Polyphenoloxidase activity in coffee leaves and its role in resistance against the coffee leaf miner and coffee leaf rust

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• 作者：Geraldo Aclé ; cio Melo ; Milton Massao Shimizu and Paulo Mazzafera
• 关键词：Coffea ; Coffee ; Rubiaceae ; Hemilea vastatrix ; Leucoptera coffeela ; Phenolic compounds ; Plant resistance ; Polyphenoloxidase
• 刊名：Phytochemistry
• 出版年：2006
• 出版时间：February 2006
• 年：2006
• 卷：67
• 期：3
• 页码：277-285
• 全文大小：462 K

文摘

In plants, PPO has been related to defense mechanism against pathogens and insects and this role was investigated in coffee trees regarding resistance against a leaf miner and coffee leaf rust disease. PPO activity was evaluated in different genotypes and in relation to methyl-jasmonate (Meja) treatment and mechanical damage. Evaluations were also performed using compatible and incompatible interactions of coffee with the fungus Hemileia vastatrix (causal agent of the leaf orange rust disease) and the insect Leucoptera coffeella (coffee leaf miner). The constitutive level of PPO activity observed for the 15 genotypes ranged from 3.8 to 88 units of activity/mg protein. However, no direct relationship was found with resistance of coffee to the fungus or insect. Chlorogenic acid (5-caffeoylquinic acid), the best substrate for coffee leaf PPO, was not related to resistance, suggesting that oxidation of other phenolics by PPO might play a role, as indicated by HPLC profiles. Mechanical damage, Meja treatment, H. vastatrix fungus inoculation and L. coffeella infestation caused different responses in PPO activity. These results suggest that coffee resistance may be related to the oxidative potential of the tissue regarding the phenolic composition rather than simply to a higher PPO activity.