The Effect of Heat Shock on Chilling Tolerance in ̔Khatooni Melon’ Seedling (Cucumis melo L.)

Document Type : Research Article

Authors

• Fardin Ghanbari
• Saadollah Akbari

Department of Horticultural Sciences, Faculty of Agriculture, Ilam University, Ilam, Iran

https://doi.org/10.22067/jhorts4.v35i1.86372

Abstract

Introduction: Melon, like other members of cucurbitaceae family, is sensitive to cold stress. Applying different cultivation techniques in the nursery can provide some degree of tolerance to environmental stresses in the plants. In the other words, applying stress conditions on plants may cause them to withstand subsequent stresses, this is so called a cross-adaptation or cross-tolerance. For example, Whitaker (1994) showed that cold stress damage can be mitigated by temperature pretreatment. This technique was then used to improve stress tolerance in different plants. In this regard, heat treatment has been used to increase the chilling tolerance in fruits and vegetables. Therefore, in this study, the possibility of increasing cold stress tolerance in melon seedlings using heat shock was investigated.
Materials and Methods: The experiment was conducted in a completely randomized design (CRD) with three replications and five treatments (including control and spraying with water at temperatures of 20, 45, 50 and 55 °C for 90 seconds) in Faculty of Agriculture of Ilam University in 2019. Heat treatments where used as foliar spray by heated water. After applying different levels of heat treatment and recovery at 24 hours, seedlings were exposed to chilling stress at 3 °C for 6 h in 6 consecutive days. All seedlings were transferred to greenhouse and after 72 hours, the related traits were measured.
Results and Discussion: Results showed that pre-treated seedlings had higher growth rate than control seedlings at the end of chilling period. Heat shock pretreatment significantly increased the content of chlorophyll, proline and hydrogen peroxide and reduced the amount of malondialdehyde compared to the control. The lowest amount of malondialdehyde (1.14 nmol g^-1 fresh weight) was observed in the 50 °C treatment, which was 50% lower than the control. Similar to other environmental stresses, low temperature usually leads ROS production and oxidative stress. Malondialdehyde content is an index to measure membrane lipid peroxidation and its measurement is a criterion of damage to plants in stress conditions. Reduction of malondialdehyde has been reported to increase cell membrane stability and increase stress tolerance in plants. In the present study, heat shock reduced the accumulation of malondialdehyde compared to the control, indicating a decrease in cold effects on the plant. Mei and Song (2010) investigated the effect of heat pretreatment on increasing high temperature tolerance in barley, and reported that using this method by stimulating the synthesis of antioxidant enzymes prevented the increase of malondialdehyde in the plant under heat stress. Therefore, maintaining the membrane structure and decreasing the accumulation of malondialdehyde in melon seedlings under cold conditions indicates an improvement of plant defense responses induced by heat shock. Environmental stresses including cold stress by producing hydrogen peroxide and other free radicals lead to oxidative stress and damage plant cells. Hydrogen peroxide is converted to water by ascorbate peroxidase, peroxide redoxin, glutathione peroxidase and guaiacol peroxidase groups. Therefore, increasing the activity of antioxidant enzymes in plants is one of the most important mechanisms of the plant to cope with stress conditions. In the present study, heat shock pretreatment significantly increased peroxidase (POD) and poly phenol oxidase (PPO) activity and increased the amount of proline and hydrogen peroxide. In this regard, it has been reported that hydrogen peroxide has a dual role in plants and its increase in stress conditions by regulating the production of antioxidant enzymes helps plants to enhance their tolerance to the stress conditions. Our results is in consistent with Ao et al. (2013) report that stated hardening pretreatment of Jatropha curcas seedlings caused to increase the antioxidant enzymes activity, plant glutathione and ascorbate content. The increases in antioxidant enzymes activity by heat shock might be a positive mechanism, which facilitate the scavenging of ROS and induce plant growth and development under chilling stress. These results indicate that antioxidant defense system has a specific role in enhancing plant tolerance to stress conditions and hydrogen peroxide play an important signaling role in plant adaptive responses.
Conclusion: In general, the results showed that heat shock (especially at 50 and 55 ^oC) caused positive physiological changes in melon seedlings and could increase their tolerance to cold stress conditions.

