Rapid genotyping of bacterial leaf blight resistant genes of rice using loop-mediated isothermal amplification assay.

The use of resistant (R) genes is the most effective strategy to manage bacterial leaf blight (BLB) disease of rice. Several attempts were made to incorporate R genes into susceptible rice cultivars using marker-assisted backcross breeding (MABB). However, MABB relies exclusively on PCR for foreground selection of R genes, which requires expensive equipment for thermo-cycling and visualization of results; hence, it is limited to sophisticated research facilities. Isothermal nucleic acid amplification techniques such as loop-mediated isothermal amplification (LAMP) assay do not require thermo-cycling during the assay. Therefore, it will be the best alternative to PCR-based genotyping. In this study, we have developed a LAMP assay for the specific and sensitive genotyping of seven BLB resistance (R) genes viz., Xa1, Xa3, Xa4, Xa7, Xa10, Xa11, and Xa21 in rice. Gene-specific primers were designed for the LAMP assay. The LAMP assay was optimized for time, temperature, and template DNA concentration. For effective detection, incubation at 60 °C for 30 min was optimum for all seven R genes. A DNA intercalating dye ethidium bromide and a calorimetric dye hydroxynaphthol blue was used for result visualization. Further, sensitivity assay revealed that the LAMP assay could detect R genes at 100 fg of template DNA compared to 1 ng and 10 pg, respectively, in conventional PCR and q-PCR assays. The LAMP assay developed in this study provides a simple, specific, sensitive, robust, and cost-effective method for foreground selection of R genes in the resistance breeding programs of resource-poor laboratory.

Electrochemical synthesis of a lithium-rich rock-salt-type oxide Li5W2O7 with reversible deintercalation properties.

Starting from the ribbon structure Li2W2O7, the lithium-rich phase Li5W2O7 with an ordered rock-salt-type structure has been synthesized, through a topotactic irreversible reaction, using both electrochemistry and soft chemistry. In contrast to Li2W2O7, the lithium-rich oxide Li5W2O7 shows reversible deintercalation properties of two lithium molecules per formula unit: a stable reversible capacity of 110 mAh/g at 1.70 V is maintained after 10 cycles. The exploration of the lithium mobility in this system shows that Li2W2O7 is a cationic conductor with σ = 4.10(-4) S/cm at 400 °C and Ea = 0.5 eV.