Expression of the sporopollenin synthesis genes in tapetal transcription factor mutants. A, The proposed hierarchical relationship between the tapetal transcription factors required for exine development. B, Results from microarray analysis of PKSA, PKSB, CYP703A2, MS2, TKPR1, TKPR2, CYP704B1, and ACOS5 expression in the inflorescences of wild type (WT), dyt1, tdf1, ams, and ms188 mutants. C, RT-qPCR analysis of the above sporopollenin synthesis genes in the inflorescences of wild-type, dyt1, tdf1, ams, ms188, and ms1 plants. x axis represents the genes, and y axis is shown as relative expression. sd is indicated as error bar.