title: Improvement in phosphate acquisition and utilization by a secretory purple acid phosphatase (OsPAP21b) in rice.
abstract: Phosphate (Pi) deficiency in soil system is a limiting factor for rice growth and yield. Majority of the soil phosphorus (P) is organic in nature, not readily available for root uptake. Low Pi-inducible purple acid phosphatases (PAPs) are hypothesized to enhance the availability of Pi in soil and cellular system. However, information on molecular and physiological roles of rice PAPs is very limited. Here, we demonstrate the role of a novel rice PAP, OsPAP21b in improving plant utilization of organic-P. OsPAP21b was found to be under the transcriptional control of OsPHR2 and strictly regulated by plant Pi status at both transcript and protein levels. Biochemically, OsPAP21b showed hydrolysis of several organophosphates at acidic pH and possessed sufficient thermostability befitting for high-temperature rice ecosystems with acidic soils. Interestingly, OsPAP21b was revealed to be a secretory PAP and encodes a distinguishable major APase (acid phosphatase) isoform under low Pi in roots. Further, OsPAP21b-overexpressing transgenics showed increased biomass, APase activity and P content in both hydroponics supplemented with organic-P sources and soil containing organic manure as sole P source. Additionally, overexpression lines depicted increased root length, biomass and lateral roots under low Pi while RNAi lines showed reduced root length and biomass as compared to WT. In the light of these evidences, present study strongly proposes OsPAP21b as a useful candidate for improving Pi acquisition and utilization in rice.
authors.affiliation: National Institute of Plant Genome Research, New Delhi, India.
authors.forename: Poonam
authors.initials: P
authors.lastname: Mehra
authors.affiliation: National Institute of Plant Genome Research, New Delhi, India.
authors.forename: Bipin Kumar
authors.initials: BK
authors.lastname: Pandey
authors.affiliation: National Institute of Plant Genome Research, New Delhi, India.
authors.forename: Jitender
authors.initials: J
authors.lastname: Giri
mesh_terms: D000135:Acid Phosphatase / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D012275:Oryza / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference
chemical_list: D006023:Glycoproteins; D010710:Phosphates; D010940:Plant Proteins; D010758:Phosphorus; C091137:purple acid phosphatase; D000135:Acid Phosphatase
keywords: P use efficiency; RNAi; acid phosphatase; organic phosphates; overexpression; root; secretory protein