Structural requirements of strigolactones for shoot branching. Regulation of shoot branching by strigolactones and brassinosteroids. The interaction between nitrogen availability and auxin. Sucrose represses the expression of the strigolactone. What are strigolactones and why are they important to. Shoot branching is regulated by competition between branches to export the phytohormone auxin into the main stem. We suggest that endogenous strigolactones or related compounds inhibit shoot branching in plants. The molecular pathways regulating branching and its adaptation to seasonal changes are not well understood in perennial plants.
Phytohormones play a central role in shoot branching control. Probing strigolactone receptors in striga hermonthica with. Prior to this finding, strigolactones were proven to be root rhizosphere. Strigolactones sls are a class of terpenoid phytohormones that were identified to inhibit bud outgrowth in 2008.
Mutantinduced branches on these plants are indicated by arrows. Shoot branching is regulated by axillary bud activities, which subsequently grow into branches. Jan 29, 20 a particularly striking illustration of this is the ability of strigolactone to promote shoot branching in the tir3 mutant background, which is difficult to explain if strigolactones act as direct inhibitors of bud growth but is a prediction of the model in which strigolactones act to modulate auxin transport. Mar 26, 2020 shoot branching results from axillary bud initiation and bud outgrowth and determines plant architecture and productivity. Bes1 functions as the coregulator of d53like smxls to inhibit. Axillary shoot apical meristems are established in the axils of the leaves produced by the primary shoot apical meristem and. Here we show that the branching phenotype of mutants in the arabidopsis p450 family member, max1, can be fully rescued by strigolactone addition, suggesting that max1 acts in sl synthesis. Representative branching mutant top and wildtype bottom phenotypes are shown for arabidopsis left and dwarf pea right. Shoot branching hormone inhibition the role of strigolactones as branching inhibitor hormone was discovered because of the use of a new set of mutant plants.
For quantifying root growth inhibition and agravitropic root growth, axenic seedlings grown vertically for 3 d on hormone free agar medium were. In contrast with annuals, in perennial plants growing in temperate and boreal regions, branching must be controlled temporally to adapt to seasonal changes. Regulation of shoot branching by strigolactones and. The interaction between sls and the tb1 locus of maize in the regulation of shoot branching is, however, quite complex. Here, we demonstrated that phosphorus pi starvation significantly reduces axillary bud outgrowth in chrysanthemum. In many plant species, the intact main shoot apex grows predominantly and axillary bud outgrowth is inhibited. Structural requirements of strigolactones for hyphal. Strigolactone inhibition of branching independent of polar auxin. The importance of strigolactone transport regulation for. Connective auxin transport contributes to strigolactone.
Strigolactones are also exuded by plants into the rhizosphere, where they promote symbiotic interactions with arbuscular mycorrhizal fungi and germination of root parasitic plants in the orobanchaceae family. Strigolactones sls are plant hormones that suppress shoot branching through perception by their receptor protein dwarf 14 d14. Sep 16, 2008 exogenous strigolactone inhibited shoot branching in pea and arabidopsis ccd mutants but not in strigolactone producing mutants. Strigolactones can also inhibit bud outgrowth in n1naphthylphthalamic acidtreated shoots that have greatly diminished auxin transport. The elevated strigolactone production in the d3 mutant sug. Structureactivity relationship studies of strigolactonerelated. Strigolactones sls were originally isolated from plant root exudates as germination stimulants for root parasitic plants of the family orobanchaceae, including witchweeds striga spp. A phenol chloroformfree method to extract nucleic acids from recalcit. New genes in the strigolactone related shoot branching pathway. However, in abaminesgtreated plants, an inhibitor of 9cisepoxycarotenoid dioxygenase nced, and the aba mutants notabilis, sitiens and. New genes in the strigolactonerelated shoot branching pathway. Pdf strigolactone inhibition of shoot branching researchgate.
