ABSTRACT
microRNAs (miRNAs) are non-coding small RNAs that regulate gene expression at post-transcriptional level.Thousands of miRNAs have been identified in legumes, but studies about miRNAs linked to peanut nodulefunctionality are scarce. In this work we analyzed transcriptional changes in peanut nodules to identifymiRNAs involved in functional processes of these organs. We found 32 miRNAs precursors differentiallyexpressed in nodules compared with roots, and predicted the potential targets of their corresponding maturemiRNAs. Among them, 20 belong to 14 conserved miRNAs families and 12 are Arachis hypogaea-specificmiRNAs. Expression levels of 3 miRNAs (ahy-miR399, ahy-miR159 and ahy-miR3508) were confirmedexperimentally by qPCR. We also demonstrated that the expression of these miRNAs was not affected byinoculation of a biocontrol bacterium or a fungal pathogen. The catalogue of differentially expressed miRNAprecursors and the expression of the corresponding mature miRNA potential targets in the nodules of A.hypogaea obtained in this work is a database of strong candidates, including A. hypogaea-specific miRNAs, forthe regulation of the nodule functionality. The analysis of their role in this process will certainly lead to thecharacterization of essential regulators in these particular aeschynomenoid nodules.
ABSTRACT
Plant-growth-promoting bacteria are often used to enhance crop yield and for biological control of phytopathogens. Bacillus sp. CHEP5 is a biocontrol agent that induces systemic resistance (ISR) in Arachis hypogaea L. (peanut) against Sclerotium rolfsii, the causal agent of root and stem wilt. In this work, the effect of the co-inoculation of Bacillus sp. CHEP5 and the peanut nodulating strain Bradyrhizobium sp. SEMIA 6144 was studied on induction of both systemic resistance and nodulation processes. Bradyrhizobium sp. SEMIA 6144 did not affect the ability of Bacillus sp. CHEP5 to protect peanut plants from S. rolfsii by ISR and the priming in challenged-plants, as evidenced by an increment in phenylalanine ammonia-lyase enzyme activity. Additionally, the capacity of Bradyrhizobium sp. SEMIA 6144 to induce nodule formation in pathogen-challenged plants was improved by the presence of Bacillus sp. CHEP5.