Fine Mapping and Cloning of the Novel Gene Qph-IAA30, which Simultaneously Affects the Plant Height, Panicle Length, Spikelet Number and Yield in Rice (Oryza Sativa L.)

Background: The plant height is one of the most important agronomic traits in rice ( Oryza sativa L.), and the introduction of semidwarf rice led to record yield increases throughout Asia in the 1960s. Near-isogenic lines (NILs) are the most powerful tools for the detection and precise mapping of quantitative trait loci (QTLs). Results: : In this study, 176 NILs were produced from the crossing and back-crossing of two rice cultivars. Specifically, Jiafuzhan, an indica rice cultivar, served as the recipient, and Hui1586, a restorer japonica cultivar, served as the donor. Using the 176 NILs, we identified a novel QTL for plant height in NIL36. First, we mapped the QTL to a 31-kb region between the markers Indel12-29 and Indel12-31. The rice genome annotation indicated the presence of three candidate genes in this region. Through gene prediction and cDNA sequencing, we confirmed that the target gene in NIL36 was Osiaa30 , hereafter referred to as qPH-iaa30 . Further analysis showed that qPH-iaa30 was produced by a 1-bp deletion in the first exon that resulted in the premature termination of OsIAA30 . K nockout experiments showed that qPH-IAA30 was responsible for the plant height phenotype. Although qPH-IAA30 from Jiafuzhan showed a higher plant height, the plant also exhibited a longer panicle length, more spikelets and a higher yield. Taken together, our results demonstrate that qPH-IAA30 has good specific application prospects in future rice breeding. Conclusions: : 176 NILs are produced from two rice cultivars, using the 176 NILs, a novel qPH-iaa30 for plant height is identified, and the qPH-IAA30 gene is responsible for the plant height phenotype.