Short-term supply of elevated phosphate alters the belowground carbon allocation costs and functions of lupin cluster roots and nodules

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• 作者：Rochelle Thuynsma ; Alex Valentine ; ^{alexvalentine@mac.com" class="auth_mail} ; ^{ajv@sun.ac.za" class="auth_mail} ; Aleysia Kleinert
• 关键词：BNF ; biological nitrogen fixation ; PNUE ; photosynthetic nitrogen use efficiency ; PPUE ; photosynthetic phosphate use efficiency ; %NDFA ; nitrogen derived from atmosphere ; RGR ; relative growth rates ; SNAR ; specific nitrogen acquisition rate ; SNUR ; specific nitrogen utilisation rate ; SPAR ; specific phosphate acquisition rate ; SPUR ; specific phosphate utilisation rate ; PEPC ; phosphoenol-pyruvate carboxylase ; PK ; pyruvate kinase ; NADH-MDH ; malate dehydrogenase ; ME ; malic enzyme ; APase ; acid phosphatas
• 刊名：Journal of Plant Physiology
• 出版年：1 May, 2014
• 年：2014
• 卷：171
• 期：8
• 页码：648-654
• 全文大小：1680 K

文摘

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Summary

Lupins can rely on both cluster roots and nodules for P acquisition and biological nitrogen fixation (BNF) respectively. The resource allocation (C, N and P) between cluster roots and nodules has been largely understudied during P-deficient conditions. The aim of this investigation was therefore to determine the changes in resource allocation between these organs during fluctuations in P supply. Lupinus albus was cultivated in sand culture for 3 weeks, with either sufficient (2 mM high) or limiting (0.1 mM low) 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, but at sufficient P-supply the construction and growth respiration costs of cluster roots declined along with their growth. In contrast to the cluster root decline at high P supply, there was an increase in nodule growth allocation and corresponding C-costs. However, this was not associated with an increase in BNF. 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.