An overview of wheat genome sequencing and its implications for crop improvement

Abstract

Wheat (Triticum aestivum L.) serves as the staple food for 30% of the global population and is a rich source of proteins, minerals and other essential nutrients. But global warming is posing a serious threat to wheat productivity worldwide, and of note, wheat is extremely sensitive to heat, where ±2◦ C temperature variation has resulted in 50% decrease in wheat production (Asseng et al. 2011). Rise in green-house gases inflicts a steady increase in global temperature which has been projected to rise up to 4.5◦ C by 2080 (IPCC 2012; http://www.ipcc.ch/). This is expected to impose enormous negative impacts on productivity of wheat and substantial risks to global food production and security. This urged the scientific research community to work towards genetic improvement of wheat, so as to impart durable stress resistance and agronomic traits in this major cereal. Efforts have been invested on transgene-based approaches and molecular breeding programmes for improvement of wheat since times, but the progress is hindered due to the nonavailability of genome sequence information. Genome sequences are imperative for understanding the molecular basis of phenotypic traits and variation of a given crop plant. Though the genome sequence of model plants such as Arabidopsis thaliana and rice has revolutionized the understanding of plant biology over a decade, it has not been translated robustly into crop improvement for major cereals including wheat. Concurrently, less genomic conservation between rice and wheat has also restricted comparative genomic studies for genetic enhancement of wheat. This necessitated the sequencing of wheat genome, which would serve as the foundation for its improvement. Unfortunately, the size and complexity of wheat genome hindered the sequencing efforts, and this resulted in wheat becoming the only major crop whose genome remained unsequenced.