TY - JOUR
T1 - Leaf Phosphorus Concentration Regulates the Development of Cluster Roots and Exudation of Carboxylates in Macadamia integrifolia
AU - Zhao, Xin
AU - Lyu, Yang
AU - Jin, Kemo
AU - Lambers, Hans
AU - Shen, Jianbo
PY - 2021/1/13
Y1 - 2021/1/13
N2 - Phosphorus (P) deficiency induces cluster-root formation and carboxylate exudation in most Proteaceae. However, how external P supply regulates these root traits in Macadamia integrifolia remains unclear. Macadamia plants were grown hydroponically with seven P levels to characterize biomass allocation, cluster-root development, and exudation of carboxylates and acid phosphatases. Plant biomass increased with increasing P supply, peaking at 5 μM P, was the same at 5–25 μM P, and declined at 50–100 μM P. Leaf P concentration increased with increasing P supply, but shoot biomass was positively correlated with leaf P concentration up to 0.7–0.8 mg P g–1 dry weight (DW), and declined with further increasing leaf P concentration. The number of cluster roots declined with increasing P supply, with a critical value of leaf P concentration at 0.7–0.8 mg P g–1 DW. We found a similar trend for carboxylate release, with a critical value of leaf P concentration at 0.5 mg g–1 DW, but the activity of acid phosphatases showed a gradually-decreasing trend with increasing P supply. Our results suggest that leaf P concentration regulates the development and functioning of cluster roots, with a critical P concentration of 0.5–0.8 mg g–1, above which macadamia growth is inhibited.
AB - Phosphorus (P) deficiency induces cluster-root formation and carboxylate exudation in most Proteaceae. However, how external P supply regulates these root traits in Macadamia integrifolia remains unclear. Macadamia plants were grown hydroponically with seven P levels to characterize biomass allocation, cluster-root development, and exudation of carboxylates and acid phosphatases. Plant biomass increased with increasing P supply, peaking at 5 μM P, was the same at 5–25 μM P, and declined at 50–100 μM P. Leaf P concentration increased with increasing P supply, but shoot biomass was positively correlated with leaf P concentration up to 0.7–0.8 mg P g–1 dry weight (DW), and declined with further increasing leaf P concentration. The number of cluster roots declined with increasing P supply, with a critical value of leaf P concentration at 0.7–0.8 mg P g–1 DW. We found a similar trend for carboxylate release, with a critical value of leaf P concentration at 0.5 mg g–1 DW, but the activity of acid phosphatases showed a gradually-decreasing trend with increasing P supply. Our results suggest that leaf P concentration regulates the development and functioning of cluster roots, with a critical P concentration of 0.5–0.8 mg g–1, above which macadamia growth is inhibited.
KW - cluster roots
KW - critical phosphorus concentration
KW - exudation
KW - phosphorus supply
KW - Proteaceae
UR - http://www.scopus.com/inward/record.url?scp=85099960038&partnerID=8YFLogxK
U2 - 10.3389/fpls.2020.610591
DO - 10.3389/fpls.2020.610591
M3 - Article
C2 - 33519868
AN - SCOPUS:85099960038
VL - 11
JO - Frontiers in Plant Science
JF - Frontiers in Plant Science
SN - 1664-462X
M1 - 610591
ER -