BIOCHEMICAL AND MOLECULAR ANALYSIS OF DROUGHT TOLERANT AND SUSCEPTIBLE CULTIVARS OF PEARL MILLET (Pennicetum glaucum L.)
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Date
2007
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Mahatma Phule Krishi Vidyapeeth, Rahuri.
Abstract
The present investigation was carried out to study the
proline metabolism in response to osmotic stress and RAPD
analysis of the genomic DNA from 4 drought tolerant and 2
drought susceptible cultivars of pearl millet with 18 random
decamer primers.
The seeds of 16 cultivars comprising of tolerant and
susceptible hybrids, R lines and local germplasm were
germinated on petriplates in duplicate sets for 5 days under
ambient conditions. An osmotic stress of –1.0 MPa was applied
to seedlings in one set with PEG-6000 solution, roots were
collected after 5 days and analyzed for changes in proline
content, P5CS activity and soluble proteins. The genomic DNA
from 2 susceptible and 4 tolerant hybrids was extracted from 15
days old seedlings grown in earthern pots. Then purified DNA
was subjected to PCR amplification with 18 random decamer
primers.Application of osmotic stress was found to increase
the proline accumulation in root tissues. Shradha cultivar had
the highest proline accumulation (17.55 µmoles g-1 fr.wt). The
P5CS activity was found to increase under stressed condition.
Shradha cultivar had the highest P5CS activity i.e. 0.50 µmole-γ
glutamyl hydroxamate g-1 min-1. Similarly application of osmotic
stress was found to increase the root soluble proteins. Shradha
cultivar had also the highest accumulation of soluble protein
content. The result indicated that an increased proline
accumulation due to stress is a good indicator of drought
tolerance in pearl millet. An increased P5CS activity during
stress indicated that fresh biosynthesis of proline in roots during
stress supported the increased enzyme synthesis and the least
protein degradation during the stress.
RAPD analysis of genomic DNA of six cultivars
revealed 37.50 to 88.89 % polymorphism with 18 random
primers. Among the primers tested OPC-20 showed a distinct
amplicon of 0.34 kb size and OPA-12 exhibited distinct amplicon
of 0.52 kb size in tolerant cultivars. These distinct bands can be
used in designing specific primers for further screening of
segregating populations of pearl millet.
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