Pre-anthesis reserve utilization for protein and carbohydrate synthesis in grains of wheat

Thomas Gebbing, Hans Schnyder

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161 Scopus citations

Abstract

We assessed the contribution of pre-anthesis reserve C to protein and carbohydrate deposition in grains of wheat (Triticum aestivum L.) using a new approach comprised of steady-state 13C/12C labeling and separation of the protein and carbohydrate fractions of mature grains. Experiments were performed with two spring wheat cultivars (Kadett and Star) grown with differential N fertilizer supply over 2 years. Pre-anthesis reserves contributed between 30% and 47% of the C in protein and 8% to 27% of the C in carbohydrates of grains. Partitioning of pre-anthesis C among the grain fractions was strongly dependent on the C/N (w/w) ratio in mobilized preanthesis biomass (r2 = 0.92). There appeared to be no significant exchange of pre-anthesis C between amino acids and carbohydrates during redistribution. The mean apparent efficiency of mobilized carbohydrate-C use in grain filling (ME(CHO), estimated as the mass of pre-anthesis C deposited in grain carbohydrates per gram of preanthesis C mobilized from carbohydrates in vegetative plant parts) was 0.72, whereas that of protein-C (ME(p)) was 0.56. However, ME(p) and ME(CHO) varied among treatments. ME(CHO) increased with increasing contributions of water-soluble carbohydrates to total preanthesis carbohydrate mobilization. ME(p) decreased with increasing residence time of protein in vegetative biomass. Possible causes for variability of ME(p) and ME(CHO) are discussed.

Original languageEnglish
Pages (from-to)871-878
Number of pages8
JournalPlant Physiology
Volume121
Issue number3
DOIs
StatePublished - Nov 1999

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