Abstract:
An experiment was conducted at the Laboratory of Plant Stress Responses, Faculty of
Agriculture, Kagawa University, Japanto investigate the protective effect of priming
with some phytopotectants [50 µM salicylic acid (SA), 4 mM, ascorbic acid (AsA)
and 2.5 mM NaCl]under drought stress condition [induced by 15 % (m/v)
polyethylene glycol, PEG-6000] in wheat. Drought stress caused higher proline (Pro)
accumulation, lower relative water content (RWC), chlorosis and growth inhibition.
Enhanced levels of the malondialdelyde (MDA) and hydrogen peroxide (H
) were
evident with the overproduction of reactive oxygen species (ROS) by disrupting the
antioxidant defense system under drought stress condition.The activities of antioxidant
enzymes viz. catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate
reductase (DHAR), monodehydroascorbate reductase (MDHAR), glutathione
reductase (GR), and glutathione peroxidase (GPX) declined under 15% PEG induced
drought stress condition. Compared to control seedlings, drought also increased
methylglyoxal (MG) formation which also induced oxidative damage by facilitating
ROS production. However, priming of wheat seeds with SA, AsA and NaCl decreased
the ROS production by decreasing AsA and increasing glutathione content and
upregulating antioxidant defense system. Additionally, increased activities of
glyoxalase I and glyoxalase II reduced the levels of MG in drought stressed-wheat
seedlings. Seed priming helps to recover the seedlings from chlorosis and growth
inhibition whereas decreased the MDA and Pro content and increased the activity of
antioxidant enzymes. Therefore it can be concluded that seed priming with SA, AsA
and NaCl confers drought stress tolerance by upregulating antioxidant defense and
glyoxalase system and helps to better seedling establishment.
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Description:
A Thesis
Submitted to the Institute of Seed Technology
Sher-e-Bangla Agricultural University, Dhaka,
In partial fulfilment of the requirements
for the degree of
MASTER OF SCIENCE
IN
SEED TECHNOLOGY
Semester: January-June, 2016
