Strigolactones Are Transported through the Xylem and Play a Key Role in Shoot Architectural Response to Phosphate Deficiency in Nonarbuscular Mycorrhizal Host Arabidopsis

Kohlen, Wouter; Charnikhova, Tatsiana; Liu, Qin; Bours, Ralph; Domagalska, Malgorzata A.; Beguerie, Sebastien; Verstappen, Francel; Leyser, Ottoline; Bouwmeester, Harro J.; Ruyter-Spira, Carolien

doi:10.1104/pp.110.164640

Cited by 422 publications

(383 citation statements)

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“…7a, b). Arabidopsis does not form arbuscular mycorrhizae and exudes only minuscule quantities of strigolactones 23 . When grown on GR24-containing medium, PDR1-OE lines proved d, P. ramosa germination induced by GR24 (n 5 3), root exudates from W115 3 W138 (W3W WT, n 5 10), W115 3 W138-pdr1 (W3W pdr1, n 5 10), V26 (n 5 4), dad1 mutants (n 5 4) or water (H 2 O, n 5 4).…”

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“…Although certain aspects of strigolactone biosynthesis and signalling have been unravelled 25 , information about the mode of strigolactone transport is scant. Strigolactones are mobile within the xylem sap 23 , but it is not known how they are released from the producing cells and whether directed cell-to-cell transport occurs. Strigolactone biosynthesis is subject to direct negative feedback regulation 26 .…”

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“…a, b, e, h, *, P , 0.05; ***, P , 0.001. a strigolactone transporter. Although strigolactones are mobile in the xylem 23 , a cellular transport system is required to deliver strigolactones to dormant buds that are not yet connected to the xylem. This idea is compatible with both current models of strigolactone-dependent branching control 27 .…”

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A petunia ABC protein controls strigolactone-dependent symbiotic signalling and branching

Kretzschmar

Kohlen

Sasse

et al. 2012

Nature

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482

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Strigolactones were originally identified as stimulators of the germination of root-parasitic weeds 1 that pose a serious threat to resource-limited agriculture 2 . They are mostly exuded from roots and function as signalling compounds in the initiation of arbuscular mycorrhizae 3 , which are plant-fungus symbionts with a global effect on carbon and phosphate cycling 4 . Recently, strigolactones were established to be phytohormones that regulate plant shoot architecture by inhibiting the outgrowth of axillary buds 5,6 . Despite their importance, it is not known how strigolactones are transported. ATP-binding cassette (ABC) transporters, however, are known to have functions in phytohormone translocation [7][8][9] . Here we show that the Petunia hybrida ABC transporter PDR1 has a key role in regulating the development of arbuscular mycorrhizae and axillary branches, by functioning as a cellular strigolactone exporter. P. hybrida pdr1 mutants are defective in strigolactone exudation from their roots, resulting in reduced symbiotic interactions. Above ground, pdr1 mutants have an enhanced branching phenotype, which is indicative of impaired strigolactone allocation. Overexpression of Petunia axillaris PDR1 in Arabidopsis thaliana results in increased tolerance to high concentrations of a synthetic strigolactone, consistent with increased export of strigolactones from the roots. PDR1 is the first known component in strigolactone transport, providing new opportunities for investigating and manipulating strigolactone-dependent processes.Strigolactones are a new class of carotenoid-derived 10 phytohormone in land plants. In addition to their role in shoot branching, strigolactones are exuded into the rhizosphere under phosphorus-limiting conditions 5 and act as growth stimulants of arbuscular mycorrhizal fungi 3 . To identify efflux carriers of arbuscular-mycorrhiza-promoting factors such as strigolactones, we used a degenerate primer approach ( Supplementary Fig. 2a) to isolate full-size PDR-type transporters (also known as ABC subtype G (ABCG) transporters) of P. hybrida that are abundant in phosphate-starved or mycorrhizal roots. The rationale behind the focus on these transporters, of which there are 15 in Arabidopsis 11 , 23 in Oryza sativa (rice) 11 and 23 putative factors in Solanum lycopersicum (tomato) ( Supplementary Fig. 3a), was that they are plasma membrane proteins often found in roots 12 , they are implicated in below-ground plantmicrobe interactions 13,14 , and they have affinities for compounds that are structurally related to strigolactones 8,9,15 . Of six primary candidates, only P. hybrida PDR1 had increased expression in roots that were subjected to either phosphate starvation (Fig. 1a) or colonization by the arbuscular mycorrhizal fungus Glomus intraradices (Fig. 1b). Furthermore, PDR1 transcript levels increased in response to treatment with the synthetic strigolactone analogue GR24 or the auxin analogue 1-naphthaleneacetic acid (NAA) (Fig. 1c). Auxin has been shown to upregulate strigolactone-bi...

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A petunia ABC protein controls strigolactone-dependent symbiotic signalling and branching

Kretzschmar

Kohlen

Sasse

et al. 2012

Nature

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482

417

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“…This could be consistent with the Pi-deficient increase in auxin sensitivity lying downstream of the strigolactone-inhibited auxin transport in regulating lateral root formation. These findings lead to the hypothesis that strigolactones might translate environmental signals into appropriate growth cues for the root system architecture although solid evidence still needs to be provided (RuyterSpira et al 2011;Ruyter-Spira and Bouwmeester 2012).…”

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Strigolactones fine-tune the root system

Rasmussen

Depuydt

Goormachtig

et al. 2013

Planta

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Strigolactones were originally discovered to be involved in parasitic weed germination, in mycorrhizal association and in the control of shoot architecture. Despite their clear role in rhizosphere signaling, comparatively less attention has been given to the belowground function of strigolactones on plant development. However, research has revealed that strigolactones play a key role in the regulation of the root system including adventitious roots, primary root length, lateral roots, root hairs and nodulation. Here, we review the recent progress regarding strigolactone regulation of the root system and the antagonism and interplay with other hormones

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“…[13][14][15][16][17] For example, SLs promote symbioses with arbuscular mycorrhizal fungi by inducing hyphal branching and they adjust shoot architecture by inhibiting tiller bud outgrowth to better adapt to a P or N deficiency. 14,[16][17][18][19][20][21] Recently, it was reported that SLs regulate the perception or response of plants to P-limited conditions. 22 In Arabidopsis, mutants of SL signaling (max2-1) and biosynthesis (max4-1) showed reduced responses to P-limited conditions relative to wild-type plants.…”

Section: Strigolactones (Sls) Regulate Root Developmentmentioning

confidence: 99%