ALTERATIONS IN DELTA-C-13 VALUES OF SEEDLING CELLULOSE ASSOCIATED WITH RESPIRATION DURING GERMINATION

DeltaC-13 values of heterotrophically synthesized cellulose of roots f rom germinating seeds treated with a respiratory uncoupler were compar ed with those produced by untreated seed. Seeds or grains having starc h as their principal storage substrate synthesized cellulose enriched in C-13 relative to their substrate. Those having lipids as their prin cipal storage substrate synthesized cellulose depleted in C-13 relativ e to their substrate. The respiratory uncoupler decreased respiration and caused lower C-13 abundance in synthesized cellulose relative to t he controls for starch-storing seeds. Decreased respiration, however, caused an increase in C-13 of synthesized cellulose from lipid-storing , seeds. The observed isotopic enrichment of cellulose with increase i n respiration in the starch-storing seeds is consistent with the hypot hesis that stems and roots of plants are isotopically enriched relativ e to leaves because of respiration.