Branching in rice.

Rice branching, including the formation of tillers and panicle branches, has been well investigated over the past several years because of its agronomic importance. A major breakthrough in elucidating rice tillering in the recent years was the discovery of strigolactones, a specific group of terpenoid lactones that can inhibit axillary bud outgrowth. Since that discovery, new tillering mutants, that is, dwarf 27 (d27) or dwarf14 (d14, also reported as d88 or htd2), have been identified with reduced strigolactone levels or strigolactone response. DWARF27 (D27) and DWARF14 (D14) probably act on strigolactone biosynthesis and signal transduction, respectively. Additionally, several genes controlling panicle branches have been identified recently. DEP1 and IPA1/WFP are essential dominant/semidominant regulators that determine rice panicle branches and thus affect the grain yields. More importantly, dep1 and ipa1 alleles have been shown to be applicable for the improvement of rice grain yields in molecular breeding.