RESUMEN
BACKGROUND: Rhizobium giardinii has been demonstrated to colonize the roots of a variety of legume species, including common beans, and to increase nitrogen fixation. This suggests that Rhizobium giardinii might be a beneficial tool for sustainable agriculture by lowering dependency on synthetic nitrogen fertilizers and enhancing soil fertility. Understanding the regulatory components in the R. giardinii A3AY_RS01 genes might also lead to the creation of innovative ways for increasing the effectiveness of nitrogen fixation in other agriculturally important bacteria. Therefore, this study was aimed to predict regulatory element of R. giardinii DNA-binding response regulator A3AY_RS01 genes. RESULTS: The locations for 19 % of the Transcriptional start site (TSSs) were within -300 bp relative to the start codon and ten candidate motifs were identified that are shared by at least 50 % of the R. giardinii A3AY_RS01 promoter input sequences from both strands. Motif 1 was revealed as the common promoter motif for all of R. giardinii A3AY_RS01 genes that serves as binding sites for TFs involved in the expression regulation of these genes. Hence, it was revealed that Motif 1 may serve as the binding site chiefly for Ferric uptake regulator (Fur) transcription factor family to regulate expression of A3AY_RS01 genes. High CpG density in the promoter than body regions were observed for most of the genes except for A3AY_RS0102950, A3AY_RS0120195 and A3AY_RS0131150 genes. Nonetheless, promoter areas were richer than body regions in both techniques. CONCLUSIONS: MV1 motif can serve as a binding site for the Fur transcription factor gene family in R. giardinii to regulate the expression of R. giardinii A3AY_RS01 genes. R. giardinii A3AY_RS01 genes are rich in CpG Islands, and play an important role in the regulation of the gene expression of nitrogen fixing in this bacterium.
RESUMEN
Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a severe disease in wheat worldwide, including Ethiopia, causing up to 100% wheat yield loss in the worst season. The use of resistant cultivars is considered to be the most effective and durable management technique for controlling the disease. Therefore, the present study targeted the genetic architecture of adult plant resistance to yellow rust in 178 wheat association panels. The panel was phenotyped for yellow rust adult-plant resistance at three locations. Phonological, yield, yield-related, and agro-morphological traits were recorded. The association panel was fingerprinted using the genotyping-by-sequencing (GBS) platform, and a total of 6,788 polymorphic single nucleotide polymorphisms (SNPs) were used for genome-wide association analysis to identify effective yellow rust resistance genes. The marker-trait association analysis was conducted using the Genome Association and Prediction Integrated Tool (GAPIT). The broad-sense heritability for the considered traits ranged from 74.52% to 88.64%, implying the presence of promising yellow rust resistance alleles in the association panel that could be deployed to improve wheat resistance to the disease. The overall linkage disequilibrium (LD) declined within an average physical distance of 31.44 Mbp at r2 = 0.2. Marker-trait association (MTA) analysis identified 148 loci significantly (p = 0.001) associated with yellow rust adult-plant resistance. Most of the detected resistance quantitative trait loci (QTLs) were located on the same chromosomes as previously reported QTLs for yellow rust resistance and mapped on chromosomes 1A, 1B, 1D, 2A, 2B, 2D, 3A, 3B, 3D, 4A, 4B, 4D, 5A, 5B, 6A, 6B, 7A, and 7D. However, 12 of the discovered MTAs were not previously documented in the wheat literature, suggesting that they could represent novel loci for stripe rust resistance. Zooming into the QTL regions in IWGSC RefSeq Annotation v1 identified crucial disease resistance-associated genes that are key in plants' defense mechanisms against pathogen infections. The detected QTLs will be helpful for marker-assisted breeding of wheat to increase resistance to stripe rust. Generally, the present study identified putative QTLs for field resistance to yellow rust and some important agronomic traits. Most of the discovered QTLs have been reported previously, indicating the potential to improve wheat resistance to yellow rust by deploying the QTLs discovered by marker-assisted selection.