Soil Metagenomics: Concepts and Applications

Soil is a living entity of the Earth, and considered as one of the main reservoir of microbial diversity. Studying the soil microbial diversity is very much necessary, as they play an important role in maintaining the health of soil by recycling the nutrients, creating soil structure and humus. However, the culture dependent approaches fail to provide clear estimates of the diversity and untapped resources. Hence, study of the microbial diversity using culture independent approaches become necessary. The field of metagenomics helps in studying the genomes of the diverse soil organisms collectively in their natural habitat which holds the promising for accessing novel genetic resources. Application of the metagenomics to the soil environment is very challenging due to several difficulties; one of which is co-extraction of humic acid with nucleic acids which hinder downstream high throughout processes. However, applying sequencing methods to soil microbial communities will help in uncovering the hidden resources like novel genes, biomolecules and other valuable products which are yet to be discovered or still unknown. Different culture independent techniques and applications of the metagenomics to study the abundant microflora of the complex and changing environment of soil discussed herein

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Development of NILs from heterogeneous inbred families for validating the rust resistance QTL in peanut (Arachis hypogaeaL.)

Heterogeneous inbred families segregating for rust resistance were identified from the two crosses involving susceptible (TAG 24 and TG 26) and resistant (GPBD 4) varieties of peanut. Rust-resistant (less than score 5) and rust-susceptible (more than score 5) plants were identified in each HIF and evaluated under rust epiphytotic conditions. The set of plants belonging to the same HIF, but differing significantly in rust resistance, not in other morphological and productivity traits, was regarded as near-isogenic lines (NILs). Largely, rust-resistant NILs had GPBD 4-type allele, and susceptible NILs carried either TAG 24 or TG 26-type allele at the three SSR loci (IPAHM103, GM1536 and GM2301) linked to a major genomic region governing rust resistance. Comparison of the remaining genomic regions between the NILs originating from each of the HIFs using transposon markers indicated a considerably high similarity of 86.4% and 83.1% in TAG 24 × GPPBD 4 and TG 26 × GPBD 4, respectively. These NILs are useful for fine mapping and expression analysis of rust resistance