Amino acids analysis of axis and cotyledons of Medicago truncatula by high performance liquid chromatography

(Work made with Marie-Thérèse RIOU - UMR 1191 PMS

I. Methods
  • Derivatization of individual amino acids with PITC
  • Extraction of amino acids from cotyledons and axis and derivatization with PITC
  • HPLC system

 


II. Separation of the PTC amino acids

 

III. Results

                 Standard error bars in the figures correspond to n = 2 to 6 different injections

 

 

IV. Conclusion

In the dried seed :

  • no or very few Gln, Thr and Ser were detected ;
  • Tyr, Arg, Glu and Asn were quantitatively the most important amino acids ;
  • Homoserine was detected only in the dried seed.
After 19 h of germination (i.e., at the emergence of the radicle) :
  • the amount of amino acids was always higher (or at least equal) in the cotyledon than in the axis ;
  • the most abundant amino acids were Arg, Glu and Tyr.

After 48 h of germination :

  • Asn was the most abundant amino acid in the axis (4200 nmoles per organ), followed by His, Ala and Ser in decreasing order and no Trp was detected ;
  • on the contrary, Trp was the most abundant amino acid in the case of cotyledon (1300 nmoles per organ), followed by Asn, His and Arg.

Thus, it appears that Asn was quantitatively by far the most abundant amino acid as it was observed for other seedlings (Rozan et al., 1999, 2000, 2001).

V. References