Insects are the dominant animals in the world, with more than one million described species. Insects, not only produce direct damage to plants but also acts as a vector for various pathogens. In recent years, next-generation sequencing (NGS) techniques have provided fascinating opportunities to understand the basic biology, biochemistry, and molecular biology of these intimate and intriguing relationships. The decrease in sequencing costs and extensive sequencing services from NGS providers has brought many scientists to be involved in genome sequencing of insects and their associated entomopathogens. By using high-throughput genomic technologies, scientists can elucidate the virulence, host adaptation and gene function of the particular entomopathogen including virus, fungi, bacteria and nematode.

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.