Interaction between strigolactone and other plant hormones Biosynthesis and Metabolism of Normal growth and development Kaori Yoneyama, X Xie, T Kisugi, T Nomura, K Yoneyama (Weed Science Center, Utsunomiya University, Japan)
CK and auxin are factors regulating shoot branching Auxin from shoot apex Promotion Suppression of CK synthesis Inhibition Decrease of CK level
How does CK affect SL production and exudation? Benzyl adenine Kinetin trans-zeatine CPPU P Distilled water ½ TT -P Treatment Sampling 7 1 17 18 days
All CKs examined strongly suppressed SL production and exudation 6 5 orobanchol 2 -epi-5-deoxystrigol 6 5 orobanchol 2 -epi-5-deoxystrigol 4 4 3 3 2 2 1 1 Control 1 µm 1 µm 1 µm t-zeatine Benzyl Kinetine adenine Adenine type 1 µm CPPU Phenyl urea type Control 1 µm 1 µm 1 µm t-zeatine Benzyl Kinetine adenine 1 µm CPPU n=3, bar=sd
SL production decreased with the increase of CK concentration in culture media 5 orobanchol 5 orobanchol 4 2 -epi-5-deoxystrigol 4 2 -epi-5-deoxystrigol 3 3 2 2 1 1.2.1 1.2.1 1 t-zeatine concentration (µm) t-zeatine concentration (µm) n=3, bar=sd
P CK P P P CK (t-zeatin) treatment suppressed expressions of D17, D1, D27 and D3 which had been up-regulated by - P D17/HTD1 Carotenoid (CCD7) D1 (CCD8) MAX1 ortholog (P45) Apocarotenoid Strigolactones or further metabolites D3 (F-box) D27 Relative mrna level Relative mrna level 8 4 8 4 D17 + P D1 + P -P + CK -P + CK - P - P Relative mrna level Relative mrna level 16 8 8 4 D27 + P D3 + P -P + CK -P + CK - P - P INHIBITION of SHOOT BRANCHING
CK application as well as P fertilization inhibits SL production CK affects P deficient metabolism? or Pi P affects CK biosynthesis? CK release of Pi from internal sources Pi Starvation Responsive Genes Elevation of intracellular Pi levels in plant tissues
CK Effects application of CK application did not affect on Pi levels Pi contents (mg/g FW) + CK Pi contents (mg/g FW) CK P P + CK + CK n=3, bar=sd Pi contents (mg/g FW)
CK application as well as P fertilization inhibits SL production CK affects P deficient metabolism? or Pi P affects CK biosynthesis?
Effects of P fertilization on CK biosynthesis P fertilization increased t-zeatine in root P t- zeatine level (ng/ g FW) * P P +P -P +P -P +P -P Leaf Stem Root * n=3, bar=sd Tukey-Kramer s HSD (P <.5)
Summary ~Effects of CK on SL production~ CK treatment as well as P fertilization decreased SL levels and expressions of genes involved in SL biosynthesis and perception. CK treatment did not affect Pi levels and P fertilization increased t-zeatine levels in root. P deficiency CK biosynthesis Low level of CK
How does auxin affect SL production and exudation? 2,4,6-trichlorophenoxyacetic acid (Anti auxin) Auxin transport inhibitor (NPA) P Distilled water ½ TT -P Treatment Sampling 7 1 17 18 days
Anti auxin and auxin transport inhibitor suppressed SL production 25 2 orobanchol 2 -epi-5-deoxystrigol 15 1 5 nd nd -P 1 µm 1 µm 1 µm 1 µm Anti auxin Auxin transport inhibitor
How does auxin affect SL production and exudation? P + IAA P IAA Distilled water ½ TT -P Treatment Sampling 7 1 17 18 days
Application of IAA to root did not affect SL production under +P or -P orobanchol 2 -epi-5-deoxystrigol orobanchol 2 -epi-5-deoxystrigol + P 1 µm IAA (+ P) - P 1 µm IAA (- P)
How does auxin affect SL production and exudation? Decapitation P P IAA treated to decapitated stem or root Distilled water ½ TT -P Treatment Sampling 7 1 17 18 days
Decapitation decreased SL production which was not restored by IAA Decapitation Decapitation Decapitation +IAA to root +IAA to shoot Intact Decapitation Decapitation Decapitation +IAA to root +IAA to shoot
Summary ~Effects of auxin on SL production~ Anti auxin and auxin transport inhibitor suppressed SL production, indicating that auxin is required for SL production. Although it was reported that auxin promotes SL biosynthesis gene expression, exogenous application of IAA to intact plants did not affect SL production. Decapitation significantly inhibited SL production and IAA did not restore it, suggesting SL production in root needs other signals beside auxin.
How do other plant hormones affect SL production? orobanchol 2 -epi-5-deoxystrigol SL exudation (% of P control) Kinetin IAA MJA CS Concentration= 1 µm
How do plant hormones affect SL production? +GA -GA +ABA -ABA +MJA -MJA +CK -CK +ACC -ACC SL exudation (% of P control) 1 5 +GA -GA +ABA -ABA +MJA -MJA +CK -CK +ACC -ACC Concentration= 1 µm
SL has many interferences?
Acknowledgements Dr Tadao Asami (University of Tokyo) Dr Kotomi Ueno (Kobe University) Dr Kohki Akiyama (Osaka Pref. University) Thank you for your kind attention!