Lignification and Qualitative Changes of Phenolic Compounds in Rice Callus Tissues Inoculated with Plant Pathogenic Fungi

Abstract

The formation of lignin or lignin-like substances were investigated in rice callus (Te-Tep) in response to fungal infection (Alternaria brassicicola, Botrytis cinerea, and Aspergillus oryzae). Lignification, regardless of infection, was not observed in rice callus. However, ferulic acid was detected as a degradation product (alkaline hydrolysis and alkaline nitrobenzene oxidation) of the callus cell wall by means of TLC and GC-MS. The amount of this substance increased with inoculation of Aspergillus oryzae. Spore germination and the mycelial growth of A. brassicicola was not affected by ferulic acid.
Qualitative changes of free phenols were also examined in relation to rice callus infected with plant pathogenic fungi. Free phenols such as vanillic, syringic, protocatechuic, caffeic and ferulic acids were not detected in rice callus tissues. Only traces of p-coumaric and p-hydroxybenzoic acids were detected.