P and N deficiency change the relative abundance and function of rhizosphere microorganisms during cluster root development of white lupin (Lupinus albus L.) |
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| Authors: | Jun Wasaki Junya Sakaguchi Takuya Yamamura Susumu Ito Takuro Shinano Mitsuru Osaki |
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| Affiliation: | 1. Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima, Japanjunw@hiroshima-u.ac.jp;3. Graduate School of Agriculture, Hokkaido University, Sapporo, Japan;4. Faculty of Agriculture, University of the Ryukyus, Okinawa, Japan;5. National Agriculture and Food Research Organization, Tohoku Agricultural Research Center, Agricultural Radiation Research Center, Fukushima, Japan;6. Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan |
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| Abstract: | We studied microbe-plant interactions of white lupin, a cluster root-forming plant, under low P and N conditions to examine increased nutrient acquisition by plants either by a shift to a more specialized microbial community or changes in microbial enzyme production. White lupin plants were grown in rhizoboxes filled with either P- or N-deficient soil; fertilized soil was used as control. After cultivation of plants in a glasshouse for 41 d, plant growth (shoot and roots) and P and N accumulation in shoots were measured. Microbial functions were analyzed by P- and N-cycling enzymes. The microbial community structure was estimated by fingerprinting (denaturing gradient gel electrophoresis) and sequencing techniques. P deficiency induced the released citrate and acid phosphomonoesterases from cluster roots and stimulated the production of microbe-derived alkaline phosphomonoesterase in the rhizosphere. P deficiency decreased microbial diversity in the cluster root rhizosphere. Increased relative abundance of Burkholderiales in the rhizosphere of P deficient plants might be responsible for the degradation of different organic P fractions such as phytates. N deficiency induced an increase of the number of nodules and P concentration in shoot as well as roots of white lupin. We clarified that high release of citrate from cluster roots might be the preferred mechanisms to meet the P demand of nodulated plants under N deficiency. In addition, the high abundance of Rhizobiales and Rhodospirillales in the rhizosphere of cluster roots showed that the importance of N-fixing microorganisms under N deficiency. The contribution of rhizosphere microorganisms due to similar activities of N-cycling enzymes under the two different N treatments is less important for N nutrition of plants. Further understanding of the regulation of cluster roots under N-deficiency will provide new information on the interactions between P and N nutrition. |
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| Keywords: | White lupin P deficiency N deficiency cluster roots rhizosphere |
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