Keywords

• Hydrogen peroxide
• Malondialdehyde
• Peroxidase
• Polyphenol oxidase
• Proline

20.1001.1.20084730.1400.35.1.6.6

References

1-       Aghdam M.S., and Bodbodak S. 2014. Postharvest heat treatment for mitigation of chilling injury in fruits and vegetables. Food and Bioprocess Technology 7(1): 37-53.

2-       Alexieva V., Sergiev I., Mapelli S., and Karanov E. 2001. The effect of drought and ultraviolet radiation on growth and stress markers in pea and wheat. Plant, Cell and Environment 24(12): 1337-1344.

3-       Ali M.B., Hahn E.J., and Paek K.Y. 2005. Effects of temperature on oxidative stress defense systems, lipid peroxidation and lipoxygenase activity in Phalaenopsis. Plant Physiology and Biochemistry 43(3): 213-223.

4-       Allen D.J., and Ort D.R. 2001. Impacts of chilling temperatures on photosynthesis in warm-climate plants. Trends in Plant Science 6(1): 36-42.

5-       Ao P.X., Li Z.G., Fan D.M., and Gong M. 2013. Involvement of antioxidant defense system in chill hardening-induced chilling tolerance in Jatropha curcas seedlings. Acta Physiologiae Plantarum 35(1): 153-160.

6-       Baldi P., Pedron L., Hietala A.M., and La Porta N. 2011. Cold tolerance in cypress (Cupressus sempervirens L.): a physiological and molecular study. Tree Genetics & Genomes 7(1): 79-90.

7-       Baninasab B. 2009. Amelioration of chilling stress by pa­clobutrazol in watermelon seedlings. Scientia Horticulture 121: 144-148.

8-       Bates L.S., Waldren R.P., and Teare I.D. 1973. Rapid determination of free proline for water-stress studies. Plant and Soil 39(1): 205-207.

9-       Chao Y.Y., Hsu Y.T., and Kao C.H. 2009. Involvement of glutathione in heat shock–and hydrogen peroxide–induced cadmium tolerance of rice (Oryza sativa L.) seedlings. Plant and Soil 318: 37-44.

10-   FAO. 2015. FAO website. http://faostat.fao.org.

11-   Ghanbari F., and Sayyari M. 2018. Controlled drought stress affects the chilling-hardening capacity of tomato seedlings as indicated by changes in phenol metabolisms, antioxidant enzymes activity, osmolytes concentration and abscisic acid accumulation. Scientia Horticulturae 229: 167-174.

12-   Ghanbari F., and Kordi S. 2019. Hardening pretreatment by drought and low temperature enhanced chilling stress tolerance of cucumber seedlings. Acta Scientiarum Polonorum-Hortorum Cultus 18: 29-37.

13-   Gong M., Chen B.O., Li Z.G., and Guo L.H. 2001. Heat-shock-induced cross adaptation to heat, chilling, drought and salt stress in maize seedlings and involvement of H₂O₂. Journal of Plant Physiology 158(9): 1125-1130.

14-   Hayat S., Hayat Q., Alyemeni M.N., Wani A.S., Pichtel J., and Ahmad A. 2012. Role of proline under changing environments: a review. Plant Signaling & Behavior 7(11): 1456-1466.

15-   Hossain M.A., Burritt D.J., and Fujita M. 2016. Cross-stress tolerance in plants: molecular mechanisms and possible involvement of reactive oxygen species and methylglyoxal detoxification systems. Abiotic Stress Response in Plants 323-375.

16-   Hossain M.A., Mostofa M.G., and Fujita M. 2013. Heat-shock positively modulates oxidative protection of salt and drought-stressed mustard (Brassica campestris L.) seedlings. Journal of Plant Science and Molecular Breeding 2(1): 1-14.

