Development and Identification of Transgenic Rice Lines with Abiotic Stress Tolerance by using a Full-length Overexpressor Gene Hunting System

The latest report on the draft genome of Brassica rapa sequence has been published. To elucidate the functions of these genes and to efficiently search for agriculturally useful genes, a Full-length cDNA Over-eXpressor (FOX) gene hunting system was used. The FOX library from Chinese cabbage was introduced into rice via Agrobacterium-mediated transformation. Approximately 1,150 FOX-rice lines were generated. Genomic PCR analysis indicated that the average length of FL-cDNAs introduced into individual lines was 900~1,200 bp. Basic Local Alignment System Tool (BLAST) analysis of the FL-cDNA genes revealed that 35.5% have unknown function. Most of the randomly selected transgenic rice lines showed overexpression (92%) of these genes relative to the wild-type Gopum. Moreover, 94% of the 850 transgenic rice lines were moderately tolerant (slightly yellow) to cold and 9 lines were tolerant (seedlings were light green). Morphological evaluation of the transgenic rice lines showed minimal phenotypic alteration (12%). Approximately 25.1% and 22% of the plants were significantly ahead in the days to heading and had elevated chlorophyll content, respectively. Other agronomic traits such as filled grains, number of tiller, panicle length, and culm and plant height were relatively less variable among the transgenic lines. These results provide a resource for defining genes that are associated with tolerance in transgenic rice lines.