Two genomic regions of a sodium azide induced rice mutant confer broad-spectrum and durable resistance to blast disease

Rice blast, one of the most destructive epidemic diseases, annually causes severe losses in grain yield worldwide. To manage blast disease, breeding resistant varieties is considered a more economic and environment-friendly strategy than chemical control. For breeding new resistant varieties, natural germplasms with broad-spectrum resistance are valuable resistant donors, but the number is limited. Therefore, artificially induced mutants are an important resource for identifying new broad-spectrum resistant (R) genes/loci. To pursue this approach, we focused on a broad-spectrum blast resistant rice mutant line SA0169, which was previously selected from a sodium azide induced mutation pool of TNG67, an elite japonica variety. We found that SA0169 was completely resistant against the 187 recently collected blast isolates and displayed durable resistance for almost 20 years. Linkage mapping and QTL-seq analysis indicated that a 1.16-Mb region on chromosome 6 (Pi169-6(t)) and a 2.37-Mb region on chromosome 11 (Pi169-11(t)) conferred the blast resistance in SA0169. Sequence analysis and genomic editing study revealed 2 and 7 candidate R genes in Pi169-6(t) and Pi169-11(t), respectively. With the assistance of mapping results, six blast and bacterial blight double resistant lines, which carried Pi169-6(t) and/or Pi169-11(t), were established. The complementation of Pi169-6(t) and Pi169-11(t), like SA0169, showed complete resistance to all tested isolates, suggesting that the combined effects of these two genomic regions largely confer the broad-spectrum resistance of SA0169. The sodium azide induced mutant SA0169 showed broad-spectrum and durable blast resistance. The broad resistance spectrum of SA0169 is contributed by the combined effects of two R regions, Pi169-6(t) and Pi169-11(t). Our study increases the understanding of the genetic basis of the broad-spectrum blast resistance induced by sodium azide mutagenesis, and lays a foundation for breeding new rice varieties with durable resistance against the blast pathogen.

Synthesis of a Novel Series of Cu(I) Complexes Bearing Alkylated 1,3,5-Triaza-7-phosphaadamantane as Homogeneous and Carbon-Supported Catalysts for the Synthesis of 1- and 2-Substituted-1,2,3-triazoles

The N-alkylation of 1,3,5-triaza-7-phosphaadamantane (PTA) with ortho-, meta- and para-substituted nitrobenzyl bromide under mild conditions afforded three hydrophilic PTA ammonium salts, which were used to obtain a new set of seven water-soluble copper(I) complexes. The new compounds were fully characterized and their catalytic activity was investigated for the low power microwave assisted one-pot azide–alkyne cycloaddition reaction in homogeneous aqueous medium to obtain disubstituted 1,2,3-triazoles. The most active catalysts were immobilized on activated carbon (AC), multi-walled carbon nanotubes (CNT), as well as surface functionalized AC and CNT, with the most efficient support being the CNT treated with nitric acid and NaOH. In the presence of the immobilized catalyst, several 1,4-disubstituted-1,2,3-triazoles were obtained from the reaction of terminal alkynes, organic halides and sodium azide in moderate yields up to 80%. Furthermore, the catalyzed reaction of terminal alkynes, formaldehyde and sodium azide afforded 2-hydroxymethyl-2H-1,2,3-triazoles in high yields up to 99%. The immobilized catalyst can be recovered and recycled through simple workup steps and reused up to five consecutive cycles without a marked loss in activity. The described catalytic systems proceed with a broad substrate scope, under microwave irradiation in aqueous medium and according to “click rules”.

Inducing, Collecting, and Storing Ascites

Ascitic fluid (also called ascites) is an intraperitoneal fluid extracted from mice that have developed a peritoneal tumor. For antibody production, the tumor is induced by injecting hybridoma cells into the peritoneum, which serves as a growth chamber for the cells. The hybridoma cells grow to high densities and continue to secrete the antibody of interest, thus creating a high-titered solution of antibodies for collection. A single mouse may yield as much as 10 mL of ascitic fluid or as little as 1 mL per batch. Antibody concentrations will typically be between 1 and 10 mg/mL. The most common problem encountered in storing ascites is contamination of these solutions with bacteria or fungi. This can be prevented by the addition of sodium azide.

Nitrogen-Based Linkers with a Mesitylene Core: Synthesis and Characterization

Mesitylene was used as a core in seven new tritopic nitrogen containing linkers. Three of the linkers, each containing three nitrile groups, were obtained through Suzuki, Sonogashira and Heck-type coupling reactions. Next, these were converted to tetrazol-5-yl moieties by the cycloaddition of sodium azide to the nitrile functionalities. The last linker, containing three 1,2,3-triazol-4-yl moieties, was synthesized by the Huisgen cycloaddition of phenyl azide to the corresponding alkyne. The latter was obtained via a Corey–Fuchs reaction sequence from the previously reported formyl derivative. As the proof of concept for their potential in MOF design, one of the nitriles was used to build an Ag-based network.

Evaluation of an antimalarial herbal mixture and each extract for DNA and chromosomal mutations in Swiss albino mice and Allium cepa cells

Toxicological evaluation of herbal medicines is necessary because of possible adverse effects that may be associated with their consumption. This study screened antimalarial herbal recipe (containing leaves of Azadirachta indica and stem-bark of Alstonia boonei) and its individual plant’s extract for DNA and chromosomes mutation potentials following the DNA fragmentation and Allium cepa assays. Superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) activity of the recipe and each extract was determined. The kinds of phytochemicals present in them were determined using the FTIR technique. Water extracts of A. indica, and A.boonei at all the tested doses caused significantly lower DNA fragmentations than those of the controls. However, at 25.0% and 50.0% recipe, there was no significant difference in the percentage fragmented DNA compared to the positive control (0.05% sodium azide). Cell division was significantly inhibited by the extracts and recipe, chromosomal aberrations were not dose dependently induced and were significantly lowered than that caused by sodium azide (positive control). The individual extracts and their recipe significantly inhibited Root growth. However, 12.5% recipe promoted root growth that was not significantly different from that of distilled water (negative control). SOD and CAT activities of each of the extracts and their recipe were dose dependent and significantly higher than those of the controls. Water extract of A. indica significantly suppressed generation of malondialdehyde compared to water extract of A. boonei and recipe as well as the control. The individual extracts and their recipe contained phenolic phytochemicals. The obtained results show that extract of A. indica, A. boonei and their recipe have good antioxidant properties with strong mitodepressive and root growth inhibitory effects except at 12.5% recipe. However, A. indica extract seems to have least cyto-muta-genotoxic effects than water extract of A. boonei and the recipe in mice and A. cepa cells. Asian J. Med. Biol. Res. 2021, 7 (3), 249-259