Identification of a Male Sterile Candidate Gene in x and Transfer of the Gene to Easter Lily () via Hybridization.

Pollen-free varieties are advantageous in promoting cut-flower production. In this study, we identified a candidate mutation which is responsible for pollen sterility in a strain of × , which was originally identified as a naturally occurred male-sterile plant in a seedling population. The pollen sterility occurred due to the degradation of pollen mother cells (PMCs) before meiotic cell division. Genetic analysis suggested that the male-sterile phenotype is attributed to one recessive locus. Transcriptome comparison between anthers of sterile and fertile plants in a segregated population identified a transcript that was expressed only in pollen-fertile plants, which is homologous to () in Arabidopsis, a gene encoding a transcription factor AtMYB35 that is known as a key regulator of pollen development. Since mutant shows male sterility, we assumed that the absence transcript of the -like gene, named as , is the reason for pollen sterility observed in the mutant. A 30 kbp-long nanopore sequence read containing was obtained from a pollen-fertile accession. PCR analyses using primers designed from the sequence suggested that at least a 30kbp-long region containing was deleted or replaced by unknown sequence in the pollen-sterile mutant. Since the cross between . × and Easter lily () is compatible, we successfully introgressed the male-sterile allele, designated as , to Easter lily. To our knowledge, this is the first report of molecular identification of a pollen-sterile candidate gene in lily. The identification and marker development of gene will assist pollen-free lily breeding of Easter lilies and other lilies.