THE ANSWER IS BLOWIN' IN THE WIND: NOVEL MECHANISM OF FOLIAR PHOSPHORUS UPTAKE FROM ATMOPSHERICALLY DEPOSTED DESERT DUST

Abstract:

Phosphorus (P) scarcity constrains plant growth in many ecosystems worldwide. The common paradigm proposes that plants acquire P almost exclusively from the soil. While most of soil P is recycled within the ecosystem , important part is supplied by atmospherically deposited dust. Here we describe a novel uptake mechanism of P directly from desert dust which bypass the soil-plant continuum. In a greenhouse experiment we show that foliar uptake of P from desert dust captured on plant leaves doubles the growth of P deficient chickpea and wheat plants, two widely cultivated crops that originate in the vicinity of deserts. In contrast, maize, which originated far off dust sources, displayed only marginal response to dust. Strikingly, P deficiency in chickpea and wheat stimulated the acquisition of insoluble P forms that conventionally perceived unavailable for plant uptake through leaf surface processes that increased leaf dust capture, maintained an acidic pH environment on the leaf surface and in chickpea, also enhanced exudation of P solubilizing organic acids. Microscopic visualization of leaf surfaces demonstrates these set of mechanisms were driven by structural changes of the plant's leaf surface induced by P deficiency. We suggest that plants that developed in dust affected regions acclimate to P deficiency by adopting soil independent foliar uptake traits that facilitate direct dust P acquisition above ground.