Temperature-Stress-Induced Impairment of Chlorophyll Biosynthetic Reactions in Cucumber and Wheat¹

Arun Kumar Tewari and Baishnab Charan Tripathy^*

School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India

Chlorophyll (Chl) biosynthesis in chill (7°C)- and heat (42°C)-stressed cucumber (Cucumis sativus L. cv poinsette) seedlings was affected by 90 and 60%, respectively. Inhibition of Chl biosynthesis was partly due to impairment of 5-aminolevulinic acid biosynthesis both in chill- (78%) and heat-stress (70%) conditions. Protochlorophyllide (Pchlide) synthesis in chill- and heat-stressed seedlings was inhibited by 90 and 70%, respectively. Severe inhibition of Pchlide biosynthesis in chill-stressed seedlings was caused by inactivations of all of the enzymes involved in protoporphyrin IX (Proto IX) synthesis, Mg-chelatase, and Mg-protoporphyrin IX monoester cyclase. In heat-stressed seedlings, although 5-aminolevulinic acid dehydratase and porphobilinogen deaminase were partially inhibited, one of the porphyrinogen-oxidizing enzymes, uroporphyrinogen decarboxylase, was stimulated and coproporphyrinogen oxidase and protoporphyrinogen oxidase were not substantially affected, which demonstrated that protoporphyrin IX synthesis was relatively more resistant to heat stress. Pchlide oxidoreductase, which is responsible for phototransformation of Pchlide to chlorophyllide, increased in heat-stress conditions by 46% over that of the control seedlings, whereas it was not affected in chill-stressed seedlings. In wheat (Triticum aestivum L. cv HD2329) seedlings porphobilinogen deaminase, Pchlide synthesis, and Pchlide oxidoreductase were affected in a manner similar to that of cucumber, suggesting that temperature stress has a broadly similar effect on Chl biosynthetic enzymes in both cucumber and wheat.

Plant Physiol. (1998) 117: 851-858
Copyright Clearance Center:   0032-0889/98/117/0851/08
© 1998 American Society of Plant Physiologists

This article has been cited by other articles:

				S. Dutta, S. Mohanty, and B. C. Tripathy Role of Temperature Stress on Chloroplast Biogenesis and Protein Import in Pea Plant Physiology, June 1, 2009; 150(2): 1050 - 1061. [Abstract] [Full Text] [PDF]

				P. V. V. Prasad, S. R. Pisipati, Z. Ristic, U. Bukovnik, and A. K. Fritz Impact of Nighttime Temperature on Physiology and Growth of Spring Wheat Crop Sci., November 24, 2008; 48(6): 2372 - 2380. [Abstract] [Full Text] [PDF]

				D. P. Dixon, A. Lapthorn, P. Madesis, E. A. Mudd, A. Day, and R. Edwards Binding and Glutathione Conjugation of Porphyrinogens by Plant Glutathione Transferases J. Biol. Chem., July 18, 2008; 283(29): 20268 - 20276. [Abstract] [Full Text] [PDF]