Effect of Cr(VI) on the development of chickpea sedes and plants and on the simbiont Mesorhizobium ciceri.

VELEZ; PA; VILLALBA PRIMITZ J; TALANO MA; AGOSTINI E; GONZALEZ PS

La Falda- Cordoba

Workshop; II LATINAMERICAN WORKSHOP ON PGPR; 2014

IntroductionEnvironmental contamination by heavy metals such as chromium (VI) is a major problem worldwide due to their toxicity and their adverse effects on humans and ecosystems, as well as for their accumulation in the food chain. Since heavy metals generally cannot be biologically degraded to less toxic products, they generate negative impacts on economic development, affecting crop production. Here we analyze the effect of different Cr (VI) concentrations on chickpea seeds germination and plants tolerance as well as on the growth and removal capacity of Mesorhizobium ciceri, a bacterial strain frequently used for chickpea seeds inoculation. Materials and MethodsChickpea seed variety Chañarito and Mesorhizobium ciceri spp. strain were employed. For germination assays and plants tolerance, different Cr (VI) concentrations were used (5 to 250 mg/l). Plants were cultivated in jars with sterile perlite. After 30-40 day dry weight and removal capacity were evaluated. On the other hand, M. ciceri was grown in YEM medium with different Cr (VI) concentrations (5-100 mg/l). Residual Cr (VI) was determined through diphenylcarbazide method.ResultsGermination assays showed a negative effect of Cr (VI) on radicle lenght whereas the hypocotyl lenght was slightly affected. This was consistent with a decrease of seeds dry weight as consequence of increasing Cr (VI) concentrations. In addition, a significant reduction in seeds dry weight was observed after 150 and 200 mg/l Cr (VI) treatments. On the other hand, plants were less tolerant than seeds, since 50 mg/l Cr (VI) completely inhibited their development. However, chickpea plants were able to remove 10 and 20 mg/l of this contaminant.Furthermore, the growth of M. ciceri decreased with increasing Cr (VI) concentrations. This strain was able to grow until lower concentrations than 100 mg/l of Cr (VI). Removal assays showed that this microorganism partially removed 10 and 20 mg/l of this heavy metal, after 7 and 10 days respectively.ConclusionChickpea seeds were more tolerant to Cr (VI) than chickpea plants. However, these plants were able to remove this heavy metal. M. ciceri tolerated and removed Cr (VI), but concentrations higher than 100 mg/l totally inhibited their growth. These results are interesting because chickpea is a valuable agronomic crop. Therefore, the analysis of metal uptake by the plant as well as the effect of Cr (VI) on its symbiont would provide knowledge to avoid economic losses and to determine whether the transfer of Cr to this crop could affect the food chain through their biomagnification.