17-   Jang J.H., and Moon K.D. 2011. Inhibition of polyphenol oxidase and peroxidase activities on fresh-cut apple by simultaneous treatment of ultrasound and ascorbic acid. Food Chemistry 124(2): 444-449.

18-   Janská A., Maršík P., Zelenková S., and Ovesná J. 2010. Cold stress and acclimation–what is important for metabolic adjustment. Plant Biology 12(3): 395-405.

19-   Kaewsuksaeng S., Tatmala N., Srilaong V., and Pongprasert N. 2015. Postharvest heat treatment delays chlorophyll degradation and maintains quality in Thai lime (Citrus aurantifolia Swingle cv. Paan) fruit. Postharvest Biology and Technology 100: 1-7.

20-   Kang H.M., and Saltveit M.E. 2001. Activity of enzymatic antioxidant defense systems in chilled and heat shocked cucumber seedling radicles. Physiologia Plantarum 113(4): 548-556.

21-   Kar M., and Mishra D. 1976. Catalase, peroxidase, and polyphenoloxidase activities during rice leaf senescence. Plant Physiology 57(2): 315-319.

22-   Kuznetsov V.V., Rakitin V.Y., and Zholkevich V.N. 1999. Effects of preliminary heat‐shock treatment on accumulation of osmolytes and drought resistance in cotton plants during water deficiency. Physiologia Plantarum 107(4): 399-406.

23-   Lei Y.B., Song S.Q., and Fu J.R. 2005. Possible involvement of anti‐oxidant enzymes in the cross‐tolerance of the germination/growth of wheat seeds to salinity and heat stress. Journal of Integrative Plant Biology 47(10): 1211-1219.

24-   Li H.Y., Li C.G., and Gong M. 2011. Short-term cold-shock at 1 C induced chilling tolerance in maize seedlings. International Conference of Biology Environment and Chemistry 1: 346-349.

25-   Maali-Amiri R., Goldenkova-Pavlova I.V., Yur’eva N.O., Pchelkin V.P., Tsydendambaev V.D., Vereshchagin A.G., and Nosov A.M. 2007. Lipid fatty acid composition of potato plants transformed with the Δ12-desaturase gene from cyanobacterium. Russian Journal of Plant Physiology 54(5): 600-606.

26-   Martin-Diana A.B., Rico D., Barry-Ryan C., Mulcahy J., Frias J., and Henehan G.T. 2005. Effect of heat shock on browning-related enzymes in minimally processed iceberg lettuce and crude extracts. Bioscience, Biotechnology, and Biochemistry 69(9): 1677-1685.

27-   Mei Y.Q., and Song S.Q. 2010. Response to temperature stress of reactive oxygen species scavenging enzymes in the cross-tolerance of barley seed germination. Journal of Zhejiang University-Science B 11(12): 965-972.

28-   Plewa M.J., Smith S.R., and Wagner E.D. 1991. Diethyldithio carbamate suppresses the plant activation of aromatic amines into mutagens by inhibiting tobacco cell peroxidase. Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 247(1): 57-64.

29-   Saltveit M.E. 2002. Heat shocks increase the chilling tolerance of rice (Oryza sativa) seedling radicles. Journal of Agricultural and Food Chemistry 50(11): 3232-3235.

30-   Stewart R.R., and Bewley J.D. 1980. Lipid peroxidation associated with accelerated aging of soybean axes. Plant Physiology 65(2): 245-248.

31-   Strain H.H., and Svec W.A. 1966. Extraction, separation, estimation and isolation of the chlorophylls. The Chlorophylls 1: 22-66.

32-   Thipyapong P., Melkonia J., Wolfe D.W., and Steffens J.C. 2004. Suppression of polyphenol oxidases increases stress tolerance in tomato. Plant Science 167(4): 693-703.

33-   Whitaker B.D. 1992. A reassessment of heat stress as a means of reducing chilling injury in tomato fruit. Physiological Basis of Postharvest Technologies 343: 281-282.