Distribution, Function and Polymorphism Characteristics of Microsatellites in Pyropia yezoensis Transcriptome

The distribution, putative function and polymorphism characteristics of simple sequence repeats (SSRs) in P. yezoensis transcriptome were analyzed in this study. In tota., 307. SSRs were detected among 2681 unigenes. Trinucleotide types were dominant, constituting 91.87% of all the microsatellites. The most abundant SSR was CCG (71.03%) and the second abundant one was AGC (234, 7.61%). A total of 111 (3.61%) dinucleotide types were found and the most abundant one was AC (51, 1.66%) which was followed by CG (34, 1.11%). SSRs identified showed a GC bases preference; GC bases constituted 89.73% of all the SSR bases. SSRs occurrence number decreased as repetitions increased. Annotation results exhibited that the majority of SSRs-containing unigenes have the functions of metabolic process', binding' and catalytic activity' and existed as the forms of cell', cell component' and organelle'. The dominant amino acids that SSRs coded were Ala (28.59%), Arg (26.02%), Gly (14.35%) and Pro (13.65%). Amplification results showed that 3 out 23 SSRs from transcriptome (13.04%) and 8 out 77 SSRs from genome (10.39%) were polymorphic.