The rice genome sequence and challenges in crop improvement
Rice has played a central role in human nutrition and culture for the past 10,000 years. Rice is unique among the major cereals such as corn and wheat in that the grain is cooked and eaten directly by humans rather than being processed for flour or oil. It is estimated that world rice production must increase by 30% in the next 20 years to meet projected demands from population increase and economic development. However, world rice production has actually declined during the last ten years. Rice grown on the most productive irrigated land has achieved nearly maximum production with current strains. Environmental degradation including pollution, increase in night time temperature due to global warming, reductions in suitable arable land, water, labor, and energy-dependent fertilizer provide additional constraints. These factors make steps to maximize rice productivity especially important. Increasing yield potential and yield stability will come from a combination of biotechnology and improved conventional breeding. Both will be dependent on a high quality rice genome sequence.
In Japan, the Ministry of Agriculture, Forestry and Fisheries (MAFF) embarked on a large-scale project on rice genome analysis in 1991 via the Rice Genome Research Program (RGP) with the aim of elucidating the genetic phenomenon of rice. With the success of the first phase of the RGP, the next phase focused on rice genome sequencing through the International Rice Genome Sequencing Project (IRGSP) and functional characterization of the genome. The completion of the rice genome sequence in 2004 paved the way for a new era of research in genetics, physiology, biochemistry and other related fields. In 2005, the MAFF started anew three large-scale projects, namely, analysis of genome diversity, QTL analysis, and development of genome breeding technology aimed at maximizing the utilization of information derived from the Nipponbare genome sequence. Then in 2008, the Genomics for Agricultural Innovation Project further explored new approaches in characterization of gene function with significant impact in agricultural productivity. From 2013, the Next-generation Genome-based Project provides the platform for more innovative researches to acquire knowledge and develop technologies critical to ensuring that rice production will meet the demands in the years ahead. The following links provide an overview of major achievements in projects on rice genomics.