Table 1. Strategies for grain improvement through starch biosynthesis.

Pathway	Strategy	Effectiveness
ATP supply	Down-regulated ANK	Increased ADPG, UDPG and starch contents
Sucrose synthesis	Over-expressed SUT1	Increased starch content
Sucrose → UDPG	Enhanced SuSy activity	Increased ADPG, UDPG and starch contents
UDPG → ADPG	Mutated Brittle1	Increased lipid content, but decreased protein and amylopectin contents
	Enhanced AGP activity	Increased starch content
	Over-expressed AGPase	Increased starch content
ADPG → Starch	Over-expressed GBSSI/Wx	Increased GC and AC
	Over-expressed SBE/ISA3	Increased GC and GT
	Over-expressed SSII	Increased GC, GT and GT
	Over-expressed SSIV	Change starch structure
	Down-regulated AMY	Increased amylopectin contents
	Over-expressed PPDK	Increased starch content, but decreased protein content
	Down-regulated Pho	Increased starch content