Fine mapping of qPAA8, a gene controlling panicle apical development in rice.

In rice, one detrimental factor influencing single panicle yield is the frequent occurrence of panicle apical abortion (PAA) under unfavorable climatic conditions. Until now, no detailed genetic information has been available to avoid PAA in rice breeding. Here, we show that the occurrence of PAA is associated with the accumulation of excess hydrogen peroxide. Quantitative trait loci (QTLs) mapping for PAA in an F(2) population derived from the cross of L-05261 (PAA line) × IRAT129 (non-PAA variety) identified seven QTLs over a logarithm of the odd (LOD) threshold of 2.5, explaining approximately 50.1% of phenotypic variance for PAA in total. Five of the QTLs with an increased effect from L-05261, were designated as qPAA3-1, qPAA3-2, qPAA4, qPAA5 and qPAA8, and accounted for 6.8%, 5.9%, 4.2%, 13.0% and 12.2% of phenotypic variance, respectively. We found that the PAA in the early heading plants was mainly controlled by qPAA8. Subsequently, using the sub-populations specific for qPAA8 based on marker-assisted selection, we further narrowed qPAA8 to a 37.6-kb interval delimited by markers RM22475 and 8-In112. These results are beneficial for PAA gene clone.