Table 1. The number of the DEAD-box, DEAH-box and DExD/H-box RNA helicase genes in Arabidopsis, Oryza sativa, Zea mays, Glycine max.

Species	DEAD-box	DEAH-box	DExD/H-box	Total	Alternative Splicing	Alternative Splicing (%)
Arabidopsis	50/66	40/52	71/99	161/217	56	25.81
Oryza sativa	51/79	33/41	65/79	149/199	50	25.12
Zea mays	57/86	31/44	50/85	136*/215	79	36.74
Glycine max	87/101	48/55	78/92	213/248	35	14.11

Note: In front of diagonal not include the number of alternative splicing; in the back of diagonal include the number of alternative splicing.

^*In Zea mays, there are two especial genes with different alternative splicing belongs to different RNA helicase subfamilies.