BSc - MSc (int.)

The study entitled “Expression profiling of laccase and β-glucan synthase genes in
Pleurotus ostreatus during different developmental stages” was conducted at College
of Agriculture, Vellayani. The objective of this study was to analyze the differential
expression of laccase and β-glucan synthase genes in two strains of P. ostreatus during
different developmental stages using quantitative Real-Time PCR (qRT- PCR).
Two strains of P. ostreatus viz., DMR P115 collected from the Directorate of Mushroom
Research (DMR), Solan, Himachal Pradesh and HUC collected from the Department of
Plant Pathology, College of Agriculture, Vellayani were used for the study. Samples
were collected from four different developmental stages viz., mycelium, primordium,
young fruiting body and mature fruiting body of P. ostreatus strains. Potato Dextrose
Agar (PDA) and Potato Dextrose Broth (PDB) were used for maintaining the pure
cultures of both strains. The cultural and morphological studies of mycelia revealed
that DMR P115 strain formed maximum radial growth on the 3rd, 5th, 7th and 9th day.
However, white, thick and fluffy growth with radiating margins were observed in both
strains.
To obtain fruiting bodies, the spawn of both strains was prepared on paddy grains and
inoculated on sterilized rubber sawdust substrate. The morphological studies of the
mushroom fruiting body revealed that DMR P115 took minimum days for spawn run,
days to produce primordia, days to produce young fruiting body and days for maturity.
Sporophore characters like stipe length, stipe diameter, pileus length, pileus diameter
and average weight of fruiting body were higher in DMR P115 strain than in HUC
strain. Maximum yield (747.429 g/kg of the substrate) and the number of sporophores
(84.429) were observed in DMR P115 strain.
The expression of laccase (POXA3) and β-glucan synthase (FKS) genes that are
important in fruiting body development and cell wall formation respectively was
analysed at different developmental stages of two strains by performing qRT-PCR.
There was a significant difference in the expression of POXA3 and FKS genes in
different developmental stages of the two strains. The expression of POXA3 was higher
in the mycelial stage of DMR P115 (5.58 fold) and HUC (2.03 fold) strains. FKS gene
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was upregulated in mycelium (29.24 fold) and mature fruiting body (58.48 fold) of
DMR P115 strain whereas in HUC strain, there was a significant upregulation only in
the mycelial stage (17.15 fold).
It can be concluded that the growth and gene expression pattern in DMR P115 and
HUC strain varies. The expression of POXA3 and FKS genes differ significantly in
different developmental stages of the two strains. POXA3 gene, which is essential for
its fruiting body development and degradation of the substrate was upregulated in the
mycelial stage of both strains. FKS gene was upregulated in the mycelium and mature
fruiting body of DMR P115 strain and the mycelial stage of HUC strain which indicates
the antioxidant and immunostimulatory properties of that strain. The findings obtained
from this study can be used as a foundation for future lines of research related to strain
improvement of P. ostreatus.