Abstract Cenostigma pyramidale is a native legume of the Brazilian semiarid region which performs symbiotic association with arbuscular mycorrhizal fungi (AMF), being an excellent model for studying genes associated with tolerance against abiotic and biotic stresses. In RT-qPCR approach, the use of reference genes is mandatory to avoid incorrect interpretation of the relative expression. This study evaluated the stability of ten candidate reference genes (CRGs) from C. pyramidale root tissues under salt stress (three collection times) and associated with AMF (three different times of salinity). The de novo transcriptome was obtained via RNA-Seq sequencing. Three algorithms were used to calculate the stability of CRGs under different conditions: (i) global (Salt, Salt+AMF, AMF and Control, and collection times), (ii) only non-inoculated plants, and (iii) AMF (only inoculated plants). HAG2, SAC1, aRP3 were the most stable CRGs for global and AMF assays, whereas HAG2, SAC1, RHS1 were the best for salt stress assay. This CRGs were used to validate the relative expression of two up-regulated transcripts in Salt2h (RAP2-3 and PIN8). Our study provides the first set of reference genes for C. pyramidale under salinity and AMF, supporting future researches on gene expression with this species.

Mollicutes are cell wall-less bacteria with a genome characterized by its small size. Chromosomal rearrangements help these organisms evade host immune surveillance and hence cause disease. Our goal was to determine genes shared by Mollicutes genomes using the bidirectional best hit methodology. The twelve studied Mollicutes share 210 genes, most of which (> 60%) fall into the following COG categories: translation, ribosomal structure and biogenesis; DNA replication, recombination and repair; nucleotide transport and metabolism and energy production and conversion. Thirty Mollicute-specific genes were identified, 22 of them previously described as essential genes in Mycoplasma genitalium.