Isolation of a Novel Lodging Resistance QTL Gene Involved in Strigolactone Signaling and Its Pyramiding with a QTL Gene Involved in Another

ABSTRACT Lodging has been a major roadblock to attaining increased crop productivity. In an attempt to understandthe mechanism for culm strength in rice, we isolated an effective quantitative trait locus (QTL), STRONGCULM3 (SCM3), the causal gene of which is identical to rice TEOSINTE BRANCHED1 (OsTB1), a gene pre-viously reported to positively control strigolactone (SL) signaling. A near-isogenic line (NIL) carrying SCM3showed enhanced culm strength and increased spikelet number despite the expected decrease in tillernumber,indicatingthatSLalsohasapositiveroleinenhancingculmstrengthandspikeletnumber.Wepro-duced a pyramiding line carrying SCM3 and SCM2, another QTL encoding APO1 involved in panicle devel-opment. The NIL-SCM2+SCM3 showed a much stronger culm than NIL-SCM2 and NIL-SCM3 and anincreased spikelet number caused by the additive effect of these QTLs. We discuss the importance ofutilizing suitable alleles of these STRONG CULM QTLs without inducing detrimental traits for breeding.Key words: culm, OsTB1, strigolactone, lodging resistance, quantitative trait lociYanoK.,OokawaT.,AyaK.,OchiaiY.,HirasawaT.,EbitaniT.,TakaradaT.,YanoM.,YamamotoT.,FukuokaS., Wu J., Ando T., Ordonio R.L., Hirano K., and Matsuoka M. (2015). Isolation of a Novel Lodging ResistanceQTLGeneInvolvedinStrigolactoneSignalingandItsPyramidingwithaQTLGeneInvolvedinAnotherMechanism.Mol. Plant. 8, 303–314.