after re-watering. These ®ndings indicate that the accumulated betaine induced by water stress was associated with drought tolerance in pear.