MEPS 136:305-309 (1996)  -  doi:10.3354/meps136305

Effect of light/dark transition on carbon translocation in eelgrass Zostera marina seedlings

Zimmerman RC, Alberte RS

Carbon translocation in the marine macrophyte Zostera marina L. (eelgrass) was investigated to elucidate the impact of light/dark transitions on sucrose partitioning between roots and shoots. After exposure of leaves to 14C-bicarbonate, the level of 14C-labelled photoassimilates increased monotonically in both leaves and fully aerobic roots of plants maintained in the light. Accumulation of 14C in roots and leaves ceased abruptly when plants were transferred to darkness that induced root anaerobiosis even though 14C levels remained high in the dark-exposed leaves. Thus, translocation of 14C photoassimilates from shoots to roots was inhibited when roots became anoxic. Anoxia induced by light limitation of photosynthesis, whether due to day/night transitions or periods of extreme light attenuation in the water column, can have an impact on carbon availability in subterranean tissues of eelgrass. As a consequence, light availability is likely to control the productivity and distribution of eelgrass in highly variable and light-limited coastal environments through its effects on carbon partitioning between shoots and roots, in addition to whole-plant carbon balance.

Seagrass . Anoxia . Translocation . Light . Photosynthesis . Carbon transport

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