Biological function identification of mutant gene <italic>HTD5</italic> regulating high tillering and dwarf traits in rice

<bold>Objective</bold> Tiller is a key factor affecting rice yield，and identifying genes related to tillering can lay the foundation for its functional analysis. <bold>Method</bold> This study used a novel high tillering and dwarf mutant（<italic>htd5</italic>）as the research material to investigate its phenotype，analyze the expression levels of high tillering and dwarf functional genes in <italic>htd5</italic>，and detect the variations in the coding region sequence of these genes in the <italic>htd5</italic> genome. <bold>Result</bold> （1）Compared with wild type（WT），the number of primary tiller，the number of secondary tiller，and the number of total tiller of <italic>htd5</italic> were markedly increased，while the plant height，the number of primary and secondary branches were significantly decreased.The elongation of inversion Ⅰ，Ⅱ，and Ⅲ internodes in the mutant <italic>htd5</italic> is hindered，and the diameter of each internode is significantly reduced.In addition，the grain width，grain thickness，and thousand grain weight of <italic>htd5</italic> were significantly decreased.（2）Compared with WT，the expression levels of the positive regulatory factors <italic>D27</italic>，<italic>D14</italic>，<italic>D3</italic>，and <italic>DHT1</italic> in strigolactones signaling pathway were significantly increased，while the expression levels of the negative regulatory factor <italic>D53</italic> significantly decreased.The sequencing analysis results indicate that there is no mutation in coding region sequence of the known high tiller and dwarf genes in the <italic>htd5</italic> genome. <bold>Conclusion</bold> <italic>HTD5</italic> is likely a novel high tillering and dwarf gene that affects rice tillering by regulating strigolactones signaling pathway in rice.