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 physiological processes such as growth, development and plant defense. The LOX mRNA content of pea (Pisum sativum L. cv. Cl 830) seeds was studied by reverse transcription-polymerase chain reaction during and after the germination process. The study of four different isoforms, LOS-2, LOX-3, LOX-g and LOX-1, showed that their expression is differentially time- and organ-regulated. Seed LOX (LOX-2 and LOX-3) transcripts were present in axes and cotyledons of dry seeds. They disappeared after radicle emergence and were replaced by the mRNA of the two other isoforms. The LOX-g and LOX-1 transcripts appeared in the axis just before growth resumption. In contrast to LOX-1, LOX-g was also expressed in cotyledons. Thus, like ''germin", LOX-g appears to be another marker of axis growth resumption. Hypotheses concerning the function of each isoform are discussed.