CHARACTERIZATION AND EXPRESSION STUDIES FOR IRON TRANSPORTER AND STORAGE GENES IN KODO MILLET (Paspalum scrobiculatum L.)
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Date
2016
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Publisher
AAU, Anand
Abstract
Kodo millet is a balanced and staple food of tribal and economically poor
section of the population. The grains of kodo millet possess excellent storage
properties and are known for health benefits. It is highly nutritious food crop with
higher fiber content along with quality protein and mineral composition, which can
serve as excellent dietary source for these elements. Poor nutritional quality of cereals
is the primary cause of disorders related to nutritional imbalance among the
population having cereal-based diet, especially those belonging to underdeveloped or
developing counties.
The present study was carried out with an aim to study the relative importance
of nutritional quality, molecular diversity existing in kodo millet and to study genes
responsible for the iron transport and storage at three developmental stages (10 DAS,
20 DAS and 30 DAS). A wide variation for the micronutrient content was observed in
grains of twenty kodo millet genotypes under study. Iron and zinc concentrations
ranged from 17.1 to 66.4 ppm and 18.3 to 29.0 ppm respectively. The highest iron
content was found to be in KAVT-13, whereas zinc in PSC-1. The observed values
were higher than the average iron content present in major cereal crops such as rice,
wheat, maize, etc. The protein content ranged from 6.86 to 10.36 %, which is
equivalent to protein content of other cereals. The percent oil content of different
genotypes varied from 1.60 to 3.13, carbohydrates 70.54 to 76.04 and starch percent
content from 59.51 to 68.63. It also showed higher crude fiber content, ranging from
13.15 to 15.57%.
Phenolic acids from defatted grains of kodo millet genotypes were analysed by
UPLC method. Among all the phenolic acids, the salicylic acid was found to be
highest in kodo millet. The phenolic acid content was found to differ from genotype
to genotype. The highest content for different phenolic acids such as proto-catechuic
acid (KAVT-25), p-Hydroxybenzoic acid (PSC-1), Chlorogenic acid (JK-48), Caffeic
acid (CO-2), Syringic acid (KAVT-13), p-Coumaric acid (KAVT-13), Ferulic acid
(DK-127), Vanilllic acid (KAVT-30), Sinapic acid (JK-41) and Cinnamic acid
(KAVT-13) were observed in different genotypes. In SDS-PAGE protein profiling of
kodo millet grains revealed 20.54 to 104.93 kDa protein. There is little variation in the
SDS-PAGE electrophoretic patterns of the twenty genotypes of kodo millet.
Iron content specific thirteen SSR markers were utilized in this study, which
generated 302 scorable bands. The average number of alleles per locus was found to
be 2.69. The highest PIC value of YS4 indicated that it would be a very useful SSR
marker for diversity analysis of kodo millet genotypes. The candidate gene markers of
NRAMP family, NRAMP1 and NRAMP3 can be useful to discriminate high and low
iron-containing genotypes. The candidate gene specific markers viz., YS1, IRT1, ZIP3
and Ferritin were found to discriminate high iron genotypes and the marker YS12 for
low iron containing genotypes.
The relative gene expression profiling of seven iron transporter and storage
related genes i.e., FRO2, IRT1, NAAT1, NAS2 and YSL2 were analyzed in roots,
whereas gene NRAMP5 and Ferritin were analyzed in leaves of GK-2 (Low Fe) and
GPUK-3 (High Fe) kodo millet varieties under three different stages viz., 10 DAS, 20
DAS and 30 DAS. Expression of two genes FRO2 and ITR1 which are part of strategy
I iron transport, was found to be correlated to high grain Fe content in kodo millet.
These genes are the part of strategy I for iron transport in plant. Expression of three
genes viz., NAAT1, NAS2 and YSL2 (Strategy II iron transport) are significantly higher
in GPUK-3 as compared to GK-2. It was possible due to deficient Fe content in the
soil at later stages of development. The expression of NRAMP5 and ferritin in kodo
millet showed differential expression in leaf at 10 to 30 days after sowing. This result
indicates that kodo millet possess the Strategy II iron (Fe) uptake system in which Fe
is absorbed by roots as Fe3+-phytosiderophore. However, in spite of being a Strategy
II plant, kodo millet identifies Fe2+ transporter (Strategy I) genes viz., FRO2 and
IRT1.
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Keywords
agriculture, biotechnology, study