| Abstract: | The activities of phenylalanine ammonia lyase PAL; EC 4.3.1.5
EC]
]and chalcone isomerase Cl; EC 5.5.1.5
EC]
] as well as the contentsof anthocyanin and total soluble hydroxyphenolic compounds wereinvestigated in maize (Zea mays L.) and soybean (Glycine maxL.) seedlings 120 h after treatment with the field dose of fiveherbicides from different groups (trifluralin, fluometuron,atrazine, alachlor, and rimsulfuron) having varied modes ofaction. The fresh weight of both species was greatly decreasedby trifluralin followed by fluometuron and atrazine. The dryweight was, in general, only slightly decreased by all the herbicideswith the largest response with trifluralin. On the other hand,the activities of PAL and Cl were greatly enhanced in both speciesby alachlor and rimsulfuron, but decreased by trifluralin. Fluometuroninduced decreases in PAL activity of maize only and decreasedCl activity of maize and soybean seedlings. Moreover, hydroxyphenoliccompounds were increased in both species by alachlor and rimsulfuronand decreased by trifluralin and atrazine. Similarly, anthocyanincontent was increased in both seedlings by alachlor and rimsulfuron,but decreased by trifluralin and fluometuron, whereas atrazinedecreased the anthocyanin content in maize only. The presentresults indicate that stress is maintained by the differentherbicides and confirm the controlling action of PAL and Clon the production of anthocyanin and phenolic compounds duringthe induced state of stress. In addition, dry weight reductionappeared to coincide with the changes in the parameters of secondarymetabolism, suggesting a regulatory role of secondary metabolismon seedling growth. Key words: Herbicides, phenylalanine ammonia lyase, chalcone isomerase, anthocyanin, hydroxyphenolics |
