The effect of MeJA on ethylene biosynthesis and induced disease resistance to Botrytis cinerea in tomato
Mengmeng Yu, Lin Shen, Bei Fan, Danying Zhao, Yang Zheng and Jiping Sheng
Postharvest Biology and Technology, Volume 54, Issue 3, December 2009, Pages 153-158
2009
บทคัดย่อ
Methyl jasmonate (MeJA), a major derivative of the plant hormone jasmonic acid, plays a critical role in inducing resistance to fungal pathogen. To study the endurance of MeJA-induced resistance and its cause, green mature tomatoes (Solanum esculentum cv. Lichun) were treated with 100 μM MeJA and nordihydroguaiaretic acid (NDGA, LOX inhibitor) at −35 kPa for 0.5 min and incubated at 25 ± 1 °C, 85–90% RH. Treatment with MeJA reduced disease symptoms in tomato fruit soon after being inoculated with Botrytis cinerea. Lesion size in MeJA-treated fruit was inhibited by 42.5%, 27.9% and 13.9% respectively (P < 0.05) in fruit inoculated 1, 3 and 6 d after treatments. At advanced stages (inoculation carried out 9 and 12 d after treatments), no inhibitory effect of MeJA were found. Ethylene biosynthesis was activated in the response of green mature tomatoes to methyl jasmonate with a rapid (1 d) and enhanced ethylene peak (0.9 ng kg−1 FW s−1). However the ethylene level was below that of the control from 6 d to 12 d. This rise was closely related with conversion of ACC to ethylene, especially a rise in ACO activity (6 h), which preceded an increase in ACS (12 h) after MeJA treatment. The development of ethylene biosynthesis was accompanied by a significant increase in LOX activity. Two significant O2·−peaks (P < 0.05) were detected in MeJA-treated fruit during storage (6.18 μmol g−1 FW min−1at 6 h and 5.68 μmol g−1 FW min−1at 3 d). The correlations between LOX, and O2·−and ACO activities were 0.75, 0.73 respectively (P < 0.05). These results indicate that MeJA-induced resistance against B. cinerea is durable, MeJA induces LOX and the superoxide radicals formed by LOX may activate ACO and ethylene biosynthesis.