Efficient acquisition of iron confers greater tolerance to saline-alkaline stress in rice (Oryza sativa L.).
To elucidate the mechanisms underlying tolerance to saline-alkaline stress in two rice genotypes, Dongdao-4 and Jigeng-88, we exposed them to medium supplemented with 10 mM Na2CO3and 40 mM NaCl (pH 8.5). Dongdao-4 plants displayed higher biomass, chlorophyll content, and photosynthetic rates, and a larger root system than Jigeng-88 under saline-alkaline conditions. Dongdao-4 had a higher shoot Na+/K+ratio than Jigeng-88 under both control and saline-alkaline conditions. Dongdao-4 exhibited stronger rhizospheric acidification than Jigeng-88 under saline-alkaline conditions, resulting from greater up-regulation of H+-ATPases at the transcriptional level. Moreover, Fe concentrations in shoots and roots of Dongdao-4 were higher than those in Jigeng-88, and a higher rate of phytosiderophore exudation was detected in Dongdao-4 versus Jigeng-88 under saline-alkaline conditions. The Fe-deficiency-responsive genes OsIRO2, OsIRT1, OsNAS1, OsNAS2, OsYSL2, and OsYSL15 were more strongly up-regulated in Dongdao-4 than Jigeng-88 plants in saline-alkaline medium, implying greater tolerance of Dongdao-4 plants to Fe deficiency. To test this hypothesis, we compared the effects of Fe deficiency on the two genotypes, and found that Dongdao-4 was more tolerant to Fe deficiency. Exposure to Fe-deficient medium led to greater rhizospheric acidification and phytosiderophore exudation in Dongdao-4 than Jigeng-88 plants. Expression levels of OsIRO2, OsIRT1, OsNAS1, OsNAS2, OsYSL2, and OsYSL15 were higher in Dongdao-4 than Jigeng-88 plants under Fe-deficient conditions. These results demonstrate that a highly efficient Fe acquisition system together with a large root system may underpin the greater tolerance of Dongdao-4 plants to saline-alkaline stress.
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, the Chinese Academy of Sciences, Beijing 100093, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
Qian
Q
Li
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, the Chinese Academy of Sciences, Beijing 100093, China.
An
A
Yang
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, the Chinese Academy of Sciences, Beijing 100093, China whzhang@ibcas.ac.cn.|University of Chinese Academy of Sciences, Beijing 100049, China.|Research Network of Global Change Biology, Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100093, China.
Wen-Hao
WH
Zhang
D002734:Chlorophyll / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000378:metabolism* / Q000502:physiology; D000090463:Iron Deficiencies; D012275:Oryza / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D010788:Photosynthesis; D018517:Plant Roots / Q000378:metabolism / Q000502:physiology; D018520:Plant Shoots / Q000378:metabolism / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D058441:Rhizosphere; D055049:Salt Tolerance / Q000502:physiology*; D012964:Sodium / Q000378:metabolism; D013312:Stress, Physiological / Q000502:physiology
D002734:Chlorophyll; D012964:Sodium; D007501:Iron; D011188:Potassium

Oryza sativa
; Dongdao-4; Jigeng-88; iron acquisition; iron deficiency; rice; saline-alkaline stress.