Identification and characterization of four novel xiaomi alleles to facilitate foxtail millet as a C4 model plant

Abstract

Abstract Diverse genetic background is essential for genetic analysis and functional genomics research in model plants. In this paper, four novel xiaomi-like mutants, named xiaomi3, xiaomi4, xiaomi5, and xiaomi6, were identified and characterized in different genetic backgrounds. These mutants exhibited an extremely early heading phenotype, with heading occurring around 30-40 days after sowing under natural long-day conditions. Significant reductions in plant height, leaf length, leaf width, panicle length, and panicle diameter were observed in the mutants compared to their corresponding wild-types. Notably, these mutants displayed diverse panicle architectures and hull colors, effectively preventing seed mixing between them. Subsequent investigation under controlled short-day and long-day conditions confirmed the significant early heading phenotype of the mutants. Molecular characterization revealed mutations in the Phytochrome C (SiPHYC) gene, including transposon insertions and a frame shift mutation, were responsible for the extremely early heading phenotype. RNA-sequencing (RNA-Seq) analysis identified 19 differentially expressed genes associated with the extremely early heading phenotype. Additionally, genome-wide InDels and SNPs were identified, providing valuable resources for marker-assisted breeding and genetic studies. These findings advance our comprehension of the genetic and molecular mechanisms underlying SiPHYC mediated photoperiod flowering, and provide valuable resources that will push xiaomi as a C4 model plant.