The mechanisms of pollination and fertilization in plants.
In flowering plants, pollen grains germinate to form pollen tubes that transport male gametes (sperm cells) to the egg cell in the embryo sac during sexual reproduction. Pollen tube biology is complex, presenting parallels with axon guidance and moving cell systems in animals. Pollen tube cells elongate on an active extracellular matrix in the style, ultimately guided by stylar and embryo sac signals. A well-documented recognition system occurs between pollen grains and the stigma in sporophytic self-incompatibility, where both receptor kinases in the stigma and their peptide ligands from pollen are now known. Complex mechanisms act to precisely target the sperm cells into the embryo sac. These events initiate double fertilization in which the two sperm cells from one pollen tube fuse to produce distinctly different products: one with the egg to produce the zygote and embryo and the other with the central cell to produce the endosperm.
Lord
Elizabeth M
EM
Department of Botany and Plant Sciences, University of California, Riverside 92521, USA. lord@citrus.ucr.edu
Russell
Scott D
SD
D002450:Cell Communication / Q000502:physiology; D005306:Fertilization / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D005854:Germ Cells / Q000166:cytology / Q000378:metabolism*; D018521:Plant Physiological Phenomena; D011058:Pollen / Q000166:cytology / Q000378:metabolism*; D012639:Seeds / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology