Ureide metabolism in plant-associated bacteria: purine plant-bacteria interactive scenarios under nitrogen deficiency

Background The erratic alterations in climate being experienced in agriculture, such as extended periods of drought or heavy rainfalls, are bringing increasing concerns about nitrogen (N) management. Even in high-input farming systems, unpredictable weather patterns can cause N deficiencies and result in nutrient losses that contribute to major pollution issues in groundwater, lakes, and even the oceans. Our present understanding of the beneficial interactions between N-deficient-challenged plants and plant-associated bacteria (PAB), mainly of the phyla Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria, is largely based on studies performed at the level of whole-plant fitness and impacts of crop yields via the abilities of bacteria to synthesize indole acetic acid and/or produce the enzyme 1-aminocyclopropane-1-carboxylate deaminase which reduces endogenous ethylene levels. Much less is known about the complex interaction that occur from the PAB’s abilities to produce N ureide (allantoin and allantoate) and how these purine intermediaries function as an N source and prime stress signals for the growth of both partners.