TY - JOUR
T1 - Globular structures in roots accumulate phosphorus to extremely high concentrations following phosphorus addition
AU - Ryan, Megan H
AU - Kaur, Parwinder
AU - Nazeri, Nazanin K
AU - Clode, Peta L
AU - Keeble-Gagnère, Gabriel
AU - Doolette, Ashlea L
AU - Smernik, Ronald J
AU - Van Aken, Olivier
AU - Nicol, Dion
AU - Maruyama, Hayato
AU - Ezawa, Tatsuhiro
AU - Lambers, Hans
AU - Millar, A Harvey
AU - Appels, Rudi
PY - 2019/6
Y1 - 2019/6
N2 - Crops with improved uptake of fertilizer phosphorus (P) would reduce P losses and confer environmental benefits. We examined how P-sufficient 6-week-old soil-grown Trifolium subterraneum plants, and 2-week-old seedlings in solution culture, accumulated P in roots after inorganic P (Pi) addition. In contrast to our expectation that vacuoles would accumulate excess P, after 7 days, X-ray microanalysis showed that vacuolar [P] remained low (<12 mmol kg-1 ). However, in the plants after P addition, some cortex cells contained globular structures extraordinarily rich in P (often >3,000 mmol kg-1 ), potassium, magnesium, and sodium. Similar structures were evident in seedlings, both before and after P addition, with their [P] increasing threefold after P addition. Nuclear magnetic resonance (NMR) spectroscopy showed seedling roots accumulated Pi following P addition, and transmission electron microscopy (TEM) revealed large plastids. For seedlings, we demonstrated that roots differentially expressed genes after P addition using RNAseq mapped to the T. subterraneum reference genome assembly and transcriptome profiles. Among the most up-regulated genes after 4 hr was TSub_g9430.t1, which is similar to plastid envelope Pi transporters (PHT4;1, PHT4;4): expression of vacuolar Pi-transporter homologs did not change. We suggest that subcellular P accumulation in globular structures, which may include plastids, aids cytosolic Pi homeostasis under high-P availability.
AB - Crops with improved uptake of fertilizer phosphorus (P) would reduce P losses and confer environmental benefits. We examined how P-sufficient 6-week-old soil-grown Trifolium subterraneum plants, and 2-week-old seedlings in solution culture, accumulated P in roots after inorganic P (Pi) addition. In contrast to our expectation that vacuoles would accumulate excess P, after 7 days, X-ray microanalysis showed that vacuolar [P] remained low (<12 mmol kg-1 ). However, in the plants after P addition, some cortex cells contained globular structures extraordinarily rich in P (often >3,000 mmol kg-1 ), potassium, magnesium, and sodium. Similar structures were evident in seedlings, both before and after P addition, with their [P] increasing threefold after P addition. Nuclear magnetic resonance (NMR) spectroscopy showed seedling roots accumulated Pi following P addition, and transmission electron microscopy (TEM) revealed large plastids. For seedlings, we demonstrated that roots differentially expressed genes after P addition using RNAseq mapped to the T. subterraneum reference genome assembly and transcriptome profiles. Among the most up-regulated genes after 4 hr was TSub_g9430.t1, which is similar to plastid envelope Pi transporters (PHT4;1, PHT4;4): expression of vacuolar Pi-transporter homologs did not change. We suggest that subcellular P accumulation in globular structures, which may include plastids, aids cytosolic Pi homeostasis under high-P availability.
U2 - 10.1111/pce.13531
DO - 10.1111/pce.13531
M3 - Article
C2 - 30734927
VL - 42
SP - 1987
EP - 2002
JO - Plant, Cell and Environment.
JF - Plant, Cell and Environment.
SN - 0140-7791
IS - 6
ER -