Ethylene signaling is critical for synergid cell functional specification and pollen tube attraction

• Published in: The Plant journal : for cell and molecular biology Vol. 96; no. 1; pp. 176 - 187
• Main Authors: Zhang, Cheng, Teng, Xiao‐Dong, Zheng, Quan‐Quan, Zhao, Yan‐Yun, Lu, Jie‐Yang, Wang, Yichuan, Guo, Hongwei, Yang, Zhong‐Nan
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.10.2018
• Subjects: Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; Arabidopsis Proteins - physiology; Attraction; EIN3‐binding F‐box1; EIN3‐binding F‐box2; Ethylene; ETHYLENE INSENSITIVE 3; ethylene signaling; Ethylenes - metabolism; Genetic analysis; Nuclear Proteins - metabolism; Nuclear Proteins - physiology; Ovule - cytology; Ovule - metabolism; Ovules; Plant Growth Regulators - metabolism; Plant reproduction; Plants, Genetically Modified; Pollen; Pollen Tube - metabolism; pollen tube attraction; Pollen tubes; Pollination; Senescence; senescence‐associated gene29; Signal Transduction; Signaling; Sugar; synergid cell; Transcription Factors - metabolism; Transcription Factors - physiology; Tubes; ethylene signaling; ETHYLENE INSENSITIVE 3; EIN3-binding F-box2; senescence-associated gene29; EIN3-binding F-box1; synergid cell; pollen tube attraction
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.14027

Summary ETHYLENE INSENSITIVE 3 (EIN3) is a key regulator of ethylene signaling, and EIN3‐BINDING F‐BOX1 (EBF1) and EBF2 are responsible for EIN3 degradation. Previous reports have shown that the ebf1 ebf2 double homozygous mutant cannot be identified. In this study, the genetic analysis revealed that the ebf1 ebf2 female gametophyte is defective. The pollination experiment showed that ebf1 ebf2 ovules failed to attract pollen tubes. In female gametophyte/ovule, the synergid cell is responsible for pollen tube attraction. Observation of the pEIN3::EIN3‐GFP transgenic lines showed that EIN3 signal was over‐accumulated at the micropylar end of ebf1 ebf2 female gametophyte. The overexpression of stabilized EIN3 in synergid cell led to the defect of pollen tube guidance. These results suggested that the over‐accumulated EIN3 in ebf1 ebf2 synergid cell blocks its pollen tube attraction which leads to the failure of ebf1 ebf2 homozygous plant. We identified that EIN3 directly activated the expression of a sugar transporter, SENESCENCE‐ASSOCIATED GENE29 (SAG29/SWEET15). Overexpression of SAG29 in synergid cells blocked pollen tube attraction, suggesting that SAG29 might play a role in ethylene signaling to repel pollen tube entry. Taken together, our study reveals that strict control of ethylene signaling is critical for the synergid cell function during plant reproduction. Significance Statement Our study reveals the mechanism of ethylene signaling in synergid functioning for pollen tube attraction and facilitates the understanding of ethylene signaling in plant reproduction.