Hybridization kinetics and gene expression in Mercurialis annua flowers: Sexual genotype —specificity and correlation with hormonal contents

Summary

Sequences specifically transcribed in each sex type of Mercurialis annua have been demonstrated by comparative analysis of their poly(A)⁺ RNA populations (homologous and heterologous hybridizations). A comparison of the curves for fertile male genotype cDNAs/fertile male genotype poly(A)⁺ RNAs and fertile male cDNAs/female genotype poly(A)⁺ RNAs clearly demonstrates that the staminate flowers of fertile male plants have 6.5% specific sequences without counterpart in poly(A)⁺ RNAs of the pistillate flowers of female genotypes. The poly(A)⁺ population of genetic females is composed primarily of amplified male transcripts [female cDNAs/male poly(A)⁺ RNAs, 100% hybridizations with the homologous curve of female cDNAs/female poly(A)⁺ RNAs]. Cytokinin reproduces the amplification of male transcripts in the course of artificial feminization of genetically male individuals and exogenous benzylaminopurine induces sequences specific for feminization. The poly(A)⁺ RNAs of the constructed sterile male strain and the restored fertile male strain present 11.5% and 9.0% specificity, respectively, with reference to staminate flowers of fertile males [sterile or restored fertile male cDNAs/fertile male poly(A)⁺ RNAs]. The existence of differential sequences even in identical organs (stamens in normal genetic male plants or restored fertile male strain, pistils in normal genetic females or constructed females bearing male sterility determinants) is clearly demonstrated and correlated with the determinant genotype of these sex types and with the hormones they contain.