Induction of phenylalanine ammonia-lyase (PAL) in insect damaged and neighboring undamaged cotton and maize seedlings

Abstract

ABSTRACTThere has been scepticism about plants responding to information from their damaged neighbor plants since it was first reported, although a growing body of evidence indicates that interplant communication may play a key role in the resistance of plants. Cotton aphids and corn borer are important insects in cotton and maize, respectively. The resistance of healthy cotton and maize plants induced by their neighbor damaged plants was investigated in this study. Phenylalanine ammonia-lyase (PAL) is a chemical marker of induced resistance in many plants. The enzymatic activity and gene expression of PAL were determined in cotton and maize seedlings damaged by wounding, aphid and corn borer attack and in intact undamaged maize and cotton seedlings growing nearby. The enzymatic activity and gene expression of PAL were significantly increased in the cotton and corn seedlings damaged by wounding or by aphid and corn borer. Furthermore, undamaged neighboring cotton and maize seedlings also showed elevated enzymatic activity and gene expression of PAL. These inductions of PAL enzymatic activity and gene expression in the damaged and undamaged seedlings suggest inter-species communication between cotton and maize.