Effect of high-temperature stress on the activity of key enzymes in the AsA-GSH cycle in ‘Yali’ pears

Abstract

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

References

[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

[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

Acknowledgements

This research was financially supported by the Natural Science Fund of Hebei Province, China: Study on APX metabolic pattern of pear fruits at high temperature and excessive sunlight stress (No. C2010000770).

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg