IN INOCULANTS Nodulaid - 17th International Nitrogen Fixation ...

17 th International Congress on Nitrogen Fixation
Fremantle, Western Australia
27 November – 1 December 2011
Title Expression of an abscisic acid-responsive ƒÀ-1,3-glucanase gene in autoregulation of
nodulation.
Author Keni-chi Osuki 1 , Akihiro Suzuki 2 , Hisatoshi Hara 1 , Akihito Takahara 1 , Masato Araragi 1 ,Tadao
Asami 3 , Keni-chi Kucho 1 , Shiro Higashi 1 , Mikiko Abe 1 and Toshiki Uchiumi 1
Poster Board Number 41
1 Graduate School of Science and Engineering, Kagoshima University,
2 Department of Environmental Science, Saga University
3 Graduate School of Agriculture and Life Science, The University of Tokyo
Host legumes control nodule number by autoregulation of nodulation (AUT), in which the presence of root
nodules inhibits further root nodule formation. AUT will consist of at least two long-distance signals, i. e. a rootderived
infection signal and a shoot-derived signal that inhibits nodulation. In Lotus japonicus, HAR1 mediates
AUT and, LjCLE-RS1 and LjCLE-RS2 have been identified as strong candidates as the infection signal. We
employed split-root system of L. japonicus to investigate plant molecules involved in inhibition of nodule
formation in AUT. Abscisic acid (ABA) and ABA responsible β-1,3-glucanase gene (designated as LjGlu1) were
focused in this study.
Plants were set up for split-root system. One side of root systems was inoculated with Mesorhizobium loti
MAFF303099. At 1, 2, 3, 5, 7, 9 and 14 days after inoculation, expression of LjGlu1 in leaves, and inoculated-
and uninoculated roots, were analyzed by quantitative RT-PCR. In the leaves, expression of LjGlu1 increased at
the 7 days after inoculation. In the inoculated- and uninoculated roots, expression of LjGlu1 increased at the 5, 7
and 9 day after inoculation. AUT response of L.japonicus is detectable 3 days after the first inoculation and that
full induction of the response occurs after 5 days (Suzuki et al 2008).These results suggest that LjGlu1 increased
in the root, when the full induction of the AUT response occurs.
Hairy roots transformed with LjCLE-RS1 driven by the Cauliflower mosaic virus 35S promoter were prepared. In
the plant that has both the transgenic and untransgenic roots, LjGlu1 was induced in not only the transgenic
roots but also untransgenic roots. These findings indicate that constitutive expression of LjCLE-RS1 also induced
expression of LjGlu1 systemically. These results suggest that LjGlu1 is functional involved in inhibition of nodule
formation in AUT.
Akihiro Suzuki , Hisatoshi Hara ,Tomoyo Kinoue ,Mikiko Abe , Toshiki Uchiumi , Ken-ichi Kucho ,Shiro Higashi
,Ann M. Hirsch ,Susumu Arima (2008).Split-root study of autoregulation of nodulation in the model legume Lotus
japonicus. J Plant Res 121:245–249
156
2011