Table I.

Comparison of select models and crops

Parameter	Arabidopsis	Barley	Brachypodium	Foxtail Millet	M. sinensis	Maize	Rice	S. viridis	Sorghum	Switchgrass	Wheat
Height (cm)	15–20	50–120	15–20	120–200	150–300	120–300	100	10–250	50–250	200–300	50–100
Densitya (plants m−2)	2,000	80–120	1,000	50	3–4	4	36	1,000	50	6	50
Growth requirementsb (controlled conditions)	Simple	Intermediate	Simple	Intermediate	Demanding	Demanding	Demanding	Simple	Demanding	Demanding	Intermediate
Efficiently crossed?	Yes	Yes	Yes	No	Yes	Yes	Yes	No	Yes	Yes	Yes
Reproduction	Selfing	Selfing	Selfing	Selfing	Outcrossing	Outcrossing/self-compatible	Selfing	Selfing	Selfing	Outcrossing	Selfing
Typical generation time (weeks)	8–12	10–20	8–12	11–13	12	8–15	12–24	6–8	13–18	26	10–20
Seeds per plant	>1,000	150–200	100–1,000	>10,000	>1,000	200–1,000	>1,000	>5,000	>1,000	>1,000	50–150
Transformation	Extremely easy	Efficient, but labor intensive	Highly efficient	Reported, but not efficient	Inefficient	Efficient, but labor intensive	Highly efficient	Efficientc	Inefficient	Efficient, but slow	Inefficient
Genome size (Mb)	119d	5,500	272d	515	5,000	2,300df	382d	515	700de	2,400	16,000
Assembled genome sequence	Finished genome sequence	Draft genome sequencing in progress	High-quality draft (finishing under way)	Draft genome	No	Draft genomef	Finished genome sequence	Draft genome sequencing in progress	Draft genomed	Sequencing in progress	Sequencing in progress
T-DNA resources	Extensive	None	10,000 lines available, 40,000 more planned	None	None	Transposon mutants are available	Extensiveg	None	None	None	None
Cell wall type	Type 1	Type 2	Type 2	Type 2	Type 2	Type 2	Type 2	Type 2	Type 2	Type 2	Type 2
Photosynthesis	C3	C3	C3	C4	C4	C4	C3	C4	C4	C4	C3

^aHigh-density planting under laboratory conditions.

^bThe difficulty of growing plants is dependent upon their size and the range of environmental conditions tolerated. Thus, small plants that tolerate varied conditions have simple growth requirements and large plants that need carefully controlled environmental conditions have demanding growth requirements.

^cUnpublished data (T. Brutnell).

^dAssembled genome size.

^eApproximately 20% of the genome was not assembled because of the repetitive nature.

^fAssembly consists of sequenced BACs many of which contain unordered genes because of the difficulty associated with assembling repetitive DNA.

^gWhile rice has extensive insertional mutant resources, the availability of the resources is constrained by quarantine restrictions and intellectual property concerns.