Photosynthetica

, Volume 47, Issue 4, pp 536–547

Wheat cultivars differing in heat tolerance show a differential response to monocarpic senescence under high-temperature stress and the involvement of serine proteases

Authors

  • S. Chauhan
    • Stress Physiology Laboratory, Water Technology CentreIndian Agricultural Research Institute
  • S. Srivalli
    • Stress Physiology Laboratory, Water Technology CentreIndian Agricultural Research Institute
  • A. R. Nautiyal
    • High Altitude Plant Physiology Research CentreH.N.B. Garhwal University
    • Stress Physiology Laboratory, Water Technology CentreIndian Agricultural Research Institute
Article

DOI: 10.1007/s11099-009-0079-3

Cite this article as:
Chauhan, S., Srivalli, S., Nautiyal, A.R. et al. Photosynthetica (2009) 47: 536. doi:10.1007/s11099-009-0079-3

Abstract

High temperature is a common constraint during anthesis and grain-filling stages of wheat leading to huge losses in yield. In order to understand the mechanism of heat tolerance during monocarpic senescence, the present study was carried out under field conditions by allowing two well characterized Triticum aestivum L. cultivars differing in heat tolerance, Hindi62 (heat-tolerant) and PBW343 (heat-susceptible), to suffer maximum heat stress under late sown conditions. Senescence was characterized by measuring photosynthesis related processes and endoproteolytic activity during non-stress environment (NSE) as well as heat-stress environment (HSE). There was a faster rate of senescence under HSE in both the genotypes. Hindi62, having pale yellow flag leaf with larger area, maintained cooler canopy under high temperatures than PBW343. The tolerance for high temperature in Hindi62 was clearly evident in terms of slower green-leaf area degradation, higher stomatal conductance, higher stability in maximum PSII efficiency, Rubisco activity and Rubisco content than PBW343. Both the genotypes exhibited lower endopeptidase activity under HSE as compared to NSE and this difference was more apparent in Hindi62. Serine proteases are the predominant proteases responsible for protein degradation under NSE as well as HSE. Flag leaf of both the genotypes exhibited high-molecular-mass endoproteases (78 kDa and 67 kDa) isoforms up to full grain maturity which were inhibited by specific serine protease inhibitor in both the environments. In conclusion, the heat-tolerant Hindi62 exhibited a slower rate of senescence than the heat-susceptible PBW343 during HSE, which may contribute towards heat stability.

Additional key words

heat stressphotosynthesisRubiscosenescenceserine proteasewheat

Abbreviations

DAA

days after anthesis

DTT

dithiothreitol

gs

stomatal conductance

F0

initial fluorescence

Fv/Fm

maximum efficiency of PSII

Fm

maximum chlorophyll fluorescence of the dark adapted state

Fm

maximum chlorophyll fluorescence of the light adapted state

FM

fresh mass

HSE

heat-stress environment

LSU

large subunit

PMSF

phenylmethylsulfonyl fluoride

NSE

non-stress environment

PMSF

phenylmethylsulphonylfluoride

PPFD

photosynthetic photon flux density

PN

net photosynthetic rate

PSII

photosystem II

PVP

polyvinyl pyrrolidone

PVPP

polyvinyl polypyrrolidone

qN

non-photochemical quenching

RuBP

ribulose-1,5-bisphosphate

Rubisco

ribulose-1,5-bisphosphate carboxylase/oxygenase

SDS-PAGE

sodium dodecyl sulfate — polyacrylamide gel electrophoresis

Tmax

maximum temperature

Tmean

mean temperature

Tmin

minimum temperature

TCA

trichloroacetic acid

Download to read the full article text

Copyright information

© Springer Science+Business Media B.V. 2010