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CHAPTER
4
RESULTS
4.1. Molecular phylogeny of chitinase and LTP genes
The cDNA clone Bar2chi screened from a library by Erysiphe graminis-
infected barley, (Hordeum vulgare L.) var Manchuria was 1.1 kb in size, the
ORF
encodes a 318 amino acid polypeptide with a calculated molecular weight of 33.4 kDa
and iswlectric point of 8.54. Amino acid sequence alignment of barley chitinuse.
Bar2chi revealed homology with other plant chitinases (Fig. I). Barley chitinase
belongs to glycoside hydrolase family 19 chitinase domain and belongs to
C~LFS
I
chitinases having N-terminal cysteine-rich, chitin-binding domain which is separated
from the catalytic domain by a proline and glycine-rich hinge region. Phylogenetic
tree constructed on the basis of amino acid sequence alignment revealed the similarity
of barley chitinase with other plant chitinases. The predicted amino acid sequence of
barley chitinase BarZchi, (Hordeum vulgare, PI 1955) has 95.3% homology with rye
chitinase (Secale cereale, Q9FRV1), 79.8% with chitinase of Poa prafensis
(AAF04454), 78.5% with chitinase of Triricum aestivum (CAA53626), 74.3% with
chitinase of Musa paradisiaca (ABD47583). 71.2% with chitinase of Zea
diploperennis (AAT4@327), 68.3% with chitinase of Oryza sativa (AAL34318),
65.1% with chitinase of Nicotiana tabacum (P08252), 61.090 with chitinase of
Solanurn tuberosum (CAA32351) and 48.4% with chitinase of Hordeum vulgare
(CAA55344) (Fig. 2).
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