Dissipation of excess photosynthetic energy contributes to salinity tolerance: A comparative study of salt-tolerant Ricinus communis and salt-sensitive Jatropha curcas

• Published in: Journal of plant physiology Vol. 171; no. 1; pp. 23 - 30
• Main Authors: Lima Neto, Milton C., Lobo, Ana K.M., Martins, Marcio O., Fontenele, Adilton V., Silveira, Joaquim Albenisio G.
• Format: Journal Article
• Language: English
• Published: Germany Elsevier GmbH 01-01-2014
• Subjects: Alcohol Oxidoreductases - metabolism; Ammonia - metabolism; Castor bean; Catalase - metabolism; Cell Respiration; Cellular; Chlorophyll - metabolism; Electron Transport; Glutamate-Ammonia Ligase - genetics; Glutamate-Ammonia Ligase - metabolism; Jatropha - drug effects; Jatropha - physiology; Jatropha - radiation effects; Light; Nitrate Reductase - genetics; Nitrate Reductase - metabolism; Nitrates - metabolism; Partitioning; Photoprotection; Photosynthesis; Physic nut; Physiology; Plant Leaves - physiology; Plant Proteins - metabolism; Plant Transpiration; Reduction (electrolytic); Ricinus - drug effects; Ricinus - physiology; Ricinus - radiation effects; Salinity; Salt stress; Salt-Tolerance; Sodium Chloride - pharmacology; Stress, Physiological; Tolerances; Water - physiology; Physic nut; Salt stress; Castor bean; Photosynthesis; Photoprotection
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/j.jplph.2013.09.002

The relationships between salt tolerance and photosynthetic mechanisms of excess energy dissipation were assessed using two species that exhibit contrasting responses to salinity, Ricinus communis (tolerant) and Jatropha curcas (sensitive). The salt tolerance of R. communis was indicated by unchanged electrolyte leakage (cellular integrity) and dry weight in leaves, whereas these parameters were greatly affected in J. curcas. The leaf Na+ content was similar in both species. Photosynthesis was intensely decreased in both species, but the reduction was more pronounced in J. curcas. In this species biochemical limitations in photosynthesis were more prominent, as indicated by increased Ci values and decreased Rubisco activity. Salinity decreased both the Vcmax (in vivo Rubisco activity) and Jmax (maximum electron transport rate) more significantly in J. curcas. The higher tolerance in R. communis was positively associated with higher photorespiratory activity, nitrate assimilation and higher cyclic electron flow. The high activity of these alternative electron sinks in R. communis was closely associated with a more efficient photoprotection mechanism. In conclusion, salt tolerance in R. communis, compared with J. curcas, is related to higher electron partitioning from the photosynthetic electron transport chain to alternative sinks.