Spectral studies on the interaction of iodine and anthracene sulfonate with bacterial phospholipids from different mutants of Salmonella minnesota.

Using spectrophotometric and spectrofluorometric techniques, the interaction of iodine and 2-anthracene sulfonate (ANS) with the phospholipids (PL) isolated from four genetically correlated Salmonella minnesota isolates viz., a smooth form (S), a deeply rough mutant (Rc) and two intermediate forms (Ra and Rb) were studied. Appearance of an isosbestic point and a new band in absorption spectra indicated charge-transfer (C-T) interaction of iodine with the PL through the formation of 1:1 complex. Stern-Volmer type fluorescence quenching of PL was observed with the addition of iodine to PL, while PL enhanced the fluorescence of anionic dye ANS. The values of the binding constants between iodine/PL and ANS/PL, measured by using suitable equations, showed a systematic gradation in the molecular properties of the PL in the membrane structure in smooth (S) and rough (Ra, Rb and Rc) mutants of Salmonella minnesota.     

Recent Advances of Genetic Resources,Genes and Genetic Approaches for Flooding Tolerance in Rice

Flooding is one of the most hazardous natural disasters and a major stress constraint to rice production throughout the world, which results in huge economic losses. The frequency and duration of flooding is predicted to increase in near future as a result of global climate change. Breeding of flooding tolerance in rice is a challenging task because of the complexity of the component traits, screening technique, environmental factors and genetic interactions. A great progress has been made during last two decades to find out the flooding tolerance mechanism in rice. An important breakthrough in submergence research was achieved by the identification of major quantitative trait locus (QTL) SUB1 in rice chromosomes that acts as the primary contributor for tolerance. This enabled the use of marker-assisted backcrossing (MABC) to transfer SUB1 QTL into popular varieties which showed yield advantages in flood prone areas. However, SUB1 varieties are not always tolerant to stagnant flooding and flooding during germination stage. So, gene pyramiding approach can be used by combining several important traits to develop new breeding rice lines that confer tolerances to different types of flooding. This review highlights the important germplasm/genetic resources of rice to different types of flooding stress. A brief discussion on the genes and genetic mechanism in rice exhibited to different types of flooding tolerance was discussed for the development of flood tolerant rice variety. Further research on developing multiple stresses tolerant rice can be achieved by combining SUB1 with other tolerance traits/genes for wider adaptation in the rain-fed rice ecosystems.