Induction of Heat Tolerance by Modulating the Xanthophyll Cycle Activity in Wheat (Triticum aestivum L.)
Loading...
Date
2019
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
DIVISION OF PLANT PHYSIOLOGY ICAR – INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI
Abstract
Wheat crop is very sensitive to heat stress. In India, as a result of delayed harvesting of sugarcane and rice
crops, often late sown wheat crop is exposed to heat stress. At very high temperature photosynthetic
machinery is badly damaged. Since photosynthesis is fundamentally associated with biomass and yield
therefore, heat stress causes reduction in crop yield. Plant carotenoids protects photosynthetic apparatus
under heat stress by scavenging reactive oxygen species, quenching triplet chlorophyll and dissipating
excess energy in the form heat via xanthophyll mediated non-photochemical quenching (NPQ).
Xanthophyll cycle reversible inter-conversion of violaxanthin to zeaxanthin plays important role in photoprotection. Therefore, it was hypothesized that heat tolerance and yield may be improved by modulating
the xanthophyll cycle activity using xanthophyll cycle activators. Thus, present study was undertaken
using two contrasting wheat varieties viz. HD 2329 and HD 3086 for analyzing physio-biochemical
alterations to gain insight into the mechanism of heat tolerance mediated by modulated xanthophyll cycle
activity and to explore the possibility of xanthophyll cycle activators in improving growth and yield under
high temperature conditions. Heat stress was imposed by delaying the sowing date i.e normal (23rd Nov
2018) and late sown (8th Jan 2019). Present study comprised two main treatments (Normal and Late sown
conditions) and four sub treatments (Foliar application of ascorbic acid (10 mM), calcium nitrate (60
mM), DTT (3mM), water (control) at booting (before anthesis) stage).
Results of the present study showed decrease in photosynthesis, Fv/Fm, Y II, RWC, MSI, Chla
, Chlb,
total Chl, total Car, anthocyanin, growth parameters, yield & its components and increase in transpiration
rate, stomatal conductance, NPQ, ascorbic acid, proline, lipid peroxidation, H2O2, activity of antioxidant
enzymes (SOD, CAT, POX, GR, APX), zeaxanthin, and VDE gene expression under late sown heat stress
condition. Application of ascorbic acid and Ca(NO3 )2 restricted lipid peroxidation and H2O2 formation
thus improved membrane stability and relative water content under heat stress. Foliar application of
ascorbic acid and Ca(NO3 )2 enhanced the photosynthesis, transpiration, stomatal conductance, Fv/Fm, Y
II, NPQ, level of Chla
, Chlb, total Chl, total Car, zeaxanthin, lutein, ascorbic acid, proline, activity of
antioxidant enzymes (SOD, CAT, POX, GR, APX), improved density of pigments profile and VDE gene
expression particularly under late sown heat stress condition. Foliar application of ascorbic acid and
Ca(NO3 )2 significantly enhanced the yield and its components, partitioning towards economic sink and
also improved heat tolerance index and heat yield stability index and reduced the value of heat
susceptible index.
From the present study, it may be concluded that xanthophyll cycle activators modulated xanthophyll
cycle activity and enhanced the yield and induced the heat tolerance in wheat by improving
photosynthetic activity, antioxidant activity, growth, membrane stability, stay green characteristics and by
reducing reactive oxygen species.
Description
T-10080
Keywords
null