Double fertilization is a key innovation for the evolutionary success of angiosperms by which the two fertilized female gametes, the egg cell and central cell, generate the embryo and endosperm, respectively. The central cell is the second female gamete, and its fertilization gives rise to the endosperm, the nurse of a seed. However, how this cell is specified and evolved in angiosperm remains unknown.
Recently, a research team led by Prof. YANG Weicai at University of Chinese Academy of Sciences and Institute of Genetics and Developmental Biology, CAS, reveals a transcriptional repression mechanism to specify the central cell in Arabidopsis and provides insight into the origination of this mechanism in Brassicaceae. The study shows that the central cell fate of agl80 mutant is misspecified to the accessory cells through a series of cell type-specific markers and a fertilization assay. The study also provides lines of evidence showing that AGL80 acts as a transcription repressor through the EAR motif to repress the expression of MYB98, which is specifically expressed in the synergid cells. Phylogenetic analysis and genetic rescue experiments provide clues that this molecular mechanism of AGL80 in the central cell might be conserved in Brassicaceae. Results from this study provide insight into the molecular determination of the second female gamete cell in Brassicaceae.
The study is published online on PNAS entitled “transcriptional repression specifies the central cell for double fertilization” on March 4. Dr. ZHANG Mengxia and Dr. ZHU Shanshan are the first authors, Prof. YANG Weicai and Prof. LI Hongju at nstitute of Genetics and Developmental Biology, CAS, are the corresponding authors. The study is supported by National Natural Science and Foundation of China and National Special Support Program for High-level Talents.
CKI1 and AGL80 specify the central cell sequentially. ac, antipodal cell; cc, central cell; sc, synergid cell; ec, egg cell
