Relevance of tilling in plant genomics

Rashid, Muhammad; Guangyuan He; Yang Guanxiao; Khurram, Ziaf

Abstract:With the development of rapid and inexpensive sequence technologies, the efficiency and accuracy in sequencing have interpreted t he genomic information of many plant species. The emphasis on genomics has been changing from complete sequenced genomes to the study of the functional genomics. To understand the function of gene(s) many approaches like RNAi, gene knockout, site-directed mutagenesis, transposon tagging etc. have been exploited for many years. All these techniques demand the use of transgenic material which is not always possible in many commercially important crops. So it is not only impeding the functional analysis of gene(s) but also retards the improvement of existing as well as the development of improved cultivars. In this review, a nontransgenic technique called Targeting Induced Local Lesions IN Genomes (TILLING) was emphasized that determines the allelic sequence of induced point mutations in gene (s) of concern. It allocates the rapid and cost-effective detection of induced point mutations in populations of physical/chemically mutagenized individuals. Ethyl methanesulfonate (EMS) is mostly used and produce G/C to A/T transition by alkylating the G residues and the alkylated G resides to base pair with T instead of pairing with C. The crop species whose genome sequence has been finished; TILLING can be used to find the alleles in gene of interest for biotic and abiotic stresses. EcoTILLING, an extension of TILLING, is an inexpensive and rapid method of discovery and analysis of single-nucleotide polymorphism (SNP) in natural populations. In TILLING parental DNA sequence whereas in EcoTILLING genomic DNA sequence is used to identify the mutations created using endonuclease (CEL I). These techniques are independent of genome size, ploidy level and reproductive system of plants. They can be applied not only to model organisms but also to economically important crops. These provide a powerful approach for gene discovery, DNA polymorphism assessment and linkage disequilibrium. It is concluded that the induced mutations and natural polymorphism can be identified by TILLING and EcoTILLING approaches, and the next task is their implementations in crop breeding.

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DOI: 10.1093/abbs/gmr078