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Botrytis Blumeria Sclerotinia

Ascomycetes. Archaeascomycotina. Euascomycotina. Hemiascomycotina. S. pombe. S. cerevisiae Ashbya gossypii. Discomycetes. Pyrenomycetes. Loculoascomycetes. Plectomycetes. Gibberella/ Fusarium F. graminearum F. verticillioides Magnaporthe Neurospora G aeumannomyces.

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Botrytis Blumeria Sclerotinia

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  1. Ascomycetes Archaeascomycotina Euascomycotina Hemiascomycotina S. pombe S. cerevisiae Ashbya gossypii Discomycetes Pyrenomycetes Loculoascomycetes Plectomycetes Gibberella/ Fusarium F. graminearum F. verticillioides Magnaporthe Neurospora Gaeumannomyces Cochliobolus Alternaria Mycosphaerella Aspergillus Coccidioides Botrytis Blumeria Sclerotinia

  2. hygB GeneX WT GeneX, hygBS hygB GeneX deletion geneX, hygBR Strategy to delete C. heterostrophus genes Virulence assay

  3. Targeted Gene Deletion 5’ flank HY 3’ flank YG your favorite gene HYG Split-Marker Deletion Scheme (Catlett et al., Fungal Genetics Newsletter, adapted from Fairhead et al (1998) GENE)

  4. Cochliobolus on corn Magnaporthe on rice

  5. Fungal Infection of Plants attachment penetration colonization

  6. Recognition Penetration Colonization What genes are needed for this complex biological process? Fungal Plant Pathogenesis

  7. Specific General Toxins Enzymes Avr proteins Signaling T-toxin avenacinase AVR9 MAP kinases tomatinase HC-toxin AVR4 G proteins PDA victorin ECP2 tetraspanins MAK1 AM-toxin NIP1 AK-toxin AVR-Pita Ptr-toxin PWL PM-toxin enniatins trichothecenes Hydrophobins? Melanins? Cell wall degrading enzymes? Fungal Pathogenicity/Virulence Factors CPS1

  8. asexual reproduction sexual reproduction Journal Of Agricultural Research Vol. XXXI. 1925 by Charles Drechsler pathogen of corn Southern Corn Leaf Blight Cochliobolus heterostrophus Ophiobolus heterostrophus (Drechsler, 1925) Cochliobolus heterostrophus (Drechsler, 1934) Anamorphs: Helminthosporium maydis (Nisikado & Miyake, 1926) Bipolaris maydis (Shoemaker, 1959) Drechslera maydis (Subramanian & P.C. Jain,1966)

  9. Canada N. Dak. Maine Minn. Vt. Vt. N.H. Wis. S. Dak. N. Y. Mass. Mass. Mich. Con. Con. R.I. Iowa Pa. N. J. Neb. Ohio Md. Md. Ill. Ill. Ind. W. Va. Mo. Kan. Va. Ky. N. C. Tenn Tenn. Okla. Ark. S. C. S. C. Ga. Miss Ga. Miss. Miss. Ala Ala. Texas La La. La. Fla. Fla. Fla. Mexico March, 1970 July, 1970 Sept. 1970 • More than 30 states affected • 15% corn crop destroyed • >$1 billion lost The Southern Corn Leaf Blight Epidemic 1970’s -- the worst plant disease epidemic on record

  10. Cochliobolus heterostrophus two races race T race O Texas male sterile (T)-cytoplasm corn 1970 Designation of race T (Smith et al; Hooker et al)

  11. OH OH OH OH OH O O O O O O O O C41 C39 OH OH OH OH OH O O O O O O O C35 OH OH OH OH O O O O O O Race T produces a host selective toxin, T-toxin 1971 Discovery of T-toxin in culture filtrates (Lim & Hooker; Gracen et al)

  12. One of the world’s three most important cereal crops The host: Corn 40% of the world corn crop is produced in the United States Grown as hybrids: as early as the 1920s 1 million tested each year (one or two marked) higher yields vigorous growth disease resistance


  14. Emasculation of Corn

  15. Cytoplasm T-urf13 mitochondrion nucleus Male sterility in T-corn Sensitivity to T- toxin T-cytoplasm corn, Cytoplasmic Male Sterility and T-toxin Sensitivity • T-corn: corn with Texas male sterile cytoplasm (T-cms, or T-cytoplasm) • T-urf13- a hybrid gene consisting of parts of 2 mitochondrial genes and one chloroplast gene URF13- a 13 kD protein (mitochondrial inner membrane) (modified from Wise et al, 1999)

  16. T-urf13 orf221 (345 bp) A MITOCHONDRIAL GENOME REARRANGEMENT CAUSED CMS-T rrn26 3’ flank + part of coding (mitochondria) cptmA part of coding (chloroplast) atp6 5’ flank (mitochondria) (modified from Wise et al, 1999) 13 KD protein (mitochondrial inner membrane) Male sterility in T-corn Sensitivity to a fungal toxin

  17. ENVIRONMENT favorable weather C. heterostrophus (the rise of race T) Southern Corn Leaf Blight (1970) T-cytoplasm corn (genetic homogeneity)

  18. T-URF-13, Expressed in E. coli, Confers Sensitivity to T-toxin race O race T

  19. COCHLIOBOLUS HETEROSTROPHUS CORN N T race O (Tox-) + + X race T (Tox+) + +++ 1 : 1 Tox1 Tox1: a single genetic locus * (Yoder and Gracen, 1975)

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