Biological Control of Schizophyllum Commune Fr. the Seedborne Pathogen of Oil Palm with Antagonistic Bacteria
Schizophyllum commune Fr. is one of the most important seedborne pathogens of oil palm. This pathogen can be isolated from fermented fruits, germinated seeds, rotten fruits and infected seeds. The fungus produced papery and leathery compact white mycelia on both sides of the agar plates and ofte...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2004
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/238/1/549532_FP_2004_11.pdf |
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| Summary: | Schizophyllum commune Fr. is one of the most important seedborne
pathogens of oil palm. This pathogen can be isolated from fermented fruits,
germinated seeds, rotten fruits and infected seeds. The fungus produced
papery and leathery compact white mycelia on both sides of the agar plates
and often produced basidiocarps (diameter less than 2 cm) with gills on
culture plates. The mycelia produced clamp connections with some hyphae
having spinulose projections. The width of the hyphae was 2 to 4 μ. Spores
produced from basidiocarp were hyaline, cylindrical and single-celled. S.
commune grew on PDA medium added 50 g/L of NaCl at 30-35oC optimum
temperature but the mycelia became dormant at 45oC. The fungus grew on
PDA medium at pH 5 to 6 and was resistant to 1% sodium hypochloride.Inoculation of S. commune Fr. on non germinating oil palm seeds by
contact was found to cause a significant decrease of seed germination to
64.3%. Mycelia covered the germ pores of seeds and penetrated the germ
pore to reach the surface of seed kernel. Inoculation of non germinating
seeds produced abnormal seedlings, inhibition of germ tube elongation and
brown discoloration of plumule and radicle. Inoculation of germinating
seeds resulted in stunted growth of seedlings, decreased root growth and
reduction in both fresh and dry weights.
Histological study of the infected seeds indicated that the mycelia
penetrated the rotted fruit to reach the testa through germ pores. Mycelium
was unable to directly penetrate the endocarp. In advanced seed infection,
white mycelia colonized the surface of seed kernel. Mycelia infected the
surface of the testa without formation of ‘appressorium’ to support
absorption to the surface of the kernel nor produced ‘haustorium’ for
absorption of nutrient from the host.
Eight out of 40 bacterial isolates from rotten fruits and infected seeds were
found to inhibit the radial growth of S. commune in the range 42.9–79.8%
and spore germination. The 8 antagonistic bacterial isolates were clustered
into 5 species by Biolog® Identification System and they were Bacillus thermoglucosidasius, Burkholderia cepacia, Pseudomonas aeruginosa,
Serratia marcescens and Serratia sp.
B. cepacia and Serratia sp. grew on NA medium containing 4% and 6% salt
concentration respectively. Both species were able to grow on Nutrient Agar
(NA) medium that were incubated at 40oC. Both species grew on NA
medium containing 0.5% and 2% sodium hypochloride respectively. Both B.
cepacia and Serratia sp. grew on NA medium with pH range 4-8.
Dipped vacuum treatment of antagonistic bacteria at 400 mm Hg vac. for 2
minutes significantly reduced the internal infection of the inoculated non
germinating oil palm seeds. B. cepacia and Serratia sp. significantly
increased percentage of seed germination. Dipped vacuum treatment was
also used to treat inoculated germinating seeds at 150 mm Hg Vac. for 2
minutes. The results showed that B. cepacia reduced seedling infection. |
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