Characterization of purple acid phosphatases involved in extracellular dNTP utilization in Stylosanthes

• Published in: Journal of experimental botany 2016-07, Vol.67 (14), p.4141-4154
• Main Authors: Liu, Pan-Dao, Xue, Ying-Bin, Chen, Zhi-Jian, Liu, Guo-Dao, Tian, Jiang
• Format: Article
• Language: English
• Subjects: Acid Phosphatase - genetics; Acid Phosphatase - metabolism; Acid Phosphatase - physiology; Deoxyribonucleotides - metabolism; Fabaceae - enzymology; Fabaceae - genetics; Fabaceae - metabolism; Gene Expression Regulation, Plant - physiology; Genotype; Glycoproteins - genetics; Glycoproteins - metabolism; Glycoproteins - physiology; Phylogeny; Plant Roots - enzymology; Plant Roots - metabolism; RESEARCH PAPER; Stylosanthes
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/erw190

Stylo (Stylosanthes spp.) is a pasture legume predominant in tropical and subtropical areas, where low phosphorus (P) availability is a major constraint for plant growth. Therefore, stylo might exhibit superior utilization of the P pool on acid soils, particularly organic P. However, little is known about mechanisms of inorganic phosphate (Pi) acquisition employed by stylo. In this study, the utilization of extracellular deoxy-ribonucleotide triphosphate (dNTP) and the underlying physiological and molecular mechanisms were examined for two stylo genotypes with contrasting P efficiency. Results showed that the P-efficient genotype, TPRC2001-1, was superior to the P-inefficient genotype, Fine-stem, when using dNTP as the sole P source. This was reflected by a higher dry weight and total P content for TPRC2001-1 than for Fine-stem, which was correlated with higher root-associated acid phosphatase (APase) activities in TPRC2001-1 under low P conditions. Subsequently, three PAP members were cloned from TPRC2001-1: SgPAP7, SgPAP10, and SgPAP26. Expression levels of these three SgPAPs were up-regulated by Pi starvation in stylo roots. Furthermore, there was a higher abundance of transcripts of SgPAP7 and SgPAP10 in TPRC2001-1 than in Finestem. Subcellular localization analysis demonstrated that these three SgPAPs were localized on the plasma membrane. Overexpression of these three SgPAPs could result in significantly increased root-associated APase activities, and thus extracellular dNTP utilization in bean hairy roots. Taken together, the results herein suggest that SgPAP7, SgPAP10, and SgPAP26 may differentially contribute to root-associated APase activities, and thus control extracellular dNTP utilization in stylo.