Heterologous expression of nifA or nodD genes improves chickpea-Mesorhizobium symbiotic performance

Abstract

Aims: The aim of this study was to investigate whether the overexpression of NifA and NodD regulators contribute to the symbiotic improvement of chickpea mesorhizobia. Methods: The native strains V-15b, ST-2 and PMI-6 were transformed with extra copies of nifA or nodD genes and several plants trial were performed. Results: Plant growth assays showed that nifA overexpression was able to improve the symbiotic effectiveness of V-15b, while nodD overexpression lead to the improvement of ST-2 and PMI-6. Hydroponic assays showed that plants inoculated with V15bnifA+ and PMI6nodD+ started developing nodules earlier than those inoculated with the corresponding control strains. In addition, the number of nodules was always higher in plants inoculated with the strains overexpressing the symbiotic genes. Analysis of histological sections of nodules formed by V15bnifA+ showed a more developed fixation zone when compared to control. On the other hand, nodules induced by PMI6nodD+ did not show a senescent zone, which was observed in nodules from plants inoculated with the control strain. Plants inoculated with PMI6nodD+ and ST2nodD+ showed a higher number of infection threads than the corresponding control inoculations. Conclusion: These results indicate that overexpressing nifA and nodD may be an important tool to achieve the improvement of the symbiotic performance of mesorhizobia.

Molecular Biology in the Improvement of Biological Nitrogen Fixation by Rhizobia and Extending the Scope to Cereals

“…Nitrogen reduction could be made more efficient by facilitating the transport of electrons in a reaction catalyzed by the nitrogenase. Overexpression of genes from nif and fix groups is being used to develop such technologies [ 13 , 14 , 15 , 16 , 17 , 18 ]. Modulation of stress response genes, phytohormone biosynthesis, phosphate solubilization, and antibiotic production are among the other areas of symbiotic interaction that are being explored to enhance rhizobia effectiveness [ 19 ].…”

The introduced strain Mesorhizobium ciceri USDA 3378 is more competitive than an indigenous strain in nodulation of chickpea in newly introduced areas of China

“…The nodulation kinetics were evaluated through an experimental hydroponic assay using inoculated chickpea plants as described by da Silva et al . (2019) with some minor modifications. Chickpea plants were grown in pots with sterilized vermiculite as substrate.…”