Characterization of a cassiicolin-encoding gene from Corynespora cassiicola, pathogen of rubber tree (Hevea brasiliensis)

• Published in: Plant science (Limerick) 2012-04, Vol.185-186, p.227-237
• Main Authors: Déon, Marine, Bourré, Yanice, Gimenez, Stéphanie, Berger, Angélique, Bieysse, Daniel, de Lamotte, Frédéric, Poncet, Joël, Roussel, Véronique, Bonnot, François, Oliver, Gérald, Franchel, Jérôme, Seguin, Marc, Leroy, Thierry, Roeckel-Drevet, Patricia, Pujade-Renaud, Valérie
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Ascomycota; Ascomycota - genetics; Ascomycota - isolation & purification; Ascomycota - pathogenicity; Base Sequence; Biological and medical sciences; Cassiicolin; Cloning, Molecular; Computational Biology; Conserved sequence; Corynespora cassiicola; Disease effector; DNA, Complementary - genetics; Forestry; Fundamental and applied biological sciences. Psychology; Fungal Proteins - chemistry; Fungal Proteins - genetics; Fungal Proteins - isolation & purification; Gene; Gene Expression Regulation, Fungal - genetics; Genetics; Hevea - microbiology; Hevea brasiliensis; Infection; Inoculation; Leaf fall; Life Sciences; Mass spectroscopy; Molecular Sequence Data; Mycelium - genetics; Mycelium - isolation & purification; Mycelium - pathogenicity; Mycotoxins - chemistry; Mycotoxins - genetics; Mycotoxins - isolation & purification; Pathogens; Plant Diseases - microbiology; Plant Leaves - microbiology; Plants genetics; Post-translation; RNA, Fungal - genetics; RNA, Fungal - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; Rubber; Sequence Analysis, DNA; Toxin; Toxins; Transcription; Trees; Virulence
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2011.10.017

► Cloning of cas gene encoding cassiicolin, CLF disease effector in rubber tree. ► Cas expressed during early phase of infection in susceptible and tolerant cultivars. ► Differences in aggressiveness not explained by variations in cassiicolin structure. ► Could be explained by differences in cas transcript levels. ► Existence of other disease effectors is suspected. Corynespora Leaf Fall (CLF) is a major disease of rubber tree (Hevea brasiliensis) caused by the Ascomycota Corynespora cassiicola. Here we describe the cloning and characterization of a gene encoding cassiicolin (Cas), a glycosylated cystein-rich small secreted protein (SSP) identified as a potential CLF disease effector in rubber tree. Three isolates with contrasted levels of aggressiveness were analyzed comparatively. The cassiicolin gene was detected – and the toxin successfully purified – from the isolates with high and medium aggressiveness (CCP and CCAM3 respectively) but not from the isolate with the lowest aggressiveness (CCAM1), suggesting the existence of a different disease effector in the later. CCP and CCAM3 carried strictly identical cassiicolin genes and produced toxins of identical mass, as evidence by mass spectrometry analysis, thus suggesting conserved post-translational modifications in addition to sequence identity. The differences in aggressiveness between CCP and CCAM3 may be attributed to differences in cassiicolin transcript levels rather than qualitative variations in cassiicolin structure. Cassiicolin may play an important role in the early phase of infection since a peak of cassiicolin transcripts occurred in 1 or 2 days after inoculation (before the occurrence of the first symptoms), in both the tolerant and the susceptible cultivars.