Molecular evolution of the maize sex-determining gene TASSELSEED2 in Bouteloua (Poaceae).
The majority of angiosperms produce hermaphrodite flowers, while a lesser number (20-30%) produce unisexual flowers. Little is known about the molecular biology of sex-determination in angiosperms, however, a few sex-determining genes have been cloned from the model system Zea mays. One of these genes is Tasselseed2 (Ts2) which has been shown to be involved in the arrest of developing pistils in male flowers. In this study, we sequenced a putative homologue of Ts2 in species of Bouteloua, a genus in the grass subfamily Chloridoideae. We found significant genetic variation at Ts2 in Bouteloua relative to other developmental genes characterized in maize and other grass species. We also found that in Bouteluoua, Ts2 is evolving non-neutrally in the hermaphrodite-flowered Bouteloua hirsuta while no difference from neutral expectation was detected at Ts2 in the monoecious/dioecious Bouteloua dimorpha. The putatively neutral gene Alcohol Dehydrogenase1 (Adh1) was also examined for the same species of Bouteloua, and no departure from neutral expectation was detected. Our results suggest that purifying selection may be acting on Ts2 in the hermaphrodite-flowered B. hirsuta while no evidence of selection was detected at Ts2 in the monoecious/dioecious B. dimorpha.
Kinney
M S
MS
Rancho Santa Ana Botanic Garden and Claremont Graduate University, 1500 N College Ave, Claremont, CA 91711, USA. michael.kinney@cgu.edu
Columbus
J T
JT
Friar
E A
EA
D001483:Base Sequence; D017931:DNA Primers; D019143:Evolution, Molecular; D040461:Gene Components; D014644:Genetic Variation; D016013:Likelihood Functions; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010641:Phenotype; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics*; D006109:Poaceae / Q000235:genetics*; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D019849:Sex Determination Processes; D013045:Species Specificity
D017931:DNA Primers; D010940:Plant Proteins; C109352:TS2 protein, Zea mays