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Aquaporin‐mediated long‐distance polyphosphate translocation directed towards the host in arbuscular mycorrhizal symbiosis: application of virus‐induced gene silencing
Author(s) -
Kikuchi Yusuke,
Hijikata Nowaki,
Ohtomo Ryo,
Handa Yoshihiro,
Kawaguchi Masayoshi,
Saito Katsuharu,
Masuta Chikara,
Ezawa Tatsuhiro
Publication year - 2016
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.14016
Subject(s) - symbiosis , gene silencing , polyphosphate , chromosomal translocation , biology , microbiology and biotechnology , gene , host (biology) , genetics , bacteria , biochemistry , phosphate
Summary Arbuscular mycorrhizal fungi translocate polyphosphate through hyphae over a long distance to deliver to the host. More than three decades ago, suppression of host transpiration was found to decelerate phosphate delivery of the fungal symbiont, leading us to hypothesize that transpiration provides a primary driving force for polyphosphate translocation, probably via creating hyphal water flow in which fungal aquaporin(s) may be involved. The impact of transpiration suppression on polyphosphate translocation through hyphae of Rhizophagus clarus was evaluated. An aquaporin gene expressed in intraradical mycelia was characterized and knocked down by virus‐induced gene silencing to investigate the involvement of the gene in polyphosphate translocation. Rhizophagus clarus aquaporin 3 ( Rc AQP 3 ) that was most highly expressed in intraradical mycelia encodes an aquaglyceroporin responsible for water transport across the plasma membrane. Knockdown of Rc AQP 3 as well as the suppression of host transpiration decelerated polyphosphate translocation in proportion to the levels of knockdown and suppression, respectively. These results provide the first insight into the mechanism underlying long‐distance polyphosphate translocation in mycorrhizal associations at the molecular level, in which host transpiration and the fungal aquaporin play key roles. A hypothetical model of the translocation is proposed for further elucidation of the mechanism.