Cyclized Induction of Phenylalanine Ammonia-Lyase Gene Expression in Rhizoctonia solani-Infected Stems of Tomato

Soil-borne fungal pathogens such as Verticillium and Rhizoctonia can colonize in the stem tissue of plant through root and lead to wilting symptoms of plant by blocking. water transportation. During the colonization of Rhizoctonia solani in the vascular tissue of tomato stems, particularly, phenylalanine ammonia-lyase (PAL) gene induction pattern was cyclized showing peak induction at two different time points (10 and 80 h) after fungal spores inoculation in vivo. In leaves or roots, however, no such cycling pattern was observed. The first induction peak may be due to an initial sporulation events leading to a second induction peak by a proliferation of fungal spores to the upper stems or other tissues from an initial spore trapping sites. Tomato PAL gene was also dramatically induced by wounding, light illumination and mercury chloride treatment but was not cyclized. Mercury chloride showed the earliest induction with all tissues even at half an hour after treatment.