Arabidopsis

Germain, Alexandre de Saint, Retailleau, Pascal, Norsikian, Stéphanie, Servajean, Vincent, Pelissier, Franck, Steinmetz, Vincent, Pillot, Jean-Paul, Rochange, Soizic, Pouvreau, Jean-Bernard & Boyer, François-Didier, 2019, Contalactone, a contaminant formed during chemical synthesis of the strigolactone reference GR 24 is also a strigolactone mimic, Phytochemistry 168, pp. 1-10 : 3

2.4. (±)-Contalactone represses hypocotyl elongation in Arabidopsis via AtD14 and AtKAI2

We also tested the bioactivity of (±)-contalactone and (±)-P270 on Arabidopsis hypocotyl elongation with SL biosynthesis (max 3-11) and perception (Atd14-1, htl-3, max 2-1) mutants. In Arabidopsis , (±)- GR 24 inhibits hypocotyl growth via AtD14 and AtKAI2 (AtHTL) ( Waters et al., 2012, 2017). Like (±)- GR 24, (±)-contalactone significantly suppressed hypocotyl elongation in wild-type plant and also in max 3-11, Atd14-1 and htl-3 mutants seedlings, but not in the max 2-1 mutant. These results confirm that (±)-contalactone can mimic the GR 24 effect not only on branching but also on hypocotyl elongation. These results show that (±)-contalactone repressed hypocotyl elongation via AtMAX2, and redundantly via AtD14 and AtKAI2, as already demonstrated for GR 24 ( Nelson et al., 2011). This suggests that AtKAI2 can perceive (±)-contalactone. However, (±)-P270 does not repress hypocotyl elongation in wild-type, max 3-11 or Atd14-1 mutant seedlings. We observed a slight inhibition of hypocotyl elongation in htl-3 and especially in max 2-1 mutant probably due to a toxic effect ( Fig. 5 ).

Figures

Fig. 5. Effect of (±)-GR24, (±)-270 and (±)-contalactone on hypocotyl elongation in Col-0, max3-11, Atd14-1, htl3 and max2-1 Arabidopsis plants. Data are means ± SE (n = 14 plants). ***P <0.001, Kruskal-Wallis rank sum test, compared to control values (CTL0).