Effect of Arsenic on Nodulation and Nitrogen Fixation of Blackgram (Vigna mungo)

Abstract

Rhizobium-legume symbiotic interaction is an efficient model system for soil remediation and reclamation. We earlier isolated an arsenic (As) (2.8 mM arsenate) tolerant and symbiotically effective Rhizobium strain, VMA301 from Vigna mungo and in this study we further characterized its efficacy for arsenic removal from the soil and its nitrogen fixation capacity. Although nodule formation is delayed in plants with As-treated composite when the inoculum was prepared without arsenic in culture medium, whereas it attains the significant number of nodules compare to plant grown in As-free soil when the inoculum was prepared with arsenic supplemented medium. Arsenic accumulation was higher in roots than root nodules. Nitrogenase activity is reduced to almost 2 fold in plants with As-treated soil but not abolished. These results suggest that this strain, VMA301, has been able to establish an effective symbiotic interaction in V. mungo in As-contaminated soil and can perform dual role of arsenic bioremediation as well as soil nitrogen improvement.

Chemolithoautotropic Diazotrophy Dominates the Nitrogen Fixation Process in Mine Tailings

“…Additionally, metal­(loid)­s, including Fe and As, also correlated with diazotroph abundance, as revealed by RF. Consequently, high metal contamination and toxicity may impede diazotrophic activities. − …”

Impact of Harsh Environmental Conditions on Nodule Formation and Dinitrogen Fixation of Legumes

“…The effects of metals on rhizobial composition within soil or nodule environment and different legume genotypes, however, have been contradictory (Wani et al 2007a(Wani et al , b, 2008a. Mandal et al (2011) reported that nitrogenase activity was reduced to almost 2 fold in plants with Arsenate-treated soil but not abolished in root nodule of blackgram. Their microscopic observations of the cross section of root nodules revealed that the effective areas of N 2 -fixing zone were reduced in plants grown in arsenic contaminated field.…”

Targeting redox metabolism of the maize‐Azospirillum brasilense interaction exposed to arsenic‐affected groundwater

“…Usually, the changes detected are as expected for such concentration (Abbas et al, 2018). Although originally the inoculation of diazotroph microorganisms had a sole and important function, to serve as a nitrogen source for crops in order to improve growth and increase yield, the utilization of such microorganisms as bioremediation tools constitutes an additional function that has gained special attention in the last 10 years (Gómez‐Sagasti & Marino, 2015; Mandal et al, 2011; Reichman, 2007). In addition, physico‐chemical transformations of metal(oid)s carried out by microorganisms in the rhizosphere depend on their intrinsic capacities (Finnegan & Chen, 2012; Lomax et al, 2012; Yang & Rosen, 2016).…”