TY - JOUR

T1 - Grass-Specific EPAD1 Is Essential for Pollen Exine Patterning in Rice

AU - Li, HuanJun

AU - Kim, Yu-Jin

AU - Yang, Liu

AU - Liu, Ze

AU - Zhang, Jie

AU - Shi, Haotian

AU - Huang, Guoqiang

AU - Persson, Staffan

AU - Zhang, Dabing

AU - Liang, Wanqi

PY - 2020

Y1 - 2020

N2 - Rice lipid binding protein EPAD1 is a male meiocyte-derived determinant that controls grass-specific pollen exine pattern formation by maintaining primexine integrity.The highly variable and species-specific pollen surface patterns are formed by sporopollenin accumulation. The template for sporopollenin deposition and polymerization is the primexine that appears on the tetrad surface, but the mechanism(s) by which primexine guides exine patterning remain elusive. Here, we report that the Poaceae-specific EXINE PATTERN DESIGNER 1 (EPAD1), which encodes a nonspecific lipid transfer protein, is required for primexine integrity and pollen exine patterning in rice (Oryza sativa). Disruption of EPAD1 leads to abnormal exine pattern and complete male sterility, although sporopollenin biosynthesis is unaffected. EPAD1 is specifically expressed in male meiocytes, indicating that reproductive cells exert genetic control over exine patterning. EPAD1 possesses an N-terminal signal peptide and three redundant glycosylphosphatidylinositol (GPI)-anchor sites at its C terminus, segments required for its function and localization to the microspore plasma membrane. In vitro assays indicate that EPAD1 can bind phospholipids. We propose that plasma membrane lipids bound by EPAD1 may be involved in recruiting and arranging regulatory proteins in the primexine to drive correct exine deposition. Our results demonstrate that EPAD1 is a meiocyte-derived determinant that controls primexine patterning in rice, and its orthologs may play a conserved role in the formation of grass-specific exine pattern elements.

AB - Rice lipid binding protein EPAD1 is a male meiocyte-derived determinant that controls grass-specific pollen exine pattern formation by maintaining primexine integrity.The highly variable and species-specific pollen surface patterns are formed by sporopollenin accumulation. The template for sporopollenin deposition and polymerization is the primexine that appears on the tetrad surface, but the mechanism(s) by which primexine guides exine patterning remain elusive. Here, we report that the Poaceae-specific EXINE PATTERN DESIGNER 1 (EPAD1), which encodes a nonspecific lipid transfer protein, is required for primexine integrity and pollen exine patterning in rice (Oryza sativa). Disruption of EPAD1 leads to abnormal exine pattern and complete male sterility, although sporopollenin biosynthesis is unaffected. EPAD1 is specifically expressed in male meiocytes, indicating that reproductive cells exert genetic control over exine patterning. EPAD1 possesses an N-terminal signal peptide and three redundant glycosylphosphatidylinositol (GPI)-anchor sites at its C terminus, segments required for its function and localization to the microspore plasma membrane. In vitro assays indicate that EPAD1 can bind phospholipids. We propose that plasma membrane lipids bound by EPAD1 may be involved in recruiting and arranging regulatory proteins in the primexine to drive correct exine deposition. Our results demonstrate that EPAD1 is a meiocyte-derived determinant that controls primexine patterning in rice, and its orthologs may play a conserved role in the formation of grass-specific exine pattern elements.

KW - LIPID TRANSFER PROTEINS

KW - PLASMA-MEMBRANE

KW - MALE-FERTILITY

KW - ANTHER DEVELOPMENT

KW - WALL DEVELOPMENT

KW - BINDING-PROTEIN

KW - PLANT PROTEIN

KW - NSLTP GENES

KW - ARABIDOPSIS

KW - PRIMEXINE

U2 - 10.1105/tpc.20.00551

DO - 10.1105/tpc.20.00551

M3 - Journal article

C2 - 33093144

VL - 32

SP - 3961

EP - 3977

JO - The Plant Cell

JF - The Plant Cell

SN - 1040-4651

IS - 12

ER -