Autochthonous halotolerant plant growth-promoting rhizobacteria promote bacoside A yield of Bacopa monnieri (L.) Nash and phytoextraction of salt-affected soil
Phytoremediation is a promising approach for reclamation of salt-affected soil.Phytoextraction is the most commonly used process,which exploits plants to absorb,immobilize,and accumulate salt in their shoots.In this study,halotolerant plant growth-promoting rhizobacteria (PGPR) were isolated from the thizosphere of wild grasses growing naturally in salt-affected areas of Lucknow,Uttar Pradesh (India) and were tested for their efficacies of salt-tolerance and plant growth-promoting (PGP) abilities.Based on 16S rRNA sequences,the most efficient halotolerant isolates possessing PGP traits were identified as Pseudomonas plecoglossicida (KM233646),Acinetobacter calcoaceticus (KM233647),Bacillus flexus (KM233648),and Bacillus safensis (KM233652).Application of these isolates as bio-inoculants significantly (P < 0.05) increased the growth and bacoside A yield of a medicinal plant,Bacopa monnieri (L.) Nash,grown on natural salt-affected soil.The phytoremediation of salt-affected soil was evident by the substantial increase in shoot Na+∶K+ ratio of bio-inoculant-treated plants.When compared to un-inoculated control plants,the soil physico-chemical properties of bio-inoculant-treated plants were improved.The shoot and root biomass (fresh and dry weights),soil enzymes,and soil nutrient parameters showed significant positive correlations with the shoot Na+∶K+ ratio.Consequently,the halotolerant PGPR screened in this study could be useful for the reclamation of saline soils concomitant with improved plant growth and bacoside A yield.
Autochthonous halotolerant plant growth-promoting rhizobacteria promote bacoside A yield of Bacopa monnieri (L.) Nash and phytoextraction of salt-affected soil