Defect in , a PHD-finger transcription factor, induces male sterility in ethyl methane sulfonate-mutagenized Chinese cabbage ( L. ssp. ).

Male sterility is an ideal character for the female parent in commercial hybrid seed production in Chinese cabbages. We identified three allele male sterile mutants /2/3 in progenies of ethyl methane sulfonate mutagenized Chinese cabbage. It was proved that their male sterilities were controlled by a same recessive nuclear gene. Cytological observation showed that the delayed tapetal programmed cell death (PCD) as well as the abnormal pollen exine and intine led to pollen abortion in these mutants. MutMap combined with KASP analyses showed that , a homologous gene of encoding a PHD-finger transcription factor and regulated pollen development, was the causal gene. A single-nucleotide mutation from G to A occurred at the 2443th base of in which results in premature termination of the PHD-finger protein translation; a single-nucleotide mutation from G to A existed at 1372th base in that makes for frameshift mutation; a single-nucleotide mutation from G to A distributed at 1887th base in which issues in the amino acid changed from Asp to Asn. The three allelic mutations in all led to the male sterile phenotype, which revealed its function in stamen development. Quantitative reverse transcription polymerase chain reaction analysis indicated that specially expressed in the anther at the early stage of pollen development and its expression level was higher in than that in the wild-type "FT." BrMS1 was located at the nucleus and a length of 12 amino acid residues at the C-terminus had transcriptional activation activity. RNA-seq indicated that the mutation in affected the transcript level of genes related to the tapetum PCD and pollen wall formation, which brought out the pollen abortion. These male sterile mutants we developed provided a novel gene resource for hybrid breeding in Chinese cabbage.