A phosphoenol pyruvate phosphatase transcript is induced in the root nodule cortex of Phaseolus vulgaris under conditions of phosphorus deficiency

Abstract

Although previous studies on N2-fixing legumes have demonstrated the contribution of acid phosphatases to their phosphorus (P) use efficiency under P-deficient growth conditions, localization of these enzymes in bean nodules has not been demonstrated. In this study, phosphoenol pyruvate phosphatase (PEPase) gene transcripts were localized within the nodule tissues of two recombinant inbred lines, RIL115 (P-deficiency tolerant) and RIL147 (P-deficiency sensitive), of Phaseolus vulgaris. Nodules were induced by Rhizobium tropici CIAT899 under hydroaeroponic conditions with a sufficient versus a deficient P supply. The results indicated that PEPase transcripts were particularly abundant in the nodule infected zone and cortex of both RILs. Analysis of fluorescence intensity indicated that nodule PEPase was induced under conditions of P deficiency to a significantly higher extent in RIL147 than in RIL115, and more in the inner cortex (91%) than in the outer cortex (71%) or the infected zone (79%). In addition, a significant increase (39%) in PEPase enzyme activity in the P-deficient RIL147 correlated with an increase (58%) in the efficiency of use in rhizobial symbiosis. It was concluded that nodule PEPase is upregulated under conditions of P deficiency in the P-deficiency-sensitive RIL147, and that this gene may contribute to adaptation of rhizobial symbiosis to low-P environments.

Legume nodules from nutrient-poor soils exhibit high plasticity of cellular phosphorus recycling and conservation during variable phosphorus supply

“…Intracellular APases break down P nucleotides, sugar-P and P-monoesters and recycle P through the supply of P for amino acid biosynthesis and nodule metabolism during P-deprivation (Penheiter et al 1997). Previous studies have also shown that an increase in intracellular nodule APase activity may constitute an adaptive mechanism for N 2 fixing legumes to tolerate P deficiency (Kouas et al 2008, Bargaz et al 2012). …”

GmEXPB2, a Cell Wall β-Expansin Gene, Affects Soybean Nodulation through Modifying Root Architecture and Promoting Nodule Formation and Development

“…Two examples are Nodule root/Cochleata from M. truncatula/pea and non-symbiotic retarded root growth in L. japonicus, which play essential roles in the development of both roots and nodules (Buzas and Gresshoff, 2007;Couzigou et al, 2012). Furthermore, P, an essential macronutrient, critically regulates root growth as well as nodulation (Bardin et al, 1996;Bonser et al, 1996;Wu and Wang, 2008;Bargaz et al, 2012;Niu et al, 2013). GmEXPB2 has been previously identified to function in adaptive changes of root growth in response to low P stress (Guo et al, 2011).…”

“…In soybean, maintaining Pi homeostasis in nodules through enhanced P transporters is very important for N 2 fixation efficiency (Qin et al, 2012). Moreover, several genes such as phosphoenol pyruvate phosphatase in common bean (Bargaz, et al, 2012) and purple acid phosphatase in soybean (Li et al, 2012) are highly upregulated in nodules at low P level, implying that these genes might be involved in the adaptation of symbiosis to Pi starvation. Previously, a soybean b-expansin gene, GmEXPB2, has been cloned from a Pi starvation-induced soybean complementary DNA library, and has been identified as being intrinsically involved in soybean root system architecture responding to Pi starvation as well as some other abiotic stresses (Guo et al, 2011).…”

Nodules from Fynbos legume Virgilia divaricata have high functional plasticity under variable P supply levels

“…Previous studies have also shown that an increase in nodule APase activity may constitute an adaptive mechanism for N 2 -fixing legumes to tolerate P deficiency (Kouas et al, 2008, Bargaz et al, 2012. White lupin secretes copious amounts of APases from its roots and proteoid roots when subjected to Pi starvation (Miller et al, 2001, Wasaki et al, 2008.…”