SUPPLY OF NUTRIENTS FROM THE FOLIAR TISSUE TO THE SEED FILLING IN SOYBEAN GENOTYPES WITH DIFFERENT RESERVE COMPOSITION

PAVLOVIC, TATIANA; SÁENZ, EZEQUIEL; POETA, FLORENCIA; BORRÁS, LUCAS; SAIGO, MARIANA; GERRARD WHEELER, MARIEL CLAUDIA

Congreso; LV SAIB- XIV PABMB; 2019

Protein and lipid content of soybean seed is a trait of great economic value. The ratio of these two components is variable and likely to bemodified, so its study is essential for future biotechnological improvements. The accumulation of storage compounds depend on the supply ofnutrients from autotrophic tissues and the internal seed metabolism. Maternal tissues provide mainly sucrose and amino acids produced duringthe senescence in the leaves. These precursors needed to build the storage compounds reach the seed through phloem. Once in the seed coat, theyenter the embryo through the apoplast, as there is no vascular connection between the coat and the embryo. The aim of this work is to study thismaternal provision and its influence on the seed final composition. For this purpose, we analyzed the polar metabolites that reach the soybeanembryo in experimental isogenic lines with contrasting contents of proteins and lipids. The experiments were carried out with plants at the onsetand in the middle of seed maturation. The embryos were removed and replaced with melted agar. The polar metabolites including sugars, aminoacids and organic acids were extracted from agar and run in gas chromatography coupled to mass spectrometry (GC-MS), using ribitol as theinternal standard. In the samples of the high lipid and low protein line, we could identify several amino acids (Ala, Ser, Thr, Asp, Gln, Asn,GABA, among others), organic acids (malate, fumarate and citrate) and carbohydrates (fructose, glucose, sucrose, among others). In contrast, inthe samples from the line with low lipid and high protein content, we were able to detect mostly carbohydrates. These results may be observedbecause proteins are deposited earlier than lipids in the seeds (see the poster of Poeta et al.), thus indicating that the carbon and nitrogen suppliesare coordinated with the metabolic demands or regulate the metabolic program of the growing embryo.