Green Synthesized ZnO Nanoparticles Improve the Growth and Phytohormones Biosynthesis and Modulate the Expression of Resistance Genes in Phaseolus vulgaris

Abstract

THE present study was conducted for green synthesis of zinc oxide nanoparticles by zinc acetate and leaf extract of Chenopodium album and emphasize its impact on Phaseolus vulgaris growth. Evaluation of the synthesized ZnO NPs was done through spectrophotometer, X-ray diffraction, and Zeta-potential. Spherical crystals with an average diameter of 25 nm were captured in the Transmission electron microscopy photographs. Phaseolus vulgaris seeds early germinated when was treated with 300mg/L ZnO NPs, as radicles were observed in 40% of the sowed seeds. ZnO NPs supplementation at 500mg /L displayed a good performance in P. vulgaris plants, which was reflected in high measurements of root length, plant height, dry biomass and chlorophylls. Endogenous plant hormones elevated in all treatments when compared with that of control or C. album extract. Indole-butyric acid (IBA) and indole-acetic acid (IAA) were induced by 300mg /L ZnO NPs. Abscisic acid (ABA) was only recorded in plants treated with 1000mg /L. High level of α-amylase was measured in plants treated with 300 and 500mg/L ZnO NPs. 500mg /L ZnO NPs up-regulated NAC gene (no apical meristem gene) with 1.2 fold as compared to the control using qRT-PCR analysis. However, the same dose had no effect on glucanase gene (GLU) expression. This study supports the possibility of using ZnO NPs as a growth promoter and may improve the plant tolerance toward stresses.