Strigolactone regulation of shoot branching in chrysanthemum. We introduce a genetically encoded hormone biosensor used to analyze strigolactone mediated processes, including the study of the components involved in the hormone perceptionsignaling complex and the structural specificity. Pin3 pin4 and pin7 accumulate in the tissues between the bud and the stem pats and their mutation reduces branching in strigolactone mutants. Strigolactones sls are a class of terpenoid phytohormones. The core sl signaling pathway has been established in the last decade. Pdf a new lead chemical for strigolactone biosynthesis. Science and application of strigolactones aliche 2020.
These results confirmed the role of slccd7 in sl biosynthesis resulting in the formation of shoot branching inhibitor and parasitic plants. The importance of strigolactone transport regulation for symbiotic signaling and shoot branching lorenzo borghi1 guowei liu1 aure. Auxincytokinin interactions in the control of shoot branching core. Development of potent inhibitors for strigolactone receptor. Pdf a carotenoidderived hormonal signal that inhibits shoot branching in plants has long escaped identification. Forests free fulltext transcriptomic analysis reveals hormonal. The elevated strigolactone production in the d3 mutant sug the d31 mutant fig. Strigolactone can promote or inhibit shoot branching by.
A new lead chemical for strigolactone biosynthesis inhibitors. A genetic framework for regulation and seasonal adaptation. Previous studies of highly branched mutants in pea rms1rms5, arabidopsis thaliana max1max4, petunia dad1dad3, and rice d3, d10, htd1d17, d14, d27 identified strigolactones or their derivates sls, as shoot branching inhibitors. Download fulltext pdf download fulltext pdf read fulltext. They are best known for their role in shoot branching but, more recently, roles for sls in other aspects of plant development have emerged. Binding of nonhydrolyzed, intact strigolactone that generates an altered dwarf14 protein surface, mediating interaction with another. The profound, systemic, and longterm effects of the auxin transport inhibitor n1naphthylphthalamic acid had very little inhibitory effect on bud outgrowth in strigolactone deficient mutants. The degree of axillary bud outgrowth is highly influenced by environmental conditions, such as nutrient availability. Mar 16, 2012 the application of the synthetic strigolactone gr24 restored the wildtype tillering branching phenotype of these mutants, suggesting the involvement of ccd7, ccd8, d27, and max1 in strigolactone biosynthesis 8, 1217. Sep 01, 2008 a carotenoidderived hormonal signal that inhibits shoot branching in plants has long escaped identification.
Strigolactone inhibition of branching independent of polar. Three ancient hormonal cues coordinate shoot branching in. May 26, 2020 control of branching is critical for optimizing growth and adaptation in plants. Strigolactones sls are carotenoidderived phytohormones and rhizosphere signaling molecules for arbuscular mycorrhizal fungi and root parasitic weeds. Dwarf14 d14 is a strigolactone receptor that plays a central role in suppression of shoot branching, and hence is a potential target to increase crop productions and biomass. Lateral branching oxidoreductase acts in the final stages of.
Interactions between auxin and strigolactone in shoot. Outgrowth is a more interesting target for breeders, since it allows greater flexibility in branching. Forward genetic screens identifying increased branching mutants. Sep 11, 2015 chrysanthemum dendranthema grandiflorum cv. Because the active shoot branching inhibitor mecla accumulates in lbo mutants, the intermediate branching phenotype of lbo mutants might be explained by the presence of mecla. Carlactone is an endogenous biosynthetic precursor for. Dec 23, 20 therefore, we tested whether the altered branching phenotypes in the bes1related mutants were regulated by sls, and found that, unlike the wildtype and a sldeficient mutant max31, bes1d mutant was insensitive to the applied gr24, a synthetic analog of sls inhibiting shoot branching, similar to max21 figure 1c. Arrows in the pathway might indicate multiple steps.
