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OsRab5a regulates endomembrane organization and storage protein trafficking in rice endosperm cells
Author(s) -
Wang Yihua,
Ren Yulong,
Liu Xi,
Jiang Ling,
Chen Liangming,
Han Xiaohua,
Jin Mingna,
Liu Shijia,
Liu Feng,
Lv Jia,
Zhou Kunneng,
Su Ning,
Bao Yiqun,
Wan Jianmin
Publication year - 2010
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2010.04370.x
Subject(s) - endosperm , endomembrane system , storage protein , microbiology and biotechnology , endoplasmic reticulum , golgi apparatus , glutelin , mutant , vacuole , biology , arabidopsis , biochemistry , gene , cytoplasm
Summary Rice glutelins are synthesized at the endoplasmic reticulum (ER) as precursors (pro‐glutelins), and are transported to protein storage vacuoles, where they are processed into mature proteins. The molecular basis of this process is largely unknown. Here, we report the isolation of a rice mutant, gpa1 , that accumulates 57 kDa pro‐glutelins in seeds and whose endosperm has a floury appearance. Transmission electron microscopy analysis showed that the gpa1 endosperm cells have an enlarged ER lumen and a smaller protein body II (PBII), and accumulated three types of newly generated subcellular structures. Moreover, a proportion of glutelins in the gpa1 endosperm cells were not delivered to PBII, and instead were mis‐targeted to two of the newly generated structures or secreted. The gene corresponding to the gpa1 mutation was found to be OsRab5a , which encodes a small GTPase. In Arabidopsis protoplasts, OsRab5a protein was found to co‐localize predominantly with AtVSR2, a molecular marker for the pre‐vacuolar compartments (PVC). We conclude that OsRab5a plays an essential role in trafficking of storage protein to PBII, possibly as part of its function in organizing the endomembrane system in developing endosperm cells of rice.