تحليل الجينوم الكامل لبعض سلالات البكتيريا الجذرية المعززة لنمو النبات (Klebsiella sp. S1 و Pseudomonas sp. S2)

Abstract

This study aims at genomic analysis of PGPRs in an attempt to understand the feasibility of using them as agents in promoting plant growth as well as in biocontrol against fungi that cause severe losses in food security such as Seeding damping off disease. This study allowed a deeper understanding of some characteristic isolates at the genetic level. In this study, two samples of rhizobacterial strain S1 and S2 were used. The genetic study by molecular analysis of the segment "ADNr 16S" and the phylogeny study made it possible to demonstrate the affinity of the S1 isolate of Klebsiella africana Kp7T with a similarity of 99.57% and the affinity for the S2 isolate of the type Pseudomonas. juntendi with a similarity of 99.64%.The genomic study of the rhizobacterial strain S1 and S2 was carried out as a study of genes associated with functional groups (COG) through the process of genetic analysis (Annotation) by the RAST server, then genetic identification using the Prokka program in order to discover and identify the genes related to the promoting plant growth mechanism , biocontrol and finally studying the genetic groups responsible for Secondary metabolism by the ANTISMASH software analysis tool. The results of the genetic analysis of the this isolats can be summarized as follows : The presence of a relatively important genetic frequency with regard to genes related to nitrogen metabolism, stress response, phosphorus metabolism, and iron acquisition and metabolism. The absence of genes responsible for motility and chemotaxis was also noted in strain S1 and its presence in strain S2.The genetic identification also allowed the discovery of genes related to the production of phytohormons, as the presence of genes involved in the production of auxin (IAA) was identified within the genome of the S1 strain important in phytostimulation, and the absence of these genes was observed in the S2 strain. Regarding nitrogen fixation, presence of genes encoding for nitrogenase enzyme which fixes atmospheric nitrogene , was detected in S1 and S2 strains . As for the genes that contribute to the dissolution of inorganic phosphorous, many of them have been identified in both strains S1 and S2, such as the genes that encode several enzymes that play an important role in the manufacture of compounds that dissolve mineral phosphates, such as glycolic acid (GA). Likewise, genes encoding the synthesis of siderophore and volatile organic compounds (VOCs) have been identified in the two strains S1 and S2, which are compounds that stimulate root formation and increase disease resistance and drought tolerance .Also, in the S1 and S2 strains, genes that contribute to stress tolerance such as betA and betB were found important one such as glycine-betaine synthesis and genes encoded for the production of antioxidant enzymes and free radical stresses against in plants, the most important of which are: SOD: Superoxide dismutase, peroxidase (POXs) and catalase (CAT). Several gene groups (Clusters) responsible for the production of secondary metabolic compounds have also been identified that play a role in biological resistance and act as antibiosis for pathogens in the S1 and S2 strains, the most important of which are NRPS and Bacteriocin. The overall results obtained show the importance of the S1 and S2 strains in promoting plant growth by providing nutrients, stress resistance and biocontrol against pathogens. Therefore, the possibility of testing their use as individual or combined biological inoculates is very encouraging to complete the applied study in the agricultural field.