Angiospermic and non-angiospermic groups comprise plant species representing short and long range of discrepancies in their morphological, physiological, biochemical, molecular, and developmental processes. Analysis at molecular level plays crucial role to ascertain the heterogeneity within and across the species. The tandem repetitive DNA elements are one of the most important elements which play a significant role in various genetic and genomic applications. Therefore, the plasticity of tandem repetitive DNA element especially simple sequence repeats (SSRs) was analyzed in the expressed sequenced tags (ESTs) of both angiospermic and non-angiospermic species comprising 75 plant species belonging to different evolutionary clades such as algae, fungi, bryophytes, pteridophytes, gymnosperms, dicots, and monocots. Significantly, angiospermic and non-angiospermic species represented distinctiveness at GC content, SSR incidence and SSR motif distributions in their EST sequences. Notably, non-angiosperms revealed more GC-content compared to angiosperms but angiosperms depicted enhanced tandem repetitions (EST-SSRs) compared to non-angiosperms. Among different types of SSRs, mononucleotide SSRs represented widespread distribution followed by trinucleotide SSRs distribution in both angiosperms and non-angiosperms. In general, SSR motifs such as A/T, AG/CT, AAG/CTT, and CCG/CGG were found to be more repeated but highly complex motifs patterns were observed within hexa, penta, and tetranucleotide SSRs, respectively. Thus, a quantity of nexus and diversification were observed within and across the species as well as evolutionary clades. To infer, differential patterns of DNA tandem identified within ESTs can unfold the genetic polymorphism, diversification, conservation, and genome evolution within and across species.
Key words: Angiospermic species; non-angiospermic species; Expressed Sequence Tags (ESTs); Tandem Repeats, Simple Sequence Repeats (SSRs); Evolutionary clades or phylogenetic clades
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