TY - JOUR
T1 - Chilling-induced leaf abscission of Ixora coccinea plants. I. Induction by oxidative stress via increased sensitivity to ethylene
AU - Michaeli, Rina
AU - Philosoph-Hadas, Sonia
AU - Riov, Joseph
AU - Meir, Shimon
PY - 1999/10
Y1 - 1999/10
N2 - Exposing ixora (Ixora coccinea) plants to chilling temperatures (3-9°C for 3 days) resulted in increased leaf abscission, initiated 3 days after transfer to 20°C. Exposure to chilling also induced a 7-fold increase in ethylene production rates of abscission zone (AZ) tissue during the initial 5 h after chilling. The ethylene burst resulted from the high levels of 1-aminocyclopropane-1-carboxylic acid (ACC) accumulated in the AZ during the chilling period. ACC levels following chilling decreased also due to enhanced conjugation to 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC). Treating plants prior to chilling with antioxidants, such as butylated hydroxyanisole (BHA), n-propyl gallate (PG), and vitamin E, significantly reduced chilling-induced leaf abscission. This effect was obtained despite the fact that ethylene production in the treated plants resembled that of chilled plants receiving no BHA. In addition, exposure of plants to ethylene (0.5-10 μl 1-1) for 1-3 days significantly enhanced leaf abscission only when they had been pre-chilled. These data imply that chilling-induced leaf abscission was closely correlated with increased sensitivity of the AZ to ethylene rather than with the chilling-induced ethylene burst. Based on the findings that the ethylene action inhibitor, 1-methylcyclopropene (1-MCP), and the antioxidant BHA inhibited both the chilling-induced and the ethylene-enhanced leaf abscission, it is concluded that: (1) although ethylene is essential for chilling-induced abscission, it is not the triggering factor; (2) oxidative processes derived from the chilling stress seem to be the trigger of chilling-induced leaf abscission, operating via increased sensitivity to ethylene.
AB - Exposing ixora (Ixora coccinea) plants to chilling temperatures (3-9°C for 3 days) resulted in increased leaf abscission, initiated 3 days after transfer to 20°C. Exposure to chilling also induced a 7-fold increase in ethylene production rates of abscission zone (AZ) tissue during the initial 5 h after chilling. The ethylene burst resulted from the high levels of 1-aminocyclopropane-1-carboxylic acid (ACC) accumulated in the AZ during the chilling period. ACC levels following chilling decreased also due to enhanced conjugation to 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC). Treating plants prior to chilling with antioxidants, such as butylated hydroxyanisole (BHA), n-propyl gallate (PG), and vitamin E, significantly reduced chilling-induced leaf abscission. This effect was obtained despite the fact that ethylene production in the treated plants resembled that of chilled plants receiving no BHA. In addition, exposure of plants to ethylene (0.5-10 μl 1-1) for 1-3 days significantly enhanced leaf abscission only when they had been pre-chilled. These data imply that chilling-induced leaf abscission was closely correlated with increased sensitivity of the AZ to ethylene rather than with the chilling-induced ethylene burst. Based on the findings that the ethylene action inhibitor, 1-methylcyclopropene (1-MCP), and the antioxidant BHA inhibited both the chilling-induced and the ethylene-enhanced leaf abscission, it is concluded that: (1) although ethylene is essential for chilling-induced abscission, it is not the triggering factor; (2) oxidative processes derived from the chilling stress seem to be the trigger of chilling-induced leaf abscission, operating via increased sensitivity to ethylene.
UR - http://www.scopus.com/inward/record.url?scp=0033407428&partnerID=8YFLogxK
U2 - 10.1034/j.1399-3054.1999.100203.x
DO - 10.1034/j.1399-3054.1999.100203.x
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AN - SCOPUS:0033407428
SN - 0031-9317
VL - 107
SP - 166
EP - 173
JO - Physiologia Plantarum
JF - Physiologia Plantarum
IS - 2
ER -