Seed hydration as a trigger of cell elongation in bean hypocotyl and radicle

Abstract

When studying root growth one usually considers roots rapidly growing by active cell division and elongation. But another situation is very attractive too—an activation of growth occurring, for example, in imbibing seeds where the cells start their growth during a rather short period measured in hours. We have shown earlier (Obroucheva, 1981) that radicle emergence, the first visible growth phenomenon in germinating seeds, is a result of cell elongation. Cell division in many seed species begins later, after radicle protrusion. It is elongation that provides rapid root protrusion and its contact with soil water. In the seeds of Vicia faba minor radical emergence and further growth of hypocotyl and root occur only by cell elongation until the axis is 1 cm in length. Thus it is a good model to look for some preliminary processes preparing the axial organs for elongation and developing along with their hydration.