Bacterial homoserine lactones as a nanocomposite fertilizer and defense regulator for chickpeas

摘要

Recent advances in agro-nanotechnology have made it possible to deliver bioactive chemicals to plants. In the present study, magnetic carbon nanofibers (Fe-CNFs, 75 g mL(-1)) were used for the delivery of acylated homoserine lactones (AHLs, 0.171 and 1.71 mg L-1) in chickpea (Cicer arietinum) plants to enhance growth as well as stress tolerance. The negative zeta potential (-22 mV) at the Fe-CNF surface supported the binding of oppositely charged AHL molecules and facilitated their translocation in the plants. Seeds grown under exposure to the AHL (10 M or 1.71 mg L-1)/Fe-CNF nanocomposite (NC) for 3 days showed a significant (p < 0.01) improvement in the germination index (GI = 13 +/- 2) and vigor index (VI = 257.5 +/- 2) with respect to the control (GI, 6 +/- 1 and VI, 78 +/- 10) and individual AHL exposure (GI, 7 +/- 1 and VI, 120 +/- 12). Seeds incubated with NC showed normal germination rates under simulated oxidative (5 mM H2O2) and salinity (200 mM NaCl) stresses, whereas germination rates decreased under identical conditions without NC. At a later stage of the plant life cycle, the plants treated with the NCs prepared with 0.171 and 1.71 mg L-1 (1 and 10 M, respectively) AHL every third day until 30 days showed a significant increase of Fe in their roots (7.14 mg g(-1)), shoot (4.27 mg g(-1)) and leaves (4.33 mg g(-1)) with respect to the control (3.53, 1.28 and 2.38 mg g(-1), respectively), indicating that NCs were effectively translocated from roots to shoot. The exposure to NC prepared with 10 M (1.71 mg L-1) AHL resulted in increased plant biomass (6.1 +/- 1.2) as well as total chlorophyll (64.6 +/- 8 g mL(-1)) and protein (5.4 +/- 0.6 mg g(-1)) contents with respect to the control (3.8 +/- 0.8; 56.7 +/- 6 and 3.7 +/- 0.4, respectively). The NC-exposed plants also showed resistance to infection by the Fusarium oxysporum f. sp. ciceri fungal pathogen. The present study developed a novel bioactive nanomaterial that serves in a dual role: a fertilizer and a defense regulator for plants.