A Novel Regulator of Central Cell-Mediated Pollen Tube Guidance Uncovered

The distinct reproductive structure and mechanism were evolved during the plant migration from ocean to the land. The loss of sperm mobility, emerging of multi-cellular gametophyte and siphonogamy attributed angiosperm the dominant terrestrial plants. Siphonogamy, a mechanism that male gametophytes (pollen) germinate a pollen tube to deliver the two immotile sperm cells to the female gametophyte for fertilization, enables angiosperm plant to complete fertilization without water and requires an active communication of the male gametophyte with the female gametophyte and maternal tissues, a process called pollen tube guidance. Pollen tube guidance is essential for plant fertilization and serves as an important reproductive isolation for interspecies crosses.

 

Researchers in Dr. YANG Weicai’s group from the Institute of Genetics and Developmental Biology, the Chinese Academy of Sciences, reported the role of CCG in the female control of pollen tube attraction in 2007. Their work demonstrated a critical role of the central cell of the female gametophyte in pollen tube guidance and challenged the traditional view that only the synergid are essential for pollen tube attraction.

 

Here they identified a novel central cell-localized nuclear protein CBP1 that interacts with CCG to regulate pollen tube guidance. Their biochemical and expression data showed that CBP1, through interaction with transcription factors AGLs and the Mediator complex, mediates the assembly of RNA Pol II transcription initiation complex to regulate the transcription of genes expressed in the central cell and/or synergid. This study uncovers the transcriptional mechanism of central cell-regulated pollen tube guidance.

 

Their findings were recently published in The Plant Cell (doi:10.1105/tpc.15.00370) with LI Hongju, ZHU Shanshan and ZHANG Mengxia as the co-first authors. This work was financially supported by grants from the Ministry of Science and Technology of China and the National Natural Science Foundation of China.

 

Author contact:

YANG Weicai Yang, Group leader

Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.

E-mail: wcyang@genetics.ac.cn

 

 

Figure. Proposed Model for CCG-CBP1 Function in Mediator-Mediated Transcription Initiation in the Central Cell. (Image by IGDB)