Chin J Plan Ecolo ›› 2009, Vol. 33 ›› Issue (5): 984-992.DOI: 10.3773/j.issn.1005-264x.2009.05.018

• Research Articles • Previous Articles     Next Articles

EFFECTS OF ROOT TEMPERATURE ON THERMOSTABILITY OF PHOTOSYNTHETIC APPARATUS IN PRUNUS MIRA SEEDLINGS

HAO Hai-Ping1, 2; JIANG Chuang-Dao1;SHI Lei1; TANG Yu-Dan1*; YAO Juan1; LI Zhi-Qiang3   

  1. 1Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; 2Graduate University of Chinese Academy of Sciences, Beijing 100049, China; 3Beijing Vocational College of Agriculture, Beijing 102442, China
  • Online:2009-09-30 Published:2009-09-30
  • Contact: TANG Yu-Dan

Abstract: Aims High temperature is one of the major abiotic factors that limit plant growth and development in many regions of the world. Although plant thermo-tolerance has been extensively investigated, little attention has been paid to the effects of root temperature on thermo-stability of the photosynthetic apparatus. Our objective was to investigate the effects of variation in root temperature on photosynthetic apparatus and explore potential mechanisms.
Methods Under high air temperature (37 and 40 ℃), root temperatures of Prunus mira seedlings were increased gradually (variable root temperature) or kept at (25±2) ℃ (appropriate root temperature) throughout the treatment. We examined relative water content, H2O2 concentration, malondialdehyde (MDA) concentration, activity of antioxidant enzymes, cholorophyll a fluorescence and ABA content in leaves. The experimental design was completely randomized, and each treatment was replicated at least three times.
Important findings The combination of high air temperature and appropriate root temperature induced a decrease in activities of antioxidant enzymes and maximum quantum yield of PSII (Fv/Fm) with rela-tively high leaf relative water content (RWC). Hydrogen peroxide (H2O2) and MDA increased, indicating the photosynthetic apparatus was damaged by high temperature. The combination of high air tem-perature and gradually increasing root temperature reduced damage to the photosynthetic apparatus with significant improvement in antioxidant enzymes activities and leaf ABA content. Therefore, root temperature plays an important role in enhancing the thermostability of the photosynthetic apparatus. First, roots at appropriate temperature maintain high relative water content of leaves, but have damaged photosynthetic apparatus. Second, roots sensed the temperature stimulus and increased the leaf ABA accumulation when root temperature increased gradually, and high leaf ABA level prevented damage to the photosynthetic apparatus and enhanced heat-resistance.