Molecular Improvement of Rice Quality

When a new variety of rice is released from a breeding program, it must undergo two major stages to determine whether it will persist. The first is adoption by farmers, and the second is acceptance by consumers. The latter will determine whether a variety becomes popular or not. For this reason, rice improvement programs aim to develop varieties that combine agronomic performance and good grain quality. Grain quality is assessed by a set of routine measurements that are rapid and low cost. The limitation of these methods is that they are not strongly linked to the sensory experience of eating rice. This is complicated by the fact that it is difficult to describe that experience and then link the descriptions to components of the grains. Increasingly, these routine tools are used as phenotyping tools to search for associated genes and mutations. These mutations are then developed into molecular markers that enable breeders to select for quality early in the process. For the physical traits of quality, this is much simpler, because length, shape, chalk, and broken grain can easily be measured and described. Several markers have been developed for some of the traits that impact sensory properties, but there is still a long path ahead to develop a complete suite of markers for both physical and sensory properties of rice.