How did a duplicated gene copy evolve into a gene in a plant? The case of .

() is a suppressor of cytoplasmic male sterility (CMS), a mitochondrion-encoded trait that has been reported in many plant species. The occurrence of CMS is considered to be independent in each lineage; hence, the question of how evolved was raised. Sugar beet resembles , a gene for quality control of the mitochondrial inner membrane. homologues comprise a small gene family in the sugar beet genome, unlike Arabidopsis and other eukaryotes. The sugar beet sequence that best matched Arabidopsis was named ; sugar beet () was another member. During anther development, mRNA was detected from the tetrad to the microspore stages, whereas mRNA was detected at the microspore stage and mRNA was detected during the meiosis and tetrad stages. A transgenic study revealed that, whereas can bind to a CMS-specific protein and alter the higher-order structure of the CMS-specific protein complex, neither nor show such activity. We favour the hypothesis that an ancestral gene duplicated to form a small gene family, and that one of the copies evolved and acquired a novel expression pattern and protein function as an , i.e. evolved via neofunctionalization.