Petunia PLEIOTROPIC DRUG RESISTANCE 1 Is a Strigolactone Short-Distance Transporter with Long-Distance Outcomes

We show that the previously reported petunia SL transporter PLEIOTROPIC DRUG RESISTANCE 1 directly accounts for short-distance SL transport and long-distance transport of SLs seems to be partially and not directly dependent on PDR1

Katsuhiro Shiratake; Michitaka Notaguchi; Haruko Makino; Yu Sawai; Lorenzo Borghi

2019

Scholarcy highlights

  • Phytohormones of the strigolactone family have been characterized as negative regulators of lateral bud outgrowth and triggers of symbioses between plants and mycorrhizal fungi
  • Scions and rootstocks were produced from wild type seedlings, SL biosynthetic mutants and the SL transport mutants pdr1 knock-out and PLEIOTROPIC DRUG RESISTANCE 1 overexpressor; the latter reported to exude higher-than-WT SL amounts toward the soil
  • The reason for these multiple ecotypes is that not every petunia background can be transformed with transgenic cassettes and a specific petunia ecotype is used for the generation of mutants via the footprint left by the naturally occurring transposon dTPh1
  • Through grafting experiments in adult petunia plants and based on our previous results of SL transport in petunia seedlings, we propose that the long-distance, shoot-ward SL transport in petunia might only require the indirect activity of PDR1
  • The local effect of pdr1 ko on bud outgrowth is quantified as strong as the lack of SL biosynthesis in dad1 mutants in this study; both mutant shoots having an average of 16–19 outgrown buds in the main stem
  • The success rate of grafting was higher than 80%
  • This equal effect shows that the transport of SL to the lateral axils is necessary for the SL-driven regulation of lateral bud outgrowth as much as SL biosynthesis and without PDR1, no alternative SL route is available
  • As the three different stem-length classes did not affect rates of bud outgrowth, we speculate that by grafting pdr1 ko scions on different rootstocks we produced random distributed issues on the transport of SL-related molecules that regulate internode elongation

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