Please wait a minute...
Frontiers of Agriculture in China

ISSN 1673-7334

ISSN 1673-744X(Online)

CN 11-5729/S

Front Agric Chin    2010, Vol. 4 Issue (4) : 463-467     DOI: 10.1007/s11703-010-1041-7
Effect of high-temperature stress on the activity of key enzymes in the AsA-GSH cycle in ‘Yali’ pears
Yingli LI1, Jianguang ZHANG1,2()
1. College of Horticulture, Agricultural University of Hebei, Baoding 071001, China; 2. Pear Engineering & Technology Research Center of Hebei Province, Baoding 071001, China
Download: PDF(174 KB)   HTML
Export: BibTeX | EndNote | Reference Manager | ProCite | RefWorks

Through treating fruits at higher temperatures, choosing natural fruits on different exposures on a tree canopy and collecting exclusively both sunburn and normal fruits, the metabolic patterns were studied by comparing the activity of key enzymes in the ascorbate-glutathione (AsA-GSH) cycle including ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR), and glutathione reductase (GR). The results indicated that the activity of three enzymes increased under around less than 35°C acclimating conditions, with no significant changes in membrane electrolyte leakage. The activity of APX, MDAR, and GR rose during the initial stage when fruits were treated at 45°C but decreased significantly as treating time extended. A time response existed in APX, MDAR, and GR to high temperature. For example, APX activity reached the maximum when fruits were treated for 1 h, however, MDAR and GR showed the peak when fruits were treated for 3 h and 5 h, respectively, implying the possible acting sequence relationship of three enzymes in the AsA-GSH cycle. In view of the whole cycle, APX served as the first enzyme directly scavenging active oxygen species, followed by a series of chain reactions to regenerate ascorbic acid (AsA), and GR served as the last post in the cycle. Because various ecological conditions existed in a tree canopy, there was a significant difference in the enzymatic activity among fruits bearing on either exterior or interior canopy. A significantly higher activity of APX and MDAR was found with exterior fruits, compared with interior ones, which may be regarded as a frequent acclimation to high temperature and excessive sunlight.

Keywords ‘Yali’ pear      high-temperature stress      AsA-GSH cycle      antioxidant enzyme      membrane lipid superoxidation     
Corresponding Authors: ZHANG Jianguang,   
Issue Date: 05 December 2010
URL:     OR
Fig.1  Membrane integrity at different temperatures
Fig.2  APX activity at different temperatures
Fig.3  MDAR activity at different temperatures
Fig.4  GR activity at different temperatures
Fig.5  Comparison of enzymatic activity between exposed and shaded fruits
Fig.6  Comparison of enzymatic activity between normal and browning fruits
Fig.7  Comparison of electrolyte leakage between normal and browning fruits
1 Chen S C, Zhang J G, Zhang Y X (2006). Review on sunburn causes and preventive practices of bagged pear fruits. Advance in pear research and production . China Agriculture Press: 489–493 (in Chinese)
2 Ding Y F, Cheng H Y, Song D Q (2008). Tolerance to extreme high temperature and changes of antioxidant enzymes activity of Nelumbo nucifera seeds. Sci China C Life Sci , 38(4): 337–347 (in Chinese)
3 Guo Y C, She G J, Zeng J M, Liang Y Y, Chen F Y, Lin W Y (2003). Study on characteristics of activity oxygen and plasma permeability in leaves of different types tall fescue varieties in different temperature stress. Pratacultural Science , 20(3): 4–8 (in Chinese)
4 Han X F, Jin Y W (2001). Causes of sunburn with bagged fruits and preventive measures in Ya pears. Deciduous Fruits , 3: 57 (in Chinese)
5 Jin S H, Xu L G, Li X Q, Wang J G, Zhu L, Jia X L (2009). Effects of long-term high temperature stress on photosynthetic characteristics and antioxidant activity in Festuca arundinacea. Scientia Silvae Sinica , 45(3): 155–159 (in Chinese)
6 Ke S S, Yang M W (2007). Effects of water stress on antioxidant system and lipid peroxidation in leaves of Rhododendron fortunei. Acta Horticultrea Sinica , 34(5): 1217–1222 (in Chinese)
7 Li Y L, Liu Y F, Zhang J G (2010). Advance in researches on AsA-GSH cycle in horticultural crops. Front Agric China , 4(1): 84–90
doi: 10.1007/s11703-009-0089-8
8 Lin L, Jiang W B, Cao J K, Wang B G, Zhao Y M (2006). Effects of postharvest GSH treatment on core browning and antioxidant metabolism in Yali pear fruit. Academic Periodical of Farm Products Processing , 8: 4–7 (in Chinese)
9 Song S Q (2005). Research Guideline for Seed Biology. Beijing: Science Press (in Chinese)
10 Yan S J, Chen J L, Liang L Y, Wang Z F, Hu X S (2008). Effects of different cooling methods on some physiological indexes of different maturity Yali pear after harvest. Journal of Chinese Institute of Food Science and Technology , 8(4): 96–101 (in Chinese)
11 Yu C J, Lin W X (2006). Physiological response to heat stress in tall fescue turf grasses. Pratacultural Science , 23(2): 75–84 (in Chinese)
12 Zhang J G, Li Y L, Di B, Sun J S (2004a). Effects of high temperature and strong light on oxidative stress of apple fruit peel on different exposures of tree crown. Scientia Agricultura Sinica , 37(1): 1976–1980 (in Chinese)
13 Zhang J G, Liu Y F, Sun J S, Larry Schrader (2004b). Effect of solar radiation on fruit surface temperature in apples. Acta Ecol Sin , 24(6): 1306–1310 (in Chinese)
14 Zhang J H, Huang W D (2007). Changes of active oxygen and antioxidant enzymes in leaves of young grape plants during cross adaptation to temperature stress. Acta Horticultrea Sinica , 34(5): 1073–1080 (in Chinese)
15 Zhang Q, Li J, Cao J K, Cui T, Jiang W B (2009). Effect of UV-C on postharvest quality and disease resistance of Yali pear fruit. Journal of China Agricultural University , 14(2): 70–74 (in Chinese)
16 Zhang S Q, Duan X W, Pang X Q, Ji Z L (2002). The Effects of cold shock on some physiological changes related to thermotolerance of postharvest bananas. Plant Physiology Communications , 38(4): 333–335 (in Chinese)
17 Zhang Y, Luo Y, Hou Y X, Jiang H, Chen Q, Tang H R (2008). Chilling acclimation induced changes in the distribution of H2O2 and antioxidant system of strawberry leaves. Agricultural Journal , 3(4): 286–291
Full text