Gibberellin (GA) Regulates Strigolactone (SL) Biosynthesis

Gibberellin (GA) regulates strigolactone (SL) biosynthesis

S. Ito , M. Umehara, A. Hanada, S. Yoshida, J. Kyozuka, M. Ueguchi-Tanaka, M. Matsuoka, K. Shirasu, S. Yamaguchi, T. Asami Structure of SL (2’-epi -5-deoxystrigol: epi -5DS)

Mock SL treatment Mock SL treatment

Root parasitic weed germination Hyphal branching in arbuscular Cook et al., Science Wild-type SL deficient mycorrhizal fungi mutant Akiyama et al., Nature

Shoot branching Umehara et al., Nature Many chemicals control SL biosynthesis

Carotenoid

Auxin Abscisic acid Ferguson et al., 2007 López-Ráez et al., 2010

Cytokinin PhosphateP Yoneyama et al., 2007 SLs One of the strigolactone biosynthesis inhibitors (TIS102)

0 µM 1 µM

TIS102 concentration GA 3 reduces the epi -5DS level in rice root exudates

N.D.

GA 3

N.D. : Not detected

・ seed germination ・ stem elongation ・ flowering ・ fruit ripening ・ GA 3 branching GA 3 reduces the SL levels in rice Epi -5DS 2’-epi -orobanchol Roots

control

0 0.1 1 10 100 5000 GA 3 concentration (nM) BL GR24 Root exudates

GA 3

0 0.1 1 10 100 5000 GA 3 concentration (nM) BL GR24 Active GAs reduce the SL levels

Roots

GA 1 GA 8 GA 3 GA 1 GA 4 GA 8

Root exudate

GA 3 GA 4

Structure of gibberellins

GA 3 GA 1 GA 4 GA 8 GA 34 GA 3 also reduces the SL levels in GA biosynthesis mutant

Roots

osga3ox2

GA 3 concentration (nM) Root exudate

WT GA defficient mutant WT osga3ox2 GA 3 doesn’t reduce the SL levels in GA signaling mutant Roots

5 cm

WT gid2-2

GA 3 concentration (nM)

Root exudate

WT gid2-2 WT gid2-2 GA 3 concentration (nM) SL is not detceted in constitutive GA response mutant

Root exudate 5 cm

WT slr1

GA 3 concentration (nM) WT slr1 GA reduce the SL levels depending on GA signaling. GA 3 also reduces the SL levels in SL signaling mutant

Roots

Root exudate

0 0 50 WT WT d3 d3 mutant GA 3 concentration (nM) GA reduce the SL levels independent of SL signaling. GA reduces the transcript levels of SL biosynthesis genes

carotenoid D17 (CCD7)

D10 D17 (CCD8)

D27

Strigolactones

GA 3 concentration (nM) GA reduces the Striga germination stimulants in rice root exudates

DW GR24 control GA 3 GA 3 +GR24

Root exudate

GR24 1 µM, GA 3 10 nM GA-treated rice reduces the Striga infection

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＊ ＊

＊: P<0.05 Conclusion

GA reduces the SL levels. the transcript levels of SL biosynthesis genes. the Striga infection.

Controlling the GA biosynthesis or signaling pathway in plants might become one of the way to contol the root parasitic weed infection.