Phosphorus and potassium solubilization from rock minerals by endophytic Burkholderia sp. strain FDN2-1 in soil and shift in diversity of bacterial endophytes of corn root tissue with crop growth stage

Abstract

Exploring diversity of endophytes from cultivated crop offers immense promise for plant growth promotion. Present study evaluated plant growth promoting efficiency, phosphorus, and potassium solubilization by bacterial endophytes of corn root in soil. Out of 24 endophytic isolates from four growth stages, 13 isolates were able to grow on nitrogen free media, 10 could solubilize phosphorus from tricalcium phosphate, and 8 isolates possessed potassium solubilizing ability from glauconite. The isolates also showed siderophore production and antifungal activity. Two isolates FDN-4-6 and FDN2-1 produced Indole acetic acid to the extent of 18.75 μg/ml and 17.47 μg/ml, respectively. The isolate FDN2-1 phylogenticlly related to Burkholderia sp. solubilized rock phosphate (250.43 μg/ml soluble P), tricalcium phosphate (416.13 μg/ml), iron phosphate (49.53 μg/ml), aluminum phosphate (85.23 μg/ml). It could also solubilize potassium from galuconite (52.37 μg/ml soluble K) and muscovite (61.87 μg/ml) in culture broth. Seed inoculation with FDN-2-1 could improve the root length and dry weight of corn seedling. Soil amended with rock phosphate and glauconite upon inoculation of FDN2-1 showed significantly (p < 0.05) higher available phosphorus (39.15 kg/ha in Vertisol and 26.05 kg/ha in Alfisol) and potassium (493 kg/ha in Vertisol and 181 kg/ha in Alfisol) after 90 days of incubation. Most of the isolates obtained from seedling stage (15 days after sowing) formed cluster with isolate obtained at later stages with two additional isolates one each at 40 and 60 days of sowing indicated high genetic similarity between the isolates from different growth stages as detected by amplified ribosomal DNA restriction analysis. The results showed favorable effect of inoculation of endophytic Burkholderia sp. on growth of corn plant and nutrient solubilization potential of the isolate FDN2-1in soil.