Stereospecificity in strigolactone biosynthesis and perception
- 2.1k Downloads
Plants produce strigolactones with different structures and different stereospecificities which provides the potential for diversity and flexibility of function.
Strigolactones (SLs) typically comprise a tricyclic ABC ring system linked through an enol-ether bridge to a butenolide D-ring. The stereochemistry of the butenolide ring is conserved but two alternative configurations of the B–C ring junction leads to two families of SLs, exemplified by strigol and orobanchol. Further modifications lead to production of many different strigolactones within each family. The D-ring structure is established by a carotenoid cleavage dioxygenase producing a single stereoisomer of carlactone, the likely precursor of all SLs. Subsequent oxidation involves cytochrome P450 enzymes of the MAX1 family. In rice, MAX1 enzymes act stereospecifically to produce 4-deoxyorobanchol and orobanchol. Strigol- and orobanchol-type SLs have different activities in the control of seed germination and shoot branching, depending on plant species. This can partly be explained by different stereospecificity of SL receptors which includes the KAI2/HTL protein family in parasitic plants and the D14 protein functioning in shoot development. Many studies use chemically synthesised SL analogues such as GR24 which is prepared as a racemic mixture of two stereoisomers, one with the same stereo-configuration as strigol, and the other its enantiomer, which does not correspond to any known SL. In Arabidopsis, these two stereoisomers are preferentially perceived by AtD14 and KAI2, respectively, which activate different developmental pathways. Thus caution should be exercised in the use of SL racemic mixtures, while conversely the use of specific stereoisomers can provide powerful tools and yield critical information about receptors and signalling pathways in operation.
KeywordsCarlactone Carotenoid α/β-Fold hydrolase Stereochemistry Strigolactone
The authors acknowledge financial support from the Australian Research Council (DP130103646; FT110100304). SMS acknowledges award of a Chinese Academy of Sciences Senior International Scientist Visiting Professorship and President’s International Fellowship (2013T1S0013).
- Abe S, Sado A, Tanaka K, Kisugi T, Asami K, Ota S, Kim HI, Yoneyama K, Xie X, Ohnishi T, Seto Y, Yamaguchi S, Akiyama K, Yoneyama K, Nomura T (2014) Carlactone is converted to carlactonoic acid by MAX1 in Arabidopsis and its methyl ester can directly interact with AtD14 in vitro. Proc Natl Acad Sci USA 111:18084–18089CrossRefPubMedPubMedCentralGoogle Scholar
- Artuso E, Ghibaudi E, Lace B, Marabello D, Vinciguerra D, Lombardi C, Koltai H, Kapulnik Y, Novero M, Occhiato EG, Scarpi D, Parisotto S, Deagostino A, Venturello P, Mayzlish-Gati E, Bier A, Prandi C (2015) Stereochemical assignment of strigolactone analogues confirms their selective biological activity. J Nat Prod 78:2624–2633CrossRefPubMedGoogle Scholar
- Booker J, Sieberer T, Wright W, Williamson L, Willett B, Stirnberg P, Turnbull C, Srinivasan M, Goddard P, Leyser O (2005) MAX1 encodes a cytochrome P450 family member that acts downstream of MAX3/4 to produce a carotenoid-derived branch-inhibiting hormone. Dev Cell 8:443–449CrossRefPubMedGoogle Scholar
- Boyer F-D, de Saint Germain A, Pillot J-P, Pouvreau J-B, Chen VX, Ramos S, Stévenin A, Simier P, Delavault P, Beau J-M, Rameau C (2012) Structure-activity relationship studies of strigolactone-related molecules for branching inhibition in garden pea: molecule design for shoot branching. Plant Physiol 159:1524–1544CrossRefPubMedPubMedCentralGoogle Scholar
- Igbinnosa I, Okonkwo SNC (1992) Stimulation of germination of seeds of cowpea witchweed (Striga gesnerioides) by sodium hypochlorite and some growth regulators. Weed Sci 40:25–28Google Scholar
- Kohlen W, Charnikhova T, Liu Q, Bours R, Domagalska MA, Beguerie S, Verstappen F, Leyser O, Bouwmeester H, Ruyter-Spira C (2011) Strigolactones are transported through the xylem and play a key role in shoot architectural response to phosphate deficiency in nonarbuscular mycorrhizal host Arabidopsis. Plant Physiol 155:974–987CrossRefPubMedPubMedCentralGoogle Scholar
- Scaffidi A, Waters MT, Sun YK, Skelton BW, Dixon KW, Ghisalberti EL, Flematti GR, Smith SM (2014) Strigolactone hormones and their stereoisomers signal through two related receptor proteins to induce different physiological responses in Arabidopsis. Plant Physiol 165:1221–1232CrossRefPubMedPubMedCentralGoogle Scholar
- Zhang Y, van Dijk AD, Scaffidi A, Flematti GR, Hofmann M, Charnikhova T, Verstappen F, Hepworth J, van der Krol S, Leyser O, Smith SM, Zwanenburg B, Al-Babili S, Ruyter-Spira C, Bouwmeester HJ (2014) Rice cytochrome P450 MAX1 homologs catalyze distinct steps in strigolactone biosynthesis. Nat Chem Biol 10:1028–1033CrossRefPubMedGoogle Scholar
- Zhao LH, Zhou XE, Wu ZS, Yi W, Xu Y, Li S, Xu TH, Liu Y, Chen RZ, Kovach A, Kang Y, Hou L, He Y, Xie C, Song W, Zhong D, Xu Y, Wang Y, Li J, Zhang C, Melcher K, Xu HE (2013) Crystal structures of two phytohormone signal-transducing α/β hydrolases: karrikin-signaling KAI2 and strigolactone-signaling DWARF14. Cell Res 23:436–439CrossRefPubMedPubMedCentralGoogle Scholar
- Zhao LH, Zhou XE, Yi W, Wu Z, Liu Y, Kang Y, Hou L, de Waal PW, Li S, Jiang Y, Scaffidi A, Flematti GR, Smith SM, Lam VQ, Griffin PR, Wang Y, Li J, Melcher K, Xu HE (2015) Destabilization of strigolactone receptor DWARF14 by binding of ligand and E3-ligase signaling effector DWARF3. Cell Res 25:1219–1236CrossRefPubMedGoogle Scholar