Fig. 1

Positional and size distributions of sRNAs in P. purpureum. a Positional distribution of RNA-seq reads on the P. purpureum chromosome. It’s just a relative position sketch as a result of no any chromosome information about this alga having been published until now. Abundant of reads were distributed between contig780 and contig2500 as the figure shown. b Size distribution of sRNAs in P. purpureum. It’s a length distribution of RNA-seq reads in the sRNA library. As shown by their frequencies, 21-nt length reads were the most abundant