Strigolactones sls represent the most recent class of hormones identified in. Strigolactone can promote or inhibit shoot branching by triggering. The highly pleiotropic tir3 mutant is hypersensitive to strigolactone inhibition of root growth shinohara et al. Brc1 expression in strigolactoneregulated shoot branching in arabidopsis. Mar 18, 20 strigolactones belong to a newly identified class of plant hormones that are involved in the inhibition of shoot branching. This recent discovery offers the possibility of using sls to regulate branching commercially, for example, in chrysanthemum, an important. Recently, we reported a fluorescence turnon probe, yoshimulactone green ylg, which generates a strong fluorescence upon the hydrolysis by d14type strigolactone receptors. Here, cytochrome p450 cyp722c is identified as a key enzyme that catalyzes the reaction of bcring closure leading to orobanchol, the most prevalent canonical sl. All tested compounds with a tricyclic lactone coupled to a methylbutenolide via an enol ether bond showed activity, but differed in the active concentration and in the branching pattern of hyphae.
Ccds are nonheme iron enzymes that cut cc double bonds by incorporating a dioxygen, yielding carbonyl products 47. Strigolactones enhance competition between shoot branches. Axillary buds are indeterminate structures that can be arrested and await endogenous or environmental cues for outgrowth. Inhibition of shoot branching by new terpenoid plant hormones. Despite the fact that multiple modes of interaction between d14 and strigolactone have recently been determined, how the hydrolase functions with d3 to. Iaa free buffer, whereas it decreased immediately after incubation with iaa buffer. Shoot branching is controlled by the formation and subsequent outgrowth of axillary buds in the axils of leaves. Therefore, understanding how strigolactones are made, transported. Auxincytokinin interactions in the control of shoot branching. Mar 31, 2014 although brassinosteroids do not directly influence shoot branching, the strigolactone dependent destruction of bes1 could potentially dampen brassinosteroid signaling. Although strigolactone appears to be involved in the shoot branching phenotype of bdl2 mutants, it is unlikely to play a role in the embryonic phenotype hamann et al. Jul 01, 2009 strigolactone pathway for shoot branching inhibition. Does abscisic acid affect strigolactone biosynthesis.
Herein, we applied a ylgbased in vitro assay to a highthroughput chemical screening and identi. Why and how plants produce diverse sls are unknown. Thus, it was suggested that lbo is necessary for complete suppression of shoot branching in plants by converting the partly bioactive mecla to a compound with greater. Strigolactone inhibition of shoot branching by victoria gomezroldan, soraya fermas, philip brewer, virginie puechpages, elizabeth dun, jeanpaul pillot, fabien letisse, radoslava matusova, saida danoun, jeancharles portais, harro bouwmeester, guillaume becard, christine beveridge, catherine rameau and soizic rochange. Few sls were tested for shoot branching inhibition so far gomezroldan et al. Strigolactonemax2induced degradation of brassinosteroid. Thus, both groups conclude that strigolactones or their derivatives not only signal to organisms that interact with plant roots but also act to regulate lateral branching. A carotenoidderived hormonal signal that inhibits shoot branching in plants has long escaped identification. Zmccd8 revealed that although sls may not completely regulate the tb1 gene in maize, they have significant additive effects on. Aug 10, 2008 strigolactone inhibition of shoot branching. Here we present evidence that carotenoid cleavage dioxygenase 8 shoot branching mutants of pea are strigolactone. Frontiers impacts of strigolactone on shoot branching. Aug 21, 2015 the noxious weed striga can take down an entire crop. However, how sls inhibit shoot branching after its perception by the receptor complex.
Inhibition of shoot branching is among the bestunderstood responses of sls in flowering plants. Strigolactones enhance competition between shoot branches by. Knockout of vvccd8 gene in grapevine affects shoot branching. Strigolactone inhibition of branching independent of polar auxin transport.
