Plant Patology Report By Group 2 (PLP3204): Lab Practical 5: Higher Fungi - Taxonomy and Pathologicaal Importance (Phylum Ascomycota)

Practical 5

HIGHER FUNGI – TAXANOMY AND PATHOLOGICAL IMPORTANCE ( PHYLUM ASCOMYCOTA )

The phylum Ascomycota are well developed fungi. The Hemiascomycetes comprising the yeast are unicellular, but all other classes produced hyphae that are septate. Most are identified from the type of conidium ( asexual spore ) that are commonly produced. They may be openly attached on conidiospores, or are contained within fruiting structure such as pycnidium ( closed ) or the acervulus. Where sexual reproduction occurs, several types of fruiting body ( called the ascocarps ) are formed, that may be closed and rounded ( cleisthothecium ), closed with ostiole ( perithecium ), saucer shaped ( apothecium ) or cushioned shaped with locules ( ascostroma ). The ascocarp contain ascus bearing the ascospores ( sexual spores ) that are usually 8 in number. Order Agonomycetales in the class Deutromycetes consists of fungi bearing neither asexual nor sexual spores. The hyphe are sterile but are known to produce sclerotium ( small and roundish hyphal aggregations )

EXERCISE

A. FUNGAL CULTURE

Pure cultures of Penicillium sp, Chaetomium sp, and Fusarium sp , Curvularia sp are provided. Make temporary slides and examine for presence of asexual stage e.g. conidium or sexual stages.

B. Plants disease specimens

1. Powdery mildew of rubber

Caused by Oidium heveae. Infect young leaves of rubber causing massive leaf fall. Fungus also lives on mature leaves throughout the year.

2. False smut of padi

Caused by Ustilaginoidea virens. Infects rice at the following stage producing symptoms of yellowish green fungal growth on seeds.

3. Citrus scab

Caused by Elsinoe fawcetti. Infects leaves, fruits and stems of citrus. Symptoms of corky lesions and causing abnormal leaf shape.

4. Leaf blight of maize/corn

Caused by Drechslera maydis

5. Sigatoka disease of banana

Caused by Mycosphaerella musicola ( telemorph ) Cercospora musae ( anamorph )

6. Moldy rot of rubber

Caused by Ceratocystis fimbriata. Infects tapping panel of rubber.

7. South American Leaf Blight ( SALB ) of rubber

Caused by Microcyclus ulei. This disease occurs only in South America and is unknown in rubber grown in Asia.

8. Sooty mould disease

Caused more than one fungi : Tripospermum sp, Capnodium sp, Limacinula sp. Infects various crop such as fruit tree. Symptoms mainly of blackish layer of fungal growth on leaves and other part plants.

9. Black mildew

Caused by Meliola sp. Similar with sooty mould disease but fungus forms scattered, blackish growths instead of layers mainly on leaves of mango and other fruit tree.

10. Blast of paddy

Caused by Pyricularia oryzae ( anamorph ) / Magnaporthe grisea ( teleomorph ). Infects paddy causing deaths in seedling. Typical symptom is the diamond shaped spot on paddy leaves.

11. Brown spot of paddy

Caused by Drechslera oryzae. Typical symptom is the rounded shaped brown spots on paddy leaves.

12. Narrow brown leaf spot of paddy

A minor disease caused by Cercospora oryzae. Symptom as in the name of disease.

13. Sheath blight of paddy

Caused by Rhizoctonia solani. Cause blakish lesions on leaf sheaths and stems. Fungus form sclerotia.

14. Foot rot

Caused by Sclerotium rolfsii. Infects many vegetable crop such as brinjal, chilli, tomato and groundnuts. Cause rots at the base of the stems identified by the whitish growth ( rhizomorphs ) of the fungus. Fungus forms sclerotia.

15. Antrachnose

Caused by differenct species :

Chilli : Colletotrichum capsici

French bean/kacang buncis : C. dematium , C. truncatum

Mango /papaya/rubber/cocoa :C. gloeosporioides

Banana : C. musae

16. Bird eye spot disease

Caused by Drechslera heveae. Symptoms on leaves as suggested by name of disease.

17. Leaf spot disease

Caused by Pestalotiopsis sp. Infects various crops of mainly palms such as coconuts, oil palm and ornamental palms. Leaf spots can be identified by presence of blackish acervulus.

18. Panama disease or banana wilt

Caused by Fusarium oxysporum f.sp. cubensis. Major disease of banana world wide causing wilt and death of plants.

C.

SLIDE

1. Saccharomyces cerevisiae.

Unicellular, yeast cell in class Hemiascomycetes

2. Penicillium sp, Aspergillus sp.

Conidia form on this species. Generally, Penicillium form phiallides which are brushlike while conidia are produced on sterigmata on conidial head in Aspergillus sp

3. Meliola sp.

Observe the hypodia, short branches of hyphae used to absorb nutrients from leaf surfaces.

4. Class Deuteromyctes

Order Moniliales:

Observe and identify fungus based on different shapes of conidia of different genus such as Alternaria, Curvularia, Cerospora and others.

5. Morchella sp

Example of class Discomycetes that produce apothecium

6. Order Melanconiales.

Conidia formed within an acervulus.

Example : Colletotrichum capsisi is sickle shaped like conidia and Colletotrichum gloeosporioides is rod shaped conidia. The genus Pestalotiopsis is also in this group.