Attached
Gyrinops walla (Walla patta) is the only member of the family Thymelaeaceae naturally
growing in Sri Lanka which produces agarwood, a fragrant resinous tissue which is highly
demanded in the world market. Since natural formation is rare, fungal inoculations are
commonly practiced to induce agarwood formation in Aquilaria species. However, the
response of live wood tissues of G. walla for the growth of fungi has not been investigated, the
present study was conducted to identify the behavior of the fungal spores on the G. walla stem
tissues after the inoculation. Non-resinous, non-wounded, fresh G. walla stem samples were
collected minimising contaminations and water loss from three different mature trees with the
age of 10-15 years in three different locations. Samples were cut into 3.0×3.0×3.0 cm and
cutting surfaces were sterilised and 5 ml of spore suspension of 107
spores ml -1
and 105
spores
ml-1
of Aspergillus niger and Fusarium solani respectively were applied to four vertical
surfaces of the wood cube until those were saturated and placed in a sterile moist chamber.
Three replicates were used for each tree for both fungal species and spore germination in sterile
distilled water was used as the control. Percentage of spore germination on live tissues was
determined at every 3 hour intervals for 36 hours and data were analysed by Kruskal-Wallis
test using MINITAB software. Results revealed that the percentage of germination was higher
in F. solani spores than A. niger after 3 hours of incubation on fresh G. walla tissues. Further
at the 15th hour, germination was almost equal in both A. niger and F. solani. Though A. niger
germination was lower until the 15th hour, it was gradually increased with time and obtained
the maximum germination percentage at about nearly 70% at the stationary phase. However,
F. solani germination was lower after the 15th hour and reached its maximum level of about
66%. However, the germination of A. niger and F. solani spores on live G. walla wood were
not significantly different (p=0.817). The findings of the present study showed that percentage
of spore germination of A. niger on live wood (70%) was higher than in water (60%). Similarly
F. solani also showed an increment of germination on live wood (66%) than in water (53%).
Results revealed that the germination on live wood tissues of A. niger and F. solani was not
inhibited by biochemical/ phytochemical compounds in wood of G. walla on the cutting
surface. The findings demonstrated the compatible interactions between two tested fungal
species and G. walla stem tissues.