A particularly striking illustration of this is the ability of strigolactone to promote shoot branching in the tir3 mutant background, which is difficult to explain if strigolactones act as direct inhibitors of bud growth but is a prediction of the model in which strigolactones act to modulate auxin transport. In arabidopsis arabidopsis thaliana, the carotenoid cleavage dioxygenases more axillary growth3 max3 and max4 act together with max1 to produce a strigolactone signaling molecule required for the inhibition of axillary bud outgrowth. Recently, sl structural requirements for shoot branching inhibition were studied in pea using a variety of natural sls and sl analogs boyer et al. Pdf inhibition of shoot branching by new terpenoid plant. Pdf shoot branching is a major determinant of plant architecture and is highly regulated by endogenous and. In the last five years, insights into the sl biosynthetic pathway have also. The authors, based on their data and recently published results, suggest that longdistance, as well local strigolactone transport might occur in a celltocell manner rather than via the xylem stream. Dl1 competes with endogenous strigolactones, thereby increasing the number of shoot branching in a model plant arabidopsis as well as in rice. Lateral branching oxidoreductase acts in the final.
Strigolactones sls, or their derivatives, were recently demonstrated to act as endogenous shoot branching inhibitors, but their biosynthesis and mechanism of. Strigolactone inhibition of shoot branching nature. Pdf inhibition of shoot branching by new terpenoid plant hormones. Shoot branching depends on both the formation of axillary buds in the axils of leaves and their subsequent outgrowth.
Mar, 2019 furthermore, the data support the idea that strigolactone modulates shoot branching at least in part through effects on auxin transport canalisation between the bud and the main stem. Frontiers impacts of strigolactone on shoot branching under. Strigolactone biosynthesis and biology molecular microbial. Strigolactones sls, or their derivatives, were recently demonstrated to act as endogenous shoot branching inhibitors, but their biosynthesis and mechanism of action are poorly understood. Their role as indispensable chemical signals for root colonization by symbiotic. Strigolactones are a structurally diverse class of plant hormones that control many aspects of shoot and root growth.
In agreement with the expected properties of the hormonal signal, exogenous strigolactone can be transported in shoots and act at low concentrations. Strigolactones inhibit auxin feedback on pindependent auxin. Jinba shoot branching is determined by bud outgrowth during the vegetative growth stage. Hydrolysis of strigolactone, resulting in a free dring that serves as a molecular glue at the entrance of the receptor, mediating interaction with another protein. New genes in the strigolactonerelated shoot branching. A genetic framework for regulation and seasonal adaptation of. Strigolactones in an experimental context springerlink. Striga seeds germinate in response to faint traces of the hormone strigolactone released by its targets.
Strigolactone inhibition of shoot branching pub med. Structural requirements of strigolactones for shoot. Direct conversion of carlactonoic acid to orobanchol by. The carotenoid cleavage dioxygenase ccd inhibitor d2 reduced strigolactone but not aba content of roots. Strigolactones are key regulators of plant development and interaction with symbiotic fungi.
We show that both max3 and max4 transcripts are positively aux. Strigolactone biosynthesis and signaling in plant development. Fields in africa are particularly susceptible to the devastation it can cause. In a similar vein, yet another study suggests that d14 exhibits strigolactone dependent binding to the gibberellic acid ga signaling protein slr1 23. Shoot branching is a highly plastic developmental trait that is greatly affected by. The artificial regulation of sl signaling has been considered a potent agricultural technique because plant architecture is strongly related to crop yield. Strigolactones are compounds thought to be derived from carotenoids and are known to trigger the germination of parasitic plant seeds and stimulate symbiotic fungi. Strigolactones sls, first identified for their role in parasitic and symbiotic interactions in the rhizosphere, constitute the most recently discovered group of plant hormones. Karrikins force a rethink of strigolactone mode of action. Strigolactone inhibition of shoot branching nasaads. Shoot branching is a highly plastic developmental trait that is greatly affect. Development of potent inhibitors for strigolactone. Rochange sf 2008 strigolactone inhibition of shoot branching.
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