Table 2.

Comparison between siRNAs and miRNAs among plants and animals.

	Animals	Plants
siRNAs	Usually, single dicer involved in all types of siRNA generation	Different dicers required in Arabidopsis (4), Rice (10)
	Redundancy at functional level not observed	Major proteins (dicer, argonaute) are functionally redundant
	Systemic spread requires SID-1 protein	Systemic spread requires PRSP1 (cucurbits) and SNF2 (Arabidopsis) protein
	Target cleavage, DNA methylation	Target cleavage, DNA methylation
	siRNAs can participate in genomic DNA elimination	No such role attributed here
miRNAs	Generally, target repression	Generally, target cleavage
	More than one miR can reside on pri-miR	Strictly one miR from one pri-miR
	Target various mRNAs	More biased towards TF transcripts
	Multiple miRNA binding sites per target	Usually single with one exception
	More than one miRNA can bind target	No report
	Duplex miRs are formed in cytosol	Duplexes miRs are formed inside nucleus
	Mature miRNAs can be trafficked back to nucleus	No such validated report
	Pri- or pre-miR are subjected to editing	No such phenomena observed
	Repressed mRNAs are stored in special organelles called P-bodies	No such structure observed