Assessment of variability for phytic acid content in mini-core germplasm lines of finger millet (Eleusine coracana (L.) Gaertn.) and development of RNAi Lines for low phytic acid content
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Date
2013-12-13
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University of Agricultural Sciences, Bengaluru
Abstract
Phytic acid is generally regarded as the primary storage form of phosphorous, from human
nutrition perspective, Phytic acid is an efficient chelator of nutritionally important mineral
cations such as Ca, Fe, Mg, Zn etc. ,and these nutrients are not bioavailable for monogastric
animals including humans. For these reasons, in the last two decades one of the
biofortification approaches has been the isolation and development of ‘low phytate’ (lpa)
cereals and legume genotypes with the aim to improve bioavailability of already existing
nutrients in food crops. Finger millet is considered as one of the important minor cereal due
to high nutritional value with highest calcium content among staples foods. Initially in our
study to access the variability for phytic acid content 124 finger millet germplasm lines were
screened for phytic acid and inorganic phosphorous content. Analysis of Variance for mean
values revealed the significant differences among the accessions for phytic acid and
Inorganic phosphorous. Further estimation of genetic parameters showed variations for the
trait were mostly due to genetic factors and Principal Component Analysis also revealed
Phytic acid is component contributing to the variability across germplasm accessions.
The rate limiting enzyme in phytic acid biosynthesis is myo-inositol 3-phosphate synthase
(MIPS) and altering MIPS expression in developing seeds may lead to a valuable reduction in
phytic acid content. In this direction, full length MIPS gene (1818 bp) from immature
embryo of finger millet was cloned. In-silico analysis of EcMIPS gene sequence showed
longest coding region of 1533 bp which encodes 510 amino acid residues with NAD Binding
5 super family domain which is characteristic feature of MIPS enzymes. Further, RNA
interference (RNAi) technology was used for down regulation of MIPS. An efficient siRNA
forming region from EcMIPS without any off- targets were identified and these regions were
used to develop RNAi constructs both under constitutive and endosperm specific promoter.
For plant transformation Agrobacterium mediated gene transfer technology was followed.
Characterization of putative transformants with reduced phytic acid content need to be
performed.
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Keywords
carbohydrates, acidity, millets, biological phenomena, sowing, inorganic acid salts, crops, minerals, enzymes, planting