Biotechnology-assisted breeding techniques implementation for rice improvement in Uruguay

Mutagenic treatment was highly effective in reducing plant height and growth duration in the parent variety EEA-404. Important variation was also observed in grain and leaf pubescence and in grain shape. Several M4 lines with desirable plant type and grain shape were selected for yield testing. Aggregated sheath spot (ASS) - Rhizoctonia oryzae sativae - disease pressure on M3 and M4 lines from INIA Tacuari was not sufficient to allow selection for this character. However, important variability in resistance to the physiological disorder Straighthead was observed among the lines. The regeneration percentage obtained with the methodology of anther culture facilitated application of this technique in a larger number of crosses. Some of the doubled haploid (DH) lines from resistant/susceptible crosses showed good yield potential and milling quality, and low incidence of stem diseases. Sequential Bulked Typing may provide an alternative to individual typing for a large number of markers, improving DNA pooling techniques based on phenotypic evaluations of quantitative traits. (author)