The lacZ U118 is an amber nonsense mutation(Am) that confers Lac─phenotype and also polarity of the downstream lacYA genes in the operon due to premature Rho-dependent transcription termination within the untranslated region of lacZ. Melibiose is a sugar which can only be utilized in a lacZ (Am) strain at high temperature (39 ̊C, when the native melibiose permease is inactive) if the downstream gene lacY encoded permease is transcribed and translated. Therefore, in lacZ (Am) strains, growth on minimal melibiose plates (0.2%) at 39°C reflects transcriptional polarity relief at the lac locus, and the same was scored after streaking the relevant strains on such medium

A calibration curve of fluorescence intensity values versuspH was prepared for BCECF-AM-loaded wt cells by incubatingcellsin YPD medium containing 50 mM MES, 50 mM HEPES, 50 mM KCl, 50 mM NaCl, 0.2 M ammonium acetate, 10 mM NaN3, 10 mM 2-deoxyglucoseand5 μM carbonyl cyanide m-chlorophenylhydrazone, titrated to five different pH values in the range of 4.0-8.0. Fluorescence intensity values were measured by excitation at 440and 490 nm with emission at 535 nm and a graph was plotted between the ratio of intensity at 490 to 440 nm versuspH. Similar to pHi calibration curve, a polynomial distribution of fluorescent intensity signal and pH was observedfor BCECF-AMprobe

CgRTT107(3.3 kb),CgRTT109(1.3 kb),CgVPS15(3.4kb) and CgVPS34(2.4kb) ORFs were PCR amplified from genomic DNA of the wild-type strain using high fidelity Platinum Pfx DNA polymerase with primers carrying restriction sites for SmaI-SalI,BamHI-SalI,XmaI-XhoIandSalI-XmaI,respectively.Amplified fragments werecloneddownstream of the PGK1promoterin the pGRB2.2 plasmid. Clones were verified by bacterial colony PCR, sequencing and complementation analysis

flash (Thermoscientific). β-Glucuronidase activity for GUS was expressed as nanomoles of MU produced/minute/108 cells

In planta siderophore gene expression was studied by measuring β-glucuronidase activity. GUS marked BXOR1 strain and wild-typeBXOR1 (control) were inoculated in the leaves of 14 day old susceptible Taichung Native 1 (TN-1) variety of rice. After 10 days of inoculation, leaves were crushed and dissolved in 1 ml of MUG extraction buffer without adding MUG substrate (4-methylumbelliferyl β-D-glucuronide). Subsequently, 250 μl extraction buffer containing MUG was added, and incubated at 37°C for appropriate time (Jefferson et al., 1987). Next, 75-μl aliquots were taken from each reaction mixture, and the reaction was terminated by the addition of 675 μl Na2CO3 (0.2 M). Fluorescence was measured against 4-methyl-umbelliferone (MU; Sigma) as standard at excitation/emission wavelength of 365/455 nm, respectively in