**Genetic Diversity of Rice Grain Quality**

Rosa Paula Cuevas and Melissa A. Fitzgerald

*Grain Quality and Nutrition Centre, International Rice Research Institute Philippines* 

#### **1. Introduction**

284 Genetic Diversity in Plants

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With the exponential and breathtaking progress in sequencing and genotyping technologies this decade is bearing witness to in rice, research programs delivering to breeding programs should perhaps focus on understanding the genetic control of different traits of eating quality, and offering genetic markers to breeding programs for inclusion on the new generation chips being developed (Boualaphanh et al., 2011). However, understanding the genetics of eating quality is difficult because consumers are not easily able to describe the sensory experience. Without a way to measure the trait, it is not possible to find an associated locus.

Thus, in order to assess consumer acceptability of breeding materials and rice cultivars, and in the absence of a clear knowledge of sensory properties, quality evaluation and breeding programs rely heavily on three indirect indicators that predict, to some degree, the cooking and sensory properties of rice: amylose content, gelatinisation temperature, and gel consistency. An understanding of the genetics behind these quality indicators can aid in screening early in breeding programs. However, as research has progressed into the genetics of those indicators, the data reveal that one major gene can be found for each trait, but the genes underlying the finer phenotypic classifications for each of those traits remain undiscovered. In this chapter, the genetic diversity of rice for these three indicators of quality and future avenues for research are reviewed.
