Effect of zinc-resistantLysinibacillusspecies inoculation on growth, physiological properties, and zinc uptake in maize (Zea maysL.)

Soil contamination by heavy metals is one of the major abiotic stresses that cause retarded plant growth and low productivity. Among the heavy metals, excessive accumulations of zinc (Zn) cause toxicity to plants. The toxicity caused by Zn could be managed by application of Zn-tolerant plant growth-promoting (PGP) bacteria. In this study, five Zn-tolerant bacteria (100-400 mg(-1)Zn resistant) were selected and identified asLysinibacillusspp. based on 16S rRNA gene sequencing. The PGP properties of theLysinibacillusspp. showed the production of indole acetic acid (60.0-84.0 mu g/ml) and siderophore, as well as solubilization of potassium. Furthermore, the isolates were evaluated under greenhouse condition with 2 g kg(-1)Zn stress and without Zn stress along with control onZea mays. The results showed thatLysinibacillusspp. coated seeds enhanced plant growth attributes and biomass yield in both conditions compared with control plants. The enhancement of root growth ranged from 49.2 to 148.6% and shoot length from 83.3 to 111.7% under Zn-stressed soils. Also, the inoculated seedlings substantially enhanced chlorophyllaandb, proline, total phenol, and ascorbic acid. The uptake of Zn by maize root ranged from 31.5 to 210.0% compared with control plants. Therefore, this study suggested that the tested Zn-tolerantLysinibacillusspp. may be used for cultivation ofZ. maysin Zn-contaminated agricultural lands.