The giant embryo(ge) mutation was genetically mapped to chromosome 7 by Koh et al. The ge mutations were analyzed at the morphologic and genetic level by Hong et al. And this publication linked the GE gene as being required for proper endosperm development. Researchers in Dupont cloned the GE gene, sequenced and characterized the ge alleles of the mutants. the three giant embryo mutant lines we obtained by treating MNU to Hwacheongbyeo, a japonica type Korean rice cultivar, differed in their embryo and endosperm size and their embryo/endosperm ratios. We named these alleles affecting the embryo size in rice GE, ge-m, ge, ge-s (GE: the wild type, ge-m: embryo slightly larger than in the wild type, ge: large embryo, ge-s: embryo even larger than in ge). The ORFs and introns of the four different alleles in the GE locus were sequenced and compared with the corresponding sequences in the patent that dupont presented. Each mutant alleles sequence showed a few SNPs in the ORF region. Two SNPs were shared among the three mutant lines and each mutant line hab one or two additional SNPs. Further studies are in progress regarding the GE RNA expression level in each mutant line and the F1 seed phenotypes and allelism relationship among the mutant lines.

This study was carried out to analyze the three embryo size mutants types (giant embryo; ge, reduced embryo; re, embryoless; eml) and to identify relationship among the genes controlling ge, re and eml genotypes. Difference of grain type and grain size in

In this experiment, three kinds of mutations(ge, re, and eml )relating to the size of embryos were used to study their generation, genetic mechanism and developmental characteristics, and the interactions between embryo and endosperm were also examined. Giant embryo mutation comprises 7 kinds including the already isolated ge, and ge-2, which share an identical gene site. The SAM and the size of radicule for the ge showed little difference compared to a normal type. The number of embryo cells did not increased as much as it would affect the size of embryo. Therefore, the enlargement of embryo was due to the enlargement of scutellum that originated from the corpulence of each cell. Both F1' s of re ]and odm 49 formed reduce embryos, and other combinations of hybridization showed all wild type of embryo sizes. Accordingly, the odm 49 must have an identical gene site of re 1, while odm 48 and odm 62 have different gene sites. Their shoots and radicules also shrank by the same ratio, however no sign of physical change was noticed. The size of embryo cell showed no change, while the number of cells was the half of that of wild types. The three gene sites of re represent all of them control the size of the entire embryo forming organs. The eml 1 was defined to have temperature sensibilities that the generation of endosperms was active at a high temperature while that was hampered at a low temperature.