Weicai Yang

Symbiotic Nitrogen Fixation Mechanism in Legumes

The root nodules of legumes have the ability of symbiotic nitrogen fixation, which is an environmentally friendly and efficient nitrogen use method in agricultural production.Symbiotic nitrogen fixation requires beneficial interaction between rhizobia and the plant host cells. To fix nitrogen, the plant needs to provide a low oxygen environment as bacterial nitrogenase is highly sensitive to oxygen.

Development of Embryo and Endosperm

Double fertilization is a flowering plant mechanism whereby two immotile sperm cells fertilize two different female gametes. After double fertilization, a seed consists of the embryo, the endosperm and the seed coat, which develop from the zygote, the fertilized central cell and the maternal integuments, respectively.

Female Gametophyte Development

In female gametophytes, eight nuclei are separated into four cell types after three rounds of nuclear divisions without cell division. After the cellularization and nuclear fusion, they develop into a mature seven-cell embryo sac, including an egg cell(ec), a central cell(cc), two synergid cells(sc) and three antipodal cells. It’s important to ensure that all the cells in the embryo sac have normal functions, so that they are well prepared for the double fertilization. In this part,

Pollen Tube Guidance Mechanism

In angiosperms, the fertilization between female and male gametes is unique when compares to other species. Angiosperms’ sperm cell which has no autonomous mobility needs pollen tube to be delivered to female gamete. When pollen tubes grow in pistil, there are complex communication systems between male and female to regulate pollen tubes target to female gametophytes.