Abstract
BackgroundPhosphorus (P), being one of the essential components of nucleic acids, cell membranes and enzymes, indispensable for diverse cellular processes like photosynthesis/carbohydrate metabolism, energy production, redox homeostasis and signaling. Crop yield is severely affected due to Phosphate (Pi) deficiency; and to cope with Pi-deficiency, plants have evolved several strategies. Some rice genotypes are compatible with low Pi availability, whereas others are sensitive to Pi deficiency. However, the underlying molecular mechanism for low Pi tolerance remains largely unexplored.ResultSeveral studies were carried out to understand Pi-deficiency responses in rice at seedling stage, but few of them targeted molecular aspects/responses of Pi-starvation at the advanced stage of growth. To delineate the molecular mechanisms for low Pi tolerance, a pair of contrasting rice (Oryza sativa L.) genotypes [viz. Pusa-44 (Pi-deficiency sensitive) and its near isogenic line (NIL-23, Pi-deficiency tolerant) harboring Phosphorus uptake 1 (Pup1) QTL from an aus landrace Kasalath] were used. Comparative morphological, physiological, and biochemical analyses confirmed some of the well-known findings. Transcriptome analysis of shoot and root tissues from 45-day-old rice plants grown hydroponically under P-sufficient (16 ppm Pi) or P-starved (0 ppm Pi) medium revealed that Pi-starvation stress causes global transcriptional reprogramming affecting several transcription factors, signaling pathways and other regulatory genes. We could identify several significantly up-regulated genes in roots of NIL-23 under Pi-starvation which might be responsible for the Pi starvation tolerance. Pathway enrichment analysis indicated significant role of certain phosphatases, transporters, transcription factors, carbohydrate metabolism, hormone-signaling, and epigenetic processes in improving P-starvation stress tolerance in NIL-23.ConclusionWe report the important candidate mechanisms for Pi acquisition/solubilization, recycling, remobilization/transport, sensing/signalling, genetic/epigenetic regulation, and cell wall structural changes to be responsible for P-starvation tolerance in NIL-23. The study provides some of the novel information useful for improving phosphorus-use efficiency in rice cultivars.
Highlights
Phosphorus (P), being one of the essential components of nucleic acids, cell membranes and enzymes, indispensable for diverse cellular processes like photosynthesis/carbohydrate metabolism, energy production, redox homeostasis and signaling
We report the important candidate mechanisms for Inorganic phosphorus (Pi) acquisition/solubilization, recycling, remobilization/transport, sensing/signalling, genetic/epigenetic regulation, and cell wall structural changes to be responsible for P-starvation tolerance in Near-isogenic line (NIL)-23
Findings of the present study showed that auxin response factor, AP2 domain containing proteins, GRAS family transcription factor containing protein, histone-like transcription factor, and HSF-type DNA-binding domain containing protein exclusively expressed (> 2.5-fold up-regulated) in root of NIL-23 (Supplementary Table S5) which is in agrement with the earlier findings [33, 34]
Summary
Phosphorus (P), being one of the essential components of nucleic acids, cell membranes and enzymes, indispensable for diverse cellular processes like photosynthesis/carbohydrate metabolism, energy production, redox homeostasis and signaling. Phosphorus (P) is one of the most important macronutrients necessary for the living organisms including plants. It is a vital constituent of several biological. Pi-deficiency in soil is becoming a global problem; application of P-fertilizer in soil has become a necessity to ensure better productivity. This is the reason for a considerable increase in the global use of P-fertilizers in crop husbandry. Limited stocks of the rock phosphate [9], lower use-efficiency of applied P-fertilizers by crop plants, and excessive application of P-fertilizers lead to the environmental damage [10]. While P acquisition refers to the Pi uptake through roots, P-use efficiency refers to the efficient remobilization/internal use of cellular Pi [11]
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