Chulalak Talubnak, Nonglak Parinthawong, and Tanimnun Jaenaksorn

DOI: 10.14456/sjst-psu.2017.78

pp. 633 - 640

Abstract

A series of experiments were conducted to investigate phytoalexin production from five varieties of lettuce in hydroponics using abiotic (2.5, 5% CuSO₄
; 0.5, 1% AgNO₃
) and biotic elicitors (non-pathogenic Pythium sp.) at different plant ages.
It showed that phytoalexin was successfully induced in tested lettuce grown in hydroponics after elicitation with abiotic
elicitors throughout the trial. Phytoalexin showed yellow fluorescent spot under 365 nm UV light with R_f
 0.45-0.48 and clear
inhibition zone where Aspergillus niger failed to develop on TLC plate. For biotic elicitors, no yellow fluorescent spot on
TLC plate was observed from tested lettuce varieties however inhibition zone at R_f
 0.9 was detected at 8-9 weeks from red oak,
green oak, and red coral. Moreover, crude extract of lettuce elicited with abiotic elicitors possessed in vitro antifungal activity
against C. gloeosporioides, C. lunata, F. oxysporum, and P. aphanidermatum probably due to phytoalexin (lettucenin A) in
the extract.