VIRULENCE OF ALTERNARIA ALTERNATA INFECTING NONI ASSOCIATED WITH PRODUCTION OF CELL WALL DEGRADING ENZYMES

摘要

Different methods of inoculations were tried for proving Koch postulates. Among them, the pin prick plus spore suspension spray was found be the best method used in a glasshouse. Out of the fifteen isolates of Alternaria alternata, isolate AA1 was highly virulent and AA6 was avirulent. The virulent isolate of A. alternata produced more cellulolytic (C1 and Cx) and pectinolytic (macerating enzymes, pectin methyl esterase and endo-polygalacturonase) enzymes in vitro than the avirulent one. The activity of cellulolytic enzymes increased with the increase in the age of the culture. Whereas, the pectinolytic enzymes were highly active in 10-day-old culture and the activities decreased with the increase in the age of the culture. Then again, the activity of enzymes produced by the avirulent isolate of pathogens did not decrease and these enzyme activities increased with the increase in the age of the culture.