STUDIES ON CONSTRUCTION OF FRAME WORK GENETIC LINKAGE MAP OF Stevia rebaudiana Bertoni USING MOLECULAR MARKERS
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Date
2013
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Abstract
ABSTRACT
The present investigation on Stevia rebaudiana was carried out with the objective to
construct frame work genetic linkage map of stevia by employing multiple marker systems.
Before starting the work on linkage map construction, genetic diversity was analyzed amongst the
available genotypes/ clones/ accessions/ morphotypes of Stevia rebaudiana to confirm two
parents with differences in rebaudioside-A and stevioside content. This study represents the first
genetic linkage study of Stevia rebaudiana comprising of multiple marker systems together.
Among the collected 16 accessions polymorphism was studied using 27 RAPD, 26 ISSR
and 50 EST-SSR. Results were analyzed in the form of dendrograms, similarity, disimmilarity
matrices and polymorphism information content. For linkage map construction, F2 population was
used as a mapping population. To survey the polymorphism among contrasting parents 170
RAPD, 26 ISSR and 89 EST SSR were employed and it was observed that 36 RAPD, 10 ISSR
and 33 EST – SSR primers were found to be polymorphic. These primers were then used for the
genotyping of the mapping population. Phenotyping was carried out by using High Performance
Liquid Chromatography (HPLC) of parents as well as segregating population. Both genotypic and
phenotypic data were used to construct a linkage map using MAPMAKER/EXP ver 3.0b. A total
of four linkage groups were constructed spanning a distance of 927.3 cM with an average distance
between loci as 16.29 cM. First linkage group (LG1) comprised of 33 markers, second linkage
group (LG2) contained 6 markers and third (LG3) and fourth group (LG4) had 16 and two
markers, respectively. On QTL identification, a total of 53 QTL locations were found for both
trait 1 (rebaudioside-A) and trait 2 (stevioside). Among 53 QTL locations of trait 1, two major
QTLs were found for rebaudioside-A viz., in the marker interval of L67- L71 (ISSR HB-11) -
(IISRS-3-L) in LG1 and in the marker interval L38 - L40 (Sigma-5383-027)- (Sigma-5383-029)
in LG3 at LOD of 2.5 and 2.7, respectively.
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Keywords
snack foods, productivity, sampling, vegetables, plant oils, potatoes, fungi, vegetative propagation, starch, proteins, Stevia rebaudiana Bertoni ,Molecular Markers