Lack of Purple Acid PhosphataseSlPAP26bcompromises the phosphorus starvation response in tomato independent of SlPHR1 and SlPHL1

Abstract

AbstractThe scarcity of soil phosphorus (P), an essential macronutrient, often limits plant growth and development. Enhanced secretion of intracellular and secretory acid phosphatases is essential to maintain cellular inorganic P (Pi) homeostasis in plants. Herein, using transcriptomics and proteomics approach, we observed upregulation of several purple acid phosphatases (PAPs), includingSlPAP1,SlPAP10b,SlPAP12,SlPAP15,SlPAP17b,SlPAP26a, andSlPAP26bin Pi-deficient tomato seedlings. Higher transcript levels ofSlPAP17bandSlPAP26bin the older senescing leaves than the younger leaves indicated active involvement of these PAPs in Pi remobilization. Subsequent detailed characterization ofSlPAP17b,SlPAP26a, andSlPAP26brevealed a prominent role ofSlPAP26bin Pi homeostasis. Silencing ofSlPAP26bled to an exacerbated P starvation response as these plants exhibited smaller shoots, lower soluble Pi, total P levels, and higher sucrose than their EV controls under Pi deprivation.SlPAP26b-silenced plants also showed misregulation of P starvation inducible genes such as phosphate transporters and glycerolipid remodellers, even under Pi-sufficient conditions. WhereasSlPAP26blevels were induced by external sucrose, its expression was found to be independent of the Myb class master regulators of P starvation response, SlPHR1 and SlPHL1. Altogether, this study identifies a prominent role ofSlPAP26bin the Pi compensation network in tomato seedlings.