Autonomy to plant growth regulators and gene expression in periwinkle cultures in vitro

Abstract

Summary To better understand the effect of habituation on gene expression in plant cells, we have compared the accumulation of specific mRNAs encoding respectively two proline-rich proteins, a chaperone protein and three enzymes linking primary and secondary metabolisms in two models of in vitro culture of periwinkle. These models consisted of two couples of a 2,4-dichlorophenoxyacetic acid-dependent/2,4-dichloro-phenoxyacetic acid independent line in which autonomy to auxin and cytokinin was obtained either through habituation or through transformation with the isopentenyltransferase gene from Agrobacterium tumefaciens . Results showed that gene expression was modified by plant growth regulator autonomy but differendy according to the type of autonomy: only the gene encoding a hydroxyproline-rich glycoprotein was regulated similarly in both PGR-independent lines. On the other hand, PGR autonomy did not lead to total insensitivity to exogenously-applied PGRs, and the two PGR autonomous lines did not accumulate indole alkaloids for different reasons.