Pedro Blanco

Diversity of Global Rice Markets and the Science Required for Consumer-Targeted Rice Breeding

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.

Response to photoxidative stress induced by cold in japonica rice is genotype dependent.

Two japonica rice genotypes, INIA Tacuarí and L2825CA, were analyzed for tolerance to low temperature during early vegetative growth. Effect on photosynthesis, energy dissipation, pigment content, xanthophyll-cycle pool conversion, hydrogen peroxide accumulation, oxidative damage and antioxidant enzyme activities were determined to better understand potential mechanisms for cold tolerance. Photoinhibition was measured using chlorophyll fluorescence and oxidative damage by lipid peroxidation and electrolyte leakage. Both genotypes were demonstrated to be cold tolerant which was consistent with their reduced levels of photoinhibition and oxidative damage compared with a cold-sensitive genotype during chilling stress. The strategy for cold tolerance differed between the two genotypes, and involved different mechanisms for disposal of excess energy. The presence of high lutein concentrations and the existence of active non-harmful energy dissipation processes through the xanthophyll cycle appeared to be responsible for chilling tolerance in INIA Tacuarí. On the other hand, increased cold tolerance of L2825CA relative to INIA Tacuarí was related to the higher constitutive superoxide dismutase (SOD, EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11) and catalase (CAT, EC 1.11.1.6).

Systematization and clinical study of dextroversion, mirror-image dextrocardia, and laevoversion.

; Current embryological and anatomical knowledge makes it possible to systematize, classify, and diagnose the malpositions of the heart by following a logical sequence. (i) The visceral situs is easily established by means of data provided by physical, radiological, and electrocardiographic studies. There is a constant relation between the venous atrium, greater lobe of the liver with suprahepatic segment of the inferior vena cava, and the visceral situs. (2) The direction of the apex: this indicates the heart position in a specific situs, determined by x-rays. Dextroversion is the malposition in situs solitus, as laevoversion is in situs inversus; dextrocardia is the normal position for the latter. (3) Truncoconal morphologies: there are 3 possibilities (a) the vessels derived from the truncus conus are not transposed, (b) the vessels are transposed, or (c) there is a common trunk. Truncoconal morphology is determined in each case by means of a biplane angiocardiogram. (4) The position of the ventricles is deduced from the truncoconal morphology, by applying the rule which establishes whether the anterior vessel or single trunk energes from the ventral ventricle; correlating the position of this ventricle with the situs, we find out whether or not there is ventricular inversion. (5) Associated malformations are diagnosed by clinical as well as haemodynamic studies, completing finally the diagnosis in every case.

Genome-Wide Association Study Using Historical Breeding Populations Discovers Genomic Regions Involved in High-Quality Rice

Genome‐wide association study (GWAS) for rice quality was performed in two breeding populations. Twenty‐two putative quantitative trait loci (QTL) were associated to rice quality. A genomic region on chromosome 6 was associated with all quality traits in the tropical japonica population. Markers for favorable haplotypes are ready for immediate use for selection.

Resistance to Multiple Temperate and Tropical Stem and Sheath Diseases of Rice

Reaction to sheath blight, stem rot, and aggregated sheath spot were tested in 641 tropical japonica and indica rice lines. Disease resistance was mapped independently from flowering time and plant height. Quantitative trait loci of major effect for resistance to the three diseases were found. A multiple disease resistance quantitative trait locus was found on chromosome 9 across tropical japonica and indica populations.

Integrating molecular markers and environmental covariates to interpret genotype by environment interaction in rice (Oryza sativa L.) grown in temperate areas

Understanding the genetic and environmental basis of genotype × environment interaction (G×E) is of fundamental importance in plant breeding. If we consider G×E in the context of genotype × year interactions (G×Y), predicting which lines will have stable and superior performance across years is an important challenge for breeders. A better understanding of the factors that contribute to the overall grain yield and quality of rice (Oryza sativa L.) will lay the foundation for developing new breeding and selection strategies for combining high quality, with high yield. In this study, we used molecular marker data and environmental covariates (EC) simultaneously to predict rice yield, milling quality traits and plant height in untested environments (years), using both reaction norm models and partial least squares (PLS), in two rice breeding populations (indica and tropical japonica). We also sought to explain G×E by differential quantitative trait loci (QTL) expression in relation to EC. Our results showed that PLS models trained with both molecular markers and EC gave better prediction accuracies than reaction norm models when predicting future years. We also detected several milling quality QTL that showed a differential expression conditional on humidity and solar radiation, providing insight for the main environmental factors affecting milling quality in temperate rice growing areas.