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Amino Acid Metabolism and Transport in Soybean Plants

2017; Linguagem: Inglês

10.5772/intechopen.68992

Takuji Ohyama, Norikuni Ohtake, Kuni Sueyoshi, Yuki Ono, Kotaro Tsutsumi, Manabu Ueno, Sayuri Tanabata, Takashi Sato, Yoshihiko Takahashi,

Soybean genetics and cultivation

The ammonium produced by nitrogen fixation in the bacteroid is rapidly excreted to cytosol of infected cell of soybean nodules and then assimilated into glutamine and glutamic acid, by glutamine synthetase/glutamate synthase pathway. Most of the nitrogen is further assimilated into ureides, allantoin, and allantoic acid, via purine synthesis, and they are transported through xylem to the shoots. Nitrate absorbed in the roots is reduced by nitrate reductase and nitrite reductase to ammonia either in the roots or leaves. The ammonia is also assimilated by glutamine synthetase/glutamate synthase pathway, and mainly transported by asparagine, and not ureides. The nitrogen transported into leaves is readily utilized for protein synthesis, and then, some of them are decomposed and retransported to roots, apical shoots, and pods via phloem mainly in the form of asparagine.