Abstract
In rice seed, alcohol soluble seed storage proteins, prolamins are classified into Cys-rich (CysR) and Cys-poor (CysP) molecules containing and not containing cysteine residue, respectively. The former is composed of CysR10, CysR14, CysR16 molecules and the latter is composed of CysP13 molecule. These prolamins are accumulated within the endoplasmic reticulum as protein body type I (PB-I). CysR10 is accumulated in the center of PB-I. To elucidate the role of CysR10 in PB-I formation, we produced the RNAi transformant to silence the gene which encodes the CysR10. In the CysR10-RNAi transformant, the malformation of PB-I and the reduction in the level of CysP13 were detected. On the other hand, esp3 mutant which reduces almost all CysR prolamins, showed the hypertrophy and deformation of PB-I. These results suggested that the existence of CysR10 is important for the orderly arrangement of the other prolamins in PB-I. Additionally it is inferred from the structural difference of PB-I between CysR10-RNAi transformant and esp3 that the malformation of PB-I in CysR10-RNAi transformant is induced by the presence of the CysR14 and CysR16.
