Yes We Can! Improving Rice Yield with Diverse Genetic Resources.

Rice breeding programs have been successful in using diverse germplasm for enhancement of pest resistance traits in rice, but traditionally have been less successful in using these materials for yield improvement. However, over the last decade Asian germplasm resources have proven to be fundamental for developing commercial rice hybrids which are grown on some 15% of the acreage in the USA and up to 50% of the acreage in China. This demonstrates the potential of exploring genetic resources for dramatically improving yield. To systematically evaluate germplasm collections for yield potential, we have developed diversity panels and have characterized these phenotypically as well as genotypically with SSR and SNP markers. We have explored germplasm from the five major Oryza sativa sub-populations and from wild related species and have identified gene pools rich in yield enhancing traits. Recently, "Rondo" was released in the USA as a high yielding long grain rice cultivar developed via mutation breeding from 4484, an accession from China. A back-crossing program using "Jefferson" (O. sativa) and an O. rufipogon accession has been successful in developing germplasm with 20% higher yield potential than Jefferson, the recurrent parent. Crosses using accessions such as PI406035 from Chad, PI400345 from South Africa, PI373139 and PI373140 from Senegal, PI403391 from Indonesia, and PI369806 from Suriname were found to produce good sources of male sterility that are now being tested with maintainer and restorer lines and in hybrid yield trials. Our ultimate goal is to link markers with yield components and to develop high throughput genomic tools that can be used by the breeding community to more effectively utilize germplasm collections for cultivar and hybrid development.