With the ever-increasing global demand for high quality rice in both local production regions and with Western consumers, we have a strong desire to understand better the importance of the different traits that make up the quality of the rice grain and obtain a full picture of rice quality demographics. Rice is by no means a ‘one size fits all’ crop. Regional preferences are not only striking, they drive the market and hence are of major economic importance in any rice breeding / improvement strategy. In this analysis, we have engaged local experts across the world to perform a full assessment of all the major rice quality trait characteristics and importantly, to determine how these are combined in the most preferred varieties for each of their regions. Physical as well as biochemical characteristics have been monitored and this has resulted in the identification of no less than 18 quality trait combinations. This complexity immediately reveals the extent of the specificity of consumer preference. Nevertheless, further assessment of these combinations at the variety level reveals that several groups still comprise varieties which consumers can readily identify as being different. This emphasises the shortcomings in the current tools we have available to assess rice quality and raises the issue of how we might correct for this in the future. Only with additional tools and research will we be able to define directed strategies for rice breeding which are able to combine important agronomic features with the demands of local consumers for specific quality attributes and hence, design new, improved crop varieties which will be awarded success in the global market.

Type II diabetes is a major chronic disease. In developing countries, the prevalence of type II diabetes is increasing enormously. Much research indicates that choice of carbohydrates, particularly those with low glycaemic index (GI) is able to assist in the management or prevention of type II diabetes. Most developing countries consume rice as the staple. The objectives of this study were to determine the variability in the GI of popular improved and traditional varieties of rice and to find the genetic basis of GI. A method to predict GI using an in vitro system was compared to the in vivo system using a range of rice varieties differing in GI. Large variability in GI, ranging from low to high GI, was found using a set of 235 varieties. The major gene that associated with GI in the 235 varieties was the Waxy gene. This paper reports the first large-scale phenotyping of this trait, provides important information for nutritionists to identify and quantify the impact of low GI rices on blood sugar status and offers a mechanism for breeding programmes to select for GI based on amylose content. Furthermore, it allows rice consumers to select particular varieties of rice as their choice of carbohydrate.

Gelatinisation temperature (GT) is one of the key traits measured in programs for breeding rice (Oryza sativa L.). It is commonly estimated by the alkali spreading value (ASV), and less commonly by differential scanning calorimetry (DSC). Using a diverse set of germplasm, it was determined that DSC values associate poorly with ASV, are not correlated with amylose content but correlate with cooking time. Rice varieties are traditionally grouped into three classes of GT based on ASV: high, intermediate and low. However, the distribution of DSC values of 4000 samples shows only two classes: high and low. Large differences in the distributions of chain lengths synthesised by starch synthase IIa (SSIIa) support the two classes as the major grouping, two haplotypes associating with each peak. Each peak of DSC values spanned 10°C. The chain length distribution of the amylopectin molecules from varieties at the upper boundary of each peak showed significantly more chains that span both the crystalline and amorphous lamellae of a cluster than varieties at the other end of that distribution. Improved varieties, classified as intermediate GT by ASV, belong to both of the classes defined by DSC, implying that some enzyme, other than SSIIa is involved in intermediate GT.