An elicitor-induced cDNA from aerial yam (Dioscorea bulbifera L) encodes apathogenesis-related type 4 protein

We established Dioscorea bulbifera (aerial yam) cell suspension cultures to study the expression off defense-related genes upon elicitation with the y am pathogenic ascomycete Colletotrichum gloeosporioides. The induction of p henylalanine-ammonia lyase (PAL) mRNA, coding for a key enzyme involved in phytoalexin biosynthesis, was observed upon elicitation. Using RT-FCR, we i solated an elicited cDNA clone with an open reading frame of 453 nucleotide s which showed high homology to cDNA sequences of pathogenesis-related prot eins belonging to the PRP-4 group. Yam PRP-4 expression is increased in eli cited cell cultures as well as in elicited leaves, and is encoded by a smal l multigene family. This is the first example for the cloning of a cDNA tha t might be involved in defense reactions of yam plants.