Plants respond to environmental mechanical stimulation, such as wind, by modifying their growth and development. To study the molecular effects of stem bending on 3-week-old walnut trees, a cDNA-AFLP approach was developed. This study allowed the identification of a cDNA, known as Jr-ZFP2, encoding a Cys2/His2-type two-zinc-fingered transcription factor. Reverse transcriptase-polymerase chain reaction analysis confirmed that Jr-ZFP2 mRNA accumulation is rapidly and transiently induced after mechanical stimulation. After bending, Jr-ZFP2 transcript increase was restricted to the stem, the organ where the mechanical solicitation was applied. Furthermore, other abiotic factors, such as cold or salt, did not modify Jr-ZFP2 mRNA accumulation in walnut stems under our experimental conditions, whereas growth studies demonstrated that salt stress was actually perceived by the plants. These results suggest that the regulation of Jr-ZFP2 expression is more sensitive to mechanical stimulus. This gene will be a good marker for studying the early stages of mechanical perception in woody plants.
