OsDof1 enhances rice (Oryza sativa L.) lodging resistance through suppression of tryptophan-dependent auxin biosynthesis

Plant height and stem strength are pivotal determinants of lodging resistance in rice. In the study, OsDof1 was identified as a highly expressed stem-specific gene via bioinformatic analyses and demonstrated its significant homology to the wheat stem-strength-associated gene TdDof. OsDof1 overexpressing lines exhibited reduced plant height and increased stem-wall thickness, thereby enhancing lodging resistance, whereas knockout lines displayed opposing phenotypic characteristics. Cytological observations revealed that OsDof1 overexpression significantly shortened cell length and increased cell width, resulting in shorter internodes, thicker stem walls, and enhanced mechanical strength. Four OsDof1 target genes involved in the IAA biosynthesis via the Trp-dependent pathway were identified through integrated RNA sequencing (RNA-seq) and DNA affinity purification sequencing (DAP-seq). Subsequent qRT-PCR analysis and luciferase reporter assays demonstrated that OsDof1 could directly bind to the promoters of the four genes and transcriptionally suppress their expression, suggesting that the enhancement of OsDof1 in lodging resistance may be associated with regulating the biosynthesis of IAA hormone. The discovery of OsDof1 provides valuable genetic resources for the use of CRISPR-Cas9 technology in molecular breeding of lodging-resistant rice.