Photosynthesis is induced in rice plants that associate with arbuscular mycorrhizal fungi and are grown under arsenate and arsenite stress.
The metalloid arsenic (As) increases in agricultural soils because of anthropogenic activities and may have phytotoxic effects depending on the available concentrations. Plant performance can be improved by arbuscular mycorrhiza (AM) association under challenging conditions, such as those caused by excessive soil As levels. In this study, the influence of AM on CO2 assimilation, chlorophyll a fluorescence, SPAD-chlorophyll contents and plant growth was investigated in rice plants exposed to arsenate (AsV) or arsenite (AsIII) and inoculated or not with Rhizophagus irregularis. Under AsV and AsIII exposure, AM rice plants had greater biomass accumulation and relative chlorophyll content, increased water-use efficiency, higher carbon assimilation rate and higher stomatal conductance and transpiration rates than non-AM rice plants did. Chlorophyll a fluorescence analysis revealed significant differences in the response of AM-associated and -non-associated plants to As. Mycorrhization increased the maximum and actual quantum yields of photosystem II and the electron transport rate, maintaining higher values even under As exposure. Apart from the negative effects of AsV and AsIII on the photosynthetic rates and PSII efficiency in rice leaves, taken together, these results indicate that AM is able to sustain higher rice photosynthesis efficiency even under elevated As concentrations, especially when As is present as AsV.
Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brazil. Electronic address: sara.adrian@gmail.com.
Sara Adrian Lopez
SA
de Andrade
Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brazil.
Adilson Pereira
AP
Domingues
Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brazil.
Paulo
P
Mazzafera
D001149:Arsenates / Q000633:toxicity*; D018053:Arsenites / Q000633:toxicity*; D018533:Biomass; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D004579:Electron Transport; D055137:Glomeromycota / Q000502:physiology; D038821:Mycorrhizae / Q000502:physiology*; D012275:Oryza / Q000254:growth & development; D010788:Photosynthesis / Q000187:drug effects*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000254:growth & development; D012989:Soil Pollutants / Q000633:toxicity*; D013312:Stress, Physiological / Q000502:physiology
D001149:Arsenates; D018053:Arsenites; D045332:Photosystem II Protein Complex; D012989:Soil Pollutants; D002734:Chlorophyll; C015001:arsenite; C025657:arsenic acid; D000077194:Chlorophyll A
Arbuscular mycorrhiza; Arsenic; Chlorophyll fluorescence; Photochemical metabolism; Rhizophagus irregularis