Anther length is the critical floral trait determining hybrid rice seed production and is controlled by many quantitative trait loci (QTL). However, the cloning of genes specifically controlling anther size has yet to be reported. Here, we report the fine mapping of qAL5.2 for anther size using backcross inbred lines (BILs) in the genetic background of Oryza sativa indica Huazhan (HZ). Gene chip analysis on the BC4F2 and BC5F1 population identified effective loci on Chr1, Chr5, and Chr8 and two genomic regions on Chr5, named qAL5.1 and qAL5.2. qAL5.2 was identified in both populations with LOD values of 17.54 and 10.19, which explained 35.73% and 25.1% of the phenotypic variances, respectively. Ultimately qAL5.2 was localized to a 73 kb region between HK139 and HK140 on chromosome 5. And we constructed two near-isogenic lines (NILs) for RNA-seq analysis, named NIL-qAL5.2HZ and NIL-qAL5.2KLY, respectively. The result of the GO enrichment analysis revealed that differential genes were significantly enriched in the carbohydrate metabolic process, extracellular region, and nucleic acid binding transcription, and KEGG enrichment analysis revealed that alpha-linolenic acid metabolism was significantly enriched. Meanwhile, candidate genes of qAL5.2 were analyzed in RNA-seq, and it was found that ORF8 is differentially expressed between NIL-qAL5.2HZ and NIL-qAL5.2KLY. The fine mapping of qAL5.2 conferring anther length will promote the breed improvement of the restorer line and understanding of the mechanisms driving crop mating patterns.
Keywords: Oryza sativa; anther length; fine mapping; hybrid rice; outcrossing.