Analysis of genetic variation in sorghum (Sorghum bicolor (L.) Moench) genotypes with various agronomical traits using SPAR methods

Genetic variation among 45 genotypes of sorghum (Sorghum bicolor L.) representing seven subpopulations was assessed using three single primer amplification reaction (SPAR) methods viz., inter-simple sequence repeat (ISSR), random amplified polymorphic DNA (RAPD) and directed amplification of minisatellite-region DNA (DAMD). Totally 15 ISSR, 8 RAPD and 7 DAMD primers generated 263 amplification products, accounting for 84.6% polymorphism across all the genotypes. The Mantel's test of correlation revealed the best correlation between ISSR and cumulative data with a correlation coefficient (r) of 0.84. Assessment of population diversity indicated that the maximum intra population genetic diversity was recorded among high FeZn lines (HFL) having maximum values of Nei's genetic diversity (h) (0.244), Shannon information index (I) (0.368) and the percentage of polymorphic loci (Pp) (72.65%) while the corresponding lowest values of 0.074, 0.109 and 17.95% respectively were observed among the members of MDT subpopulation. The mean coefficient of gene differentiation (GST) and the gene flow (Nm) between populations were observed to be 0.396 and 0.7680 respectively. The analysis of molecular variance (AMOVA) suggested that maximum genetic variation exists within populations (95%) than among populations (5%). Thus the information obtained from this study could be utilized in sorghum breeding programmes for the development of varieties with improved nutrition and agronomic values in future

Contribution of Microbe-Mediated Processes in Nitrogen Cycle to Attain Environmental Equilibrium

Nitrogen (N), the most important element, is required by all living organisms for the synthesis of complex organic molecules like amino acids, proteins, lipids etc. Nitrogen cycle is considered to be the most complex yet arguably important cycle next to carbon cycle. Nitrogen cycle includes oxic and anoxic reactions like organic N mineralization, ammonia assimilation, nitrification denitrification, anaerobic ammonium oxidation (anammox), dissimilatory nitrate reduction to ammonium (DNRA), comammox, codenitrification etc. Nitrogen cycling is one of the most crucial processes required for the recycling of essential chemical requirements on the planet. Soil microorganisms not only improve N-cycle balance but also pave the way for sustainable agricultural practices, leading to improved soil properties and crop productivity as most plants are opportunistic in the uptake of soluble or available forms of N from soil. Microbial N transformations are influenced by plants to improve their nutrition and vice versa. Diverse microorganisms, versatile metabolic activities, and varied biotic and abiotic conditions may result in the shift in the equilibrium state of different N-cycling processes. This chapter is an overview of the mechanisms and genes involved in the diverse microorganisms associated in the operation of nitrogen cycle and the roles of such microorganisms in different agroecosystems