Comparative study of free amino acids from root nodules of four tree legume species


  • R. Qadri
  • A. Mahmood
  • M. Athar
  • N. Mahmood


Free amino acid composition in nitrogen fixing root nodules of the leguminosae (Fabaceae) Albizia lebbeck (L.) Benth., Pithecellobium dulce (Robx.) Benth., Samanea saman (Jacq.) Merr. of subfamily Mimosoideae and Dalbergia sissoo Roxb. ex DC of subfamily Papilio-noideae was determined. In all, 14 amino acids were detected. On the basis of their contribution to the total amino acid composition of nodules, seven of them, namely aspartic acid, glutamic acid, serine, tyrosine, alanine, leucine and valine were designated as major amino acids. They were present in all four species. They together formed the bulk of the total amino acid nitrogen (TAAN). Seven amino acids, i.e. histidine, lysine, cystine, glycine, isoleucine, phenylalanine and arginine were sporadically distributed in nodules of all the four legume species. They were present in small amounts and were designated as minor amino acids. The TAAN in members of Mimosoideae was found higher than the Papilionoideae. Minor amino acids were not detected in nodules of Papilionoideae. The pattern of free amino acids in the root nodules of these four legume trees was compared with non-leguminous and actinorhizal nodules.
Abbreviations: h: hour; µL: microlitre; mJ: milliliter; TAAN: total amino acid nitrogen