Exploration of microbiome of medicinally important plants as biocontrol agents against Phytophthora parasitica

Molecular and metabolic traits of some Egyptian species of Cassia L. and Senna Mill (Fabaceae-Caesalpinioideae)

The genus Cassia and Senna have been classified under subfamily Caesalpinioideae of family Fabaceae (Leguminosae) of order Fabales. There is a scarce taxonomical studies of the genus Cassia and Senna inhabiting Egyptian environments, thus, the main objective of the current was to revise and authenticate the phylogenetic relationship between studied taxa of the species of the genera Cassia and Senna in Egypt using the recent tools of ITS barcoding, RAPD analysis and metabolic profiling, in comparing to the traditional taxonomical features. From the cluster analysis of the traditional 27 morphological characters, the studied taxa were categorized into two major clades with an average taxonomic distance of 4.3. The clade I include Cassia fistula, C. renigera, C. javanica L subsp. nodosa and C. roughiia that belongs to series Obolospermae, and C. grandis that belongs to series Grandes. The clade (II) includes Senna surattensis and S. alata at taxonomic level 3.6. The taxonomical description of the studied taxa was confirmed from the molecular analysis of ITS sequences and RAPD analysis. The ITS sequences of the tested plants species C. fistula L, C. grandis MD4, C. javanica subsp. nodosa MD7, C. roxburghii MD5, C. renigera MD5 were deposited at genbank with accession numbers MW367973, MZ960447, MW386305, MW326753 and MW32685, respectively. While, the ITS sequences of the S. surrattensis and S. alata were deposited into genbank accession # MD14 MW367670 and MD20 MW412635, respectively. Thus, from the molecular analysis, two clades were clearly separated into Clade I of Cassia and Clade II of Senna. The cluster I represented by C. fistula, C. renigera, C. roxburghii, and C. javanica sub nodosa, and the cluster II represented by S. alata and S. surattensis. From the PCA of RAPD, a clearly discrimination between the two Taxa was observed revealing the characteristic grouping of Cassia and Senna. The species Senna alata and Senna surattensis were grouped together, but the species of C. renigera, C. javanica, C. roxburghii and C. grandis was grouped on a distinct group. The separation of Cassia and Senna species into two clusters verify the segregation of the genus Cassia L. senso lato into two distinct genera namely Senna P. and Cassia L. The morphological, molecular traits of the studied plants were authenticated from the metabolic profiling by GC-MS analysis. Among the 23 identified metabolites, four compounds namely hexadecanoic acid, methyl ester, 9-Octadecenoic acid (Z)-ethyl ester and Vitamin E were detected with fluctuated concentrations, among C. fistula, C. grandis, C. javanica subsp. nodosa and C. roxburghii. Conclusively, the traditional morphological features, molecular barcoding using ITS sequences, RAPD analysis and metabolic traits by GC-MS analysis, authenticates the taxonomical diversity of the genus Cassia and Senna.

Bioprospecting Plant Growth Promoting Rhizobacteria for Enhancing the Biological Properties and Phytochemical Composition of Medicinally Important Crops

Traditionally, medicinal plants have long been used as a natural therapy. Plant-derived extracts or phytochemicals have been exploited as food additives and for curing many health-related ailments. The secondary metabolites produced by many plants have become an integral part of human health and have strengthened the value of plant extracts as herbal medicines. To fulfil the demand of health care systems, food and pharmaceutical industries, interest in the cultivation of precious medicinal plants to harvest bio-active compounds has increased considerably worldwide. To achieve maximum biomass and yield, growers generally apply chemical fertilizers which have detrimental impacts on the growth, development and phytoconstituents of such therapeutically important plants. Application of beneficial rhizosphere microbiota is an alternative strategy to enhance the production of valuable medicinal plants under both conventional and stressed conditions due to its low cost, environmentally friendly behaviour and non-destructive impact on fertility of soil, plants and human health. The microbiological approach improves plant growth by various direct and indirect mechanisms involving the abatement of various abiotic stresses. Given the negative impacts of fertilizers and multiple benefits of microbiological resources, the role of plant growth promoting rhizobacteria (PGPR) in the production of biomass and their impact on the quality of bio-active compounds (phytochemicals) and mitigation of abiotic stress to herbal plants have been described in this review. The PGPR based enhancement in the herbal products has potential for use as a low cost phytomedicine which can be used to improve health care systems.

LC-MS/MS-based profiling of bioactive metabolites of endophytic bacteria from Cannabis sativa and their anti-Phytophthora activity

Protection of crop plants from phytopathogens through endophytic bacteria is a newly emerged area of biocontrol. In this study, endophytic bacteria were isolated from the rhizosphere of Cannabis sativa. Based on initial antimicrobial screening, three (03) bacteria Serratia marcescens MOSEL-w2, Enterobacter cloacae MOSEL-w7, and Paenibacillus MOSEL-w13 were selected. Antimicrobial assays of these selected bacteria against Phytophthora parasitica revealed that E. cloacae MOSEL-w7 and Paenibacillus sp. MOSEL-w13 possessed strong activity against P. parasitica. All these bacterial extracts showed strong inhibition against P. parasitica at different concentrations (4-400 µg mL^-1). P. parasitica hyphae treated with ethyl acetate extract of E. cloacae MOSEL-w7 resulted in severe growth abnormalities compared to control. The extracts were further evaluated for in vivo detached-leaf assay against P. parasitica on the wild type tobacco. Application of 1% ethyl acetate bacterial extract of S. marcescens MOSEL-w2, E. cloacae MOSEL-w7, and Paenibacillus sp. MOSEL-w13 reduced P. parasitica induced lesion sizes and lesion frequencies by 60-80%. HPLC based fractions of each extract also showed bioactivity against P. parasitica. A total of 24 compounds were found in the S. marcescens MOSEL-w2, 15 compounds in E. cloacae MOSEL-w7 and 20 compounds found in Paenibacillus sp. MOSEL-w13. LC-MS/MS analyses showed different bioactive compounds in the bacterial extracts such as Cotinine (alkylpyrrolidine), L-tryptophan, L-lysine, L-Dopa, and L-ornithine. These results suggest that S. marcescens MOSEL-w2, E. cloacae MOSEL-w7, and Paenibacillus MOSEL-w13 are a source of bioactive metabolites and could be used in combination with other biocontrol agents, with other modes of action for controlling diseases caused by Phytophthora in crops. They could be a clue for the broad-spectrum biopesticides for agriculturally significant crops.