Phenolic regulation of resistance to Microcyclus ulei Henn v. Arx. infection in Hevea progenies

Abstract

Three progenies of Hevea, with different levels of resistance to isolation of M. ulei (UNA) were studied. The progenies were: Fx 25 (moderately susceptible), Fx 2804 (highly susceptible) and P10 (resistant). The inoculation was made at the fourth flushing, with six to eight day-old leaflets. The progenies were maintained in a growth chamber. After 24, 72 and 144 hours, inoculated and noninoculated leaflets were collected to determine phenol, anthocyanin and chlorophyll contents. Progenies Fx 25 and Fx 2804 showed low phenol levels, decreasing levels of chlorophyll and a great number of injuries and sporulation. Progenie P10 showed high levels of phenol and chlorophyll, compared to the control. It did not show any injury. The anthocyanin levels decreased in all progenies. Consequently, Hevea resistance to M. ulei infection seems to be related to variations of leaf phenol levels.