Protein disulfide isomerase (PDI) is a chaperone protein that involves in oxidative protein folding by acting as catalysts and folding assistants in the endoplasmic reticulum (ER). Genome database showed that rice contains three PDI-like genes. But, their functions and subcellullar localization are not clearly identified. Here, we show possible functions of rice PDI (OsPDI) during seed development. Seeds of OsPDI T-DNA insertion mutants which were identified by genomic DNA PCR and western blot display chalky phenotype. Electron microscope analysis revealed that endosperms of the OsPDIL1-1Δ mutant show imperfect packing of round starch granules, causing floury-white color. Abnormal form of protein body I (PB-I) containing prolamin and thick aleurone layer were also observed in the OsPDIL1-1Δ mutants. Protein content per seed was significantly low in the OsPDIL1-1Δ mutant. However, free sugar content was high in the OsPDIL1-1Δ mutant seed. Northern and western blot analyses showed that during seed development, OsPDI protein is steadily accumulated in the seed until maturation while its transcript level was highest at 10 days after flowering and rapidly decreased to basal level. In addition, OsPDI strongly interacts with cysteine protease OsCP1 and chaperone BiP protein accumulates in OsPDIL1-1Δ mutant. Besides, proteomic analysis of the OsPDIL1-1Δ mutant seed showed that OsPDI is post-translationally regulated and its loss causes accumulation of many types of seed proteins. Our results indicate that OsPDI plays a critical role in seed development through its regulatory activity for various proteins.

Grain yield, one of the most important agronomic traits, is greatly affected by architecture in rice. Here, we show that an OsPrMC3, a rice PrMC3 orthologue with a lipase or esterase domain, involves in yielding by tillering. Phenotypic analysis of T-DNA insertion mutant revealed that it has high number of tillers than wild type although height and leaf width are shorter and narrower than wild type. Size and branch number of panicle were greatly reduced in the mutant, which resulted in significant decrease of seed number per panicle and dry weight of the seeds. OsPrMC3 is highly expressed in the leaf during the early stage of development. However, it is mainly expressed in mature seed and root after flowering although its expression is detected in all of the tissues. Our result indicates that OsPrMC3 involves in leaf growth and tillering during vegetative growth and also seed development after flowering, suggesting its crucial regulatory role in yielding

To produce abiotic stress resistant transgenic cucumber, the cotyledonary node explants of cucumber (c.v. Eunsung) were inoculated with A. tumefaciens strain EHA105 containing the binary vector (pPZP211) carrying Nit gene. The 491 explants inoculated with bacterium solution for 30 min were maintained on 50 mg/L paromomycin contained shoot induction (SI) medium for first 2 weeks and then subcultured on 100 mg/L paromomycin to obtain transgenic adventitious shoots for 4 x 14 days. So far, 5 plant were selected, and then acclimated in soil. Of them, 3 transgenic plants with Nit gene were confirmed by Southern blot analysis.