Do cluster roots contribute to the costs of carbon and nitrogen metabolism during variations in phosphate supply in the legume Lupinus albus
Year: 2013
Type: article
Abstract: The generally low concentrations of P and N in the soil, causes most plants to experience nutrient deficiency during their life cycle.Lupins can rely on both cluster roots and nodules for P acquisition and biological nitrogen fixation (BNF) respectively.The legume Lupinus albus is able to survive under low nutrient conditions, because it has two specialized belowground organs for the acquisition of N and P. In this regard, cluster roots increase P uptake and root nodules acquire atmospheric N2 via biological nitrogen fixation (BNF).Although these organs normally tolerates low P conditions, very little is known about their physiological and metabolic flexibility during variations in P supply.Furthermore, the resource allocation (C, N and P) between cluster roots and nodules has also been largely understudied.The aim of this investigation was therefore to determine the resource allocation, physiological and metabolic flexibility of these organs during variations in P supply.Although variation on P supply had no effect on the total biomass, there were significant differences in specialised below-ground organ allocation to cluster roots and nodule formation.Cluster root formation and the associated C-costs increased during low P supply.In contrast to the cluster root decline at high P supply, there was an increase in nodule growth allocation and corresponding C-costs.Since cluster roots were able to increase P acquisition under low P conditions, this below-ground investment may also have benefited the P nutrition of nodules.These findings provide evidence that when lupins acquire N via BNF in their nodules, there may be a trade-off in resource allocation between cluster roots and nodules.The short-term elevated P supply, caused an increased allocation of C and respiratory costs to nodules, at the expense of cluster roots.This alteration was also reflected in the increase in nodule enzyme activities related to organic acid synthesis, such as Phosphoenol-pyruvate Carboxylase (PEPC), Pyruvate Kinase (PK), Malate Dehydrogenase (NADH-MDH) and Malic Enzyme (ME).In cluster roots, the elevated P conditions, caused a decline in these organic acid synthesizing enzymes.This suggests that during short-term elevated P supply, there is a great degree of physiological and metabolic flexibility in the lupin nutrient acquiring structures.
Author: Rochelle Thuynsma
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
Funder: Harry Crossley Foundation
OpenAlex ID: W2121578866