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Analysis of simple sequence repeats and key enzymes for galactomannan content in guar [Cyamopsis tetragonoloba (L.) Taub.] genotypes

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Title Analysis of simple sequence repeats and key enzymes for galactomannan content in guar [Cyamopsis tetragonoloba (L.) Taub.] genotypes
 
Creator Wadhwa, Neha
 
Contributor Joshi, U.N.
 
Subject polysaccharides, genotypes, genetics, sowing, enzymes, developmental stages, planting, dna, crops, gums
 
Description Cyamopsis tetragonoloba (L.) Taub., commonly known as “guar”, traditionally used as forage
crop, has gained the status of an industrial crop in present times, due to the presence of galactomannan
(guar gum) in its endosperm. This investigation was carried out to assess biochemical and genetic
diversity in this crop w.r.t. galactomannan content and to understand the enzymes for galactomannan
metabolism. SSRs are the most preferred molecular markers for studying genetic diversity but, till now,
there is no report of the use of EST-SSRs targeting galactomannan content. Galactomannan content
was estimated from mature seeds of 140 guar genotypes and was found in the range of 15.12 to 36.68
per cent. The leaves from plants grown under net house conditions were sampled for DNA extraction
and pods of 17 diverse genotypes were sampled at 25, 32, 39 & 46 DAF for α-galactosyltransferase, ß-
D-mannosidase and ß-1,4-mannanase assays. α-galactosyltransferase activity was found in high
positive correlation with the galactomannan content. The NCBI-EST (National Centre for
Biotechnology Information-Expressed Sequence Tag) clusterbean database, having 16476 ESTs, was
retrieved and mined with SSRIT tool for SSR identification. Sixty six ESTs related to galactomannan
metabolism were found, out of which 36 EST-SSRs and four gene-specific markers were designed, that
were used for amplification and diversity analysis. Dinucleotide repeats were in highest proportion
(63.4%) followed by tri- (30.0%), tetra- (5.2%), penta- (1.1%) and hexanucleotides (0.3%). The
molecular analysis divided the 140 clusterbean genotypes into two major clusters at the similarity
coefficient of 0.62. Low and high gum containing clusterbean genotypes were found to make two
different clusters at similarity coefficient of 0.68. Sequence analysis of C. senegelensis (wild species)
and HG563 (cultivated species), resulted in to two contigs of 758 and 793 bp, respectively. Multiple
sequence alignment of these contigs against HES1401 resulted into the presence of 75 SNPs and 108
In/Dels. HG 563 was observed to have a major deletion and addition of nucleotide sequence as
compared to wild species, C. senegalensis.
 
Date 2016-02-04T11:49:58Z
2016-02-04T11:49:58Z
2015
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/64155
 
Language en
 
Format application/pdf
 
Publisher CCSHAU