COMPARATIVE STRUCTURAL AND FUNCTIONAL ANALYSIS OF NBS-LRR TYPE RESISTANCE (R) GENES FROM SORGHUM [Sorghum bicolor (L.) Moench]
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Date
2007-08-30
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University of Agricultural Sciences GKVK, Banglore
Abstract
Sorghum [Sorghum bicolor (L.) Moench) is an important crop of
semiarid regions where it suffers from several biotic stresses. Identification
and characterization of resistance genes is a long term solution towards
development of disease resistant cultivars. Here, we report for the first
time, the isolation and characterization of full-length CC-NBS-LRR type
disease resistance gene homologue [SbRGAlM] from sorghum. Among a
set of 13 NBS-LRR sorghum resistance gene analogue [SRGAs) elucidated
previously in our lab, SRGA114 was found to be unique among the
characterized RGAs. Based on the short sequence information of
SRGA114, a 3,220bp composite cDNA including 371bp of 5' untranslated
region (UTR) and 88bp of 3' UTR was amplified using 5' and 3' rapid
amplification of cDNA ends (RACE) technique. Further, the entire coding
region of 2,733bp was cloned by nested PGR using specific primers
designed from 5' and 3' RACE products. It encodes a predicted polypeptide
of 910 amino acids with a computed molecular weight of 104.1kDa.
The deduced SbRGAlM protein consists of a N-terminal coiled-coil (CC)
domain, nucleotide binding site (NBS), three imperfect leucine rich repeats
(LRR) and nine potential N-linked glycosylation sites. These domains are
known to participate in protein-protein interaction and signal
transduction during plant response to pathogen. Sequence analysis of
SbRGAlM showed high homology with reported NBS-LRR type resistance
genes of maize, rice and barley. Functional validation of SbRGAlM by its
transfer in susceptible cultivars of sorghum will have a significant impact
as a strategy in translational genomics for disease management.
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