Strigolactone and abscisic acid synthesis and signaling pathways are enhanced in the wheat oligo-tillering mutant .

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Tiller number greatly contributes to grain yield in wheat. Using ethylmethanesulfonate mutagenesis, we previously discovered the oligo-tillering mutant . The tiller number was significantly lower in than in the corresponding wild type from the early tillering stage until the heading stage. Compared to the wild type, the thousand-grain weight and grain length were increased by 15.41% and 31.44%, respectively, whereas the plant height and spike length were decreased by 26.13% and 37.25%, respectively. Transcriptomic analysis was conducted at the regreening and jointing stages to identify differential expressed genes (DEGs). Functional enrichment analysis with the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) databases showed differential expression of genes associated with ADP binding, transmembrane transport, and transcriptional regulation during tiller development. Differences in tiller number in led to the upregulation of genes in the strigolactone (SL) and abscisic acid (ABA) pathways. Specifically, the SL biosynthesis genes (), , , and () were upregulated by 3.37- to 8.23-fold; the SL signal transduction genes and were upregulated by 1.81- and 1.32-fold, respectively; the ABA biosynthesis genes -- () and were upregulated by 1.66- and 3.4-fold, respectively; and () and () genes were upregulated by 1.30- to 4.79-fold. This suggested that the tiller number reduction in was due to alterations in plant hormone pathways. Genes known to promote tillering growth were upregulated, whereas those known to inhibit tillering growth were downregulated. For example, (), which promotes tiller development, was upregulated by 8.23-fold in ; (), which inhibits tiller development, was downregulated by 1.74-fold. There were no significant differences in the expression levels of () or (), indicating that the tiller reduction in was not controlled by known genes. Our findings provide valuable data for subsequent research into the genetic bases and regulatory mechanisms of wheat tillering.

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The online version contains supplementary material available at 10.1007/s11032-024-01450-3.