TY - JOUR
T1 - Changes in spatiotemporal protein and amino acid gradients in wheat caryopsis after N-topdressing
AU - Zhong, Yingxin
AU - Vidkjær, Nanna Hjort
AU - Massange-Sanchez, Julio A.
AU - Laursen, Bente Birgitte
AU - Gislum, René
AU - Borg, Søren
AU - Jiang, Dong
AU - Hebelstrup, Kim Henrik
PY - 2020
Y1 - 2020
N2 - Wheat grain nitrogen content displays large variations within different pearling fractions of grains because of radial gradients in the protein content. We identified how spatiotemporal mechanisms regulate this. The protein gradients emerged clearly at 19 days after anthesis, with the highest N content in aleurone and seed coat, followed by outer endosperm, whereas the lowest was in middle and inner endosperm. Laser microdissection, qRT-PCR and LC–MS were used to dissect tissue from aleurone, outer endosperm, middle endosperm, inner endosperm and transfer cells, measure gene expression and levels of free and protein-bound amino acids, respectively. The results showed that different FAA transportation pathways worked in parallel during grain filling stage while the grain protein gradient did not follow spatial expression of storage proteins. Additionally, two nitrogen (N) topdressing timings were conducted, either at the emergence of top third leaf (standard timing) or top first leaf (delayed timing), finding that delayed N topdressing enhanced both amino acids supply and protein synthesis capacity. The results provide insight into protein synthesis and amino acid transport pathways in endosperm and suggest targets for the enhancement of specialty pearled wheat with higher quality.
AB - Wheat grain nitrogen content displays large variations within different pearling fractions of grains because of radial gradients in the protein content. We identified how spatiotemporal mechanisms regulate this. The protein gradients emerged clearly at 19 days after anthesis, with the highest N content in aleurone and seed coat, followed by outer endosperm, whereas the lowest was in middle and inner endosperm. Laser microdissection, qRT-PCR and LC–MS were used to dissect tissue from aleurone, outer endosperm, middle endosperm, inner endosperm and transfer cells, measure gene expression and levels of free and protein-bound amino acids, respectively. The results showed that different FAA transportation pathways worked in parallel during grain filling stage while the grain protein gradient did not follow spatial expression of storage proteins. Additionally, two nitrogen (N) topdressing timings were conducted, either at the emergence of top third leaf (standard timing) or top first leaf (delayed timing), finding that delayed N topdressing enhanced both amino acids supply and protein synthesis capacity. The results provide insight into protein synthesis and amino acid transport pathways in endosperm and suggest targets for the enhancement of specialty pearled wheat with higher quality.
KW - Amino acids
KW - Gene expression profiling
KW - Laser capture microdissection
KW - Spatial distribution
KW - Wheat caryopsis
UR - http://www.scopus.com/inward/record.url?scp=85075569860&partnerID=8YFLogxK
U2 - 10.1016/j.plantsci.2019.110336
DO - 10.1016/j.plantsci.2019.110336
M3 - Journal article
C2 - 31928684
AN - SCOPUS:85075569860
SN - 0168-9452
VL - 291
JO - Plant Science
JF - Plant Science
M1 - 110336
ER -