Abstract
In CMS-S of maize (Zea mays L.), mitochondrial orf355-orf77 and the nuclear restorer of fertility designated as Rf3/rf3 interact to control fertility of gametophytes. Genes expressed differentially in young leaves and pollen were screened using complementary DNA amplified fragment length polymorphism (cDNA-AFLP) combined with a set of Rf3/rf3 near isogenic lines. Sixty-four combinations of AFLP primers produced 2,450 observed transcript-derived fragments (TDFs). The differentially expressed TDFs were assorted into seven different expressed types, of which, 33 TDFs expressed only in fertile pollen and three expressed in fertile materials specifically were cloned and sequenced. Sequencing analysis indicated that 33 tentative unique genes were obtained and assigned into eight different categories including protein synthesis and fate, post-transcript regulation, signal transduction, and so on. TDF-E1 was indicated representing a gene coding a protein containing pentatricopeptide repeat (PPR) motif by BLASTx analysis, which temporarily denominated as PPRE1. Real-time polymerase chain reaction analysis revealed that PPRE1 expressed far more strongly in pollen of S-Mo17Rf3Rf3 than in other materials investigated. Polymorphism analysis of PPRE1 in genomes showed difference between S-Mo17Rf3Rf3 and S-Mo17rf3rf3. Taken together, we proposed that PPRE1 may be a promising candidate gene for restoration of fertility in maize S-CMS, as a set of near-isogenic lines had identical cytoplasm and eliminated most noise from nuclear genetic backgrounds. Another gene, which corresponds to TDF-A5 and codes 26S protease regulatory particle non-ATPase subunit5 was also discussed about its potential role in participating in the repression of mitochondrial programmed cell death associated with sterile pollen in S-type cytoplasm.
Published Version
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