Cisgenic overexpression of cytosolic glutamine synthetase improves nitrogen utilization efficiency in barley and prevents grain protein decline under elevated CO₂

TY - JOUR

T1 - Cisgenic overexpression of cytosolic glutamine synthetase improves nitrogen utilization efficiency in barley and prevents grain protein decline under elevated CO2

AU - Gao, Yajie

AU - de Bang, Thomas C.

AU - Schjoerring, Jan K.

PY - 2019/7

Y1 - 2019/7

N2 - Cytosolic glutamine synthetase (GS1) plays a central role in nitrogen (N) metabolism. The importance of GS1 in N remobilization during reproductive growth has been reported in cereal species but attempts to improve N utilization efficiency (NUE) by overexpressing GS1 have yielded inconsistent results. Here, we demonstrate that transformation of barley (Hordeum vulgare L.) plants using a cisgenic strategy to express an extra copy of native HvGS1-1 lead to increased HvGS1.1 expression and GS1 enzyme activity. GS1 overexpressing lines exhibited higher grain yields and NUE than wild-type plants when grown under three different N supplies and two levels of atmospheric CO2. In contrast with the wild-type, the grain protein concentration in the GS1 overexpressing lines did not decline when plants were exposed to elevated (800–900 μL/L) atmospheric CO2. We conclude that an increase in GS1 activity obtained through cisgenic overexpression of HvGS1-1 can improve grain yield and NUE in barley. The extra capacity for N assimilation obtained by GS1 overexpression may also provide a means to prevent declining grain protein levels under elevated atmospheric CO2.

AB - Cytosolic glutamine synthetase (GS1) plays a central role in nitrogen (N) metabolism. The importance of GS1 in N remobilization during reproductive growth has been reported in cereal species but attempts to improve N utilization efficiency (NUE) by overexpressing GS1 have yielded inconsistent results. Here, we demonstrate that transformation of barley (Hordeum vulgare L.) plants using a cisgenic strategy to express an extra copy of native HvGS1-1 lead to increased HvGS1.1 expression and GS1 enzyme activity. GS1 overexpressing lines exhibited higher grain yields and NUE than wild-type plants when grown under three different N supplies and two levels of atmospheric CO2. In contrast with the wild-type, the grain protein concentration in the GS1 overexpressing lines did not decline when plants were exposed to elevated (800–900 μL/L) atmospheric CO2. We conclude that an increase in GS1 activity obtained through cisgenic overexpression of HvGS1-1 can improve grain yield and NUE in barley. The extra capacity for N assimilation obtained by GS1 overexpression may also provide a means to prevent declining grain protein levels under elevated atmospheric CO2.

KW - barley

KW - carbon dioxide (CO)

KW - cisgenesis

KW - glutamine synthetase (GS)

KW - grain protein

KW - Nitrogen use efficiency (NUE)

UR - http://www.scopus.com/inward/record.url?scp=85059140793&partnerID=8YFLogxK

U2 - 10.1111/pbi.13046

DO - 10.1111/pbi.13046

M3 - Journal article

C2 - 30525274

AN - SCOPUS:85059140793

SN - 1467-7644

VL - 17

SP - 1209

EP - 1221

JO - Plant Biotechnology Journal

JF - Plant Biotechnology Journal

IS - 7

ER -