Background: We publish the first available transcriptome assembly of guar (Cyamopsis tetragonoloba (L.) Taub.), a well-known source of guar gum (food additive E 412). At high latitudes, e.g., in Russia, the main challenge for guar cultivation is the long photoperiod during summer, which delays flowering and maturation of guar plants. Meanwhile, identifying of genes affecting the photoperiod sensitivity of guar would have a major impact on the development of marker-assisted breeding of this valuable food crop. Methods: RNA isolated from leaves of early and late flowering guar plants grown under long-day conditions were used to generate de novo transcriptome assembly. A similarity search was conducted using BLASTN 2.2.31+ with default settings to identify homologous sequences of soybean maturity genes E1-E4 in guar transcriptome and genome assembly. Gene prediction tools such as AUGUSTUS and FGENESH+ were used to predict the exon-intron structure of the candidate genes. Functional annotation of the amino acid sequence was performed using InterProScan v. 5.68-100. Results: The transcriptome assembly contained sequences of 96,447 clustered transcript isoforms in the leaves of guar plants grown under long-day conditions. The transcriptome assembly was annotated using BLAST against the Glycine max genome, and 42,615 guar transcripts (44.2%) were found to be similar to soybean genes. We used the developed transcriptome assembly to discover orthologs of the E1-E4 soybean loci in the guar genome that have the greatest impact on the flowering and maturation of this closely related, short-day legume crop. A high level of identity was detected between peptide sequences encoding by orthologous genes E1 and CtE1 (80%), E2 and CtE2 (93%), E3 and CtE3 (83%), and E4 and CtE4 (91%). The sequences and the intron-exon structure of the genes in soybean and guar were similar, suggesting that the genetic pathways underlying basic flowering mechanisms are conserved between these two legume crops. Conclusions: The revealed intron-exon structure of the guar genes CtE1-CtE4 creates possibilities for their targeted mutagenesis, e.g., using CRISPR-Cas and developing new guar germplasm with low sensitivity to photoperiod.

CRISPR/Cas systems (Clustered regularly interspaced palindromic repeats / CRISPR-associated) are rapidly becoming a commonplace and popular tool for gene editing in research and clinical contexts. However, the quality of CRISPR/Cas experiments depends heavily on the guide RNA (gRNA) design; therefore, a reliable, easy, and rapid method for verifying gRNA cleavage efficacy is necessary. Engineered nuclease-induced translocations (ENIT) are an easy and cost-efficient method for the verification of gRNA efficacy, which involves tracking induced chromosomal mutations, using polymerase chain reaction (PCR). We have customized this method using both direct PCR and nested PCR approaches and have been able to reduce the sample preparation time. We present a simple and reliable gRNA testing approach that requires no specific enzymes or equipment.•The approach requires only routinely used enzymes and equipment.•Cost- and time-efficient, requiring approximately 30 min for PCR sample preparation, without requiring DNA purification.•High sensitivity, with induced translocation detected in 100 of 10,000 cells in the general population.

In this study, for the first time, the genes encoding the mammalian steroidogenesis system—cytochrome P450scc (CYP11A1), and its native redox partners adrenodoxin and adrenodoxin reductase—were successfully expressed in the methylobacterium Methylorubrum extorquens. The advantage of using methylobacteria as an expression chassis is that they grow on inexpensive mineral media, use methanol as a carbon and energy source, and do not possess their own sterol catabolism systems. Using recombinant methylobacteria, the valuable steroid pregnenolone was obtained as a sole metabolite from cholesterol. The effect of media composition, bioconversion conditions such as methanol and N-sources content, modes of substrate addition, detergents, methyl-β-cyclodextrin, biomass, and aeration on pregnenolone accumulation was investigated. Under optimized conditions, its yield exceeded 100 mg/L. The results demonstrate a proof of concept relating to the use of bacteria lacking their own steroid degradation systems as microbial chassis for heterologous steroidogenesis systems, including mammalian cytochrome CYP11A1.