Carotenoid Metabolism & Mycorrhiza

The massive local accumulation of CH/MR apocarotenoids in arbusculated cells of mycorrhizal roots clearly involves activation of both carotenoid-producing and carotenoid cleaving steps indicating that these compounds are not produced from existing root carotenoids. Whereas CH/MR are virtually absent from non-mycorrhizal roots, SLs are produced in such roots and are synthesized most strongly under phosphate starvation conditions. However, it is not clear whether SLs are formed from root carotenoid pools or whether their formation depends on upregulation of carotenoid biosynthesis as well. We are analyzing several isogene families involved in carotenogenesis for their regulation in roots starved for certain mineral nutrients including phosphate as compared to their regulation upon mycorrhization.