cDNA cloning of a sorghum pathogenesis-related protein (PR-10) and differential expression of defense-related genes following inoculation with Cochliobolus heterostrophus or Colletotrichum sublineolum

• Published in: Molecular plant-microbe interactions Vol. 12; no. 6; pp. 479 - 489
• Main Authors: LO, S.-C. C, HIPSKIND, J. D, NICHOLSON, R. L
• Format: Journal Article
• Language: English
• Published: St Paul, MN APS Press 01.06.1999; The American Phytopathological Society
• Subjects: 3-deoxyanthocyanidin; Agronomy. Soil science and plant productions; Amino Acid Sequence; anthracnose; Ascomycota - pathogenicity; Base Sequence; Biological and medical sciences; Bipolaris; Bipolaris maydis; Cloning, Molecular; Cochliobolus heterostrophus; Colletotrichum sublineolum; DNA, Complementary; Edible Grain - genetics; Edible Grain - microbiology; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Gene Expression Regulation, Plant; Genetics and breeding of economic plants; incompatible interactions; Molecular Sequence Data; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; Pest resistance; Phytopathology. Animal pests. Plant and forest protection; Plant pathogens; Plant Proteins - biosynthesis; Plant Proteins - chemistry; Plant Proteins - genetics; Plants - genetics; Recombinant Proteins - biosynthesis; Recombinant Proteins - chemistry; Sequence Alignment; Sequence Homology, Amino Acid; Varietal selection. Specialized plant breeding, plant breeding aims; Incompatibility; Acyltransferases; Plant pathogen; Nucleotide sequence; Enzyme; Transferases; Host agent relation; Homology; Cochliobolus heterostrophus; Gene expression; Pathogenesis related protein; Fungus resistance; Fungi; Naringenin-chalcone synthase; Phytoalexin; Defense mechanism; Ascomycetes; Aminoacid sequence; Thallophyta
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/MPMI.1999.12.6.479

A sorghum cDNA clone was isolated by differential screening of a cDNA library prepared from mesocotyls (cultivar DK18) inoculated with fungal pathogenes. The deduced translation product shows sequence similarity to a family of intracellular pathogenesis-related proteins (PR-10) with a potential ribonuclease function. We studied the accumulation of PR-10 and chalcone synthase (CHS) transcripts in mesocotyls following inoculation with Cochliobolus heterostrophus or Colletotrichum sublineolum. CHS is involved in phytoalexin synthesis in sorghum. Coordinate expression of PR-10 and CHS genes was localized in the area of inoculation along with the accumulation of phytoalexins. C. heterostrophus is a nonpathogen of sorghum and cytological studies indicated that cultivar DK18 is resistant to C. sublineolum, a sorghum pathogen. We demonstrated that the two fungi triggered different time courses of plant defense reactions. Inoculation with C. heterostrophus resulted in rapid accumulation of PR-10 and CHS transcripts after appressoria had become mature. Accumulation of these transcripts was delayed in plants inoculated with C. sublineolum until penetration of host tissue had been completed and infection vesicles had formed. Results suggest that different recognition events are involved in the expression of resistance to the two fungi used or that C. sublineolum suppresses the nonspecific induction of defense responses.