AOBPreview originally published online on August 29, 2007
Annals of Botany 2007 100(4):839-848; doi:10.1093/aob/mcm181
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Chill-Induced Decrease in Capacity of RuBP Carboxylation and Associated H2O2 Accumulation in Cucumber Leaves are Alleviated by Grafting onto Figleaf Gourd
1 Department of Horticulture, Huajiachi Campus, Zhejiang University, Kaixuan Road 268, Hangzhou, PR China 310029
2 Key Laboratory of Horticultural Plants Growth, Development and Biotechnology, Agricultural Ministry of China, Kaixuan Road 268, Hangzhou, PR China 310029
3 Departament de Biologia Vegetal, Universitat de Barcelona, 645 Diagonal Av, E-08028 Barcelona, Spain
* For correspondence. E-mail jqyu{at}zju.edu.cn
Received: 10 April 2007 Returned for revision: 16 June 2007 Accepted: 3 July 2007 Published electronically: 29 August 2007
Background and Aims: Chilling results in a significant decrease in Rubisco content and increased generation of reactive oxygen species (ROS) in cucumber (Cucumis sativus), a chilling-sensitive species. The role of roots in the regulation of the tolerance is unknown. Here, cucumber plants grafted onto figleaf gourd (Cucurbita ficifolia), a chilling-tolerant species were used to study the role of roots in the regulation of shoot functioning and the associated root-to-shoot communication.
Methods: Gas exchange and chlorophyll fluorescence were measured using an infrared gas analyser combined with a pulse amplitude fluorimeter during chilling at 14 °C or 7 °C and subsequent recovery. At the same time, Rubisco content and activity and ROS generation were spectrophotometrically assayed. Abscisic acid and cytokinin concentrations in xylem sap were also determined by enzyme-linked immunosorbent assay.
Key Results and Conclusions: Grafted plants showed a significantly higher light-saturated rate of CO2 assimilation (Asat) than own-rooted plants when roots were gradually cooled, but no differences were detected when shoots were cooled. Chill at 7 °C irreversibly reduced Asat, and significantly decreased maximum carboxylation activity, Rubisco content and initial Rubisco activity. However, grafted plants showed weaker inhibition, together with decreased electron flux in the water–water cycle. Higher activity of antioxidant enzymes with less ROS production was found in grafted plants. In addition, ABA concentration increased by 48·4-fold whilst cytokinin concentration decreased by 91·5 % in the xylem sap of own-rooted plants after exposure to a 7 °C chill. In comparison, ABA and cytokinin concentrations increased by 10·5-fold and 36·9 %, respectively, for the grafted plants. Improved plant growth was also observed in grafted plants after the chill. These results suggest that some signals coming from chilling-resistant roots (i.e. ABA and cytokinins) protect leaf photosynthesis in shoots of chilling-sensitive plants.
Key words: Chilling, chlorophyll fluorescence, Cucumis sativus, electron transport flux, grafting, photosynthesis, reactive oxygen species, water–water cycle
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  K. Suzuki, K. Nagasuga, and M. Okada The Chilling Injury Induced by High Root Temperature in the Leaves of Rice Seedlings Plant Cell Physiol., March 1, 2008; 49(3): 433 - 442. [Abstract] [Full Text] [PDF]
|
|