Mitochondrial orf355-orf77 and the nuclear fertility restorer locus Rf3/rf3 mutually control the fertility of male gametes in CMS-S in maize （Zea mays L.）. A fragment of gene Zm26Sub5 was identified through cDNA-AFLP from a set of Rf3/rf3 near-isogenic lines in a previous study. In the present study, real-time PCR analysis revealed that Zm26Sub5 expression levels were much higher in pollen of S-Mo17Rf3Rf3 than in pollen of S-Mo17rf3rf3, and also higher than in fresh leaves, mature leaves, and roots of both S-Mo17Rf3Rf3 and S-Mo17rf3rf3. In silico cloning of full-length cDNA was successfully implemented. Gene Zm26Sub5 was 1 451 bp in size, of which 1 329 bp encoded a protein with 443 amino acids. The structure of this gene was analyzed by comparing its full length cDNA to homologous genomic DNA sequence （GenBank accession： Ac209463.3）. Subsequent sequence analysis led to sub cellular localization of protein ZM26SUB5, and construction of a phylogenetic tree. In silico mapping indicated that Zm26Sub5 was located on chromosome 5 and closed to a reported starch-filled pollen ratio QTL. ZM26SUB5, therefore might have potential roles in repressing mitochondrial PCD which is associated with sterile activity in pollen in S-type cytoplasm.
