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SUMMARY: Brassica carinata (BBCC) commonly referred to as Ethiopian mustard is a natural allotetraploid containing the genomes of Brassica nigra (BB) and Brassica oleracea (CC). It is an oilseed crop endemic to the northeastern regions of Africa. Although it is under limited cultivation, B. carinata is valuable as it is resistant/highly tolerant to most of the pathogens affecting widely cultivated Brassica species of the U's triangle. We report a chromosome‐scale genome assembly of B. carinata accession HC20 using long‐read Oxford Nanopore sequencing and Bionano optical maps. The assembly has a scaffold N50 of ~39.8 Mb and covers ~1.11 Gb of the genome. We compared the long‐read genome assemblies of the U's triangle species and found extensive gene collinearity between the diploids and allopolyploids with no evidence of major gene losses. Therefore, B. juncea (AABB), B. napus (AACC), and B. carinata can be regarded as strict allopolyploids. We cataloged the nucleotide‐binding and leucine‐rich repeat immune receptor (NLR) repertoire of B. carinata and, identified 465 NLRs, and compared these with the NLRs in the other Brassica species. We investigated the extent and nature of early‐generation genomic interactions between the constituent genomes of B. carinata and B. juncea in interspecific crosses between the two species. Besides the expected recombination between the constituent B genomes, extensive homoeologous exchanges were observed between the A and C genomes. Interspecific crosses, therefore, can be used for transferring disease resistance from B. carinata to B. juncea and broadening the genetic base of the two allotetraploid species. Significance Statement: We report a highly contiguous genome assembly of allotetraploid mustard Brassica carinata HC20 (BBCC) which contains resistance to many diseases affecting the other extensively cultivated Brassica species of the U's triangle. Comparative analyses of the long‐read assemblies of the six Brassica species revealed high gene collinearity between the three diploid and their allotetraploid species. We tracked the early‐generation genomic interactions between the subgenomes of B. carinata (BBCC) and B. juncea (AABB) in their interspecific crosses using molecular karyotyping and proposed strategies to utilize this information for genomic introgressions. [ABSTRACT FROM AUTHOR]

Alternaria leaf blight, a disease of oilseed Brassicas is caused by a necrotrophic phytopathogenic fungus Alternaria brassicae. The details of its pathogenesis and defence responses elicited in the host upon infection have not been thoroughly investigated. Here, Arabidopsis accession Gre-0 was identified to be highly susceptible to A. brassicae. A comparative histopathological analysis for disease progression and plant responses to A. brassicae in Arabidopsis and Brassica juncea revealed significant similarities between the two compatible pathosystems. Interestingly, in both the compatible hosts, ROS accumulation, cell death and callose deposition correlated with the development of the disease. Based on our results we propose that Arabidopsis- Alternaria brassicae can be an apt model pathosystem since it emulates the dynamics of the pathogen interaction with its natural host- Brassicas. The existing genetic diversity in Arabidopsis can be a starting point to screen for variation in responses to Alternaria leaf blight. Furthermore, several tools available for Arabidopsis can facilitate the dissection of genetic and molecular basis of resistance. [ABSTRACT FROM AUTHOR]

Medicinal and aromatic plants (MAPs) are a rich source of bioactive compounds that are immensely important due to their potential use in pharmacological and agricultural applications. Here, we have evaluated the antimicrobial activity of essential oils (EOs) from three different species of Ocimum: O. gratissimum (EO1), O. tenuiflorum (EO2), and O. sanctum (EO3). The EOs were screened for antibacterial activity against pathogenic strains of Escherichia coli, Enterobacter cloacae and methicillin-resistant Staphylococcus aureus (MRSA). The essential oils EO1 and EO3 showed significant growth inhibition of the tested bacteria. Likewise, all EOs exhibited antifungal potential against the broad-spectrum plant fungal pathogen Sclerotinia sclerotiorum that causes white-mould disease in plants. Moreover, the antimicrobial potential of the EOs correlates well with their antioxidant activity determined by DPPH free radical scavenging activity. The biochemical analysis of the EOs employing high-performance thin-layer chromatography, gas chromatography-mass spectrometry, and Fourier transform infrared spectroscopy, revealed the presence of distinct phytoconstituents that might be responsible for their differential bioactivity. Furthermore, an in-silico evaluation of the candidate phytoconstituents using molecular docking analysis suggests their potential for antimicrobial applications. Altogether, our results clearly show that EO1 and EO3 possess promising antimicrobial properties, and therefore could be utilized as a potential antimicrobial agent. [ABSTRACT FROM AUTHOR]

β- glucans are the dietary nutrients present in oats, barley, algae, and mushrooms. The macromolecules are well known for their immune-modulatory activity; however, how the human gut bacteria digest them is vaguely understood. In this study, Bacteroides uniformis JCM 13288  T was found to grow on laminarin, pustulan, and porphyran. We sequenced the genome of the strain, which was about 5.05 megabase pairs and contained 4868 protein-coding genes. On the basis of growth patterns of the bacterium, two putative polysaccharide utilization loci for β- glucans were identified from the genome, and associated four putative genes were cloned, expressed, purified, and characterized. Three glycoside hydrolases (GHs) that were endo-acting enzymes ( Bu GH16, Bu GH30, and Bu GH158), and one which was an exo-acting ( Bu GH3) enzyme. The Bu GH3, Bu GH16, and Bu GH158 can cleave linear exo/endo- β- 1-3 linkages while Bu GH30 can digest endo- β- 1-6 linkages. Bu GH30 and Bu GH158 were further explored for their roles in digesting β- glucans and generation of oligosaccharides, respectively. The Bu GH30 predominately found to cleave long chain β- 1-6 linked glucans, and obtained final product was gentiobiose. The Bu GH158 used for producing oligosaccharides varying from degree of polymerization 2 to 7 from soluble curdlan. We demonstrated that these oligosaccharides can be utilized by gut bacteria, which either did not grow or poorly grew on laminarin. Thus, B. uniformis JCM 13288  T is not only capable of utilizing β- glucans but also shares these glycans with human gut bacteria for potentially maintaining the gut microbial homeostasis.