▁primarily ▁as ▁am mon ium , ▁an ▁array ▁of ▁am mon ium ▁trans porter ▁gen es ▁are ▁up ▁reg ulated ▁in ▁the ▁plant ▁partners , ▁and ▁addition ally ▁the ▁my cor rh iz al ▁fung al ▁partners ▁often ▁up reg ulate ▁a ▁group ▁of ▁prote ase ▁gen es ▁as ▁well ▁as ▁external ▁am ino ▁acid ▁per me ases , ▁nit rate ▁trans por ters ▁and ▁am mon ium ▁trans por ters . ▁As ▁proposed ▁by ▁Camer on ▁ 2 0 0 6 ▁and ▁F och i ▁ 2 0 1 6 , ▁nit ro gen ▁may ▁also ▁be ▁transferred ▁as ▁am ino ▁ac ids ▁such ▁as ▁arg in ine , ▁g ly c ine ▁and ▁gl ut am ine ▁into ▁the ▁cell ▁via ▁a ▁select ▁few ▁special ized ▁am ino ▁acid ▁trans por ters . ▁When ▁in ▁sym bi otic ▁relationship ▁with ▁orch id ▁plants ▁the ▁my cor rh iz al ▁fung us ▁T . ▁cal os por a ▁up reg ul ates ▁the ▁expression ▁of ▁Sv A AP 1 ▁and ▁Sv A AP 2 , ▁these ▁gen es ▁encode ▁am ino ▁acid ▁per me ases , ▁supporting ▁the ▁hypothesis ▁that ▁am ino ▁ac ids ▁are ▁an ▁important ▁mole c ule ▁involved ▁in ▁nit ro gen ▁transport . ▁A min o ▁ac ids ▁contain ▁a ▁significant ▁amount ▁of ▁carbon ▁as ▁well ▁and ▁the ▁transport ▁of ▁carbon ▁may ▁be ▁the ▁primary ▁driving ▁cause ▁of ▁the ▁observed ▁up reg ulation ▁of ▁the ▁am ino ▁acid ▁trans porter ▁gen es , ▁none ▁the ▁less ▁nit ro