Cloning and characterisation of a maize carotenoid cleavage dioxygenase (ZmCCD1) and its involvement in the biosynthesis of apocarotenoids with various roles in mutualistic and parasitic interactions

We have demonstrated that the strigolactones are derived from the carotenoid pathway probably with the involvement of a carotenoid cleaving enzyme

Zhongkui Sun; Joachim Hans; Michael H. Walter; Radoslava Matusova; Jules Beekwilder; Francel W. A. Verstappen; Zhao Ming; Esther van Echtelt; Dieter Strack; Ton Bisseling; Harro J. Bouwmeester


Scholarcy highlights

  • Carotenoid cleavage dioxygenases and 9-cis-epoxycarotenoid dioxygenases constitute a family of enzymes that catalyse the cleavage of carotenoids at speciWc double bonds
  • The maize CCD1 had two open-reading frames starting with an ATG, one of 1,650 bp and another of 1,623 bp, encoding proteins of 550 and 541 amino acids, respectively, with calculated molecular weight of about 61 kD
  • We have shown that a recombinant maize carotenoid cleavage dioxygenase, ZmCCD1, cleaves carotenoid substrates at the 9, 10 positions leading to the formation of C13 apocarotenoids, that vary according to the substrate, and most likely a C14-dialdehyde
  • We have demonstrated here that ZmCCD1 transcript levels are up-regulated in mycorrhizal maize roots upon colonisation by arbuscular mycorrhizal fungi
  • Cyclohexenone and mycorradicin formation is preceded by the up-regulation of many genes of the carotenoid biosynthetic pathway such as deoxyxylulose-5-phosphate synthase 2, d-xylulose-5-phosphate reductoisomerase, and phytoene desaturase probably leading to a considerable increase in carotenoid precursor pools in the roots of plants colonised by AM fungi
  • Our future work will be to overexpress and knockout ZmCCD1 in maize—or orthologs in other plant species—to study the importance of the cyclohexenone and mycorradicin derivatives for the symbiotic interaction of plants with AM fungi and to study whether root-directed CCD1 overexpression without mycorrhizal colonisation leads to reduced strigolactone formation
  • It could potentially be used to develop crop varieties with improved Striga resistance through a lower production of germination stimulants

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