Characterization of Al-responsive citrate excretion and citrate-transporting MATEs in Eucalyptuscamaldulensis
Many plant species excrete organic acids into the rhizosphere in response to aluminum stress to protect sensitive cells from aluminum rhizotoxicity. When the roots of Eucalyptus camaldulensis , a major source of pulp production, were incubated in aluminum-toxic medium, citrate released into the solu...
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Published in | Planta Vol. 237; no. 4; pp. 979 - 989 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Berlin/Heidelberg
Springer-Verlag
01.04.2013
Springer Nature B.V |
Subjects | |
Online Access | Get full text |
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Summary: | Many plant species excrete organic acids into the rhizosphere in response to aluminum stress to protect sensitive cells from aluminum rhizotoxicity. When the roots of
Eucalyptus camaldulensis
, a major source of pulp production, were incubated in aluminum-toxic medium, citrate released into the solution increased as a function of time. Citrate excretion was inducible by aluminum, but not by copper or sodium chloride stresses. This indicated that citrate is the major responsive organic acid released from the roots of this plant species to protect the root tips from aluminum damage. Four genes highly homologs to known citrate-transporting multidrugs and toxic compounds exclusion proteins, named
EcMATE1
–
4
, were isolated using polymerase chain reaction-based cloning techniques. Their predicted proteins included 12 membrane spanning domains, a common structural feature of citrate-transporting MATE proteins, and consisted of 502–579 amino acids with >60 % homology to orthologous genes in other plant species. One of the homologs, designated
EcMATE1
, was expressed in the roots more abundantly than in the shoots and in response to both Al and low pH stresses. Ectopic expression of
EcMATE1
and
3
in tobacco hairy roots enhanced Al-responsive citrate excretion. Pharmacological characterization indicated that Al-responsive citrate excretion involved a protein phosphorylation/dephosphorylation process. These results indicate that citrate excretion through citrate-transporting multidrugs and toxic compounds exclusion proteins is one of the important aluminum-tolerance mechanisms in
Eucalyptus camaldulensis
. |
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ISSN: | 0032-0935 1432-2048 |
DOI: | 10.1007/s00425-012-1810-z |