AOBPreview originally published online on July 18, 2003
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Annals of Botany 92: 385-391, 2003
© 2003 Annals of Botany Company
Photo- and Antioxidative Protection During Summer Leaf Senescence in Pistacia lentiscus L. Grown under Mediterranean Field Conditions
1 Unitat d’Ecofisiologia CSIC-CEAB-CREAF, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
* For correspondence at: Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Avinguda Diagonal 645, E-08028 Barcelona, Spain. Fax +34 934112842, e-mail smunne{at}ub.edu
Received: 14 February 2003; Returned for revision: 14 May 2003; Accepted: 29 May 2003 Published electronically: 18 July 2003
Summer leaf senescence in Pistacia lentiscus L. plants serves to remobilize nutrients from the oldest leaves to the youngest ones, and therefore contributes to plant survival during the adverse climatic conditions typical of Mediterranean summers, i.e. water deficit superimposed on high solar radiation and high temperatures. To evaluate the extent of photo- and antioxidative protection during leaf senescence of this species, changes in carotenoids, including xanthophyll cycle pigments, and in the levels of ascorbate and 
-tocopherol were measured prior to and during summer leaf senescence in 3-year-old plants grown under Mediterranean field conditions. Although a chlorophyll loss of approx. 20 % was observed during the first stages of leaf senescence, no damage to the photosynthetic apparatus occurred as indicated by constant maximum efficiencies of photosystem II photochemistry. During this period the de-epoxidation state of the xanthophyll cycle, and lutein, neoxanthin and ascorbate levels were kept constant. At the same time ß-carotene and -tocopherol levels increased by approx. 9 and 70 %, respectively, presumably conferring photo- and antioxidative protection to the photosynthetic apparatus. By contrast, during the later stages of leaf senescence, characterized by severe chlorophyll loss, carotenoids were moderately degraded (neoxanthin by approx. 20 %, and both lutein and ß-carotene by approx. 35 %), ascorbate decreased by approx. 80 % and -tocopherol was not detected in senescing leaves. This study demonstrates that mechanisms of photo- and antioxidative protection may play a major role in maintaining chloroplast function during the first stages of leaf senescence, while antioxidant defences are lost during the latest stages of senescence.
Key words: antioxidant, ascorbate, carotenoid, chlorophyll, leaf senescence, lentisc (Pistacia lentiscus L.), oxidative stress, photoprotection, tocopherol, xanthophyll cycle.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  Y. Xu and B. Huang Effects of Foliar-Applied Ethylene Inhibitor and Synthetic Cytokinin on Creeping Bentgrass to Enhance Heat Tolerance Crop Sci., August 7, 2009; 49(5): 1876 - 1884. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Azaizeh, P. Ljubuncic, I. Portnaya, O. Said, U. Cogan, and A. Bomzon Fertilization-Induced Changes in Growth Parameters and Antioxidant Activity of Medicinal Plants Used in Traditional Arab Medicine Evid. Based Complement. Altern. Med., December 1, 2005; 2(4): 549 - 556. [Abstract] [Full Text] [PDF]
|
|