ABSTRACT: Chemical hybridization agent (CHA)-induced male sterility is becoming one of the most useful tools for the crop heterosis in seed production. We had previously discovered monosulfuron ester sodium (Mes), an acetolactate synthase (ALS) inhibitor of the herbicide sulfonylurea family, could induce rapeseed (Brassica napus L.) male sterility. To investigate the mechanism of Mes inducing male sterility, a cytological analysis and comparative transcriptome analysis were performed between Mes-treated plants leaves and different developmental stage anthers and those of the Mock-treated plants. Cytological analysis exhibited that Mes destroyed plastids ultrastructure and depressed the materials accumulation during anther development and maturation process. Comparative transcriptome analysis identified a total of 1501 transcripts differentially expressed in the leaves and different developmental stage anthers. Subcellular localization analysis, functional analysis and pathway analysis were carried out to obtain the clues that plastid was the seriously damaged organelle, and many genes involved in carbon and lipid metabolism and cellular transport differentially expressed. Detailed expression pattern analysis of genes related with these functions were conducted and verified by RT-PCR. In addition, several transcription factors, protein kinases and hormone related genes were identified. Carbohydrate content analysis confirmed carbon metabolism were influenced by Mes. Taken together, we proposed a putative action mode that Mes inhibited activity of acetolactate synthase, which localized in plastid in plants, and then disturbed the normal supply of carbon and lipid metabolite for anther development, finally displayed male sterility. This results have important significance for uncovering the metabolic gene regulation during anther development and may provide more potential targets for developing new male sterility inducing CHAs in rapeseed breeding. Rapeseed (Brassica napus L.) plants were foliar sprayed with 0.1μg mL-1 Monosulfuron ester sodium (Mes) solution containing 50ppm DMF and 5ppm Tween 80 for about 15 ml per plant. Young leaves (C2Y1, C2Y2, C2Y3; T2Y1, T2Y2, T2Y3) of the main inflorescences and developing anthers (including small buds (C2S1, C2S2, C2S3; T2S1, T2S2, T2S3), middle anthers (C2M1, C2M2, C2M3; T2M1, T2M2, T2M3), and large anthers (C2L1, C2L2, C2L3; T2L1, T2L2, T2L3)) from Mes-treated and Mock-treated plants were collected for each experiment. Each tissue has three independent biological replicates.
