Characterization of Zm26Sub5 and Its Potential Roles in Regulating Pollen Fertility of S-CMS in Maize

Mitochondrial orf355-orf77 and the nuclear fertility restorer locus Rf3/rf3 mutually control the fertility of male gametes inCMS-S in maize (Zea maya L.). A fragment of gene Zm26Sub5 was identified through cDNA-AFLP from a set of Rf3/rf3near-isogenie 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-MoI7Rf3Rf3 than in pollen of S-Mo 17rf3rf3, and also higher than in fresh leaves, mature leaves, and roots of both S-Mo 17Rf3Rf3 and S-Mo 17rf3rf3. In silico cloning of full-length cDNA was successfully implemented.Gene Zm26Sub5 was 1451 bp in size, of which 1329 bp encoded a protein with 443 amino acids. The structure of this genewas analyzed by comparing its full length cDNA to homologous genomie 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. ZM26SUBS, therefore might have potential roles in repressing mitochondrial PCD which is associated with sterile activity in pollen in S-type cytoplasm.