The desiccation-tolerant state in seeds is associated with high levels of certain sugars and maturation proteins. The aim of this work was to evaluate the contributions of these components to desiccation tolerance in soybean (Glycine max [L.] Merrill cv Chippewa 64). When axes of immature seeds (34 d after flowering) were excised and gradually dried (6 d), desiccation tolerance was induced. By contrast, seeds held at high relative humidity for the same period were destroyed by desiccation. Maturation proteins rapidly accumulated in the axes whether the seeds were slowly dried or maintained at high relative humidity. During slow drying, sucrose content increased to five times the level present in the axes of seeds held at high relative humidity (128 versus 25 pg/axis, respectively). Stachyose content increased dramatically from barely detectable levels upon excision to 483 pg/axis during slow drying but did not increase significantly when seeds were incubated at high relative humidity. Galactinol was the only saccharide that accumulated to higher levels in axes from seeds incubated at high relative humidity relative to axes from seeds that were slowly dried. This suggests that slow drying serves to induce the accumulation of the raffinose series sugars at a point after galactinol biosynthesis. We conclude that stachyose plays an important role in conferring desiccation tolerance.The remarkable mechanism that allows most mature angiosperm seeds to survive desiccation to extremely low water contents is poorly understood. Among the protective components that have been proposed to be important in the acquisition of desiccation tolerance during seed development are proteins and soluble sugars. The group of proteins known as Late Embryogenesis Accumulating, or Lea (13), proteins include some that accumulate during the maturation drying phase of seed development. Some of these maturation proteins have been correlated with the ability of the seed to progress into seedling growth (29), whereas others have been correlated with desiccation tolerance (2, 4). However, some additional process is apparently necessary for the development of desiccation tolerance. We have shown that maturation protein accumulation alone is not sufficient to confer desiccation tolerance in developing soybean (4 characteristic of mature orthodox seeds (1). They have been implicated by correlation as adaptive agents for desiccation tolerance during seed development and germination (9,18,19). In particular, cultivars of soybean (Glycine max) accumulate high levels of the raffinose series of oligosaccharides, particularly stachyose, in addition to sucrose (12,18,21,31). Evidence for the protective role of soluble sugars has also been inferred from model systems (7, 11). The soluble sugar, trehalose, protects cytosolic components in yeast against desiccation-, frost-, and heat-induced damage in vivo (34). It is thought that the hydroxyl constituents of sugars may replace the hydration shell around membranes and thus prevent structural damage a...

1. Kinetin-induced transport of P(32) in detached corn leaves is shown to be limited to the axial direction of the leaves, i.e. along the axis of the vascular bundles. It is not apparently dependent on the water flow in the xylem, and it can be blocked by steam-killed zones or by metabolic inhibitors. It is concluded that kinetin-induced redistribution of phosphates in isolated corn leaves takes place in the phloem. 2. The movement of P(32) is preferentially toward the base of the excised leaf, indicating a natural mobilization center at the leaf base. 3. Kinetin treated parts of leaves attract and accumulate P(32). They do not accumulate the radioisotopes Na(22), Rb(86), Cl(36) and I(131); but the transport of Na(22) directed towards kinetin centers is enhanced. 4. Two "mobilizing centers" established by kinetin application along the leaf axis do not attract P(32) from intermediate tissue at the same time in opposite directions. They compete with each other for the transport system: both the direction and the velocity of movement are determined by the difference of the "mobilizing forces". Thus, mobilization is either to one or to the other mobilizing center. 5. Under conditions of enhanced transport (i.e. in presence of kinetin centers), the distribution curves of P(32) and Na(22) are flattened. This change would be expected for the mass-flow type of transport. 6. It is concluded that "mobilizing centers" in isolated corn leaves stimulate a mass-flow transport in the phloem. Evidence is presented that they act as suction pumps. Some general aspects of phloem transport are discussed.

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A large number of experiments have'been reported in the literature on photoperiodism indicati'ng that light is essential to the photoperiodic induction of flowering.. For example, KLEBS (5) was unable to find flower primordia in darkened Sempervivum, GARNER and ALLARD (3) found that prolonged darkness would not produce flowers in long-or short-day plants, BORTHWICK and PARKER (2), HAMNER (4) and MANN (7)