A cloning and expression study of three pectic lyase genes from Colletotrichum gloeosporioides f. sp. malvae

Three extracellular full-length pectic lyase cDNAs were successfully cloned from an intracellular hemibiotrophic fungus, Colletotrichum gloeosporioides f. sp. malvae, a pathogen of round-leaved mallow (Malva pusilla). Expression of pel-1, pel-2, and pnl-2 was measured in cultures grown in mallow cell wall extract, pectin and glucose broths, and results indicated that these genes were regulated at the transcriptional level by the presence/absence of different inducers. Comparison of the transcript levels to total pectic lyase activities produced in these broths indicated that post-transcriptional mechanisms were regulating the production of enzymes. pel-1 and pnl-2 are likely to be involved in saprotrophic growth since they were not expressed in planta. Pectic lyase activity was detected both during necrotrophy and the later stage of biotrophy. Only transcripts of pel-2 were detected in planta and in glucose broths, and therefore pel-2 may play a role in pathogenesis.