Endomembrane‐mediated storage protein trafficking in plants: Golgi‐dependent or Golgi‐independent?
Yulong Ren, Yongfei Wang, Yu Zhang, Tian Pan, Erchao Duan, Xiuhao Bao, Jianping Zhu, Xuan Teng, Pengcheng Zhang, Chuanwei Gu, Hui Dong, Fan Wang, Yunlong Wang, Yiqun Bao, Yihua Wang, Jianmin Wan
Abstract
Seed storage proteins (SSPs) accumulated within plant seeds constitute the major protein nutrition sources for human and livestock. SSPs are synthesized on the endoplasmic reticulum and are then deposited in plant-specific protein bodies, including endoplasmic reticulum-derived protein bodies and protein storage vacuoles. Plant seeds have evolved a distinct endomembrane system to accomplish SSP transport. There are two distinct types of trafficking pathways contributing to SSP delivery to protein storage vacuoles: one is Golgi-dependent and the other is Golgi-independent. In recent years, molecular, genetic, and biochemical studies have shed light on the complex network controlling SSP trafficking, to which both evolutionarily conserved molecular machineries and plant-unique regulators contribute. In this review, we discuss current knowledge of protein body biogenesis and endomembrane-mediated SSP transport, focusing on endoplasmic reticulum export and post-Golgi traffic. This knowledge supports a dominant role for the Golgi-dependent pathways in SSP transport in Arabidopsis and rice. In addition, we describe cutting-edge strategies for dissecting the endomembrane trafficking system in plant seeds to advance the field.