Planta (2008) 229:225–233 DOI 10.1007/s00425-008-0822-1 123 ORIGINAL ARTICLE Mycosporine-like amino acids (MAAs) proWle of a rice-Weld cyanobacterium Anabaena doliolum as inXuenced by PAR and UVR Shailendra P. Singh · Rajeshwar P. Sinha · Manfred Klisch · Donat-P. Häder Received: 5 June 2008 / Accepted: 11 September 2008 / Published online: 2 October 2008  Springer-Verlag 2008 Abstract The mycosporine-like amino acid (MAA) proWle of a rice-Weld cyanobacterium, Anabaena doliolum, was studied under PAR and PAR + UVR conditions. The high-performance liquid chromatographic analysis of water-soluble compounds reveals the biosynthesis of three MAAs, mycosporine-glycine ( max = 310 nm), porphyra- 334 ( max = 334 nm) and shinorine ( max = 334 nm), with retention times of 4.1, 3.5 and 2.3 min, respectively. This is the Wrst report for the occurrence of mycosporine-glycine and porphyra-334 in addition to shinorine in Anabaena strains studied so far. The results indicate that mycospo- rine-glycine (monosubstituted) acts as a precursor for the biosynthesis of the bisubstituted MAAs shinorine and por- phyra-334. Mycosporine-glycine was under constitutive control while porphyra-334 and shinorine were induced by UV-B radiation, indicating the involvement of UV-regu- lated enzymes in the biotransformation of MAAs. It seems that A. doliolum is able to protect its cell machinery from UVR by synthesizing a complex set of MAAs and thus is able to survive successfully during the summer in its natu- ral brightly lit habitats. Keywords Anabaena doliolum · Mycosporine-like amino acids · Mycosporine-glycine · Porphyra-334 · Shinorine · UVR Abbreviations HPLC High-performance liquid chromatography MAAs Mycosporine-like amino acids PAR Photosynthetically active radiation UVR Ultraviolet radiation UV-A Ultraviolet-A UV-B Ultraviolet-B Introduction Cyanobacteria are gram-negative prokaryotes having a cos- mopolitan distribution ranging from hot springs to the Arc- tic and Antarctic regions (Stanier and Cohen-Bazire 1977). They were the Wrst photosynthetic oxygen-evolving pro- karyotes which appeared during Precambrian era (Brocks et al. 1999; Schopf 2000). Cyanobacteria are important primary producers in both terrestrial as well as aquatic ecosystems contributing considerably to the net primary productivity. In addition, their inherent capacity to Wx atmospheric nitrogen makes them ecologically important. These nitrogen-Wxing organisms are an important compo- nent of microbial populations in wetland habitats where their contribution, especially in maintaining the fertility of rice-Welds as natural biofertilizers, has been well recog- nized (Vaishampayan et al. 2001). The continued depletion of the stratospheric ozone layer due to atmospheric pollutants such as chloroXuorocarbons, chlorocarbons and organo-bromides has resulted in an increase in UV-B (280–315 nm) radiation on the Earth’s surface during the last few decades (Crutzen 1992; Lubin and Jensen 1995). The process of ozone depletion has been reported at mid latitude and especially in the Antarctic where ozone levels decline by more than 70% during late winter and early spring in the polar vortex (Smith et al. S. P. Singh · M. Klisch · D.-P. Häder (&) Department of Biology, Chair of Plant Ecophysiology, Friedrich-Alexander University Erlangen-Nuremberg, Staudtstrasse 5, 91058 Erlangen, Germany e-mail: dphaeder@biologie.uni-erlangen.de R. P. Sinha Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi 221005, India