Arbuscular mycorrhizal symbiosis ameliorates the optimum quantum yield of photosystem II and reduces non-photochemical quenching in rice plants subjected to salt stress.
Rice is the most important food crop in the world and is a primary source of food for more than half of the world population. However, salinity is considered the most common abiotic stress reducing its productivity. Soil salinity inhibits photosynthetic processes, which can induce an over-reduction of the reaction centres in photosystem II (PSII), damaging the photosynthetic machinery. The arbuscular mycorrhizal (AM) symbiosis may improve host plant tolerance to salinity, but it is not clear how the AM symbiosis affects the plant photosynthetic capacity, particularly the efficiency of PSII. This study aimed at determining the influence of the AM symbiosis on the performance of PSII in rice plants subjected to salinity. Photosynthetic activity, plant gas-exchange parameters, accumulation of photosynthetic pigments and rubisco activity and gene expression were also measured in order to analyse comprehensively the response of the photosynthetic processes to AM symbiosis and salinity. Results showed that the AM symbiosis enhanced the actual quantum yield of PSII photochemistry and reduced the quantum yield of non-photochemical quenching in rice plants subjected to salinity. AM rice plants maintained higher net photosynthetic rate, stomatal conductance and transpiration rate than nonAM plants. Thus, we propose that AM rice plants had a higher photochemical efficiency for CO2 fixation and solar energy utilization and this increases plant salt tolerance by preventing the injury to the photosystems reaction centres and by allowing a better utilization of light energy in photochemical processes. All these processes translated into higher photosynthetic and rubisco activities in AM rice plants and improved plant biomass production under salinity.
Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín (CSIC), Profesor Albareda n° 1, 18008 Granada, Spain.
Rosa
R
Porcel
Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain.
Susana
S
Redondo-Gómez
Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain.
Enrique
E
Mateos-Naranjo
Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín (CSIC), Profesor Albareda n° 1, 18008 Granada, Spain.
Ricardo
R
Aroca
Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma, Mexico.
Rosalva
R
Garcia
Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín (CSIC), Profesor Albareda n° 1, 18008 Granada, Spain. Electronic address: juanmanuel.ruiz@eez.csic.es.
Juan Manuel
JM
Ruiz-Lozano
D038821:Mycorrhizae / Q000502:physiology*; D012275:Oryza / Q000378:metabolism* / Q000382:microbiology*; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology*; D013559:Symbiosis
D045332:Photosystem II Protein Complex; D012965:Sodium Chloride
Arbuscular mycorrhizal symbiosis; Non-photochemical quenching; Optimum quantum yield; Oryza sativa; Photosystem II; Salt stress