Table 1.

Distribution of core RNAi machinery components, small RNAs, and experimentally induced RNAi in algal species^g

Species or strain	Genome size (Mb)	AGO-Piwi like	Dicer like	RDR like	miRNAs/siRNAs	RNAi	Reference(s)
Archaeplastida
Green algae
Ostreococcus tauri	12.5	−	−	−	U	U	21
Ostreococcus lucimarinus	13.2	−	−	−	U	U	68
Micromonas sp. strain RCC299	20.9	+ (1)	−	−	U	U	95
Micromonas sp. strain CCMP1545	21.9	−	−	−	U	U	95
Chlorella variabilis NC64A	46.0	+ (1)	+ (1)	−	U	U	6
Coccomyxa sp. strain C-169a	49.0	+ (2)	?	+ (1)	U	U
Chlamydomonas reinhardtii	120.0	+ (3)	+ (3)	−	Y	Y	46, 59, 79
Volvox carterib	138.0	+ (2)	+ (1)	−	U	Y	16, 24, 74
Dunaliella salina	300.0	U	U	U	U	Y	44, 85
Red algae
Cyanidioschyzon merolae	16.5	−	−	−	U	U	57
Porphyra yezoensisb	260.0	U	U	U	Y	U	52, 56
Chromalveolata
Stramenopiles
Diatoms
Phaeodactylum tricornutum	27.4	+ (1)	?	+ (1)	Y	Y	7, 22, 77
Thalassiosira pseudonana	32.4	+ (1)	?	+ (2)	U	U	3
Fragilariopsis cylindrusc	80.5	+ (2)	+ (2)	?	U	U
Brown alga Ectocarpus siliculosusb	214.0	+ (1)	+ (1)	+ (2)	Y	U	17
Yellow-green alga Vaucheria frigidad	U	U	U	U	U	Y	87
Pelagophyte Aureococcus anophagefferens	56.0	−	−	−	U	U	31
Haptophyte Emiliania huxleyi CCMP1516e	168.0	+ (1)f	?	+ (3)f	U	U
Rhizaria, chlorarachniophytes	U	U	U	U	U	U
Excavata, euglenoid Euglena gracilis	U	U	U	U	U	Y	42, 43

^ahttp://genome.jgi-psf.org/Coc_C169_1/Coc_C169_1.home.html.

^bMulticellular algal species.

^chttp://genome.jgi-psf.org/Fracy1/Fracy1.home.html.

^dCoenocytic filamentous alga.

^ehttp://genome.jgi-psf.org/Emihu1/Emihu1.home.html.

^fPossibly additional genes in the genome; evaluation limited by incomplete models in draft genome.

^gAbbreviations: −, gene absent from the genome; +, gene present in the genome (number of encoding genes indicated in parentheses); ?, gene possibly present in the genome but fairly divergent from canonical models; U, unknown; Y, occurrence of miRNAs/siRNAs or of experimentally induced RNAi.