auxin; mycorrhization; membrane transport; strigolactone; exodermis; hypodermal passage cell
Liu Guo-Wei, Pfeiffer Johannes, Brito-Francisco Rita, Emonet Aurelia, Stirnemann Marina, Gübeli Christian, Hutter Olivier, Sasse Joelle, Mattheyer Christian, Stelzer Ernst, Walter Achim, Martinoia Enrico, Borghi Lorenzo (2017), Changes in the allocation of endogenous strigolactone improve plant biomass production on phosphate‐poor soils, in New Phytologist
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Park Jiyoung, Lee Youngsook, Martinoia Enrico, Geisler Markus (2017), Plant hormone transporters: what we know and what we would like to know, in BMC Biology
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SummaryStrigolactones (SLs) have initially been discovered as germination stimulants for parasitic weeds. It took forty years until it was recognized that these compounds play many important roles in the interaction between the environment and the plant by inducing hyphal branching of mycorrhizal fungi and in plant development by regulating the plant architecture. As for human hormones also plant hormones are very often transported from their site of synthesis to their site of action, often over long distances. We are therefore interested how SLs are transported from the root tip to the soil as well as to the above-ground part of the plant, since grafting experiments indicated that such a transport takes place. In former works we reported the identification and characterization of a SLs transporter from petunia, the ABC transporter PDR1, and showed that this transporter is required for the exudation of SLs to the soil and to the above-ground part of the plant. Plants mutated in PDR1 are much less efficient in attracting mycorrhizal fungi and shoot lateral branching is more pronounced, due to a weaker SL transport. In this work we wish to learn more about the role of SLs -related processes. During the last ten years our knowledge about SLs has increased tremendously. However, our knowledge about SLs transport, allocation and regulation requires still a better understanding. The same is true for the role of SLs and plant nutrition. SLs do not only enhance mycorrhization, and therefore nutrient uptake (mainly phosphate and nitrogen), but have also an impact on root architecture and recently we observed that they play also an important role in defining the number of hypodermis passage cells (HPCs). HPCs are non-suberized cells of the exodermis and the exclusive entry points for mycorrhiza. In addition it is likely that due to the missing suberin they play also an important role in plant nutrition.To address these questions we have generated several tools and performed a large number of preliminary experiments that will allow us to progress rapidly to answer the following questions:i)Is overexpression of PDR1 that results in higher SL exudation to soil a reliable tool to improve phosphate nutrition in plants growing on nutrient-poor soils?ii)What is the connection between PDR1, SL biosynthesis and regulatory pathways in establishing and/ or maintaing HPCs? iii)How specific is the root nutrient uptake via HPCs? Which ions / molecules find their way to the plant via HPCs?iv)Three main players have been reported to have an impact on lateral shoot branching: auxin, sucrose and SLs. What regulates SL allocation to the bud and which roles plays PDR1 on the other 2 signaling pathways ? v)How is PDR1 activity and expression regulated?In conclusion, our work will contribute to the rapidly increasing knowledge about SLs by investigating novel, so far not-addressed aspects.