ASCOMYCETES

VERY SIMILAR TO DEUTEROMYCETES BUT HAVE A KNOWN SEXUAL STAGE

SIMILARITIES:

1. HAPLOID MYCELIUM WITH CROSS WALLS

2. PRODUCE CONIDIA IN CONIDIAPHORES

a. CONIDIA = ASEXUAL SPORES

3. CAUSE PLANT DISEASES

DIFFERENCES:

1. ASCOMYCETES PRODUCE ASCOSPORES

THE SEXUAL STAGE IS OFTEN CALLED THE PERFECT STAGE

THE SEXUAL STAGE IS OFTEN FOUND AT THE END OF A GROWING SEASON AND IS AN OVERWINTERING STAGE

FORMATION OF ASCUS AND ASCOSPORES IN MOST ASCOMYCETES

1. FEMALE SEX CELL (ASCOGONIUM)FERTILIZED BY

AN ANTHERIDIUM OR A SPERMATIUM.

2. FERTILIZED ASCOGONIUM PRODUCE ASCOGONOUS

HYPHAE (DIKARYOTIC CONTAIN TWO NUCLEI)

3. TIPS OF HYPHAE DEVELOPE INTO AN ASCUS

4. TWO NUCLEI FUSE AND PRODUCE A ZYGOTE

5. ZYGOTE UNDERGOES MEIOSIS AND 4 HAPLOID

NUCLEI FORM

6. 4 HAPLOID NUCLEI DIVIDE BY MITOSIS TO

FORM 8 HAPLOID NUCLEI

7. EACH NUCLEUS SURROUNDED BY CELL WALL TO

BECOME AN ASCOSPORE

MOST ASCOSPORES ARE CONTAINED IN ASCOCARPS

ASEXUAL REPRODUCTIVE STRUCTURES ARE:

1. PYCNIDIA HOLLOW, SPHERICAL OR FLASK-

SHAPED STRUCTURES

2. ACERVULUS THICK MOUNDS OF HYPHAE

PRODUCING CONIDIA ON THEIR TIPS

LIFE CYCLE OR CYCLE OF INFECTION

1. ASCOSPORES GERMINATES IN SPRING BY

FORMING A GERM TUBE TO INFECT A PLANT

2. GERM TUBE GROWS INTO A HYPHAE AND

MYCELIUM WITH CROSS WALLS

3. MYCELIUM FORMS CONIDIOPHORES THAT

PRODUCE CONIDIA TO INFECT MORE PLANTS

4. AT THE END OF THE GROWING SEASON,

ASCOSPORES FORM

SOME FUNGI OVERWINTER AS MYCELIUM OR CONIDIA

DISEASES CAUSED BY ASCOMYCETES

SOOTY MOLDS LIVE ON INSECT DROPPINGS ON THE SURFACES OF PLANTS

LEAF CURL DISEASES

POWDERY MILDEW CAUSED BY FUNGI THAT CAN ONLY LIVE ON LIVING TISSUE SO THEY ARE OBLIGATE PARASITES