Germination-associated changes in the transcript content of pea seedling lipoxygenases. Lipoxygenase-g: a new marker of axis growth resumption

Plant lipoxygenases (LOXs; EC 1.13.11.12) are thought to be involved in phy siological processes such as growth, development and plant defense. The LOX mRNA content of pea (Pisum sativum L. cv. Cl 830) seeds was studied by rev erse transcription-polymerase chain reaction during and after the germinati on process. The study of four different isoforms, LOS-2, LOX-3, LOX-g and L OX-1, showed that their expression is differentially time- and organ-regula ted. Seed LOX (LOX-2 and LOX-3) transcripts were present in axes and cotyle dons of dry seeds. They disappeared after radicle emergence and were replac ed by the mRNA of the two other isoforms. The LOX-g and LOX-1 transcripts a ppeared in the axis just before growth resumption. In contrast to LOX-1, LO X-g was also expressed in cotyledons. Thus, like ''germin", LOX-g appears t o be another marker of axis growth resumption. Hypotheses concerning the fu nction of each isoform are discussed.