LAUSR

Abstract Cytoplasmic male sterility (CMS) is an important tool for hybrid seed production in the fibrous crop Boehmeria nivea (L.) Gaudich. Dysfunction of mitochondrial ATP synthase normally leads to male sterility. However, the expression regulation and evolution of the ATP synthase subunit genes controlling male development is still unclear. While few available mitochondrial transformation strategies limited studying mitochondrial copy of atp9, the function of nuclear atp9 copy with exactly the same coding sequence are not clearly elucidated. In this article, we show that transformation of B. nivea atp9 RNAi vectors into tobacco plants resulted in nearly half of the pollens sterile, which provide direct experimental evidence that the atp9 gene could be used in developing male sterile lines in plants. Bioinformatics analysis revealed that H+-binding site Glu57 of the c subunit of ATP synthase is highly conservative in B. nivea, showing essential function of atp9 during evolution. Molecular evolution analysis revealed that the synonymous substitution rate (dS) of mitochondrial atp9 in B. nivea is faster than in other plants, which could be a reason for its cytoplasmic male sterility and strong environmental adaptations.