Effect of cowpea aphid on the biosynthetic pathway of salicylic acid in Glycine max cv. Namdan at reproductive growth stages

Cowpea aphid (Aphis craccivora Koch) infestation accumulated phytohormone salicylic acid (SA) in leaves of soybean (Glycine max cv. Namdan) as these soybean plants were at stages R1 (beginning to bloom) and R3 (beginning pod development). Activity of major enzymes involving biosynthesis of SA, such as phenylalanine ammonia-lyase (PAL), benzoic acid 2-hydroxylase (BA2H), was also enhanced under aphid effect.