Direct acquisition of organic N by white clover even in the presence of inorganic N

TY - JOUR

T1 - Direct acquisition of organic N by white clover even in the presence of inorganic N

AU - Czaban, Weronika

AU - Jämtgård, Sandra

AU - Näsholm, Torgny

AU - Rasmussen, Jim

AU - Nicolaisen, Mogens

AU - Fomsgaard, Inge S.

PY - 2016/10/1

Y1 - 2016/10/1

N2 - Aim: This study was conducted to answer the question of whether clover can absorb asparagine in the presence and absence of inorganic nitrogen, as well as to determine the resulting concentration of post-uptake compounds closely involved in asparagine metabolism. Methods: Clover was grown at two asparagine concentrations (10 μM and 1 mM) supplied in both the absence and presence of ammonium nitrate. Using dual-labeled 13C 15N-asparagine, the uptake rate was analyzed via bulk 15N and 13C excess and the detection of intact 13C 15N-asparagine in white clover. Results: The results from the two methods indicated greater utilization of 13C 15N-asparagine in the 10 μM treatment than in the 1 mM treatment. The 13C 15N-asparagine uptake rate was higher when 13C 15N-asparagine was provided alone than when it was supplemented with inorganic nitrogen. Up to nine times lower uptake rates were obtained when intact 13C 15N-asparagine was measured than when bulk 15N and 13C excess were analyzed. The labeled amino acids that are closely related to 13C 15N-asparagine metabolism (aspartic acid, glutamic acid and glutamine) were detected in clover roots and shoots. Conclusions: Using two different methods, white clover’s potential to absorb intact asparagine, even in the presence of inorganic nitrogen, was confirmed. The dual-methodology approach employed in this study demonstrates how the post-uptake metabolism can affect quantification of amino acid uptake.

AB - Aim: This study was conducted to answer the question of whether clover can absorb asparagine in the presence and absence of inorganic nitrogen, as well as to determine the resulting concentration of post-uptake compounds closely involved in asparagine metabolism. Methods: Clover was grown at two asparagine concentrations (10 μM and 1 mM) supplied in both the absence and presence of ammonium nitrate. Using dual-labeled 13C 15N-asparagine, the uptake rate was analyzed via bulk 15N and 13C excess and the detection of intact 13C 15N-asparagine in white clover. Results: The results from the two methods indicated greater utilization of 13C 15N-asparagine in the 10 μM treatment than in the 1 mM treatment. The 13C 15N-asparagine uptake rate was higher when 13C 15N-asparagine was provided alone than when it was supplemented with inorganic nitrogen. Up to nine times lower uptake rates were obtained when intact 13C 15N-asparagine was measured than when bulk 15N and 13C excess were analyzed. The labeled amino acids that are closely related to 13C 15N-asparagine metabolism (aspartic acid, glutamic acid and glutamine) were detected in clover roots and shoots. Conclusions: Using two different methods, white clover’s potential to absorb intact asparagine, even in the presence of inorganic nitrogen, was confirmed. The dual-methodology approach employed in this study demonstrates how the post-uptake metabolism can affect quantification of amino acid uptake.

KW - amino acids

KW - asparagine metabolism

KW - inorganic nitrogen

KW - uptake

KW - white clover

UR - http://www.scopus.com/inward/record.url?scp=84963716447&partnerID=8YFLogxK

U2 - 10.1007/s11104-016-2896-z

DO - 10.1007/s11104-016-2896-z

M3 - Journal article

SN - 0032-079X

VL - 407

SP - 91

EP - 107

JO - Plant and Soil

JF - Plant and Soil

IS - 1

ER -