Repetition of Hydrogen Peroxide Treatment Induces a Chilling Tolerance Comparable to Cold Acclimation in Mung Bean

Abstract

Mung bean seedlings ( Vigna radiata L.) of the cultivar Tainan No. 5 (a chilling-sensitive cultivar) pretreated with multiple sprays of 200 m m H 2 O 2 showed a tolerance to chilling at 4 °C for 36 h, measured by electrolyte leakage, that was greater than that induced by a single treatment and similar to that induced by cold-acclimation at 10 °C for 48 h. Two H 2 O 2 treatments at an interval of 3 h gave the optimum chilling tolerance. Tolerance induced by H 2 O 2 could be distinguished from that induced by acclimation at 10 °C according to length at 4 °C and corresponding electrolyte leakage. Chilling tolerance induced by H 2 O 2 depended on accumulation of glutathione (GSH), which could be significantly reversed by pretreatment with buthionine sulfoximine (BSO). In contrast, tolerance induced by incubation at 10 °C for 48 h in light was neither accompanied by accumulation of GSH nor reversed by BSO, suggesting that there are at least two independent mechanisms of developing chilling tolerance. Chilling tolerance of both cold-acclimated and H 2 O 2 -treated seedlings was decreased by ethyleneglycol-bis(aminoethylether)- N , N ′-tetraacetic acid (EGTA) but not by ruthenium red, indicating that the influx of Ca 2+ from extracellular, but not intracellular, pools is an important signal in the induction of tolerance. In confirmation, sprays of Ca 2+ could be substituted for H 2 O 2 .