Nitric oxide is involved in phosphorus deficiency‐induced cluster‐root development and citrate exudation in white lupin

Abstract

Summary• White lupin (Lupinus albus) forms specialized cluster roots characterized by exudation of organic anions under phosphorus (P) deficiency. Here, the role of nitric oxide (NO) in P deficiency-induced cluster-root formation and citrate exudation was evaluated.• White lupin plants were treated with the NO donor sodium nitroprusside (SNP) and scavenger or inhibitor of NO synthase under conditions of P deficiency (0 lM) or P sufficiency (50 lM).• Phosphorus deficiency enhanced NO production in primary and lateral root tips, with a greater increase in cluster roots than in noncluster roots. NO concentrations decreased with cluster root development from the pre-emergent stage, through the juvenile stage, to the mature stage. The P deficiency-induced increase in NO production was inhibited by antagonists of NO synthase and xanthine oxidoreductase, suggesting the involvement of these enzymes in NO production. SNP markedly increased the number of cluster roots. Citrate exudation from different root segments in P-deficient roots was positively correlated with endogenous root NO concentrations.• These findings demonstrate differential patterns of NO production in white lupin, depending on root zone, developmental stage and P nutritional status. NO appears to play a regulatory role in the formation of cluster roots and citrate exudation in white lupin under conditions of P deficiency.

Plant adaptations to severely phosphorus-impoverished soils

“…Wang et al [42] showed that P deficiency induces nitric oxide production. As for auxin, the levels are highest in the pre-emergent stage, and decrease during cluster-root maturation.…”

Physiological and molecular alterations in plants exposed to high [CO2] under phosphorus stress

“…In-depth study on molecular mechanisms defining the phosphate signalling pathway showed that Pup1-specific protein kinase gene, PSTOL1 is involved in regulating root growth and architecture during early stages (Gamuyao et al, 2012). Allele-specific markers for this gene have been reported recently (Pariasca-Tanaka et al, 2014).The systemic response to P starvation is carried through a complex signalling network which involves plant hormones (Nacry et al, 2005;Pérez-Torres et al, 2008;Li et al, 2012), sugars (Karthikeyan et al, 2007) and nitric oxide (Wang et al, 2010), and collectively result in the altered carbohydrate distribution between roots and shoots. Moreover, transcription factors such as PHR1 (OsPHR1, OsPHR2, PvPHR1, ZmPHR1, TaPHR1), PTF1 (OsPTF1, ZmPTF1), MYB2P-1 (OsMYB2P1), MYB62, WRKY (WRKY75, WRKY6), bHLH32 and ZAT6 are involved in the signalling network to regulate plant adaptation to P stress (Yi et al, 2005;Devaiah et al, 2007a, b;Chen et al, 2007;Valdes-Lopez et al, 2008;Zhou et al, 2008;Devaiah et al, 2009;Chen et al, 2009;Li et al, 2011;Dai et al, 2012;Wang et al, 2013).…”

Update on White Lupin Cluster Root Acclimation to Phosphorus Deficiency Update on Lupin Cluster Roots

“…Correa-Aragunde et al (2006) further showed that NO mediates the expression of cell cycle-regulatory genes in tomato pericycle cells to induce lateral root primordia formation, suggesting a NO-mediated auxindependent cell cycle gene regulation in tomato. Recently, NO was demonstrated to be involved in adaptive responses of white lupin to P starvation (Wang et al, 2010). Accumulation of NO was found in P-deficient white lupin roots, particularly in cluster rootlet primordia prior to and during emergence (Fig.…”

“…These studies, together with the findings of Correa-Aragunde et al (2006) in tomato, support the hypothesis that NO seems to be required in lateral root initiation and root primordia formation. In addition to studies on the role of NO in cluster root formation, Wang et al (2010) also investigated the enzymes putatively involved in NO generation in cluster roots. Inhibitor studies and gene expression analyses show that a NO-synthase-like enzyme and xanthine oxidoreductase are required for the accumulation of NO in cluster roots.…”