Upregulation of <i><scp>DWARF</scp>27</i> is associated with increased strigolactone levels under sulfur deficiency in rice

<jats:title>Abstract</jats:title><jats:p>Plants produce strigolactones (<jats:styled-content style="fixed-case">SL</jats:styled-content>s) in roots in response to nitrogen or phosphate deficiency. To evaluate <jats:styled-content style="fixed-case">SL</jats:styled-content> levels under other mineral deficiencies in rice, we cultivated rice seedlings in hydroponic media without nitrogen, phosphorus, potassium, sulfur, calcium, magnesium, and iron. Tiller bud outgrowth was stimulated under calcium deficiency because of low <jats:styled-content style="fixed-case">SL</jats:styled-content> levels. <jats:styled-content style="fixed-case">SL</jats:styled-content> levels increased under sulfur deficiency, in addition to phosphate, and nitrogen deficiencies. To explore which genes are key regulators of <jats:styled-content style="fixed-case">SL</jats:styled-content> production under sulfur deficiency, we analyzed the expression of <jats:styled-content style="fixed-case">SL</jats:styled-content>‐related genes in sulfur‐sufficient and sulfur‐deficient conditions. An <jats:styled-content style="fixed-case">SL</jats:styled-content> biosynthesis gene, <jats:italic><jats:styled-content style="fixed-case">DWARF</jats:styled-content>27</jats:italic> (<jats:italic>D27</jats:italic>), was strongly expressed under sulfur deficiency, and its expression was decreased by sulfur supply. The levels of <jats:italic>D10</jats:italic>,<jats:italic> D17</jats:italic>, and <jats:italic>Os<jats:styled-content style="fixed-case">MAX</jats:styled-content>1</jats:italic> transcripts did not differ between sulfur‐sufficient and sulfur‐deficient conditions. These results suggest that the increased <jats:styled-content style="fixed-case">SL</jats:styled-content> levels under sulfur deficiency are due to a high expression of <jats:italic>D27</jats:italic>. A combination of nitrogen, phosphorus, and sulfur deficiencies had no additive synergistic effect on <jats:styled-content style="fixed-case">SL</jats:styled-content> production. Under combined phosphorus and sulfur deficiency, the expression levels of most <jats:styled-content style="fixed-case">SL</jats:styled-content> biosynthesis genes were elevated. The number of tiller buds in the <jats:italic>d27</jats:italic> mutant was higher than in the wild type, but lower than in other <jats:italic>d</jats:italic> mutants. Under sulfur deficiency, the chlorophyll content of <jats:italic>d27</jats:italic> was lower than those of other <jats:italic>d</jats:italic> mutants. These results indicate that <jats:italic>D27</jats:italic> plays an important role in adaptation to sulfur deficiency in rice.</jats:p>